Merge branch 'AttachmentsToChat'

android/app/src/main/AndroidManifest.xml

@@ -34,6 +34,9 @@
             android:name=".activities.HomeActivity"
             android:windowSoftInputMode="adjustResize"
             android:exported="false" />
+        <activity
+            android:name=".activities.ForgotPasswordActivity"
+            android:exported="false" />
         <activity
             android:name=".activities.MainActivity"
             android:exported="true">

android/app/src/main/java/com/example/petstoremobile/activities/ForgotPasswordActivity.java

@@ -0,0 +1,46 @@
+package com.example.petstoremobile.activities;
+
+import android.os.Bundle;
+import android.widget.Toast;
+
+import androidx.activity.EdgeToEdge;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.graphics.Insets;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.WindowInsetsCompat;
+
+import com.example.petstoremobile.databinding.ActivityForgotPasswordBinding;
+import com.example.petstoremobile.utils.InputValidator;
+
+import dagger.hilt.android.AndroidEntryPoint;
+
+@AndroidEntryPoint
+public class ForgotPasswordActivity extends AppCompatActivity {
+
+    private ActivityForgotPasswordBinding binding;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        EdgeToEdge.enable(this);
+        super.onCreate(savedInstanceState);
+        binding = ActivityForgotPasswordBinding.inflate(getLayoutInflater());
+        setContentView(binding.getRoot());
+
+        ViewCompat.setOnApplyWindowInsetsListener(binding.forgotPasswordRoot, (v, insets) -> {
+            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
+            return insets;
+        });
+
+        binding.btnSubmit.setOnClickListener(v -> {
+            if (InputValidator.isValidEmail(binding.etEmail)) {
+                String email = binding.etEmail.getText().toString().trim();
+                // TODO: Implement password reset logic here
+                Toast.makeText(this, "If this email is linked, a reset email will be sent.", Toast.LENGTH_LONG).show();
+                finish();
+            }
+        });
+
+        binding.btnBackToLogin.setOnClickListener(v -> finish());
+    }
+}

android/app/src/main/java/com/example/petstoremobile/activities/MainActivity.java

@@ -89,6 +89,11 @@ public class MainActivity extends AppCompatActivity {
 
             performLogin(username, password);
         });
+
+        // Set click listener for forgot password link
+        binding.tvForgotPassword.setOnClickListener(v -> {
+            startActivity(new Intent(this, ForgotPasswordActivity.class));
+        });
     }
 
     /**
@@ -133,6 +138,7 @@ public class MainActivity extends AppCompatActivity {
             if (resource != null && resource.status != Resource.Status.LOADING) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     tokenManager.saveUserId(resource.data.getId());
+                    tokenManager.savePrimaryStoreId(resource.data.getStoreId());
                 }
                 Toast.makeText(this, "Login successful", Toast.LENGTH_SHORT).show();
                 startActivity(new Intent(this, HomeActivity.class));

android/app/src/main/java/com/example/petstoremobile/adapters/CustomerAdapter.java

@@ -0,0 +1,80 @@
+package com.example.petstoremobile.adapters;
+
+import android.graphics.Color;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.api.UserApi;
+import com.example.petstoremobile.databinding.ItemCustomerBinding;
+import com.example.petstoremobile.dtos.CustomerDTO;
+import com.example.petstoremobile.utils.GlideUtils;
+
+import java.util.List;
+
+public class CustomerAdapter extends RecyclerView.Adapter<CustomerAdapter.CustomerViewHolder> {
+
+    private List<CustomerDTO> list;
+    private OnCustomerClickListener listener;
+    private String baseUrl;
+    private String token;
+
+    public interface OnCustomerClickListener {
+        void onCustomerClick(int position);
+    }
+
+    public CustomerAdapter(List<CustomerDTO> list, OnCustomerClickListener listener) {
+        this.list = list;
+        this.listener = listener;
+    }
+
+    public void setBaseUrl(String baseUrl) { this.baseUrl = baseUrl; }
+    public void setToken(String token) { this.token = token; }
+
+    public static class CustomerViewHolder extends RecyclerView.ViewHolder {
+        final ItemCustomerBinding binding;
+
+        public CustomerViewHolder(@NonNull ItemCustomerBinding binding) {
+            super(binding.getRoot());
+            this.binding = binding;
+        }
+    }
+
+    @NonNull
+    @Override
+    public CustomerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        ItemCustomerBinding binding = ItemCustomerBinding.inflate(
+                LayoutInflater.from(parent.getContext()), parent, false);
+        return new CustomerViewHolder(binding);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull CustomerViewHolder holder, int position) {
+        CustomerDTO c = list.get(position);
+        ItemCustomerBinding b = holder.binding;
+
+        b.tvCustomerFullName.setText(c.getFullName() != null ? c.getFullName() : "");
+        b.tvCustomerUsername.setText("@" + (c.getUsername() != null ? c.getUsername() : ""));
+        b.tvCustomerEmail.setText(c.getEmail() != null ? c.getEmail() : "");
+
+        int points = c.getLoyaltyPoints() != null ? c.getLoyaltyPoints() : 0;
+        b.tvCustomerLoyalty.setText(points + " pts");
+
+        boolean active = Boolean.TRUE.equals(c.getActive());
+        b.tvCustomerStatus.setText(active ? "Active" : "Inactive");
+        b.tvCustomerStatus.setTextColor(active ? Color.parseColor("#4CAF50") : Color.parseColor("#F44336"));
+
+        if (baseUrl != null && c.getCustomerId() != null) {
+            String imageUrl = baseUrl + String.format(UserApi.AVATAR_PATH, c.getCustomerId());
+            GlideUtils.loadImageWithTokenCircle(holder.itemView.getContext(), b.ivCustomerProfile, imageUrl, token, R.drawable.placeholder);
+        } else {
+            b.ivCustomerProfile.setImageResource(R.drawable.placeholder);
+        }
+
+        holder.itemView.setOnClickListener(v -> listener.onCustomerClick(position));
+    }
+
+    @Override
+    public int getItemCount() { return list.size(); }
+}

android/app/src/main/java/com/example/petstoremobile/api/AdoptionApi.java

@@ -24,7 +24,8 @@ public interface AdoptionApi {
             @Query("status") String status,
             @Query("storeId") Long storeId,
             @Query("date") String date,
-            @Query("employeeId") Long employeeId);
+            @Query("employeeId") Long employeeId,
+            @Query("sort") String sort);
 
     @GET("api/v1/adoptions/{id}")
     Call<AdoptionDTO> getAdoptionById(@Path("id") Long id);

android/app/src/main/java/com/example/petstoremobile/api/AppointmentApi.java

@@ -24,7 +24,8 @@ public interface AppointmentApi {
             @Query("status") String status,
             @Query("storeId") Long storeId,
             @Query("date") String date,
-            @Query("employeeId") Long employeeId);
+            @Query("employeeId") Long employeeId,
+            @Query("sort") String sort);
 
     @GET("api/v1/appointments/{id}")
     Call<AppointmentDTO> getAppointmentById(@Path("id") Long id);

android/app/src/main/java/com/example/petstoremobile/api/CustomerApi.java

@@ -7,11 +7,14 @@ import com.example.petstoremobile.dtos.PageResponse;
 import java.util.List;
 
 import retrofit2.Call;
+import retrofit2.http.Body;
+import retrofit2.http.DELETE;
 import retrofit2.http.GET;
+import retrofit2.http.POST;
+import retrofit2.http.PUT;
 import retrofit2.http.Path;
 import retrofit2.http.Query;
 
-//api calls to get customers
 public interface CustomerApi {
 
     @GET("api/v1/customers")
@@ -20,6 +23,15 @@ public interface CustomerApi {
     @GET("api/v1/customers/{customerId}")
     Call<CustomerDTO> getCustomerById(@Path("customerId") Long customerId);
 
+    @PUT("api/v1/customers/{customerId}")
+    Call<CustomerDTO> updateCustomer(@Path("customerId") Long customerId, @Body CustomerDTO customer);
+
+    @DELETE("api/v1/customers/{customerId}")
+    Call<Void> deleteCustomer(@Path("customerId") Long customerId);
+
+    @POST("api/v1/auth/register")
+    Call<CustomerDTO> registerCustomer(@Body CustomerDTO customer);
+
     @GET("api/v1/dropdowns/customers")
     Call<List<DropdownDTO>> getCustomerDropdowns();
 }

android/app/src/main/java/com/example/petstoremobile/api/PetApi.java

@@ -47,6 +47,9 @@ public interface PetApi {
     @GET("api/v1/dropdowns/pets")
     Call<List<DropdownDTO>> getPetDropdowns();
 
+    @GET("api/v1/dropdowns/pet-species")
+    Call<List<DropdownDTO>> getPetSpeciesDropdowns();
+
     // Get pet by id
     @GET("api/v1/pets/{id}")
     Call<PetDTO> getPetById(@Path("id") Long id);

android/app/src/main/java/com/example/petstoremobile/api/auth/TokenManager.java

@@ -15,6 +15,7 @@ public class TokenManager {
     private static final String ROLE_KEY = "role";
     private static final String PREFS_NAME = "auth_prefs";
     private static final String USER_ID_KEY = "user_id";
+    private static final String PRIMARY_STORE_ID_KEY = "primary_store_id";
 
     private SharedPreferences prefs;
 
@@ -54,6 +55,19 @@ public class TokenManager {
         prefs.edit().putLong(USER_ID_KEY, userId).apply();
     }
 
+    public void savePrimaryStoreId(Long storeId) {
+        if (storeId != null) {
+            prefs.edit().putLong(PRIMARY_STORE_ID_KEY, storeId).apply();
+        } else {
+            prefs.edit().remove(PRIMARY_STORE_ID_KEY).apply();
+        }
+    }
+
+    public Long getPrimaryStoreId() {
+        long id = prefs.getLong(PRIMARY_STORE_ID_KEY, -1L);
+        return id == -1L ? null : id;
+    }
+
     //Check if logged in
     public boolean isLoggedIn() {
         return getToken() != null;

android/app/src/main/java/com/example/petstoremobile/dtos/CustomerDTO.java

@@ -5,61 +5,72 @@ import com.google.gson.annotations.SerializedName;
 public class CustomerDTO {
     @SerializedName("id")
     private Long customerId;
+    private String username;
     private String firstName;
     private String lastName;
+    private String fullName;
     private String email;
+    private String phone;
+    private Boolean active;
+    private Integer loyaltyPoints;
+    private Long primaryStoreId;
     private String createdAt;
     private String updatedAt;
+    private String password;
 
-    public Long getCustomerId() {
+    public CustomerDTO() {}
-        return customerId;
-    }
 
-    public void setCustomerId(Long customerId) {
+    public CustomerDTO(String username, String password, String firstName, String lastName,
-        this.customerId = customerId;
+                       String email, String phone) {
-    }
+        this.username = username;
-
+        this.password = password;
-    public String getFirstName() {
-        return firstName;
-    }
-
-    public void setFirstName(String firstName) {
         this.firstName = firstName;
-    }
-
-    public String getLastName() {
-        return lastName;
-    }
-
-    public void setLastName(String lastName) {
         this.lastName = lastName;
-    }
-
-    public String getEmail() {
-        return email;
-    }
-
-    public void setEmail(String email) {
         this.email = email;
+        this.phone = phone;
     }
 
+    public Long getCustomerId() { return customerId; }
+    public void setCustomerId(Long customerId) { this.customerId = customerId; }
+
+    public String getUsername() { return username; }
+    public void setUsername(String username) { this.username = username; }
+
+    public String getFirstName() { return firstName; }
+    public void setFirstName(String firstName) { this.firstName = firstName; }
+
+    public String getLastName() { return lastName; }
+    public void setLastName(String lastName) { this.lastName = lastName; }
+
     public String getFullName() {
-        return firstName + " " + lastName;
+        if (fullName != null) return fullName;
+        String f = firstName != null ? firstName : "";
+        String l = lastName != null ? lastName : "";
+        return (f + " " + l).trim();
     }
+    public void setFullName(String fullName) { this.fullName = fullName; }
 
-    public String getCreatedAt() {
+    public String getEmail() { return email; }
-        return createdAt;
+    public void setEmail(String email) { this.email = email; }
-    }
 
-    public void setCreatedAt(String createdAt) {
+    public String getPhone() { return phone; }
-        this.createdAt = createdAt;
+    public void setPhone(String phone) { this.phone = phone; }
-    }
 
-    public String getUpdatedAt() {
+    public Boolean getActive() { return active; }
-        return updatedAt;
+    public void setActive(Boolean active) { this.active = active; }
-    }
 
-    public void setUpdatedAt(String updatedAt) {
+    public Integer getLoyaltyPoints() { return loyaltyPoints; }
-        this.updatedAt = updatedAt;
+    public void setLoyaltyPoints(Integer loyaltyPoints) { this.loyaltyPoints = loyaltyPoints; }
-    }
+
+    public Long getPrimaryStoreId() { return primaryStoreId; }
+    public void setPrimaryStoreId(Long primaryStoreId) { this.primaryStoreId = primaryStoreId; }
+
+    public String getCreatedAt() { return createdAt; }
+    public void setCreatedAt(String createdAt) { this.createdAt = createdAt; }
+
+    public String getUpdatedAt() { return updatedAt; }
+    public void setUpdatedAt(String updatedAt) { this.updatedAt = updatedAt; }
+
+    public String getPassword() { return password; }
+    public void setPassword(String password) { this.password = password; }
 }

android/app/src/main/java/com/example/petstoremobile/dtos/SaleDTO.java

@@ -102,6 +102,10 @@ public class SaleDTO {
         return couponId;
     }
 
+    public void setCouponId(Long couponId) {
+        this.couponId = couponId;
+    }
+
     public Integer getPointsEarned() {
         return pointsEarned;
     }

android/app/src/main/java/com/example/petstoremobile/fragments/ListFragment.java

@@ -89,6 +89,7 @@ public class ListFragment extends Fragment {
         binding.drawerPurchaseOrderView.setOnClickListener(v -> navigateTo(R.id.nav_purchase_order));
         binding.drawerSale.setOnClickListener(v -> navigateTo(R.id.nav_sale));
         binding.drawerStaff.setOnClickListener(v -> navigateTo(R.id.nav_staff));
+        binding.drawerCustomers.setOnClickListener(v -> navigateTo(R.id.nav_customer));
         binding.drawerAnalytics.setOnClickListener(v -> navigateTo(R.id.nav_analytics));
         binding.drawerCoupons.setOnClickListener(v -> navigateTo(R.id.nav_coupon));
 

android/app/src/main/java/com/example/petstoremobile/fragments/ProfileFragment.java

@@ -160,7 +160,8 @@ public class ProfileFragment extends Fragment {
             android.content.Intent serviceIntent = new android.content.Intent(requireContext(), ChatNotificationService.class);
             requireContext().stopService(serviceIntent);
 
-            tokenManager.clearLoginData(); // clear the token for next login
+            // clear the token for next login
+            tokenManager.clearLoginData();
             //get the intent to the main activity and clear the back stack so the back button won't allow the user to go back to the previous screen
             android.content.Intent intent = new android.content.Intent(getActivity(), MainActivity.class);
             intent.addFlags(android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP | android.content.Intent.FLAG_ACTIVITY_NEW_TASK);

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/AdoptionFragment.java

@@ -17,6 +17,7 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.adapters.AdoptionAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentAdoptionBinding;
 import com.example.petstoremobile.dtos.AdoptionDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -38,6 +39,8 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 @AndroidEntryPoint
@@ -52,6 +55,8 @@ public class AdoptionFragment extends Fragment implements AdoptionAdapter.OnAdop
     private boolean isMonthMode = false;
     private final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd", Locale.getDefault());
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -117,7 +122,7 @@ public class AdoptionFragment extends Fragment implements AdoptionAdapter.OnAdop
     public void onResume() {
         super.onResume();
         loadAdoptions();
-        viewModel.loadStores();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     private void toggleCalendarMode() {
@@ -128,8 +133,18 @@ public class AdoptionFragment extends Fragment implements AdoptionAdapter.OnAdop
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilterAdoption, binding.layoutFilterAdoption, 
+        if (isStaff()) {
-                binding.etSearchAdoption, binding.spinnerStatusAdoption, binding.spinnerStoreAdoption);
+            UIUtils.setupFilterToggle(binding.btnToggleFilterAdoption, binding.layoutFilterAdoption,
+                    binding.etSearchAdoption, binding.spinnerStatusAdoption);
+            binding.spinnerStoreAdoption.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilterAdoption, binding.layoutFilterAdoption,
+                    binding.etSearchAdoption, binding.spinnerStatusAdoption, binding.spinnerStoreAdoption);
+        }
+    }
+
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
     }
 
     private void setupCalendar() {
@@ -195,10 +210,15 @@ public class AdoptionFragment extends Fragment implements AdoptionAdapter.OnAdop
         String query = binding.etSearchAdoption.getText().toString().trim();
         String status = binding.spinnerStatusAdoption.getSelectedItem() != null ? binding.spinnerStatusAdoption.getSelectedItem().toString() : "All Statuses";
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStoreAdoption.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStoreAdoption.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStoreAdoption.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStoreAdoption.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         String selectedDateString = null;

