Stripe Payment

backend/src/main/java/com/petshop/backend/controller/CartController.java

@@ -0,0 +1,84 @@
+package com.petshop.backend.controller;
+
+import com.petshop.backend.dto.cart.*;
+import com.petshop.backend.service.CartService;
+import com.petshop.backend.util.AuthenticationHelper;
+import jakarta.validation.Valid;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/v1/cart")
+public class CartController {
+
+    private final CartService cartService;
+
+    public CartController(CartService cartService) {
+        this.cartService = cartService;
+    }
+
+    @GetMapping
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CartResponse> getActiveCart(@RequestParam Long storeId) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+        CartResponse cart = cartService.getActiveCart(userId, storeId);
+
+        if (cart == null) {
+
+            return ResponseEntity.noContent().build();
+        }
+
+        return ResponseEntity.ok(cart);
+    }
+
+    @PostMapping("/add")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CartResponse> addItem(@Valid @RequestBody AddToCartRequest request) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+
+        return ResponseEntity.ok(cartService.addItem(userId, request));
+    }
+
+    @PutMapping("/update")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CartResponse> updateItem(@Valid @RequestBody UpdateCartItemRequest request) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+
+        return ResponseEntity.ok(cartService.updateItem(userId, request));
+    }
+
+    @DeleteMapping("/remove/{cartItemId}")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CartResponse> removeItem(@PathVariable Long cartItemId) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+
+        return ResponseEntity.ok(cartService.removeItem(userId, cartItemId));
+    }
+
+    @DeleteMapping("/clear")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<Void> clearCart(@RequestParam Long storeId) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+        cartService.clearCart(userId, storeId);
+
+        return ResponseEntity.noContent().build();
+    }
+
+    @PostMapping("/apply-coupon")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CartResponse> applyCoupon(
+            @RequestParam Long storeId,
+            @Valid @RequestBody ApplyCouponRequest request) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+
+        return ResponseEntity.ok(cartService.applyCoupon(userId, storeId, request.getCouponCode()));
+    }
+
+    @PostMapping("/checkout")
+    @PreAuthorize("isAuthenticated()")
+    public ResponseEntity<CheckoutResponse> checkout(@Valid @RequestBody CheckoutRequest request) {
+        Long userId = AuthenticationHelper.getAuthenticatedUserId();
+
+        return ResponseEntity.ok(cartService.checkout(userId, request.getStoreId(), request.getPaymentMethodId()));}
+}

backend/src/main/java/com/petshop/backend/controller/StoreController.java

@@ -14,7 +14,6 @@ import org.springframework.web.bind.annotation.*;
 
 @RestController
 @RequestMapping("/api/v1/stores")
-@PreAuthorize("hasRole('ADMIN')")
 public class StoreController {
 
     private final StoreService storeService;
@@ -24,6 +23,7 @@ public class StoreController {
     }
 
     @GetMapping
+    @PreAuthorize("isAuthenticated()")
     public ResponseEntity<Page<StoreResponse>> getAllStores(
             @RequestParam(required = false) String q,
             Pageable pageable) {
@@ -31,6 +31,7 @@ public class StoreController {
     }
 
     @GetMapping("/{id}")
+    @PreAuthorize("isAuthenticated()")
     public ResponseEntity<StoreResponse> getStoreById(@PathVariable Long id) {
         return ResponseEntity.ok(storeService.getStoreById(id));
     }

backend/src/main/java/com/petshop/backend/dto/cart/AddToCartRequest.java

@@ -0,0 +1,43 @@
+package com.petshop.backend.dto.cart;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+
+public class AddToCartRequest {
+
+    @NotNull
+    private Long prodId;
+
+    @NotNull
+    private Long storeId;
+
+    @NotNull
+    @Min(1)
+    private Integer quantity;
+
+    public Long getProdId() {
+        
+        return prodId;
+    }
+    
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public Long getStoreId() { 
+
+        return storeId; 
+    }
+
+    public void setStoreId(Long storeId) {
+        this.storeId = storeId;
+    }
+
+    public Integer getQuantity() {
+        
+        return quantity;
+    }
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/cart/ApplyCouponRequest.java