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/AppointmentFragment.java

@@ -17,6 +17,7 @@ import android.view.ViewGroup;
 
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.adapters.AppointmentAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentAppointmentBinding;
 import com.example.petstoremobile.dtos.AppointmentDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -39,6 +40,8 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 @AndroidEntryPoint
@@ -52,6 +55,8 @@ public class AppointmentFragment extends Fragment implements AppointmentAdapter.
     private AuthViewModel authViewModel;
     private BulkDeleteHandler bulkDeleteHandler;
 
+    @Inject TokenManager tokenManager;
+
     private CalendarDay selectedCalendarDay;
     private boolean isMonthMode = false;
     private Long currentUserId = null;
@@ -126,7 +131,7 @@ public class AppointmentFragment extends Fragment implements AppointmentAdapter.
     public void onResume() {
         super.onResume();
         loadAppointmentData();
-        viewModel.loadStores();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     private void toggleCalendarMode() {
@@ -151,8 +156,13 @@ public class AppointmentFragment extends Fragment implements AppointmentAdapter.
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchAppointment,
+        if (isStaff()) {
-                binding.spinnerStatus, binding.spinnerStore);
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchAppointment, binding.spinnerStatus);
+            binding.spinnerStore.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchAppointment,
+                    binding.spinnerStatus, binding.spinnerStore);
+        }
     }
 
     private void setupCalendar() {
@@ -227,14 +237,23 @@ public class AppointmentFragment extends Fragment implements AppointmentAdapter.
         }
     }
 
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
+    }
+
     private void loadAppointmentData() {
         String query = binding.etSearchAppointment.getText().toString().trim();
         String status = binding.spinnerStatus.getSelectedItem() != null ? binding.spinnerStatus.getSelectedItem().toString() : "All Statuses";
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         String selectedDateString = null;

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/CustomerFragment.java

@@ -0,0 +1,125 @@
+package com.example.petstoremobile.fragments.listfragments;
+
+import android.os.Bundle;
+import android.view.*;
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.navigation.fragment.NavHostFragment;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import com.example.petstoremobile.R;
+import com.example.petstoremobile.adapters.CustomerAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
+import com.example.petstoremobile.databinding.FragmentCustomerBinding;
+import com.example.petstoremobile.dtos.CustomerDTO;
+import com.example.petstoremobile.utils.SpinnerUtils;
+import com.example.petstoremobile.utils.UIUtils;
+import com.example.petstoremobile.viewmodels.CustomerListViewModel;
+import dagger.hilt.android.AndroidEntryPoint;
+import java.util.*;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+
+@AndroidEntryPoint
+public class CustomerFragment extends Fragment implements CustomerAdapter.OnCustomerClickListener {
+
+    private FragmentCustomerBinding binding;
+    private CustomerListViewModel viewModel;
+    private List<CustomerDTO> customerList = new ArrayList<>();
+    private CustomerAdapter adapter;
+
+    @Inject @Named("baseUrl") String baseUrl;
+    @Inject TokenManager tokenManager;
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        binding = FragmentCustomerBinding.inflate(inflater, container, false);
+        viewModel = new ViewModelProvider(this).get(CustomerListViewModel.class);
+
+        setupRecyclerView();
+        setupSearch();
+        setupStatusFilter();
+        setupSwipeRefresh();
+        observeViewModel();
+
+        viewModel.loadCustomers();
+
+        binding.fabAddCustomer.setOnClickListener(v -> openDetail(-1));
+
+        UIUtils.setupHamburgerMenu(binding.btnHamburgerCustomer, this);
+        UIUtils.setupFilterToggle(binding.btnToggleFilterCustomer, binding.layoutFilterCustomer,
+                binding.etSearchCustomer, binding.spinnerStatusCustomer);
+
+        return binding.getRoot();
+    }
+
+    private void observeViewModel() {
+        viewModel.getFilteredCustomers().observe(getViewLifecycleOwner(), list -> {
+            customerList.clear();
+            customerList.addAll(list);
+            adapter.notifyDataSetChanged();
+        });
+
+        viewModel.getIsLoading().observe(getViewLifecycleOwner(), loading -> {
+            binding.swipeRefreshCustomer.setRefreshing(loading);
+        });
+    }
+
+    private void setupRecyclerView() {
+        adapter = new CustomerAdapter(customerList, this);
+        adapter.setBaseUrl(baseUrl);
+        adapter.setToken(tokenManager.getToken());
+        binding.recyclerViewCustomer.setLayoutManager(new LinearLayoutManager(getContext()));
+        binding.recyclerViewCustomer.setAdapter(adapter);
+    }
+
+    private void setupStatusFilter() {
+        String[] statuses = {"All Statuses", "Active", "Inactive"};
+        SpinnerUtils.setupStringFilterSpinner(requireContext(), binding.spinnerStatusCustomer, statuses, this::applyFilters);
+    }
+
+    private void setupSearch() {
+        UIUtils.attachSearch(binding.etSearchCustomer, this::applyFilters);
+    }
+
+    private void applyFilters() {
+        String query = binding.etSearchCustomer.getText().toString().trim();
+        String status = binding.spinnerStatusCustomer.getSelectedItem() != null ?
+                binding.spinnerStatusCustomer.getSelectedItem().toString() : "All Statuses";
+        viewModel.filter(query, status);
+    }
+
+    private void setupSwipeRefresh() {
+        binding.swipeRefreshCustomer.setOnRefreshListener(viewModel::loadCustomers);
+    }
+
+    private void openDetail(int position) {
+        Bundle args = new Bundle();
+        if (position != -1) {
+            CustomerDTO c = customerList.get(position);
+            args.putLong("customerId", c.getCustomerId() != null ? c.getCustomerId() : -1);
+            args.putString("username", c.getUsername() != null ? c.getUsername() : "");
+            args.putString("firstName", c.getFirstName() != null ? c.getFirstName() : "");
+            args.putString("lastName", c.getLastName() != null ? c.getLastName() : "");
+            args.putString("email", c.getEmail() != null ? c.getEmail() : "");
+            args.putString("phone", c.getPhone() != null ? c.getPhone() : "");
+            args.putBoolean("active", Boolean.TRUE.equals(c.getActive()));
+            args.putInt("loyaltyPoints", c.getLoyaltyPoints() != null ? c.getLoyaltyPoints() : 0);
+            args.putBoolean("isEditing", true);
+        }
+        NavHostFragment.findNavController(this).navigate(R.id.nav_customer_detail, args);
+    }
+
+    @Override
+    public void onCustomerClick(int position) {
+        openDetail(position);
+    }
+
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        binding = null;
+    }
+}

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/InventoryFragment.java

@@ -16,6 +16,7 @@ import androidx.recyclerview.widget.RecyclerView;
 
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.adapters.InventoryAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentInventoryBinding;
 import com.example.petstoremobile.dtos.InventoryDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -27,6 +28,8 @@ import com.example.petstoremobile.utils.SpinnerUtils;
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 @AndroidEntryPoint
@@ -38,6 +41,8 @@ public class InventoryFragment extends Fragment implements InventoryAdapter.OnIn
     private InventoryListViewModel viewModel;
     private BulkDeleteHandler bulkDeleteHandler;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -99,7 +104,7 @@ public class InventoryFragment extends Fragment implements InventoryAdapter.OnIn
     @Override
     public void onResume() {
         super.onResume();
-        viewModel.loadStores();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     @Override
@@ -109,7 +114,16 @@ public class InventoryFragment extends Fragment implements InventoryAdapter.OnIn
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchInventory, binding.spinnerStore);
+        if (isStaff()) {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchInventory);
+            binding.spinnerStore.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchInventory, binding.spinnerStore);
+        }
+    }
+
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
     }
 
     private void setupSearch() {
@@ -150,10 +164,15 @@ public class InventoryFragment extends Fragment implements InventoryAdapter.OnIn
         String query = binding.etSearchInventory != null ? binding.etSearchInventory.getText().toString().trim() : "";
         if (query.isEmpty()) query = null;
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         viewModel.loadInventory(reset, query, storeId);

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/PetFragment.java

@@ -88,6 +88,11 @@ public class PetFragment extends Fragment implements PetAdapter.OnPetClickListen
         viewModel.getIsLoading().observe(getViewLifecycleOwner(), loading -> {
             binding.swipeRefreshPet.setRefreshing(loading);
         });
+
+        viewModel.getSpeciesOptions().observe(getViewLifecycleOwner(), options -> {
+            String[] arr = options.toArray(new String[0]);
+            SpinnerUtils.setupStringFilterSpinner(requireContext(), binding.spinnerSpecies, arr, this::loadPetData);
+        });
     }
 
     private void setupBulkDelete() {
@@ -107,12 +112,23 @@ public class PetFragment extends Fragment implements PetAdapter.OnPetClickListen
     public void onResume() {
         super.onResume();
         loadPetData();
-        viewModel.loadStores();
+        viewModel.loadSpecies();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPet,
+        if (isStaff()) {
-                binding.spinnerStatus, binding.spinnerSpecies, binding.spinnerStore);
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPet,
+                    binding.spinnerStatus, binding.spinnerSpecies);
+            binding.spinnerStore.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPet,
+                    binding.spinnerStatus, binding.spinnerSpecies, binding.spinnerStore);
+        }
+    }
+
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
     }
 
     private void setupSearch() {
@@ -125,8 +141,8 @@ public class PetFragment extends Fragment implements PetAdapter.OnPetClickListen
     }
 
     private void setupSpeciesFilter() {
-        String[] species = {"All Species", "Dog", "Cat", "Bird", "Rabbit", "Fish", "Hamster"};
+        String[] initial = {"All Species"};
-        SpinnerUtils.setupStringFilterSpinner(requireContext(), binding.spinnerSpecies, species, this::loadPetData);
+        SpinnerUtils.setupStringFilterSpinner(requireContext(), binding.spinnerSpecies, initial, this::loadPetData);
     }
 
     private void setupStoreFilter() {
@@ -142,10 +158,15 @@ public class PetFragment extends Fragment implements PetAdapter.OnPetClickListen
         String status = binding.spinnerStatus.getSelectedItem() != null ? binding.spinnerStatus.getSelectedItem().toString() : "All Statuses";
         String species = binding.spinnerSpecies.getSelectedItem() != null ? binding.spinnerSpecies.getSelectedItem().toString() : "All Species";
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         viewModel.loadPets(query, status, species, storeId);

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/PurchaseOrderFragment.java

@@ -14,6 +14,7 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.adapters.PurchaseOrderAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentPurchaseOrderBinding;
 import com.example.petstoremobile.dtos.PurchaseOrderDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -24,6 +25,8 @@ import com.example.petstoremobile.viewmodels.PurchaseOrderListViewModel;
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 @AndroidEntryPoint
@@ -35,6 +38,8 @@ public class PurchaseOrderFragment extends Fragment
     private PurchaseOrderAdapter adapter;
     private PurchaseOrderListViewModel viewModel;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -79,11 +84,20 @@ public class PurchaseOrderFragment extends Fragment
     public void onResume() {
         super.onResume();
         loadData();
-        viewModel.loadStores();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPO, binding.spinnerStore);
+        if (isStaff()) {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPO);
+            binding.spinnerStore.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchPO, binding.spinnerStore);
+        }
+    }
+
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
     }
 
     private void setupSearch() {
@@ -108,10 +122,15 @@ public class PurchaseOrderFragment extends Fragment
         String query = binding.etSearchPO != null ? binding.etSearchPO.getText().toString().trim() : "";
         if (query.isEmpty()) query = null;
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         viewModel.loadPurchaseOrders(query, storeId);

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/SaleFragment.java

@@ -15,6 +15,7 @@ import android.widget.Toast;
 
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.adapters.SaleAdapter;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentSaleBinding;
 import com.example.petstoremobile.dtos.SaleDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -25,6 +26,8 @@ import com.example.petstoremobile.viewmodels.SaleListViewModel;
 import java.util.ArrayList;
 import java.util.List;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 @AndroidEntryPoint
@@ -35,6 +38,8 @@ public class SaleFragment extends Fragment implements SaleAdapter.OnSaleClickLis
     private SaleAdapter adapter;
     private SaleListViewModel viewModel;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
@@ -87,12 +92,22 @@ public class SaleFragment extends Fragment implements SaleAdapter.OnSaleClickLis
     @Override
     public void onResume() {
         super.onResume();
-        viewModel.loadStores();
+        if (!isStaff()) viewModel.loadStores();
     }
 
     private void setupFilterToggle() {
-        UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchSale, 
+        if (isStaff()) {
-                binding.spinnerPaymentMethod, binding.spinnerStore, binding.spinnerRefundStatus);
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchSale,
+                    binding.spinnerPaymentMethod, binding.spinnerRefundStatus);
+            binding.spinnerStore.setVisibility(View.GONE);
+        } else {
+            UIUtils.setupFilterToggle(binding.btnToggleFilter, binding.layoutFilter, binding.etSearchSale,
+                    binding.spinnerPaymentMethod, binding.spinnerStore, binding.spinnerRefundStatus);
+        }
+    }
+
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
     }
 
     private void setupStoreFilter() {
@@ -149,10 +164,15 @@ public class SaleFragment extends Fragment implements SaleAdapter.OnSaleClickLis
             paymentMethod = (String) binding.spinnerPaymentMethod.getSelectedItem();
         }
 
-        Long storeId = null;
+        Long storeId;
-        List<StoreDTO> stores = viewModel.getStores().getValue();
+        if (isStaff()) {
-        if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+            storeId = tokenManager.getPrimaryStoreId();
-            storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+        } else {
+            storeId = null;
+            List<StoreDTO> stores = viewModel.getStores().getValue();
+            if (binding.spinnerStore.getSelectedItemPosition() > 0 && stores != null && !stores.isEmpty()) {
+                storeId = stores.get(binding.spinnerStore.getSelectedItemPosition() - 1).getStoreId();
+            }
         }
 
         Boolean isRefund = null;

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/AdoptionDetailFragment.java

@@ -17,11 +17,14 @@ import com.example.petstoremobile.utils.InputValidator;
 import com.example.petstoremobile.utils.Resource;
 import com.example.petstoremobile.utils.SpinnerUtils;
 import com.example.petstoremobile.utils.UIUtils;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.viewmodels.AdoptionDetailViewModel;
 
 import java.math.BigDecimal;
 import java.util.*;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 /**
@@ -34,6 +37,8 @@ public class AdoptionDetailFragment extends Fragment {
     private AdoptionDetailViewModel viewModel;
     private boolean isUpdatingUI = false;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -82,7 +87,7 @@ public class AdoptionDetailFragment extends Fragment {
 
         viewModel.getStoreList().observe(getViewLifecycleOwner(), list -> {
             AdoptionDetailViewModel.ViewState state = viewModel.getViewState().getValue();
-            Long storeId = state != null ? state.selectedStoreId : null;
+            Long storeId = isStaff() ? tokenManager.getPrimaryStoreId() : (state != null ? state.selectedStoreId : null);
             SpinnerUtils.populateSpinner(requireContext(), binding.spinnerAdoptionStore, list,
                     DropdownDTO::getLabel, "-- Select Store --", storeId, DropdownDTO::getId);
         });
@@ -113,6 +118,7 @@ public class AdoptionDetailFragment extends Fragment {
         binding.spinnerAdoptionCustomer.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onCustomerSelected(position);
             }
             @Override
@@ -122,6 +128,7 @@ public class AdoptionDetailFragment extends Fragment {
         binding.spinnerAdoptionStore.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onStoreSelected(position);
             }
             @Override
@@ -210,9 +217,15 @@ public class AdoptionDetailFragment extends Fragment {
         if (employees != null) SpinnerUtils.populateSpinner(requireContext(), binding.spinnerAdoptionEmployee,
                 employees, DropdownDTO::getLabel, "-- Select Staff --", state.selectedEmployeeId, DropdownDTO::getId);
 
+        if (isStaff()) UIUtils.setViewsEnabled(false, binding.spinnerAdoptionStore);
+
         isUpdatingUI = false;
     }
 
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
+    }
+
     private void saveAdoption() {
         if (!InputValidator.isSpinnerSelected(binding.spinnerAdoptionCustomer, "Customer")) return;
         if (!InputValidator.isSpinnerSelected(binding.spinnerAdoptionPet, "Pet")) return;
@@ -225,9 +238,16 @@ public class AdoptionDetailFragment extends Fragment {
             try { fee = new BigDecimal(feeStr); } catch (NumberFormatException ignored) {}
         }
 
-        DropdownDTO customer = viewModel.getCustomerList().getValue().get(binding.spinnerAdoptionCustomer.getSelectedItemPosition() - 1);
+        List<DropdownDTO> customerListVal  = viewModel.getCustomerList().getValue();
-        DropdownDTO pet      = viewModel.getPetList().getValue().get(binding.spinnerAdoptionPet.getSelectedItemPosition() - 1);
+        List<DropdownDTO> petListVal       = viewModel.getPetList().getValue();
-        DropdownDTO store    = viewModel.getStoreList().getValue().get(binding.spinnerAdoptionStore.getSelectedItemPosition() - 1);
+        List<DropdownDTO> storeListVal     = viewModel.getStoreList().getValue();
+        if (customerListVal == null || petListVal == null || storeListVal == null) {
+            Toast.makeText(getContext(), "Data not loaded yet, please try again", Toast.LENGTH_SHORT).show();
+            return;
+        }
+        DropdownDTO customer = customerListVal.get(binding.spinnerAdoptionCustomer.getSelectedItemPosition() - 1);
+        DropdownDTO pet      = petListVal.get(binding.spinnerAdoptionPet.getSelectedItemPosition() - 1);
+        DropdownDTO store    = storeListVal.get(binding.spinnerAdoptionStore.getSelectedItemPosition() - 1);
 
         Long employeeId = null;
         if (binding.spinnerAdoptionEmployee.getSelectedItemPosition() > 0 && viewModel.getEmployeeList().getValue() != null) {

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/AppointmentDetailFragment.java

@@ -23,10 +23,13 @@ import com.example.petstoremobile.utils.InputValidator;
 import com.example.petstoremobile.utils.Resource;
 import com.example.petstoremobile.utils.SpinnerUtils;
 import com.example.petstoremobile.utils.UIUtils;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.viewmodels.AppointmentDetailViewModel;
 
 import java.util.List;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 /**
@@ -43,6 +46,8 @@ public class AppointmentDetailFragment extends Fragment {
     private AppointmentDetailViewModel viewModel;
     private boolean isUpdatingUI = false;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -89,6 +94,7 @@ public class AppointmentDetailFragment extends Fragment {
         binding.spinnerCustomer.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onCustomerSelected(position);
             }
             @Override
@@ -98,6 +104,7 @@ public class AppointmentDetailFragment extends Fragment {
         binding.spinnerStore.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                if (isUpdatingUI) return;
                 viewModel.onStoreSelected(position);
             }
             @Override
@@ -129,7 +136,7 @@ public class AppointmentDetailFragment extends Fragment {
 
         viewModel.getStores().observe(getViewLifecycleOwner(), list -> {
             AppointmentDetailViewModel.ViewState state = viewModel.getViewState().getValue();
-            Long id = state != null ? state.selectedStoreId : null;
+            Long id = isStaff() ? tokenManager.getPrimaryStoreId() : (state != null ? state.selectedStoreId : null);
             SpinnerUtils.populateSpinner(requireContext(), binding.spinnerStore, list, DropdownDTO::getLabel, "-- Select Store --", id, DropdownDTO::getId);
         });
 
@@ -201,9 +208,15 @@ public class AppointmentDetailFragment extends Fragment {
         if (staff != null) SpinnerUtils.populateSpinner(requireContext(), binding.spinnerStaff,
                 staff, DropdownDTO::getLabel, "-- Select Staff --", state.selectedStaffId, DropdownDTO::getId);
 
+        if (isStaff()) binding.spinnerStore.setEnabled(false);
+
         isUpdatingUI = false;
     }
 
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
+    }
+
     private void notifyDateTimeStatusChange() {
         if (isUpdatingUI) return;
 
@@ -248,7 +261,12 @@ public class AppointmentDetailFragment extends Fragment {
 
         String date = binding.etAppointmentDate.getText().toString().trim();
         String time = buildTimeString();
-        String status = binding.spinnerAppointmentStatus.getSelectedItem().toString().toUpperCase();
+        Object selectedStatus = binding.spinnerAppointmentStatus.getSelectedItem();
+        if (selectedStatus == null) {
+            Toast.makeText(getContext(), "Please select a status", Toast.LENGTH_SHORT).show();
+            return;
+        }
+        String status = selectedStatus.toString().toUpperCase();
 
         if (!viewModel.isValidFutureBooking(status, date, time)) {
             DialogUtils.showInfoDialog(requireContext(), "Invalid Time", "Booked appointments must be in the future.");

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/CouponDetailFragment.java

@@ -16,6 +16,7 @@ import androidx.navigation.Navigation;
 import com.example.petstoremobile.R;
 import com.example.petstoremobile.databinding.FragmentCouponDetailBinding;
 import com.example.petstoremobile.dtos.CouponDTO;
+import com.example.petstoremobile.utils.DateTimeUtils;
 import com.example.petstoremobile.utils.InputValidator;
 import com.example.petstoremobile.utils.Resource;
 import com.example.petstoremobile.utils.UIUtils;
@@ -95,6 +96,9 @@ public class CouponDetailFragment extends Fragment {
     }
 
     private void loadCouponDetails() {
+        binding.tvCouponId.setText(DateTimeUtils.formatId(couponId));
+        binding.tvCouponId.setVisibility(View.VISIBLE);
+
         viewModel.loadCoupon(couponId).observe(getViewLifecycleOwner(), resource -> {
             if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 CouponDTO coupon = resource.data;

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/CustomerDetailFragment.java

@@ -0,0 +1,175 @@
+package com.example.petstoremobile.fragments.listfragments.detailfragments;
+
+import android.os.Bundle;
+import android.view.*;
+import android.widget.*;
+import androidx.annotation.NonNull;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.navigation.fragment.NavHostFragment;
+import com.example.petstoremobile.databinding.FragmentCustomerDetailBinding;
+import com.example.petstoremobile.dtos.CustomerDTO;
+import com.example.petstoremobile.utils.DialogUtils;
+import com.example.petstoremobile.utils.InputValidator;
+import com.example.petstoremobile.utils.SpinnerUtils;
+import com.example.petstoremobile.utils.UIUtils;
+import com.example.petstoremobile.viewmodels.CustomerDetailViewModel;
+import com.example.petstoremobile.utils.Resource;
+
+import dagger.hilt.android.AndroidEntryPoint;
+
+@AndroidEntryPoint
+public class CustomerDetailFragment extends Fragment {
+
+    private FragmentCustomerDetailBinding binding;
+    private CustomerDetailViewModel viewModel;
+
+    private final String[] STATUSES = {"Active", "Inactive"};
+
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
+                             Bundle savedInstanceState) {
+        binding = FragmentCustomerDetailBinding.inflate(inflater, container, false);
+        viewModel = new ViewModelProvider(this).get(CustomerDetailViewModel.class);
+
+        setupSpinners();
+        handleArguments();
+
+        binding.btnCustomerBack.setOnClickListener(v -> navigateBack());
+        binding.btnSaveCustomer.setOnClickListener(v -> save());
+        binding.btnDeleteCustomer.setOnClickListener(v -> confirmDelete());
+
+        UIUtils.formatPhoneInput(binding.etCustomerPhone);
+
+        return binding.getRoot();
+    }
+
+    private void setupSpinners() {
+        SpinnerUtils.setupStringSpinner(requireContext(), binding.spinnerCustomerStatus, STATUSES);
+    }
+
+    private void handleArguments() {
+        Bundle a = getArguments();
+        if (a != null && a.getBoolean("isEditing", false)) {
+            long customerId = a.getLong("customerId", -1);
+            viewModel.setCustomerId(customerId, true);
+
+            binding.tvCustomerMode.setText("Edit Customer");
+            binding.tvCustomerId.setText("ID: " + customerId);
+            binding.tvCustomerId.setVisibility(View.VISIBLE);
+            binding.btnDeleteCustomer.setVisibility(View.VISIBLE);
+
+            // Hide password field in edit mode
+            binding.tvCustomerPasswordLabel.setVisibility(View.GONE);
+            binding.etCustomerPassword.setVisibility(View.GONE);
+
+            // Show loyalty points
+            binding.tvLoyaltyPointsLabel.setVisibility(View.VISIBLE);
+            binding.tvCustomerLoyaltyPoints.setVisibility(View.VISIBLE);
+
+            loadCustomerData(customerId);
+        } else {
+            viewModel.setCustomerId(-1, false);
+            binding.tvCustomerMode.setText("Add Customer");
+            binding.btnDeleteCustomer.setVisibility(View.GONE);
+            binding.tvCustomerId.setVisibility(View.GONE);
+            binding.tvLoyaltyPointsLabel.setVisibility(View.GONE);
+            binding.tvCustomerLoyaltyPoints.setVisibility(View.GONE);
+        }
+    }
+
+    private void loadCustomerData(long id) {
+        viewModel.loadCustomer(id).observe(getViewLifecycleOwner(), resource -> {
+            if (resource != null) {
+                setLoading(resource.status == Resource.Status.LOADING);
+                if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
+                    CustomerDTO c = resource.data;
+                    binding.etCustomerUsername.setText(c.getUsername() != null ? c.getUsername() : "");
+                    binding.etCustomerFirstName.setText(c.getFirstName() != null ? c.getFirstName() : "");
+                    binding.etCustomerLastName.setText(c.getLastName() != null ? c.getLastName() : "");
+                    binding.etCustomerEmail.setText(c.getEmail() != null ? c.getEmail() : "");
+                    binding.etCustomerPhone.setText(c.getPhone() != null ? c.getPhone() : "");
+                    binding.spinnerCustomerStatus.setSelection(Boolean.TRUE.equals(c.getActive()) ? 0 : 1);
+                    int pts = c.getLoyaltyPoints() != null ? c.getLoyaltyPoints() : 0;
+                    binding.tvCustomerLoyaltyPoints.setText(String.valueOf(pts));
+                }
+            }
+        });
+    }
+
+    private void setLoading(boolean loading) {
+        if (binding != null && binding.progressBar != null) {
+            binding.progressBar.setVisibility(loading ? View.VISIBLE : View.GONE);
+        }
+    }
+
+    private void save() {
+        if (!InputValidator.isNotEmpty(binding.etCustomerUsername, "Username")) return;
+
+        if (!viewModel.isEditing()) {
+            if (!InputValidator.isNotEmpty(binding.etCustomerPassword, "Password")) return;
+            String pass = binding.etCustomerPassword.getText().toString();
+            if (pass.length() < 6) {
+                binding.etCustomerPassword.setError("At least 6 characters");
+                binding.etCustomerPassword.requestFocus();
+                return;
+            }
+        }
+
+        if (!InputValidator.isNotEmpty(binding.etCustomerFirstName, "First Name")) return;
+        if (!InputValidator.isNotEmpty(binding.etCustomerLastName, "Last Name")) return;
+        if (!InputValidator.isValidEmail(binding.etCustomerEmail)) return;
+        if (!InputValidator.isValidPhone(binding.etCustomerPhone)) return;
+
+        String username  = binding.etCustomerUsername.getText().toString().trim();
+        String password  = viewModel.isEditing() ? null : binding.etCustomerPassword.getText().toString().trim();
+        String firstName = binding.etCustomerFirstName.getText().toString().trim();
+        String lastName  = binding.etCustomerLastName.getText().toString().trim();
+        String email     = binding.etCustomerEmail.getText().toString().trim();
+        String phone     = binding.etCustomerPhone.getText().toString().trim();
+        boolean active   = binding.spinnerCustomerStatus.getSelectedItemPosition() == 0;
+
+        CustomerDTO dto = new CustomerDTO(username, password, firstName, lastName, email, phone);
+        dto.setFullName(firstName + " " + lastName);
+        dto.setActive(active);
+
+        viewModel.saveCustomer(dto).observe(getViewLifecycleOwner(), resource -> {
+            if (resource != null) {
+                setLoading(resource.status == Resource.Status.LOADING);
+                if (resource.status == Resource.Status.SUCCESS) {
+                    Toast.makeText(getContext(),
+                            viewModel.isEditing() ? "Updated successfully" : "Customer created",
+                            Toast.LENGTH_SHORT).show();
+                    navigateBack();
+                } else if (resource.status == Resource.Status.ERROR) {
+                    Toast.makeText(getContext(), "Error: " + resource.message, Toast.LENGTH_LONG).show();
+                }
+            }
+        });
+    }
+
+    private void confirmDelete() {
+        DialogUtils.showDeleteConfirmDialog(requireContext(), "Customer", () ->
+                viewModel.deleteCustomer().observe(getViewLifecycleOwner(), resource -> {
+                    if (resource != null) {
+                        setLoading(resource.status == Resource.Status.LOADING);
+                        if (resource.status == Resource.Status.SUCCESS) {
+                            navigateBack();
+                        } else if (resource.status == Resource.Status.ERROR) {
+                            Toast.makeText(getContext(), "Delete failed: " + resource.message,
+                                    Toast.LENGTH_SHORT).show();
+                        }
+                    }
+                }));
+    }
+
+    private void navigateBack() {
+        NavHostFragment.findNavController(this).popBackStack();
+    }
+
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        binding = null;
+    }
+}

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/PetDetailFragment.java

@@ -4,6 +4,7 @@ import android.os.Bundle;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.navigation.fragment.NavHostFragment;
@@ -17,6 +18,7 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import com.example.petstoremobile.R;
+import com.example.petstoremobile.api.auth.TokenManager;
 import com.example.petstoremobile.databinding.FragmentPetDetailBinding;
 import com.example.petstoremobile.dtos.DropdownDTO;
 import com.example.petstoremobile.dtos.PetDTO;
@@ -29,8 +31,11 @@ import com.example.petstoremobile.utils.SpinnerUtils;
 import com.example.petstoremobile.utils.UIUtils;
 import com.example.petstoremobile.viewmodels.PetDetailViewModel;
 
+import java.util.List;
 import java.util.Locale;
 
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 
 /**
@@ -43,6 +48,8 @@ public class PetDetailFragment extends Fragment {
     private PetDetailViewModel viewModel;
     private boolean isUpdatingUI = false;
 
+    @Inject TokenManager tokenManager;
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -81,8 +88,19 @@ public class PetDetailFragment extends Fragment {
 
         viewModel.getStoreList().observe(getViewLifecycleOwner(), list -> {
             PetDetailViewModel.ViewState state = viewModel.getViewState().getValue();
-            Long selectedStoreId = state != null ? state.selectedStoreId : null;
+            boolean staffCreating = isStaff() && (state == null || !state.isEditing);
+            boolean storeEnabled = state == null || state.isStoreEnabled;
+            Long selectedStoreId = (staffCreating && storeEnabled) ? tokenManager.getPrimaryStoreId() : (state != null ? state.selectedStoreId : null);
             updateStoreSpinnerSelection(selectedStoreId);
+            if (staffCreating && storeEnabled) UIUtils.setViewsEnabled(false, binding.spinnerStore);
+        });
+
+        viewModel.getSpeciesList().observe(getViewLifecycleOwner(), list -> {
+            PetDetailViewModel.ViewState state = viewModel.getViewState().getValue();
+            String selectedSpecies = state != null ? state.selectedSpecies : null;
+            SpinnerUtils.populateSpinner(requireContext(), binding.spinnerPetSpecies, list,
+                    DropdownDTO::getLabel, "-- Select Species --", null, DropdownDTO::getId);
+            SpinnerUtils.setSelectionByValue(binding.spinnerPetSpecies, selectedSpecies);
         });
     }
 