@@ -0,0 +1,17 @@
+package com.petshop.backend.dto.cart;
+
+import jakarta.validation.constraints.NotBlank;
+
+public class ApplyCouponRequest {
+
+    @NotBlank
+    private String couponCode;
+
+    public String getCouponCode() {
+        return couponCode;
+    }
+
+    public void setCouponCode(String couponCode) {
+        this.couponCode = couponCode;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/cart/CartItemResponse.java

@@ -0,0 +1,90 @@
+package com.petshop.backend.dto.cart;
+
+import java.math.BigDecimal;
+
+public class CartItemResponse {
+
+    private Long cartItemId;
+    private Long prodId;
+    private String prodName;
+    private String imageUrl;
+    private BigDecimal unitPrice;
+    private Integer quantity;
+    private BigDecimal lineTotal;
+
+    public CartItemResponse() {
+    }
+
+    public CartItemResponse(Long cartItemId, Long prodId, String prodName, String imageUrl,
+                            BigDecimal unitPrice, Integer quantity, BigDecimal lineTotal) {
+        this.cartItemId = cartItemId;
+        this.prodId = prodId;
+        this.prodName = prodName;
+        this.imageUrl = imageUrl;
+        this.unitPrice = unitPrice;
+        this.quantity = quantity;
+        this.lineTotal = lineTotal;
+    }
+
+    public Long getCartItemId() {
+
+        return cartItemId;
+    }
+
+    public void setCartItemId(Long cartItemId) {
+        this.cartItemId = cartItemId;
+    }
+
+    public Long getProdId() {
+
+        return prodId;
+    }
+
+    public void setProdId(Long prodId) {
+        this.prodId = prodId;
+    }
+
+    public String getProdName() {
+
+        return prodName;
+    }
+
+    public void setProdName(String prodName) {
+        this.prodName = prodName;
+    }
+
+    public String getImageUrl() {
+        return imageUrl;
+    }
+
+    public void setImageUrl(String imageUrl) {
+        this.imageUrl = imageUrl;
+    }
+
+    public BigDecimal getUnitPrice() {
+        
+        return unitPrice;
+    }
+
+    public void setUnitPrice(BigDecimal unitPrice) {
+        this.unitPrice = unitPrice;
+    }
+
+    public Integer getQuantity() {
+        
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+
+    public BigDecimal getLineTotal() {
+
+        return lineTotal;
+    }
+
+    public void setLineTotal(BigDecimal lineTotal) {
+        this.lineTotal = lineTotal;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/cart/CartResponse.java

@@ -0,0 +1,43 @@
+package com.petshop.backend.dto.cart;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+public class CartResponse {
+
+    private Long cartId;
+    private Long storeId;
+    private String cartStatus;
+    private List<CartItemResponse> items;
+    private BigDecimal subtotalAmount;
+    private BigDecimal discountAmount;
+    private BigDecimal totalAmount;
+    private String couponCode;
+
+    public CartResponse() {
+    }
+
+    public Long getCartId() { return cartId; }
+    public void setCartId(Long cartId) { this.cartId = cartId; }
+
+    public Long getStoreId() { return storeId; }
+    public void setStoreId(Long storeId) { this.storeId = storeId; }
+
+    public String getCartStatus() { return cartStatus; }
+    public void setCartStatus(String cartStatus) { this.cartStatus = cartStatus; }
+
+    public List<CartItemResponse> getItems() { return items; }
+    public void setItems(List<CartItemResponse> items) { this.items = items; }
+
+    public BigDecimal getSubtotalAmount() { return subtotalAmount; }
+    public void setSubtotalAmount(BigDecimal subtotalAmount) { this.subtotalAmount = subtotalAmount; }
+
+    public BigDecimal getDiscountAmount() { return discountAmount; }
+    public void setDiscountAmount(BigDecimal discountAmount) { this.discountAmount = discountAmount; }
+
+    public BigDecimal getTotalAmount() { return totalAmount; }
+    public void setTotalAmount(BigDecimal totalAmount) { this.totalAmount = totalAmount; }
+
+    public String getCouponCode() { return couponCode; }
+    public void setCouponCode(String couponCode) { this.couponCode = couponCode; }
+}

backend/src/main/java/com/petshop/backend/dto/cart/CheckoutRequest.java

@@ -0,0 +1,24 @@
+package com.petshop.backend.dto.cart;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+
+public class CheckoutRequest {
+
+    @NotNull
+    private Long storeId;
+
+    @NotBlank
+    private String paymentMethodId;
+
+    public Long getStoreId() { return storeId; }
+    public void setStoreId(Long storeId) { this.storeId = storeId; }
+
+    public String getPaymentMethodId() {
+        return paymentMethodId;
+    }
+
+    public void setPaymentMethodId(String paymentMethodId) {
+        this.paymentMethodId = paymentMethodId;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/cart/CheckoutResponse.java

@@ -0,0 +1,57 @@
+package com.petshop.backend.dto.cart;
+
+import java.math.BigDecimal;
+
+public class CheckoutResponse {
+
+    private Long cartId;
+    private String clientSecret;
+    private BigDecimal totalAmount;
+    private String status;
+
+    public CheckoutResponse() {
+    }
+
+    public CheckoutResponse(Long cartId, String clientSecret, BigDecimal totalAmount, String status) {
+        this.cartId = cartId;
+        this.clientSecret = clientSecret;
+        this.totalAmount = totalAmount;
+        this.status = status;
+    }
+
+    public Long getCartId() {
+    
+        return cartId;
+    }
+
+    public void setCartId(Long cartId) {
+        this.cartId = cartId;
+    }
+
+    public String getClientSecret() {
+        
+        return clientSecret;
+    }
+
+    public void setClientSecret(String clientSecret) {
+        this.clientSecret = clientSecret;
+    }
+
+    public BigDecimal getTotalAmount() {
+        
+        return totalAmount;
+    }
+
+    public void setTotalAmount(BigDecimal totalAmount) {
+        this.totalAmount = totalAmount;
+    }
+
+    public String getStatus() {
+        
+        return status;
+    }
+
+    public void setStatus(String status) {
+        this.status = status;
+    }
+}

backend/src/main/java/com/petshop/backend/dto/cart/UpdateCartItemRequest.java

@@ -0,0 +1,32 @@
+package com.petshop.backend.dto.cart;
+
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+
+public class UpdateCartItemRequest {
+
+    @NotNull
+    private Long cartItemId;
+
+    @NotNull
+    @Min(1)
+    private Integer quantity;
+
+    public Long getCartItemId() {
+        
+        return cartItemId;
+    }
+
+    public void setCartItemId(Long cartItemId) {
+        this.cartItemId = cartItemId;
+    }
+
+    public Integer getQuantity() {
+        
+        return quantity;
+    }
+
+    public void setQuantity(Integer quantity) {
+        this.quantity = quantity;
+    }
+}

backend/src/main/java/com/petshop/backend/repository/CartItemRepository.java

@@ -5,9 +5,14 @@ import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 
 import java.util.List;
+import java.util.Optional;
 
 @Repository
 public interface CartItemRepository extends JpaRepository<CartItem, Long> {
 
     List<CartItem> findByCartCartId(Long cartId);
+
+    Optional<CartItem> findByCartCartIdAndProductProdId(Long cartId, Long prodId);
+
+    void deleteByCartCartId(Long cartId);
 }

backend/src/main/java/com/petshop/backend/repository/CartRepository.java

@@ -2,6 +2,8 @@ package com.petshop.backend.repository;
 
 import com.petshop.backend.entity.Cart;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
 import java.util.List;
@@ -13,4 +15,9 @@ public interface CartRepository extends JpaRepository<Cart, Long> {
     List<Cart> findByUserId(Long userId);
 