@@ -100,13 +118,16 @@ public class PetDetailFragment extends Fragment {
 
     private void savePet() {
         if (!InputValidator.isNotEmpty(binding.etPetName, "Pet Name")) return;
-        if (!InputValidator.isNotEmpty(binding.etPetSpecies, "Species")) return;
+        if (!InputValidator.isSpinnerSelected(binding.spinnerPetSpecies, "Species")) return;
         if (!InputValidator.isNotEmpty(binding.etPetBreed, "Breed")) return;
         if (!InputValidator.isPositiveInteger(binding.etPetAge, "Age")) return;
         if (!InputValidator.isPositiveDecimal(binding.etPetPrice, "Price")) return;
 
         String name = binding.etPetName.getText().toString().trim();
-        String species = binding.etPetSpecies.getText().toString().trim();
+        List<DropdownDTO> speciesOptions = viewModel.getSpeciesList().getValue();
+        String species = (speciesOptions != null && binding.spinnerPetSpecies.getSelectedItemPosition() > 0)
+                ? speciesOptions.get(binding.spinnerPetSpecies.getSelectedItemPosition() - 1).getLabel()
+                : "";
         String breed = binding.etPetBreed.getText().toString().trim();
         int age = Integer.parseInt(binding.etPetAge.getText().toString().trim());
         double price = Double.parseDouble(binding.etPetPrice.getText().toString().trim());
@@ -143,6 +164,20 @@ public class PetDetailFragment extends Fragment {
         petDTO.setCustomerId(customerId);
         petDTO.setStoreId(storeId);
 
+        boolean ownerChanged = !java.util.Objects.equals(viewModel.getOriginalCustomerId(), customerId);
+        if (!isStaff() && viewModel.isEditing() && viewModel.isOriginallyOwnedOrAdopted() && ownerChanged) {
+            new AlertDialog.Builder(requireContext())
+                    .setTitle("Change Owner")
+                    .setMessage("Are you sure you want to change the owner of this pet?")
+                    .setPositiveButton("Yes", (d, w) -> performSave(petDTO, name))
+                    .setNegativeButton("Cancel", null)
+                    .show();
+        } else {
+            performSave(petDTO, name);
+        }
+    }
+
+    private void performSave(PetDTO petDTO, String name) {
         viewModel.savePet(petDTO).observe(getViewLifecycleOwner(), resource -> {
             if (resource == null) return;
             setLoading(resource.status == Resource.Status.LOADING);
@@ -202,7 +237,6 @@ public class PetDetailFragment extends Fragment {
             if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 PetDTO p = resource.data;
                 binding.etPetName.setText(p.getPetName());
-                binding.etPetSpecies.setText(p.getPetSpecies());
                 binding.etPetBreed.setText(p.getPetBreed());
                 binding.etPetAge.setText(String.valueOf(p.getPetAge()));
                 if (p.getPetPrice() != null) {
@@ -241,6 +275,11 @@ public class PetDetailFragment extends Fragment {
     private void setupSpinner() {
         SpinnerUtils.setupStringSpinner(requireContext(), binding.spinnerPetStatus, new String[]{});
 
+        SpinnerUtils.setOnIndexSelectedListener(binding.spinnerPetSpecies, p -> {
+            if (isUpdatingUI) return;
+            viewModel.onSpeciesSelected(p);
+        });
+
         binding.spinnerCustomer.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
             @Override
             public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
@@ -290,7 +329,7 @@ public class PetDetailFragment extends Fragment {
         binding.btnDeletePet.setVisibility(state.isDeleteVisible ? View.VISIBLE : View.GONE);
         binding.btnSavePet.setText(state.saveButtonText);
 
-        UIUtils.setViewsEnabled(state.isSpeciesEnabled, binding.etPetSpecies);
+        UIUtils.setViewsEnabled(state.isSpeciesEnabled, binding.spinnerPetSpecies);
         UIUtils.setViewsEnabled(state.isBreedEnabled, binding.etPetBreed);
         UIUtils.setViewsEnabled(state.isCustomerEnabled, binding.spinnerCustomer);
         UIUtils.setViewsEnabled(state.isStoreEnabled, binding.spinnerStore);
@@ -301,6 +340,13 @@ public class PetDetailFragment extends Fragment {
         updateCustomerSpinnerSelection(state.selectedCustomerId);
         updateStoreSpinnerSelection(state.selectedStoreId);
 
+        List<DropdownDTO> species = viewModel.getSpeciesList().getValue();
+        if (species != null) {
+            SpinnerUtils.populateSpinner(requireContext(), binding.spinnerPetSpecies, species,
+                    DropdownDTO::getLabel, "-- Select Species --", null, DropdownDTO::getId);
+            SpinnerUtils.setSelectionByValue(binding.spinnerPetSpecies, state.selectedSpecies);
+        }
+
         if (!state.isCustomerEnabled && binding.spinnerCustomer.getSelectedItemPosition() != 0) {
             binding.spinnerCustomer.setSelection(0);
         }
@@ -308,9 +354,22 @@ public class PetDetailFragment extends Fragment {
             binding.spinnerStore.setSelection(0);
         }
 
+        if (isStaff() && !state.isEditing && state.isStoreEnabled) {
+            updateStoreSpinnerSelection(tokenManager.getPrimaryStoreId());
+            UIUtils.setViewsEnabled(false, binding.spinnerStore);
+        }
+
+        if (isStaff() && state.isEditing && viewModel.isOriginallyOwnedOrAdopted()) {
+            UIUtils.setViewsEnabled(false, binding.spinnerCustomer, binding.spinnerPetStatus, binding.spinnerStore);
+        }
+
         isUpdatingUI = false;
     }
 
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
+    }
+
     private void clearSpinnerError(Spinner spinner) {
         View selectedView = spinner.getSelectedView();
         if (selectedView instanceof TextView) {

android/app/src/main/java/com/example/petstoremobile/fragments/listfragments/detailfragments/SaleDetailFragment.java

@@ -17,6 +17,10 @@ import com.example.petstoremobile.utils.DialogUtils;
 import com.example.petstoremobile.utils.InputValidator;
 import com.example.petstoremobile.utils.Resource;
 import com.example.petstoremobile.utils.UIUtils;
+import com.example.petstoremobile.api.auth.TokenManager;
+
+import javax.inject.Inject;
+
 import dagger.hilt.android.AndroidEntryPoint;
 import java.math.BigDecimal;
 import java.util.*;
@@ -27,6 +31,8 @@ public class SaleDetailFragment extends Fragment {
     private FragmentSaleDetailBinding binding;
     private SaleDetailViewModel viewModel;
 
+    @Inject TokenManager tokenManager;
+
     private final String[] PAYMENT_METHODS = { "Cash", "Card"};
 
     @Override
@@ -42,11 +48,13 @@ public class SaleDetailFragment extends Fragment {
 
         if (viewModel.isViewOnly()) {
             binding.llAddItemRow.setVisibility(View.GONE);
+            binding.llCouponInput.setVisibility(View.GONE);
             binding.btnSaveSale.setVisibility(View.GONE);
             UIUtils.setViewsEnabled(false, binding.spinnerSaleStore, binding.spinnerSaleCustomer, binding.spinnerPaymentMethod);
         } else {
             loadData();
             setupAddItem();
+            setupCoupon();
         }
 
         binding.btnSaleBack.setOnClickListener(v -> navigateBack());
@@ -56,10 +64,18 @@ public class SaleDetailFragment extends Fragment {
         return binding.getRoot();
     }
 
+    private boolean isStaff() {
+        return "STAFF".equalsIgnoreCase(tokenManager.getRole());
+    }
+
     private void observeViewModel() {
         viewModel.getStoreList().observe(getViewLifecycleOwner(), list -> {
+            Long selectedStoreId = isStaff() ? tokenManager.getPrimaryStoreId() : -1L;
             SpinnerUtils.populateSpinner(requireContext(), binding.spinnerSaleStore, list,
-                    DropdownDTO::getLabel, "-- Select Store --", -1L, DropdownDTO::getId);
+                    DropdownDTO::getLabel, "-- Select Store --", selectedStoreId, DropdownDTO::getId);
+            if (isStaff()) {
+                binding.spinnerSaleStore.setEnabled(false);
+            }
         });
 
         viewModel.getCustomerList().observe(getViewLifecycleOwner(), list -> {
@@ -185,13 +201,77 @@ public class SaleDetailFragment extends Fragment {
                 if (sale.getItems() != null) {
                     binding.llSaleItems.removeAllViews();
                     for (SaleDTO.SaleItemDTO item : sale.getItems()) {
-                        addItemRow(item.getProductName(), Math.abs(item.getQuantity()), item.getUnitPrice());
+                        addItemRow(item.getProductName(), Math.abs(item.getQuantity()), item.getUnitPrice(), null);
                     }
                 }
             }
         });
     }
 
+    private void setupCoupon() {
+        binding.btnApplyCoupon.setOnClickListener(v -> {
+            String code = binding.etCouponCode.getText().toString().trim();
+            if (code.isEmpty()) {
+                Toast.makeText(getContext(), "Enter a coupon code", Toast.LENGTH_SHORT).show();
+                return;
+            }
+            setLoading(true);
+            viewModel.lookupCoupon(code).observe(getViewLifecycleOwner(), resource -> {
+                if (resource == null) return;
+                setLoading(resource.status == Resource.Status.LOADING);
+                if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
+                    CouponDTO coupon = resource.data;
+                    if (Boolean.FALSE.equals(coupon.getActive())) {
+                        showCouponError("This coupon is no longer active.");
+                        return;
+                    }
+                    if (coupon.getMinOrderAmount() != null &&
+                            viewModel.calculateSubtotal().compareTo(coupon.getMinOrderAmount()) < 0) {
+                        showCouponError("Minimum order of $" + coupon.getMinOrderAmount() + " required.");
+                        return;
+                    }
+                    viewModel.setAppliedCoupon(coupon);
+                    applyAppliedCouponUI(coupon);
+                    updateTotal();
+                } else if (resource.status == Resource.Status.ERROR) {
+                    showCouponError("Invalid coupon code.");
+                }
+            });
+        });
+
+        binding.btnClearCoupon.setOnClickListener(v -> {
+            viewModel.clearCoupon();
+            binding.etCouponCode.setText("");
+            binding.tvCouponInfo.setVisibility(View.GONE);
+            binding.btnClearCoupon.setVisibility(View.GONE);
+            binding.btnApplyCoupon.setVisibility(View.VISIBLE);
+            binding.etCouponCode.setEnabled(true);
+            binding.llCouponDiscount.setVisibility(View.GONE);
+            updateTotal();
+        });
+    }
+
+    private void applyAppliedCouponUI(CouponDTO coupon) {
+        String info;
+        if ("PERCENTAGE".equalsIgnoreCase(coupon.getDiscountType())) {
+            info = coupon.getDiscountValue().stripTrailingZeros().toPlainString() + "% off applied";
+        } else {
+            info = "$" + coupon.getDiscountValue() + " off applied";
+        }
+        binding.tvCouponInfo.setText(info);
+        binding.tvCouponInfo.setTextColor(0xFF4CAF50);
+        binding.tvCouponInfo.setVisibility(View.VISIBLE);
+        binding.btnClearCoupon.setVisibility(View.VISIBLE);
+        binding.btnApplyCoupon.setVisibility(View.GONE);
+        binding.etCouponCode.setEnabled(false);
+    }
+
+    private void showCouponError(String message) {
+        binding.tvCouponInfo.setText(message);
+        binding.tvCouponInfo.setTextColor(0xFFE53935);
+        binding.tvCouponInfo.setVisibility(View.VISIBLE);
+    }
+
     private void setupAddItem() {
         binding.btnAddItem.setOnClickListener(v -> {
             if (!InputValidator.isSpinnerSelected(binding.spinnerSaleProduct, "Product")) return;
@@ -228,15 +308,16 @@ public class SaleDetailFragment extends Fragment {
                     break;
                 }
             }
-            addItemRow(name, item.getQuantity(), price);
+            addItemRow(name, item.getQuantity(), price, item.getProdId());
         }
     }
 
-    private void addItemRow(String name, int qty, BigDecimal price) {
+    private void addItemRow(String name, int qty, BigDecimal price, Long prodId) {
         if (getContext() == null) return;
         LinearLayout row = new LinearLayout(getContext());
         row.setOrientation(LinearLayout.HORIZONTAL);
         row.setPadding(0, 8, 0, 8);
+        row.setGravity(android.view.Gravity.CENTER_VERTICAL);
 
         TextView tvName = new TextView(getContext());
         tvName.setLayoutParams(new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.WRAP_CONTENT, 2f));
@@ -253,12 +334,34 @@ public class SaleDetailFragment extends Fragment {
         row.addView(tvName);
         row.addView(tvQty);
         row.addView(tvPrice);
+
+        if (prodId != null) {
+            Button btnRemove = new Button(getContext());
+            btnRemove.setLayoutParams(new LinearLayout.LayoutParams(
+                    LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT));
+            btnRemove.setText("✕");
+            btnRemove.setTextSize(12f);
+            btnRemove.setBackgroundTintList(android.content.res.ColorStateList.valueOf(0xFFE53935));
+            btnRemove.setTextColor(0xFFFFFFFF);
+            btnRemove.setPadding(16, 4, 16, 4);
+            btnRemove.setOnClickListener(v -> viewModel.removeFromCart(prodId));
+            row.addView(btnRemove);
+        }
+
         binding.llSaleItems.addView(row);
     }
 
     private void updateTotal() {
-        BigDecimal total = viewModel.calculateSubtotal();
+        BigDecimal subtotal = viewModel.calculateSubtotal();
-        binding.tvSaleSubtotal.setText("$" + total);
+        BigDecimal discount = viewModel.calculateDiscount();
+        BigDecimal total = subtotal.subtract(discount);
+        binding.tvSaleSubtotal.setText("$" + subtotal);
+        if (discount.compareTo(BigDecimal.ZERO) > 0) {
+            binding.llCouponDiscount.setVisibility(View.VISIBLE);
+            binding.tvSaleCouponDiscount.setText("-$" + discount);
+        } else {
+            binding.llCouponDiscount.setVisibility(View.GONE);
+        }
         binding.tvSaleDetailTotal.setText("Total: $" + total);
     }
 
@@ -279,6 +382,7 @@ public class SaleDetailFragment extends Fragment {
         }
 
         SaleDTO dto = new SaleDTO(store.getId(), payment, viewModel.getCartItems().getValue(), false, null, customerId);
+        dto.setCouponId(viewModel.getAppliedCouponId());
 
         viewModel.createSale(dto).observe(getViewLifecycleOwner(), resource -> {
             if (resource != null) {

android/app/src/main/java/com/example/petstoremobile/repositories/AdoptionRepository.java

@@ -24,8 +24,8 @@ public class AdoptionRepository extends BaseRepository {
     /**
      * Retrieves a paginated list of all adoptions from the API.
      */
-    public LiveData<Resource<PageResponse<AdoptionDTO>>> getAllAdoptions(int page, int size, String query, String status, Long storeId, String date, Long employeeId) {
+    public LiveData<Resource<PageResponse<AdoptionDTO>>> getAllAdoptions(int page, int size, String query, String status, Long storeId, String date, Long employeeId, String sort) {
-        return executeCall(adoptionApi.getAllAdoptions(page, size, query, status, storeId, date, employeeId));
+        return executeCall(adoptionApi.getAllAdoptions(page, size, query, status, storeId, date, employeeId, sort));
     }
 
     /**

android/app/src/main/java/com/example/petstoremobile/repositories/AppointmentRepository.java

@@ -24,8 +24,8 @@ public class AppointmentRepository extends BaseRepository {
     /**
      * Retrieves a paginated list of all appointments from the API with filtering.
      */
-    public LiveData<Resource<PageResponse<AppointmentDTO>>> getAllAppointments(int page, int size, String query, String status, Long storeId, String date, Long employeeId) {
+    public LiveData<Resource<PageResponse<AppointmentDTO>>> getAllAppointments(int page, int size, String query, String status, Long storeId, String date, Long employeeId, String sort) {
-        return executeCall(appointmentApi.getAllAppointments(page, size, query, status, storeId, date, employeeId));
+        return executeCall(appointmentApi.getAllAppointments(page, size, query, status, storeId, date, employeeId, sort));
     }
 
     /**

android/app/src/main/java/com/example/petstoremobile/repositories/CouponRepository.java

@@ -30,6 +30,10 @@ public class CouponRepository extends BaseRepository {
         return executeCall(couponApi.getCouponById(id));
     }
 
+    public LiveData<Resource<CouponDTO>> getCouponByCode(String code) {
+        return executeCall(couponApi.getCouponByCode(code));
+    }
+
     public LiveData<Resource<CouponDTO>> createCoupon(CouponDTO coupon) {
         return executeCall(couponApi.createCoupon(coupon));
     }

android/app/src/main/java/com/example/petstoremobile/repositories/CustomerRepository.java

@@ -23,23 +23,26 @@ public class CustomerRepository extends BaseRepository {
         this.customerApi = customerApi;
     }
 
-    /**
-     * Retrieves a paginated list of all customers from the API.
-     */
     public LiveData<Resource<PageResponse<CustomerDTO>>> getAllCustomers(int page, int size) {
         return executeCall(customerApi.getAllCustomers(page, size));
     }
 
-    /**
-     * Retrieves a specific customer by their ID.
-     */
     public LiveData<Resource<CustomerDTO>> getCustomerById(Long id) {
         return executeCall(customerApi.getCustomerById(id));
     }
 
-    /**
+    public LiveData<Resource<CustomerDTO>> createCustomer(CustomerDTO dto) {
-     * Retrieves a list of customer dropdowns from the API.
+        return executeCall(customerApi.registerCustomer(dto));
-     */
+    }
+
+    public LiveData<Resource<CustomerDTO>> updateCustomer(Long id, CustomerDTO dto) {
+        return executeCall(customerApi.updateCustomer(id, dto));
+    }
+
+    public LiveData<Resource<Void>> deleteCustomer(Long id) {
+        return executeCall(customerApi.deleteCustomer(id));
+    }
+
     public LiveData<Resource<List<DropdownDTO>>> getCustomerDropdowns() {
         return executeCall(customerApi.getCustomerDropdowns());
     }

android/app/src/main/java/com/example/petstoremobile/repositories/PetRepository.java

@@ -54,6 +54,10 @@ public class PetRepository extends BaseRepository {
         return executeCall(petApi.getPetDropdowns());
     }
 
+    public LiveData<Resource<List<DropdownDTO>>> getPetSpeciesDropdowns() {
+        return executeCall(petApi.getPetSpeciesDropdowns());
+    }
+
     /**
      * Retrieves available pets for a specific store.
      */

android/app/src/main/java/com/example/petstoremobile/viewmodels/AdoptionDetailViewModel.java

@@ -13,6 +13,8 @@ import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.DateTimeUtils;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -71,18 +73,17 @@ public class AdoptionDetailViewModel extends ViewModel {
             state.saveButtonText = isEditing ? "Save" : "Add";
             state.isAdoptionIdVisible = isEditing;
             state.isDeleteVisible = isEditing;
-            state.isFeeEnabled = false; // fee is always read-only
+            state.isFeeEnabled = false;
             if (!isEditing) {
                 state.isCustomerEnabled = true;
                 state.isStoreEnabled = true;
-                state.isPetEnabled = false; // until customer selected
+                state.isPetEnabled = false;
-                state.isEmployeeEnabled = false; // until store selected
+                state.isEmployeeEnabled = false;
                 state.isDateEnabled = true;
                 state.isStatusEnabled = true;
                 state.availableStatuses = new String[]{"Pending"};
                 state.selectedStatus = "Pending";
             } else {
-                // edit: date-based logic applied after load
                 state.isCustomerEnabled = false;
                 state.isStoreEnabled = false;
                 state.isPetEnabled = false;
@@ -95,12 +96,12 @@ public class AdoptionDetailViewModel extends ViewModel {
 
     public void loadInitialFormData(boolean isEditing) {
         // Pets are loaded dynamically based on store selection; no pre-load needed.
-        customerRepository.getCustomerDropdowns().observeForever(r -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 customerList.setValue(r.data);
             }
         });
-        storeRepository.getStoreDropdowns().observeForever(r -> {
+        observeOnce(storeRepository.getStoreDropdowns(), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 storeList.setValue(r.data);
             }
@@ -155,7 +156,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadAvailablePetsByStore(Long storeId) {
-        petRepository.getAvailablePetsByStore(storeId).observeForever(r -> {
+        observeOnce(petRepository.getAvailablePetsByStore(storeId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 List<DropdownDTO> dropdowns = new ArrayList<>();
                 for (com.example.petstoremobile.dtos.PetDTO pet : r.data.getContent()) {
@@ -167,7 +168,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadPetPrice(Long petId) {
-        petRepository.getPetById(petId).observeForever(r -> {
+        observeOnce(petRepository.getPetById(petId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 com.example.petstoremobile.dtos.PetDTO pet = r.data;
                 // In edit mode, add the pet to the list so the spinner can display its name
@@ -185,7 +186,7 @@ public class AdoptionDetailViewModel extends ViewModel {
     }
 
     private void loadEmployeesForStore(Long storeId) {
-        storeRepository.getStoreEmployees(storeId).observeForever(r -> {
+        observeOnce(storeRepository.getStoreEmployees(storeId), r -> {
             if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) {
                 employeeList.setValue(r.data);
             }
@@ -217,6 +218,10 @@ public class AdoptionDetailViewModel extends ViewModel {
                 s.isEmployeeEnabled = true;
                 s.isDateEnabled = true;
                 s.isStatusEnabled = true;
+            } else {
+                // Date cleared: disable everything except the date field so user can pick again
+                setAllEditableFieldsEnabled(s, false);
+                s.isDateEnabled = true;
             }
         });
     }
@@ -240,7 +245,7 @@ public class AdoptionDetailViewModel extends ViewModel {
 
     public LiveData<Resource<AdoptionDTO>> loadAdoption() {
         MutableLiveData<Resource<AdoptionDTO>> result = new MutableLiveData<>();
-        adoptionRepository.getAdoptionById(adoptionId).observeForever(resource -> {
+        observeOnce(adoptionRepository.getAdoptionById(adoptionId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 AdoptionDTO a = resource.data;
                 String formattedStatus = DateTimeUtils.formatStatusFromBackend(
@@ -248,10 +253,10 @@ public class AdoptionDetailViewModel extends ViewModel {
                 String adoptionDate = a.getAdoptionDate() != null ? a.getAdoptionDate() : "";
 
                 updateViewState(state -> {
-                    state.selectedPetId = a.getPetId() != null ? a.getPetId() : -1;
+                    state.selectedPetId = a.getPetId();
-                    state.selectedCustomerId = a.getCustomerId() != null ? a.getCustomerId() : -1;
+                    state.selectedCustomerId = a.getCustomerId();
-                    state.selectedStoreId = a.getSourceStoreId() != null ? a.getSourceStoreId() : -1;
+                    state.selectedStoreId = a.getSourceStoreId();
-                    state.selectedEmployeeId = a.getEmployeeId() != null ? a.getEmployeeId() : -1;
+                    state.selectedEmployeeId = a.getEmployeeId();
                     state.adoptionDate = adoptionDate;
                     state.adoptionFee = a.getAdoptionFee() != null ? a.getAdoptionFee().toPlainString() : "";
                     state.selectedStatus = formattedStatus;
@@ -321,6 +326,21 @@ public class AdoptionDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    /**
+     * Observes a LiveData once, removing the observer after the first response.
+     * */
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isAdoptionIdVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/AdoptionListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.AdoptionRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -53,7 +55,7 @@ public class AdoptionListViewModel extends ViewModel {
         if ("All Statuses".equals(status)) status = null;
 
         isLoading.setValue(true);
-        adoptionRepository.getAllAdoptions(currentPage, PAGE_SIZE, query, status, storeId, date, employeeId).observeForever(resource -> {
+        observeOnce(adoptionRepository.getAllAdoptions(currentPage, PAGE_SIZE, query, status, storeId, date, employeeId, "adoptionId,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<AdoptionDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(adoptions.getValue());
@@ -70,13 +72,25 @@ public class AdoptionListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteAdoptions(List<String> ids) {
         return adoptionRepository.bulkDeleteAdoptions(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/AnalyticsViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.SaleDTO;
 import com.example.petstoremobile.repositories.SaleRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 import java.util.ArrayList;
@@ -49,7 +51,7 @@ public class AnalyticsViewModel extends ViewModel {
     public void loadAnalytics() {
         isLoading.setValue(true);
         errorMessage.setValue(null);
-        saleRepository.getAllSales(0, 2000, null, null, null, null, "saleDate,desc").observeForever(resource -> {
+        observeOnce(saleRepository.getAllSales(0, 2000, null, null, null, null, "saleDate,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     cachedSales = resource.data.getContent();
@@ -247,6 +249,18 @@ public class AnalyticsViewModel extends ViewModel {
         return "Daily Revenue (" + s + " – " + e + ")";
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class FilterState {
         public String startDate = "";
         public String endDate = "";

android/app/src/main/java/com/example/petstoremobile/viewmodels/AppointmentDetailViewModel.java

@@ -15,6 +15,8 @@ import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.DateTimeUtils;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -42,6 +44,7 @@ public class AppointmentDetailViewModel extends ViewModel {
 
     private long appointmentId = -1;
     private boolean isOriginallyCancel = false;
+    private boolean isOriginallyCompletedOrMissed = false;
     private Long currentCustomerId;
     private Long currentStoreId;
     private Long currentPetId;
@@ -71,14 +74,14 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads initial dropdown data for customers, stores, and services.
      */
     public void loadInitialFormData() {
-        customerRepository.getCustomerDropdowns().observeForever(r -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), r -> {
-            if (r.status == Resource.Status.SUCCESS) customers.setValue(r.data);
+            if (r != null && r.status == Resource.Status.SUCCESS) customers.setValue(r.data);
         });
-        storeRepository.getStoreDropdowns().observeForever(r -> {
+        observeOnce(storeRepository.getStoreDropdowns(), r -> {
-            if (r.status == Resource.Status.SUCCESS) stores.setValue(r.data);
+            if (r != null && r.status == Resource.Status.SUCCESS) stores.setValue(r.data);
         });
-        serviceRepository.getAllServices(0, 200, null, "serviceName").observeForever(r -> {
+        observeOnce(serviceRepository.getAllServices(0, 200, null, "serviceName"), r -> {
-            if (r.status == Resource.Status.SUCCESS && r.data != null) services.setValue(r.data.getContent());
+            if (r != null && r.status == Resource.Status.SUCCESS && r.data != null) services.setValue(r.data.getContent());
         });
     }
 
@@ -206,8 +209,8 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads the list of pets for a specific customer.
      */
     private void loadPetsForCustomer(Long customerId) {
-        petRepository.getCustomerPets(customerId).observeForever(r -> {
+        observeOnce(petRepository.getCustomerPets(customerId), r -> {
-            if (r.status == Resource.Status.SUCCESS) customerPets.setValue(r.data);
+            if (r != null && r.status == Resource.Status.SUCCESS) customerPets.setValue(r.data);
         });
     }
 
@@ -215,8 +218,8 @@ public class AppointmentDetailViewModel extends ViewModel {
      * Loads the list of employees for a specific store.
      */
     private void loadEmployeesForStore(Long storeId) {
-        storeRepository.getStoreEmployees(storeId).observeForever(r -> {
+        observeOnce(storeRepository.getStoreEmployees(storeId), r -> {
-            if (r.status == Resource.Status.SUCCESS) storeEmployees.setValue(r.data);
+            if (r != null && r.status == Resource.Status.SUCCESS) storeEmployees.setValue(r.data);
         });
     }
 
@@ -227,10 +230,12 @@ public class AppointmentDetailViewModel extends ViewModel {
      */
     public LiveData<Resource<AppointmentDTO>> loadAppointment() {
         MutableLiveData<Resource<AppointmentDTO>> result = new MutableLiveData<>();
-        repository.getAppointmentById(appointmentId).observeForever(resource -> {
+        observeOnce(repository.getAppointmentById(appointmentId), resource -> {
-            if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
+            if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 AppointmentDTO a = resource.data;
                 isOriginallyCancel = "CANCELLED".equalsIgnoreCase(a.getAppointmentStatus());
+                isOriginallyCompletedOrMissed = "COMPLETED".equalsIgnoreCase(a.getAppointmentStatus())
+                        || "MISSED".equalsIgnoreCase(a.getAppointmentStatus());
                 currentCustomerId = a.getCustomerId();
                 currentStoreId = a.getStoreId();
                 currentPetId = a.getPetId();
@@ -282,21 +287,18 @@ public class AppointmentDetailViewModel extends ViewModel {
     public void onDateOrTimeChanged(String date, String time, String currentStatus) {
         updateViewState(s -> {
             s.availableStatuses = calculateAvailableStatuses(s.isEditing, date, time, currentStatus);
-            // Keep selectedStatus if still valid; prefer explicit currentStatus from UI if valid
             java.util.List<String> available = java.util.Arrays.asList(s.availableStatuses);
             if (!currentStatus.isEmpty() && available.contains(currentStatus)) {
                 s.selectedStatus = currentStatus;
             } else if (!available.contains(s.selectedStatus) && s.availableStatuses.length > 0) {
                 s.selectedStatus = s.availableStatuses[0];
             }
-            boolean isPast = DateTimeUtils.isDateTimeInPast(date, time);
-
             if (isOriginallyCancel) {
                 s.isPast = true;
                 setAllFieldsEnabled(s, false);
                 s.isStatusEnabled = false;
                 s.isSaveVisible = false;
-            } else if (isPast) {
+            } else if (isOriginallyCompletedOrMissed) {
                 s.isPast = true;
                 setAllFieldsEnabled(s, false);
                 s.isStatusEnabled = true;
@@ -322,7 +324,7 @@ public class AppointmentDetailViewModel extends ViewModel {
         if (!isEditing) return new String[]{"Booked"};
         if (date == null || date.isEmpty()) return new String[]{};
         if (isOriginallyCancel) return new String[]{"Cancelled"};
-        if (DateTimeUtils.isDateTimeInPast(date, currentTime)) return new String[]{"Completed", "Missed"};
+        if (isOriginallyCompletedOrMissed) return new String[]{"Completed", "Missed"};
         return new String[]{"Booked", "Cancelled"};
     }
 
@@ -355,8 +357,8 @@ public class AppointmentDetailViewModel extends ViewModel {
                 s.isCustomerEnabled = true;
                 s.isStoreEnabled = true;
                 s.isServiceEnabled = true;
-                s.isPetEnabled = false; // until customer selected
+                s.isPetEnabled = false;
-                s.isStaffEnabled = false; // until store selected
+                s.isStaffEnabled = false;
                 s.availableStatuses = new String[]{"Booked"};
                 s.selectedStatus = "Booked";
             }
@@ -385,6 +387,19 @@ public class AppointmentDetailViewModel extends ViewModel {
         void run(T t);
     }
 
+    /** Observes a LiveData once, removing the observer after the first non-loading response. */
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     /**
      * A Class to show the states of Appointment Detail Fragment.
      */

android/app/src/main/java/com/example/petstoremobile/viewmodels/AppointmentListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.AppointmentRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -39,7 +41,7 @@ public class AppointmentListViewModel extends ViewModel {
 
     public void loadAppointments(String query, String status, Long storeId, String date, Long employeeId) {
         isLoading.setValue(true);
-        appointmentRepository.getAllAppointments(0, 500, query, status, storeId, date, employeeId).observeForever(resource -> {
+        observeOnce(appointmentRepository.getAllAppointments(0, 500, query, status, storeId, date, employeeId, "appointmentId,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     appointments.setValue(resource.data.getContent());
@@ -52,13 +54,25 @@ public class AppointmentListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteAppointments(List<String> ids) {
         return appointmentRepository.bulkDeleteAppointments(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/CouponListViewModel.java

@@ -9,6 +9,8 @@ import com.example.petstoremobile.dtos.PageResponse;
 import com.example.petstoremobile.repositories.CouponRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -32,7 +34,7 @@ public class CouponListViewModel extends ViewModel {
 
     public void loadCoupons(int page, int size, Boolean active, String discountType, String sort) {
         isLoading.setValue(true);
-        repository.getAllCoupons(page, size, active, discountType, sort).observeForever(resource -> {
+        observeOnce(repository.getAllCoupons(page, size, active, discountType, sort), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     coupons.setValue(resource.data.getContent());
@@ -44,6 +46,18 @@ public class CouponListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteCoupons(List<Long> ids) {
         return repository.bulkDeleteCoupons(ids);
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/CustomerDetailViewModel.java