     Optional<Cart> findByUserIdAndCartStatus(Long userId, String cartStatus);
+
+    @Query("SELECT c FROM Cart c WHERE c.user.id = :userId AND c.store.storeId = :storeId AND c.cartStatus = :status")
+    Optional<Cart> findActiveCartByUserAndStore(@Param("userId") Long userId,
+                                                @Param("storeId") Long storeId,
+                                                @Param("status") String status);
 }

backend/src/main/java/com/petshop/backend/repository/CouponRepository.java

@@ -10,4 +10,6 @@ import java.util.Optional;
 public interface CouponRepository extends JpaRepository<Coupon, Long> {
 
     Optional<Coupon> findByCouponCode(String couponCode);
+
+    Optional<Coupon> findByCouponCodeIgnoreCase(String couponCode);
 }

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

@@ -0,0 +1,301 @@
+package com.petshop.backend.service;
+
+import com.petshop.backend.dto.cart.*;
+import com.petshop.backend.entity.*;
+import com.petshop.backend.exception.BusinessException;
+import com.petshop.backend.exception.ResourceNotFoundException;
+import com.petshop.backend.repository.*;
+import com.stripe.Stripe;
+import com.stripe.exception.StripeException;
+import com.stripe.model.PaymentIntent;
+import com.stripe.param.PaymentIntentCreateParams;
+import jakarta.annotation.PostConstruct;
+import jakarta.transaction.Transactional;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.time.LocalDateTime;
+import java.util.List;
+
+@Service
+public class CartService {
+
+    private final CartRepository cartRepository;
+    private final CartItemRepository cartItemRepository;
+    private final UserRepository userRepository;
+    private final StoreRepository storeRepository;
+    private final ProductRepository productRepository;
+    private final CouponRepository couponRepository;
+
+    @Value("${stripe.secret-key:}")
+    private String stripeSecretKey;
+
+    public CartService(CartRepository cartRepository,
+                       CartItemRepository cartItemRepository,
+                       UserRepository userRepository,
+                       StoreRepository storeRepository,
+                       ProductRepository productRepository,
+                       CouponRepository couponRepository) {
+        this.cartRepository = cartRepository;
+        this.cartItemRepository = cartItemRepository;
+        this.userRepository = userRepository;
+        this.storeRepository = storeRepository;
+        this.productRepository = productRepository;
+        this.couponRepository = couponRepository;
+    }
+
+    @PostConstruct
+    public void initStripe() {
+        if (stripeSecretKey != null && !stripeSecretKey.isBlank()) {
+            Stripe.apiKey = stripeSecretKey;
+        }
+    }
+
+    public CartResponse getActiveCart(Long userId, Long storeId) {
+        return cartRepository
+                .findActiveCartByUserAndStore(userId, storeId, "ACTIVE")
+                .map(this::toResponse)
+                .orElse(null);
+    }
+
+    @Transactional
+    public CartResponse addItem(Long userId, AddToCartRequest request) {
+        User user = userRepository.findById(userId).orElseThrow(() -> new ResourceNotFoundException("User not found"));
+        StoreLocation store = storeRepository.findById(request.getStoreId()).orElseThrow(() -> new ResourceNotFoundException("Store not found"));
+        Product product = productRepository.findById(request.getProdId()).orElseThrow(() -> new ResourceNotFoundException("Product not found"));
+
+        if (request.getQuantity() < 1) {
+            throw new BusinessException("Quantity must be at least 1");
+        }
+
+        Cart cart = cartRepository
+                .findActiveCartByUserAndStore(userId, request.getStoreId(), "ACTIVE")
+                .orElseGet(() -> {
+                    Cart newCart = new Cart();
+                    newCart.setUser(user);