@@ -0,0 +1,49 @@
+package com.example.petstoremobile.viewmodels;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.ViewModel;
+
+import com.example.petstoremobile.dtos.CustomerDTO;
+import com.example.petstoremobile.repositories.CustomerRepository;
+import com.example.petstoremobile.utils.Resource;
+
+import javax.inject.Inject;
+
+import dagger.hilt.android.lifecycle.HiltViewModel;
+
+@HiltViewModel
+public class CustomerDetailViewModel extends ViewModel {
+    private final CustomerRepository repository;
+
+    private long customerId = -1;
+    private boolean isEditing = false;
+
+    @Inject
+    public CustomerDetailViewModel(CustomerRepository repository) {
+        this.repository = repository;
+    }
+
+    public void setCustomerId(long id, boolean isEditing) {
+        this.customerId = id;
+        this.isEditing = isEditing;
+    }
+
+    public long getCustomerId() { return customerId; }
+    public boolean isEditing() { return isEditing; }
+
+    public LiveData<Resource<CustomerDTO>> loadCustomer(long id) {
+        return repository.getCustomerById(id);
+    }
+
+    public LiveData<Resource<CustomerDTO>> saveCustomer(CustomerDTO dto) {
+        if (isEditing && customerId > 0) {
+            return repository.updateCustomer(customerId, dto);
+        } else {
+            return repository.createCustomer(dto);
+        }
+    }
+
+    public LiveData<Resource<Void>> deleteCustomer() {
+        return repository.deleteCustomer(customerId);
+    }
+}

android/app/src/main/java/com/example/petstoremobile/viewmodels/CustomerListViewModel.java

@@ -0,0 +1,93 @@
+package com.example.petstoremobile.viewmodels;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.ViewModel;
+
+import com.example.petstoremobile.dtos.CustomerDTO;
+import com.example.petstoremobile.repositories.CustomerRepository;
+import com.example.petstoremobile.utils.Resource;
+
+import androidx.lifecycle.Observer;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.inject.Inject;
+
+import dagger.hilt.android.lifecycle.HiltViewModel;
+
+@HiltViewModel
+public class CustomerListViewModel extends ViewModel {
+    private final CustomerRepository repository;
+
+    private final MutableLiveData<List<CustomerDTO>> customers = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<List<CustomerDTO>> filteredCustomers = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<Boolean> isLoading = new MutableLiveData<>(false);
+
+    private String lastQuery = "";
+    private String lastStatus = "All Statuses";
+
+    @Inject
+    public CustomerListViewModel(CustomerRepository repository) {
+        this.repository = repository;
+    }
+
+    public LiveData<List<CustomerDTO>> getFilteredCustomers() { return filteredCustomers; }
+    public LiveData<Boolean> getIsLoading() { return isLoading; }
+
+    public void loadCustomers() {
+        isLoading.setValue(true);
+        observeOnce(repository.getAllCustomers(0, 200), resource -> {
+            if (resource != null) {
+                if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
+                    customers.setValue(resource.data.getContent());
+                    filter(lastQuery, lastStatus);
+                    isLoading.setValue(false);
+                } else if (resource.status == Resource.Status.ERROR) {
+                    isLoading.setValue(false);
+                }
+            }
+        });
+    }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
+    public void filter(String query, String status) {
+        this.lastQuery = query;
+        this.lastStatus = status;
+
+        List<CustomerDTO> all = customers.getValue();
+        if (all == null) return;
+
+        List<CustomerDTO> filtered = new ArrayList<>();
+        String lowerQuery = query.toLowerCase();
+
+        for (CustomerDTO c : all) {
+            boolean matchesQuery = query.isEmpty() ||
+                    (c.getFullName() != null && c.getFullName().toLowerCase().contains(lowerQuery)) ||
+                    (c.getUsername() != null && c.getUsername().toLowerCase().contains(lowerQuery)) ||
+                    (c.getEmail() != null && c.getEmail().toLowerCase().contains(lowerQuery)) ||
+                    (c.getPhone() != null && c.getPhone().toLowerCase().contains(lowerQuery));
+
+            boolean matchesStatus = status.equals("All Statuses") ||
+                    (status.equals("Active") && Boolean.TRUE.equals(c.getActive())) ||
+                    (status.equals("Inactive") && Boolean.FALSE.equals(c.getActive()));
+
+            if (matchesQuery && matchesStatus) {
+                filtered.add(c);
+            }
+        }
+        filteredCustomers.setValue(filtered);
+    }
+}

android/app/src/main/java/com/example/petstoremobile/viewmodels/InventoryListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.InventoryRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -51,7 +53,7 @@ public class InventoryListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        inventoryRepository.getAllInventory(query, storeId, currentPage, PAGE_SIZE, "product.prodName").observeForever(resource -> {
+        observeOnce(inventoryRepository.getAllInventory(query, storeId, currentPage, PAGE_SIZE, "product.prodName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<InventoryDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(inventory.getValue());
@@ -68,13 +70,25 @@ public class InventoryListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteInventory(List<String> ids) {
         return inventoryRepository.bulkDeleteInventory(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/PetDetailViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.PetRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -30,12 +32,16 @@ public class PetDetailViewModel extends ViewModel {
 
     private final MutableLiveData<List<DropdownDTO>> customerList = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<List<DropdownDTO>> storeList = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<List<DropdownDTO>> speciesList = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<Boolean> isLoading = new MutableLiveData<>(false);
     private final MutableLiveData<ViewState> viewState = new MutableLiveData<>(new ViewState());
 
     private long petId = -1;
     private Long selectedCustomerId = null;
     private Long selectedStoreId = null;
+    private String selectedSpecies = null;
+    private boolean isOriginallyOwnedOrAdopted = false;
+    private Long originalCustomerId = null;
 
     @Inject
     public PetDetailViewModel(PetRepository petRepository, CustomerRepository customerRepository, StoreRepository storeRepository) {
@@ -45,17 +51,23 @@ public class PetDetailViewModel extends ViewModel {
     }
 
     public void loadInitialFormData() {
-        customerRepository.getCustomerDropdowns().observeForever(resource -> {
+        observeOnce(customerRepository.getCustomerDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 customerList.setValue(resource.data);
             }
         });
 
-        storeRepository.getStoreDropdowns().observeForever(resource -> {
+        observeOnce(storeRepository.getStoreDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 storeList.setValue(resource.data);
             }
         });
+
+        observeOnce(petRepository.getPetSpeciesDropdowns(), resource -> {
+            if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
+                speciesList.setValue(resource.data);
+            }
+        });
     }
 
     public void setPetId(long id) {
@@ -72,6 +84,14 @@ public class PetDetailViewModel extends ViewModel {
         return current != null && current.isEditing;
     }
 
+    public boolean isOriginallyOwnedOrAdopted() {
+        return isOriginallyOwnedOrAdopted;
+    }
+
+    public Long getOriginalCustomerId() {
+        return originalCustomerId;
+    }
+
     public LiveData<ViewState> getViewState() {
         return viewState;
     }
@@ -87,6 +107,16 @@ public class PetDetailViewModel extends ViewModel {
         updateViewState(state -> state.selectedCustomerId = selectedCustomerId);
     }
 
+    public void onSpeciesSelected(int position) {
+        List<DropdownDTO> list = speciesList.getValue();
+        if (position > 0 && list != null && position <= list.size()) {
+            selectedSpecies = list.get(position - 1).getLabel();
+        } else {
+            selectedSpecies = null;
+        }
+        updateViewState(state -> state.selectedSpecies = selectedSpecies);
+    }
+
     public void onStoreSelected(int position) {
         List<DropdownDTO> list = storeList.getValue();
         if (position > 0 && list != null && position <= list.size()) {
@@ -123,8 +153,10 @@ public class PetDetailViewModel extends ViewModel {
             if (!isEditing) {
                 selectedCustomerId = null;
                 selectedStoreId = null;
+                selectedSpecies = null;
                 state.selectedCustomerId = null;
                 state.selectedStoreId = null;
+                state.selectedSpecies = null;
                 state.selectedStatus = STATUS_AVAILABLE;
                 state.isCustomerEnabled = false;
                 state.isStoreEnabled = true;
@@ -134,15 +166,20 @@ public class PetDetailViewModel extends ViewModel {
 
     public LiveData<Resource<PetDTO>> loadPet() {
         MutableLiveData<Resource<PetDTO>> result = new MutableLiveData<>();
-        petRepository.getPetById(petId).observeForever(resource -> {
+        observeOnce(petRepository.getPetById(petId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 PetDTO pet = resource.data;
                 selectedCustomerId = pet.getCustomerId();
                 selectedStoreId = pet.getStoreId();
+                selectedSpecies = pet.getPetSpecies();
+                isOriginallyOwnedOrAdopted = STATUS_OWNED.equalsIgnoreCase(pet.getPetStatus())
+                        || STATUS_ADOPTED.equalsIgnoreCase(pet.getPetStatus());
+                originalCustomerId = pet.getCustomerId();
 
                 updateViewState(state -> {
                     state.selectedCustomerId = selectedCustomerId;
                     state.selectedStoreId = selectedStoreId;
+                    state.selectedSpecies = selectedSpecies;
                     state.selectedStatus = normalizeStatus(pet.getPetStatus());
                     applyStatusRules(state, false);
                 });
@@ -174,6 +211,10 @@ public class PetDetailViewModel extends ViewModel {
         return storeList;
     }
 
+    public LiveData<List<DropdownDTO>> getSpeciesList() {
+        return speciesList;
+    }
+
     public LiveData<Boolean> getIsLoading() {
         return isLoading;
     }
@@ -227,6 +268,17 @@ public class PetDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 
     public static class ViewState {
         public boolean isEditing = false;
@@ -240,6 +292,7 @@ public class PetDetailViewModel extends ViewModel {
         public String saveButtonText = "Add";
         public String[] availableStatuses = new String[]{STATUS_AVAILABLE, STATUS_ADOPTED, STATUS_OWNED};
         public String selectedStatus = STATUS_AVAILABLE;
+        public String selectedSpecies = null;
         public Long selectedCustomerId = null;
         public Long selectedStoreId = null;
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/PetListViewModel.java

@@ -5,6 +5,7 @@ import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
 import com.example.petstoremobile.dtos.BulkDeleteRequest;
+import com.example.petstoremobile.dtos.DropdownDTO;
 import com.example.petstoremobile.dtos.PageResponse;
 import com.example.petstoremobile.dtos.PetDTO;
 import com.example.petstoremobile.dtos.StoreDTO;
@@ -12,6 +13,8 @@ import com.example.petstoremobile.repositories.PetRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -26,6 +29,7 @@ public class PetListViewModel extends ViewModel {
 
     private final MutableLiveData<List<PetDTO>> pets = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<List<StoreDTO>> stores = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<List<String>> speciesOptions = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<Boolean> isLoading = new MutableLiveData<>(false);
 
     @Inject
@@ -36,6 +40,7 @@ public class PetListViewModel extends ViewModel {
 
     public LiveData<List<PetDTO>> getPets() { return pets; }
     public LiveData<List<StoreDTO>> getStores() { return stores; }
+    public LiveData<List<String>> getSpeciesOptions() { return speciesOptions; }
     public LiveData<Boolean> getIsLoading() { return isLoading; }
 
     public void loadPets(String query, String status, String species, Long storeId) {
@@ -43,7 +48,7 @@ public class PetListViewModel extends ViewModel {
         if ("All Species".equals(species)) species = null;
 
         isLoading.setValue(true);
-        petRepository.getAllPets(0, 100, query, status, species, storeId, null, "petName").observeForever(resource -> {
+        observeOnce(petRepository.getAllPets(0, 100, query, status, species, storeId, null, "petName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     pets.setValue(resource.data.getContent());
@@ -55,14 +60,39 @@ public class PetListViewModel extends ViewModel {
         });
     }
 
+    public void loadSpecies() {
+        observeOnce(petRepository.getPetSpeciesDropdowns(), resource -> {
+            if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
+                List<String> labels = new ArrayList<>();
+                labels.add("All Species");
+                for (DropdownDTO dto : resource.data) {
+                    labels.add(dto.getLabel());
+                }
+                speciesOptions.setValue(labels);
+            }
+        });
+    }
+
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeletePets(List<String> ids) {
         return petRepository.bulkDeletePets(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ProductListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.CategoryRepository;
 import com.example.petstoremobile.repositories.ProductRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -38,7 +40,7 @@ public class ProductListViewModel extends ViewModel {
 
     public void loadProducts(String query, Long categoryId) {
         isLoading.setValue(true);
-        productRepository.getAllProducts(query, categoryId, 0, 100, "prodName").observeForever(resource -> {
+        observeOnce(productRepository.getAllProducts(query, categoryId, 0, 100, "prodName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     products.setValue(resource.data.getContent());
@@ -51,10 +53,22 @@ public class ProductListViewModel extends ViewModel {
     }
 
     public void loadCategories() {
-        productRepository.getCategoryDropdowns().observeForever(resource -> {
+        observeOnce(productRepository.getCategoryDropdowns(), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 categories.setValue(resource.data);
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ProductSupplierListViewModel.java

@@ -13,6 +13,8 @@ import com.example.petstoremobile.repositories.ProductSupplierRepository;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -45,7 +47,7 @@ public class ProductSupplierListViewModel extends ViewModel {
 
     public void loadProductSuppliers(String query, Long productId, Long supplierId) {
         isLoading.setValue(true);
-        psRepository.getAllProductSuppliers(0, 100, query, productId, supplierId, "productName").observeForever(resource -> {
+        observeOnce(psRepository.getAllProductSuppliers(0, 100, query, productId, supplierId, "productName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     productSuppliers.setValue(resource.data.getContent());
@@ -58,19 +60,31 @@ public class ProductSupplierListViewModel extends ViewModel {
     }
 
     public void loadFilterData() {
-        productRepository.getAllProducts(null, null, 0, 100, "prodName").observeForever(resource -> {
+        observeOnce(productRepository.getAllProducts(null, null, 0, 100, "prodName"), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 products.setValue(resource.data.getContent());
             }
         });
 
-        supplierRepository.getAllSuppliers(0, 100, null, "supCompany").observeForever(resource -> {
+        observeOnce(supplierRepository.getAllSuppliers(0, 100, null, "supCompany"), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 suppliers.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteProductSuppliers(List<String> ids) {
         return psRepository.bulkDeleteProductSuppliers(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/PurchaseOrderListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.PurchaseOrderRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -38,7 +40,7 @@ public class PurchaseOrderListViewModel extends ViewModel {
 
     public void loadPurchaseOrders(String query, Long storeId) {
         isLoading.setValue(true);
-        purchaseOrderRepository.getAllPurchaseOrders(0, 100, query, storeId, "purchaseOrderId,desc").observeForever(resource -> {
+        observeOnce(purchaseOrderRepository.getAllPurchaseOrders(0, 100, query, storeId, "purchaseOrderId,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     purchaseOrders.setValue(resource.data.getContent());
@@ -51,10 +53,22 @@ public class PurchaseOrderListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/SaleDetailViewModel.java

@@ -4,9 +4,11 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
+import com.example.petstoremobile.dtos.CouponDTO;
 import com.example.petstoremobile.dtos.DropdownDTO;
 import com.example.petstoremobile.dtos.ProductDTO;
 import com.example.petstoremobile.dtos.SaleDTO;
+import com.example.petstoremobile.repositories.CouponRepository;
 import com.example.petstoremobile.repositories.CustomerRepository;
 import com.example.petstoremobile.repositories.ProductRepository;
 import com.example.petstoremobile.repositories.SaleRepository;
@@ -27,6 +29,7 @@ public class SaleDetailViewModel extends ViewModel {
     private final StoreRepository storeRepository;
     private final CustomerRepository customerRepository;
     private final ProductRepository productRepository;
+    private final CouponRepository couponRepository;
 
     private long saleId = -1;
     private boolean viewOnly = false;
@@ -35,15 +38,18 @@ public class SaleDetailViewModel extends ViewModel {
     private final MutableLiveData<List<DropdownDTO>> customerList = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<List<ProductDTO>> productList = new MutableLiveData<>(new ArrayList<>());
     private final MutableLiveData<List<SaleDTO.SaleItemDTO>> cartItems = new MutableLiveData<>(new ArrayList<>());
+    private final MutableLiveData<CouponDTO> appliedCoupon = new MutableLiveData<>(null);
     private final MutableLiveData<Boolean> isLoading = new MutableLiveData<>(false);
 
     @Inject
     public SaleDetailViewModel(SaleRepository saleRepository, StoreRepository storeRepository,
-                               CustomerRepository customerRepository, ProductRepository productRepository) {
+                               CustomerRepository customerRepository, ProductRepository productRepository,
+                               CouponRepository couponRepository) {
         this.saleRepository = saleRepository;
         this.storeRepository = storeRepository;
         this.customerRepository = customerRepository;
         this.productRepository = productRepository;
+        this.couponRepository = couponRepository;
     }
 
     public void setSaleId(long id, boolean viewOnly) {
@@ -89,8 +95,46 @@ public class SaleDetailViewModel extends ViewModel {
         cartItems.setValue(currentCart);
     }
 
+    public void removeFromCart(Long prodId) {
+        List<SaleDTO.SaleItemDTO> currentCart = new ArrayList<>(cartItems.getValue());
+        currentCart.removeIf(item -> item.getProdId().equals(prodId));
+        cartItems.setValue(currentCart);
+    }
+
     public LiveData<List<SaleDTO.SaleItemDTO>> getCartItems() { return cartItems; }
 
+    public LiveData<Resource<CouponDTO>> lookupCoupon(String code) {
+        return couponRepository.getCouponByCode(code);
+    }
+
+    public void setAppliedCoupon(CouponDTO coupon) {
+        appliedCoupon.setValue(coupon);
+    }
+
+    public void clearCoupon() {
+        appliedCoupon.setValue(null);
+    }
+
+    public LiveData<CouponDTO> getAppliedCoupon() {
+        return appliedCoupon;
+    }
+
+    public Long getAppliedCouponId() {
+        CouponDTO coupon = appliedCoupon.getValue();
+        return coupon != null ? coupon.getCouponId() : null;
+    }
+
+    public BigDecimal calculateDiscount() {
+        CouponDTO coupon = appliedCoupon.getValue();
+        if (coupon == null || coupon.getDiscountValue() == null) return BigDecimal.ZERO;
+        BigDecimal subtotal = calculateSubtotal();
+        if ("PERCENTAGE".equalsIgnoreCase(coupon.getDiscountType())) {
+            return subtotal.multiply(coupon.getDiscountValue()).divide(BigDecimal.valueOf(100), 2, java.math.RoundingMode.HALF_UP);
+        } else {
+            return coupon.getDiscountValue().min(subtotal);
+        }
+    }
+
     public BigDecimal calculateSubtotal() {
         BigDecimal total = BigDecimal.ZERO;
         List<SaleDTO.SaleItemDTO> items = cartItems.getValue();

android/app/src/main/java/com/example/petstoremobile/viewmodels/SaleListViewModel.java

@@ -11,6 +11,8 @@ import com.example.petstoremobile.repositories.SaleRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -51,7 +53,7 @@ public class SaleListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        saleRepository.getAllSales(currentPage, PAGE_SIZE, query, paymentMethod, storeId, isRefund, "saleDate,desc").observeForever(resource -> {
+        observeOnce(saleRepository.getAllSales(currentPage, PAGE_SIZE, query, paymentMethod, storeId, isRefund, "saleDate,desc"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<SaleDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(sales.getValue());
@@ -68,10 +70,22 @@ public class SaleListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
+
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
 }

android/app/src/main/java/com/example/petstoremobile/viewmodels/ServiceDetailViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.ServiceDTO;
 import com.example.petstoremobile.repositories.ServiceRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import javax.inject.Inject;
 
 import dagger.hilt.android.lifecycle.HiltViewModel;
@@ -55,7 +57,7 @@ public class ServiceDetailViewModel extends ViewModel {
 
     public LiveData<Resource<ServiceDTO>> loadService() {
         MutableLiveData<Resource<ServiceDTO>> result = new MutableLiveData<>();
-        repository.getServiceById(serviceId).observeForever(resource -> {
+        observeOnce(repository.getServiceById(serviceId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 ServiceDTO service = resource.data;
                 updateViewState(state -> {
@@ -106,6 +108,18 @@ public class ServiceDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isDeleteVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/ServiceListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.dtos.ServiceDTO;
 import com.example.petstoremobile.repositories.ServiceRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -46,7 +48,7 @@ public class ServiceListViewModel extends ViewModel {
         }
 
         isLoading.setValue(true);
-        repository.getAllServices(currentPage, PAGE_SIZE, query, "serviceName").observeForever(resource -> {
+        observeOnce(repository.getAllServices(currentPage, PAGE_SIZE, query, "serviceName"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     List<ServiceDTO> currentList = reset ? new ArrayList<>() : new ArrayList<>(services.getValue());
@@ -62,6 +64,18 @@ public class ServiceListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteServices(List<String> ids) {
         return repository.bulkDeleteServices(new BulkDeleteRequest(ids));
     }

android/app/src/main/java/com/example/petstoremobile/viewmodels/StaffListViewModel.java

@@ -10,6 +10,8 @@ import com.example.petstoremobile.repositories.EmployeeRepository;
 import com.example.petstoremobile.repositories.StoreRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -42,7 +44,7 @@ public class StaffListViewModel extends ViewModel {
 
     public void loadStaff() {
         isLoading.setValue(true);
-        repository.getAllEmployees(0, 100).observeForever(resource -> {
+        observeOnce(repository.getAllEmployees(0, 100), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     employees.setValue(resource.data.getContent());
@@ -56,13 +58,25 @@ public class StaffListViewModel extends ViewModel {
     }
 
     public void loadStores() {
-        storeRepository.getAllStores(0, 100).observeForever(resource -> {
+        observeOnce(storeRepository.getAllStores(0, 100), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 stores.setValue(resource.data.getContent());
             }
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public void filter(String query, Long storeId, String status) {
         this.lastQuery = query;
         this.lastStoreId = storeId;

android/app/src/main/java/com/example/petstoremobile/viewmodels/SupplierDetailViewModel.java

@@ -8,6 +8,8 @@ import com.example.petstoremobile.dtos.SupplierDTO;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import javax.inject.Inject;
 
 import dagger.hilt.android.lifecycle.HiltViewModel;
@@ -55,7 +57,7 @@ public class SupplierDetailViewModel extends ViewModel {
 
     public LiveData<Resource<SupplierDTO>> loadSupplier() {
         MutableLiveData<Resource<SupplierDTO>> result = new MutableLiveData<>();
-        repository.getSupplierById(supId).observeForever(resource -> {
+        observeOnce(repository.getSupplierById(supId), resource -> {
             if (resource != null && resource.status == Resource.Status.SUCCESS && resource.data != null) {
                 SupplierDTO s = resource.data;
                 updateViewState(state -> {
@@ -99,6 +101,18 @@ public class SupplierDetailViewModel extends ViewModel {
         void run(T target);
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public static class ViewState {
         public boolean isEditing = false;
         public boolean isDeleteVisible = false;

android/app/src/main/java/com/example/petstoremobile/viewmodels/SupplierListViewModel.java

@@ -9,6 +9,8 @@ import com.example.petstoremobile.dtos.SupplierDTO;
 import com.example.petstoremobile.repositories.SupplierRepository;
 import com.example.petstoremobile.utils.Resource;
 
+import androidx.lifecycle.Observer;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -33,7 +35,7 @@ public class SupplierListViewModel extends ViewModel {
 
     public void loadSuppliers(String query) {
         isLoading.setValue(true);
-        repository.getAllSuppliers(0, 100, query, "supCompany").observeForever(resource -> {
+        observeOnce(repository.getAllSuppliers(0, 100, query, "supCompany"), resource -> {
             if (resource != null) {
                 if (resource.status == Resource.Status.SUCCESS && resource.data != null) {
                     suppliers.setValue(resource.data.getContent());
@@ -45,6 +47,18 @@ public class SupplierListViewModel extends ViewModel {
         });
     }
 
+    private <T> void observeOnce(LiveData<Resource<T>> liveData, Observer<Resource<T>> handler) {
+        liveData.observeForever(new Observer<Resource<T>>() {
+            @Override
+            public void onChanged(Resource<T> resource) {
+                if (resource == null || resource.status != Resource.Status.LOADING) {
+                    liveData.removeObserver(this);
+                }
+                handler.onChanged(resource);
+            }
+        });
+    }
+
     public LiveData<Resource<Void>> bulkDeleteSuppliers(List<String> ids) {
         return repository.bulkDeleteSuppliers(new BulkDeleteRequest(ids));
     }

android/app/src/main/res/layout/activity_forgot_password.xml

@@ -0,0 +1,93 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/forgot_password_root"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical"
+    android:background="@color/primary_dark"
+    android:padding="32dp">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:gravity="center"
+        android:orientation="vertical">
+
+        <ImageView
+            android:layout_width="120dp"
+            android:layout_height="120dp"
+            android:layout_marginBottom="24dp"
+            android:scaleType="fitCenter"
+            android:src="@drawable/petstore_logo" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Forgot Password"
+            android:textColor="@color/white"
+            android:textSize="24sp"
+            android:textStyle="bold"
+            android:layout_marginBottom="8dp"/>
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Enter your email to reset your password"
+            android:textColor="@color/text_light"
+            android:textSize="14sp"
+            android:textAlignment="center"/>
+
+    </LinearLayout>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:background="@color/white"
+        android:padding="24dp"
+        android:elevation="4dp">
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="Email Address"
+            android:textColor="@color/text_dark"
+            android:textSize="12sp"
+            android:layout_marginBottom="4dp"/>
+
+        <EditText
+            android:id="@+id/etEmail"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:hint="example@email.com"
+            android:inputType="textEmailAddress"
+            android:layout_marginBottom="24dp"
+            android:textColor="@color/text_dark"/>
+
+        <Button
+            android:id="@+id/btnSubmit"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="Send Reset Link"
+            android:backgroundTint="@color/accent_coral"
+            android:textColor="@color/white"
+            android:textSize="16sp"/>
+
+        <Button
+            android:id="@+id/btnBackToLogin"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:text="Back to Login"
+            style="@style/Widget.MaterialComponents.Button.TextButton"
+            android:textColor="@color/accent_blue"
+            android:layout_marginTop="8dp"/>
+
+    </LinearLayout>
+
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_weight="0.5"/>
+
+</LinearLayout>

android/app/src/main/res/layout/activity_main.xml

@@ -109,6 +109,18 @@
             android:textColor="@color/white"
             android:textSize="16sp"/>
 
+        <TextView
+            android:id="@+id/tvForgotPassword"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center"
+            android:layout_marginTop="16dp"
+            android:text="Forgot your password?"
+            android:textColor="@color/accent_blue"
+            android:textSize="14sp"
+            android:clickable="true"
+            android:focusable="true"/>
+
     </LinearLayout>
 
 </LinearLayout>

android/app/src/main/res/layout/fragment_coupon_detail.xml

@@ -60,6 +60,17 @@
                     android:padding="16dp"
                     android:layout_marginBottom="16dp">
 
+                    <TextView
+                        android:id="@+id/tvCouponId"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:textColor="@color/text_light"
+                        android:textSize="11sp"
+                        android:textStyle="italic"
+                        android:layout_gravity="end"
+                        android:layout_marginBottom="8dp"
+                        android:visibility="gone"/>
+
                     <!-- Coupon Code -->
                     <TextView
                         android:layout_width="wrap_content"

android/app/src/main/res/layout/fragment_customer.xml

@@ -0,0 +1,131 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/background_grey">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <LinearLayout
+            android:id="@+id/headerCustomer"
+            android:layout_width="match_parent"
+            android:layout_height="56dp"
+            android:background="@color/primary_dark"
+            android:gravity="center_vertical"
+            android:paddingStart="16dp"
+            android:paddingEnd="16dp">
+
+            <ImageButton
+                android:id="@+id/btnHamburgerCustomer"
+                android:layout_width="48dp"
+                android:layout_height="48dp"
+                android:src="@drawable/baseline_menu_36"
+                android:background="?attr/selectableItemBackgroundBorderless"
+                android:contentDescription="Open menu"/>
+
+            <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Customers"
+                android:textColor="@color/white"
+                android:textSize="20sp"
+                android:textStyle="bold"
+                android:layout_marginStart="8dp"/>
+
+            <ImageButton
+                android:id="@+id/btnToggleFilterCustomer"
+                android:layout_width="48dp"
+                android:layout_height="48dp"
+                android:src="@android:drawable/ic_menu_search"
+                android:background="?attr/selectableItemBackgroundBorderless"
+                app:tint="@color/white"
+                android:contentDescription="Toggle filter"/>
+
+        </LinearLayout>
+
+        <LinearLayout
+            android:id="@+id/layoutFilterCustomer"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:paddingStart="12dp"
+            android:paddingEnd="12dp"
+            android:paddingTop="10dp"
+            android:paddingBottom="10dp"
+            android:visibility="gone"
+            android:background="@color/primary_dark"
+            android:elevation="4dp">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="44dp"
+                android:background="@drawable/bg_search_bar"
+                android:gravity="center_vertical"
+                android:paddingStart="12dp"
+                android:paddingEnd="12dp">
+
+                <ImageView
+                    android:layout_width="18dp"
+                    android:layout_height="18dp"
+                    android:src="@android:drawable/ic_menu_search"
+                    android:alpha="0.6"/>
+
+                <EditText
+                    android:id="@+id/etSearchCustomer"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:hint="Search customers..."
+                    android:inputType="text"
+                    android:background="@android:color/transparent"
+                    android:textColor="@color/text_dark"
+                    android:textColorHint="#99000000"
+                    android:textSize="14sp"
+                    android:paddingStart="8dp"
+                    android:paddingEnd="8dp"/>
+
+            </LinearLayout>
+
+            <Spinner
+                android:id="@+id/spinnerStatusCustomer"
+                android:layout_width="match_parent"
+                android:layout_height="44dp"
+                android:background="@drawable/bg_spinner"
+                android:paddingStart="12dp"
+                android:paddingEnd="8dp"
+                android:layout_marginTop="8dp"/>
+
+        </LinearLayout>
+
+        <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+            android:id="@+id/swipeRefreshCustomer"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent">
+
+            <androidx.recyclerview.widget.RecyclerView
+                android:id="@+id/recyclerViewCustomer"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:padding="8dp"/>
+
+        </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
+
+    </LinearLayout>
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/fabAddCustomer"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|end"
+        android:layout_margin="16dp"
+        android:backgroundTint="@color/accent_coral"
+        android:contentDescription="Add Customer"
+        app:srcCompat="@android:drawable/ic_input_add"
+        app:tint="@color/white"/>
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

android/app/src/main/res/layout/fragment_customer_detail.xml

@@ -0,0 +1,252 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical"
+        android:background="@color/background_grey">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="56dp"
+            android:background="@color/primary_dark"
+            android:gravity="center_vertical"
+            android:paddingStart="16dp"
+            android:paddingEnd="16dp"
+            android:orientation="horizontal">
+
+            <TextView
+                android:id="@+id/tvCustomerMode"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Add Customer"
+                android:textColor="@color/white"
+                android:textSize="20sp"
+                android:textStyle="bold"/>
+
+            <Button
+                android:id="@+id/btnDeleteCustomer"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:backgroundTint="@color/accent_coral"
+                android:text="Delete"
+                android:textColor="@color/white"/>
+
+        </LinearLayout>
+
+        <ScrollView
+            android:layout_width="match_parent"
+            android:layout_height="0dp"
+            android:layout_weight="1">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="vertical"
+                android:padding="24dp">
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="vertical"
+                    android:background="@drawable/rounded_card"
+                    android:padding="16dp"
+                    android:layout_marginBottom="16dp">
+
+                    <TextView
+                        android:id="@+id/tvCustomerId"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:textColor="@color/text_light"
+                        android:textSize="11sp"
+                        android:textStyle="italic"
+                        android:layout_gravity="end"
+                        android:layout_marginBottom="8dp"/>
+
+                    <!-- Username -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Username"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerUsername"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter username"
+                        android:inputType="text"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Password -->
+                    <TextView
+                        android:id="@+id/tvCustomerPasswordLabel"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Password"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerPassword"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter password (min 6 characters)"
+                        android:inputType="textPassword"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- First Name -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="First Name"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerFirstName"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter first name"
+                        android:inputType="textPersonName"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Last Name -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Last Name"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerLastName"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter last name"
+                        android:inputType="textPersonName"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Email -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Email"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerEmail"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter email"
+                        android:inputType="textEmailAddress"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Phone -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Phone"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <EditText
+                        android:id="@+id/etCustomerPhone"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="Enter phone number"
+                        android:inputType="phone"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Status -->
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Status"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <Spinner
+                        android:id="@+id/spinnerCustomerStatus"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginBottom="16dp"/>
+
+                    <!-- Loyalty Points (read-only) -->
+                    <TextView
+                        android:id="@+id/tvLoyaltyPointsLabel"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="Loyalty Points"
+                        android:textColor="@color/text_dark"
+                        android:textSize="12sp"
+                        android:layout_marginBottom="4dp"/>
+
+                    <TextView
+                        android:id="@+id/tvCustomerLoyaltyPoints"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="0"
+                        android:textColor="@color/text_dark"
+                        android:textSize="16sp"
+                        android:layout_marginBottom="8dp"/>
+
+                </LinearLayout>
+
+            </LinearLayout>
+
+        </ScrollView>
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:background="@color/white"
+            android:padding="16dp">
+
+            <Button
+                android:id="@+id/btnCustomerBack"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:layout_marginEnd="8dp"
+                android:text="Back"
+                android:backgroundTint="@color/primary_medium"
+                android:textColor="@color/white"/>
+
+            <Button
+                android:id="@+id/btnSaveCustomer"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:layout_marginStart="8dp"
+                android:text="Save"
+                android:backgroundTint="@color/accent_coral"
+                android:textColor="@color/white"/>
+
+        </LinearLayout>
+
+    </LinearLayout>
+
+    <ProgressBar
+        android:id="@+id/progressBar"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:visibility="gone"
+        android:indeterminateTint="@color/accent_coral"/>
+
+</FrameLayout>

android/app/src/main/res/layout/fragment_list.xml

@@ -146,6 +146,23 @@
                         android:textSize="15sp"/>
                 </LinearLayout>
 