+                    newCart.setStore(store);
+                    newCart.setCartStatus("ACTIVE");
+
+                    return cartRepository.save(newCart);
+                });
+
+        cartItemRepository.findByCartCartIdAndProductProdId(cart.getCartId(), product.getProdId())
+                .ifPresentOrElse(
+                        existing -> existing.setQuantity(existing.getQuantity() + request.getQuantity()),
+                        () -> {
+                            CartItem item = new CartItem();
+                            item.setCart(cart);
+                            item.setProduct(product);
+                            item.setQuantity(request.getQuantity());
+                            item.setUnitPrice(product.getProdPrice());
+                            cartItemRepository.save(item);
+                        }
+                );
+
+        recalculate(cart);
+
+        return toResponse(cart);
+    }
+
+    @Transactional
+    public CartResponse updateItem(Long userId, UpdateCartItemRequest request) {
+        CartItem item = cartItemRepository.findById(request.getCartItemId())
+                .orElseThrow(() -> new ResourceNotFoundException("Cart item not found"));
+
+        if (!item.getCart().getUser().getId().equals(userId)) {
+            throw new BusinessException("Access denied");
+        }
+
+        if (!item.getCart().getCartStatus().equals("ACTIVE")) {
+            throw new BusinessException("Cart is not active");
+        }
+
+        if (request.getQuantity() < 1) {
+            throw new BusinessException("Quantity must be at least 1");
+        }
+
+        item.setQuantity(request.getQuantity());
+        cartItemRepository.save(item);
+        recalculate(item.getCart());
+
+        return toResponse(item.getCart());
+    }
+
+    @Transactional
+    public CartResponse removeItem(Long userId, Long cartItemId) {
+        CartItem item = cartItemRepository.findById(cartItemId)
+                .orElseThrow(() -> new ResourceNotFoundException("Cart item not found"));
+
+        if (!item.getCart().getUser().getId().equals(userId)) {
+            throw new BusinessException("Access denied");
+        }
+
+        if (!item.getCart().getCartStatus().equals("ACTIVE")) {
+            throw new BusinessException("Cart is not active");
+        }
+
+        Cart cart = item.getCart();
+        cartItemRepository.delete(item);
+        recalculate(cart);
+
+        return toResponse(cart);
+    }
+
+    @Transactional
+    public void clearCart(Long userId, Long storeId) {
+        cartRepository.findActiveCartByUserAndStore(userId, storeId, "ACTIVE")
+                .ifPresent(cart -> {
+                    cartItemRepository.deleteByCartCartId(cart.getCartId());
+                    cart.setSubtotalAmount(BigDecimal.ZERO);
+                    cart.setDiscountAmount(BigDecimal.ZERO);
+                    cart.setTotalAmount(BigDecimal.ZERO);
+                    cart.setCoupon(null);
+                    cartRepository.save(cart);
+                });
+    }
+
+    @Transactional
+    public CartResponse applyCoupon(Long userId, Long storeId, String couponCode) {
+        Cart cart = cartRepository
+                .findActiveCartByUserAndStore(userId, storeId, "ACTIVE")
+                .orElseThrow(() -> new BusinessException("No active cart found"));
+
+        Coupon coupon = couponRepository.findByCouponCodeIgnoreCase(couponCode)
+                .orElseThrow(() -> new BusinessException("Invalid coupon code"));
+
+        LocalDateTime now = LocalDateTime.now();
+
+        if (!coupon.getActive()) {
+            throw new BusinessException("Coupon is no longer active");
+        }
+
+        if (coupon.getStartsAt() != null && now.isBefore(coupon.getStartsAt())) {
+            throw new BusinessException("Coupon is not yet valid");
+        }
+