+                <LinearLayout
+                    android:id="@+id/drawerCustomers"
+                    android:layout_width="match_parent"
+                    android:layout_height="48dp"
+                    android:orientation="horizontal"
+                    android:gravity="center_vertical"
+                    android:paddingStart="16dp"
+                    android:paddingEnd="16dp"
+                    android:background="?attr/selectableItemBackground">
+                    <TextView
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:text="Customers"
+                        android:textColor="@color/white"
+                        android:textSize="15sp"/>
+                </LinearLayout>
+
                 <LinearLayout
                     android:id="@+id/drawerServices"
                     android:layout_width="match_parent"
@@ -345,6 +362,7 @@
                             android:textColor="@color/white"
                             android:textSize="15sp"/>
                     </LinearLayout>
+
                 </LinearLayout>
 
             </LinearLayout>

android/app/src/main/res/layout/fragment_pet_detail.xml

@@ -95,14 +95,11 @@
                         android:textSize="12sp"
                         android:layout_marginBottom="4dp"/>
 
-                    <EditText
+                    <Spinner
-                        android:id="@+id/etPetSpecies"
+                        android:id="@+id/spinnerPetSpecies"
                         android:layout_width="match_parent"
                         android:layout_height="wrap_content"
-                        android:hint="e.g. Dog, Cat, Bird"
+                        android:layout_marginBottom="16dp"/>
-                        android:inputType="text"
-                        android:layout_marginBottom="16dp"
-                        android:textColor="@color/text_dark"/>
 
                     <TextView
                         android:layout_width="wrap_content"

android/app/src/main/res/layout/fragment_sale_detail.xml

@@ -262,6 +262,66 @@
                         android:layout_height="wrap_content"
                         android:orientation="vertical"/>
 
+                    <LinearLayout
+                        android:id="@+id/llCouponInput"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:orientation="vertical"
+                        android:layout_marginTop="12dp">
+
+                        <TextView
+                            android:layout_width="wrap_content"
+                            android:layout_height="wrap_content"
+                            android:text="Coupon Code"
+                            android:textColor="@color/text_dark"
+                            android:textSize="12sp"
+                            android:layout_marginBottom="4dp"/>
+
+                        <LinearLayout
+                            android:layout_width="match_parent"
+                            android:layout_height="wrap_content"
+                            android:orientation="horizontal"
+                            android:gravity="center_vertical">
+
+                            <EditText
+                                android:id="@+id/etCouponCode"
+                                android:layout_width="0dp"
+                                android:layout_height="wrap_content"
+                                android:layout_weight="1"
+                                android:hint="Enter coupon code"
+                                android:inputType="textCapCharacters"
+                                android:layout_marginEnd="8dp"/>
+
+                            <Button
+                                android:id="@+id/btnApplyCoupon"
+                                android:layout_width="wrap_content"
+                                android:layout_height="wrap_content"
+                                android:text="Apply"
+                                android:backgroundTint="@color/primary_medium"
+                                android:textColor="@color/white"/>
+
+                            <Button
+                                android:id="@+id/btnClearCoupon"
+                                android:layout_width="wrap_content"
+                                android:layout_height="wrap_content"
+                                android:text="Clear"
+                                android:backgroundTint="@color/accent_coral"
+                                android:textColor="@color/white"
+                                android:layout_marginStart="4dp"
+                                android:visibility="gone"/>
+
+                        </LinearLayout>
+
+                        <TextView
+                            android:id="@+id/tvCouponInfo"
+                            android:layout_width="match_parent"
+                            android:layout_height="wrap_content"
+                            android:textSize="12sp"
+                            android:layout_marginTop="4dp"
+                            android:visibility="gone"/>
+
+                    </LinearLayout>
+
                     <View
                         android:layout_width="match_parent"
                         android:layout_height="1dp"

android/app/src/main/res/layout/item_customer.xml

@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:paddingStart="16dp"
+    android:paddingEnd="16dp"
+    android:paddingTop="16dp"
+    android:paddingBottom="16dp"
+    android:background="@color/white">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="horizontal"
+        android:gravity="center_vertical">
+
+        <com.google.android.material.imageview.ShapeableImageView
+            android:id="@+id/ivCustomerProfile"
+            android:layout_width="64dp"
+            android:layout_height="64dp"
+            android:layout_marginEnd="16dp"
+            android:scaleType="centerCrop"
+            android:src="@drawable/placeholder"
+            app:shapeAppearanceOverlay="@style/CircleImageView"
+            app:strokeWidth="2dp"
+            app:strokeColor="#BDBDBD"
+            android:padding="2dp"
+            android:contentDescription="Customer Profile Image" />
+
+        <LinearLayout
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:orientation="vertical">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:gravity="center_vertical">
+
+                <TextView
+                    android:id="@+id/tvCustomerFullName"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:ellipsize="end"
+                    android:maxLines="1"
+                    android:text="Full Name"
+                    android:textColor="@color/text_dark"
+                    android:textSize="18sp"
+                    android:textStyle="bold" />
+
+                <TextView
+                    android:id="@+id/tvCustomerLoyalty"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:paddingStart="8dp"
+                    android:paddingTop="3dp"
+                    android:paddingEnd="8dp"
+                    android:paddingBottom="3dp"
+                    android:text="0 pts"
+                    android:textColor="@color/white"
+                    android:textSize="11sp"
+                    android:background="#FF9800" />
+
+            </LinearLayout>
+
+            <TextView
+                android:id="@+id/tvCustomerUsername"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="2dp"
+                android:text="@username"
+                android:textColor="#888888"
+                android:textSize="14sp" />
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:orientation="horizontal"
+                android:gravity="center_vertical"
+                android:layout_marginTop="4dp">
+
+                <TextView
+                    android:id="@+id/tvCustomerEmail"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_weight="1"
+                    android:text="email@example.com"
+                    android:textColor="#888888"
+                    android:textSize="13sp"
+                    android:ellipsize="end"
+                    android:maxLines="1"/>
+
+                <TextView
+                    android:id="@+id/tvCustomerStatus"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Active"
+                    android:textColor="@color/accent_coral"
+                    android:textSize="13sp"
+                    android:textStyle="bold" />
+
+            </LinearLayout>
+        </LinearLayout>
+    </LinearLayout>
+
+    <View
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:background="#F0F0F0"
+        android:layout_marginTop="12dp"/>
+
+</LinearLayout>

android/app/src/main/res/navigation/list_nav_graph.xml

@@ -151,6 +151,18 @@
         android:label="Staff Details"
         tools:layout="@layout/fragment_staff_detail" />
 
+    <fragment
+        android:id="@+id/nav_customer"
+        android:name="com.example.petstoremobile.fragments.listfragments.CustomerFragment"
+        android:label="Customers"
+        tools:layout="@layout/fragment_customer" />
+
+    <fragment
+        android:id="@+id/nav_customer_detail"
+        android:name="com.example.petstoremobile.fragments.listfragments.detailfragments.CustomerDetailFragment"
+        android:label="Customer Details"
+        tools:layout="@layout/fragment_customer_detail" />
+
     <fragment
         android:id="@+id/nav_analytics"
         android:name="com.example.petstoremobile.fragments.listfragments.AnalyticsFragment"

backend/src/main/java/com/petshop/backend/dto/sale/SaleResponse.java

@@ -12,6 +12,8 @@ public class SaleResponse {
     private String employeeName;
     private Long storeId;
     private String storeName;
+    private Long customerId;
+    private String customerName;
     private BigDecimal totalAmount;
     private BigDecimal subtotalAmount;
     private BigDecimal couponDiscountAmount;
@@ -77,6 +79,22 @@ public class SaleResponse {
         this.storeName = storeName;
     }
 
+    public Long getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(Long customerId) {
+        this.customerId = customerId;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+
     public BigDecimal getTotalAmount() {
         return totalAmount;
     }

backend/src/main/java/com/petshop/backend/service/SaleService.java

@@ -13,6 +13,7 @@ import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.List;
@@ -20,6 +21,8 @@ import java.util.List;
 @Service
 public class SaleService {
 
+    private static final BigDecimal EMPLOYEE_DISCOUNT_PERCENT = new BigDecimal("0.10");
+
     private final SaleRepository saleRepository;
     private final ProductRepository productRepository;
     private final StoreRepository storeRepository;
@@ -76,6 +79,7 @@ public class SaleService {
         if (request.getCouponId() != null) {
             Coupon coupon = couponRepository.findById(request.getCouponId())
                     .orElseThrow(() -> new ResourceNotFoundException("Coupon not found with id: " + request.getCouponId()));
+            validateCoupon(coupon);
             sale.setCoupon(coupon);
         }
 
@@ -85,8 +89,9 @@ public class SaleService {
             sale.setCart(cart);
         }
 
+        User customer = null;
         if (request.getCustomerId() != null) {
-            User customer = userRepository.findById(request.getCustomerId())
+            customer = userRepository.findById(request.getCustomerId())
                     .orElseThrow(() -> new ResourceNotFoundException("Customer not found with id: " + request.getCustomerId()));
             sale.setCustomer(customer);
         }
@@ -97,7 +102,7 @@ public class SaleService {
             sale.setOriginalSale(originalSale);
         }
 
-        BigDecimal totalAmount = BigDecimal.ZERO;
+        BigDecimal subtotalAmount = BigDecimal.ZERO;
         List<SaleItem> saleItems = new ArrayList<>();
 
         if (sale.getIsRefund() && sale.getOriginalSale() != null) {
@@ -145,9 +150,11 @@ public class SaleService {
                 saleItem.setUnitPrice(unitPrice);
 
                 saleItems.add(saleItem);
-                totalAmount = totalAmount.add(itemTotal);
+                subtotalAmount = subtotalAmount.add(itemTotal);
             }
-            totalAmount = totalAmount.negate();
+            subtotalAmount = subtotalAmount.negate();
+            sale.setSubtotalAmount(subtotalAmount);
+            sale.setTotalAmount(subtotalAmount);
         } else {
             for (var itemRequest : request.getItems()) {
                 Product product = productRepository.findById(itemRequest.getProdId())
@@ -174,17 +181,77 @@ public class SaleService {
                 saleItem.setUnitPrice(unitPrice);
 
                 saleItems.add(saleItem);
-                totalAmount = totalAmount.add(itemTotal);
+                subtotalAmount = subtotalAmount.add(itemTotal);
+            }
+            sale.setSubtotalAmount(subtotalAmount);
+
+            BigDecimal couponDiscount = calculateCouponDiscount(sale.getCoupon(), subtotalAmount);
+            sale.setCouponDiscountAmount(couponDiscount);
+
+            BigDecimal employeeDiscount = calculateEmployeeDiscount(customer, subtotalAmount.subtract(couponDiscount));
+            sale.setEmployeeDiscountAmount(employeeDiscount);
+
+            BigDecimal finalTotal = subtotalAmount.subtract(couponDiscount).subtract(employeeDiscount);
+            sale.setTotalAmount(finalTotal.max(BigDecimal.ZERO));
+
+            sale.setPointsEarned(sale.getTotalAmount().setScale(0, RoundingMode.FLOOR).intValue());
+            if (customer != null) {
+                customer.setLoyaltyPoints(customer.getLoyaltyPoints() + sale.getPointsEarned());
+                userRepository.save(customer);
             }
         }
 
-        sale.setTotalAmount(totalAmount);
         sale.setItems(saleItems);
 
         Sale savedSale = saleRepository.save(sale);
         return mapToResponse(savedSale);
     }
 
+    private void validateCoupon(Coupon coupon) {
+        if (!Boolean.TRUE.equals(coupon.getActive())) {
+            throw new BusinessException("Coupon is not active");
+        }
+        LocalDateTime now = LocalDateTime.now();
+        if (coupon.getStartsAt() != null && now.isBefore(coupon.getStartsAt())) {
+            throw new BusinessException("Coupon has not started yet");
+        }
+        if (coupon.getEndsAt() != null && now.isAfter(coupon.getEndsAt())) {
+            throw new BusinessException("Coupon has expired");
+        }
+    }
+
+    private BigDecimal calculateCouponDiscount(Coupon coupon, BigDecimal subtotal) {
+        if (coupon == null || subtotal.compareTo(BigDecimal.ZERO) <= 0) {
+            return BigDecimal.ZERO;
+        }
+
+        if (coupon.getMinOrderAmount() != null && subtotal.compareTo(coupon.getMinOrderAmount()) < 0) {
+            return BigDecimal.ZERO;
+        }
+
+        BigDecimal discount = BigDecimal.ZERO;
+        String type = coupon.getDiscountType().trim().toUpperCase();
+        if ("PERCENTAGE".equals(type) || "PERCENT".equals(type)) {
+            discount = subtotal.multiply(coupon.getDiscountValue().divide(new BigDecimal("100"), 4, RoundingMode.HALF_UP));
+        } else if ("FIXED".equals(type)) {
+            discount = coupon.getDiscountValue();
+        }
+
+        return discount.min(subtotal).setScale(2, RoundingMode.HALF_UP);
+    }
+
+    private BigDecimal calculateEmployeeDiscount(User customer, BigDecimal remainingAmount) {
+        if (customer == null || remainingAmount.compareTo(BigDecimal.ZERO) <= 0) {
+            return BigDecimal.ZERO;
+        }
+
+        if (customer.getRole() == User.Role.STAFF || customer.getRole() == User.Role.ADMIN) {
+            return remainingAmount.multiply(EMPLOYEE_DISCOUNT_PERCENT).setScale(2, RoundingMode.HALF_UP);
+        }
+
+        return BigDecimal.ZERO;
+    }
+
     private SaleResponse mapToResponse(Sale sale) {
         SaleResponse response = new SaleResponse();
         response.setSaleId(sale.getSaleId());
@@ -197,6 +264,11 @@ public class SaleService {
             response.setStoreName(sale.getStore().getStoreName());
         }
 
+        if (sale.getCustomer() != null) {
+            response.setCustomerId(sale.getCustomer().getId());
+            response.setCustomerName(sale.getCustomer().getFirstName() + " " + sale.getCustomer().getLastName());
+        }
+
         response.setTotalAmount(sale.getTotalAmount());
         response.setSubtotalAmount(sale.getSubtotalAmount());
         response.setCouponDiscountAmount(sale.getCouponDiscountAmount());