+        if (coupon.getEndsAt() != null && now.isAfter(coupon.getEndsAt())) {
+            throw new BusinessException("Coupon has expired");
+        }
+
+        if (coupon.getMinOrderAmount() != null && cart.getSubtotalAmount().compareTo(coupon.getMinOrderAmount()) < 0) {
+            throw new BusinessException("Minimum order amount of $" + coupon.getMinOrderAmount() + " required");
+        }
+
+        cart.setCoupon(coupon);
+        recalculate(cart);
+
+        return toResponse(cart);
+    }
+
+    @Transactional
+    public CheckoutResponse checkout(Long userId, Long storeId, String paymentMethodId) {
+        Cart cart = cartRepository
+                .findActiveCartByUserAndStore(userId, storeId, "ACTIVE")
+                .orElseThrow(() -> new BusinessException("No active cart found"));
+
+        List<CartItem> items = cartItemRepository.findByCartCartId(cart.getCartId());
+        if (items.isEmpty()) {
+            throw new BusinessException("Cart is empty");
+        }
+
+        long amountInCents = cart.getTotalAmount()
+                .multiply(BigDecimal.valueOf(100))
+                .setScale(0, RoundingMode.HALF_UP)
+                .longValue();
+
+        if (amountInCents < 50) {
+            throw new BusinessException("Order total is too low to process payment");
+        }
+
+        try {
+            PaymentIntentCreateParams params = PaymentIntentCreateParams.builder()
+                    .setAmount(amountInCents)
+                    .setCurrency("usd")
+                    .setPaymentMethod(paymentMethodId)
+                    .setConfirm(true)
+                    .setReturnUrl("http://localhost:3000/cart/confirmation")
+                    .putMetadata("cartId", String.valueOf(cart.getCartId()))
+                    .putMetadata("userId", String.valueOf(userId))
+                    .build();
+
+            PaymentIntent intent = PaymentIntent.create(params);
+
+            if ("succeeded".equals(intent.getStatus())
+                    || "requires_action".equals(intent.getStatus())) {
+                cart.setCartStatus("CHECKED_OUT");
+                cartRepository.save(cart);
+            }
+
+            return new CheckoutResponse(
+                    cart.getCartId(),
+                    intent.getClientSecret(),
+                    cart.getTotalAmount(),
+                    intent.getStatus()
+            );
+
+        } 
+        
+        catch (StripeException e) {
+            throw new BusinessException("Payment processing failed: " + e.getMessage());
+        }
+    }
+
+    private void recalculate(Cart cart) {
+        List<CartItem> items = cartItemRepository.findByCartCartId(cart.getCartId());
+
+        BigDecimal subtotal = items.stream()
+                .map(i -> i.getUnitPrice().multiply(BigDecimal.valueOf(i.getQuantity())))
+                .reduce(BigDecimal.ZERO, BigDecimal::add);
+
+        cart.setSubtotalAmount(subtotal);
+
+        BigDecimal discount = BigDecimal.ZERO;
+        Coupon coupon = cart.getCoupon();
+
+        if (coupon != null) {
+            if ("PERCENTAGE".equalsIgnoreCase(coupon.getDiscountType())) {
+                discount = subtotal.multiply(coupon.getDiscountValue())
+                        .divide(BigDecimal.valueOf(100), 2, RoundingMode.HALF_UP);
+            } 
+            
+            else if ("FIXED".equalsIgnoreCase(coupon.getDiscountType())) {
+                discount = coupon.getDiscountValue().min(subtotal);
+            }
+        }
+
+        discount = discount.max(BigDecimal.ZERO).min(subtotal);
+        cart.setDiscountAmount(discount);
+        cart.setTotalAmount(subtotal.subtract(discount).max(BigDecimal.ZERO));
+        cartRepository.save(cart);
+    }
+
+    private CartResponse toResponse(Cart cart) {
+        List<CartItemResponse> itemResponses = cartItemRepository
+                .findByCartCartId(cart.getCartId())
+                .stream()
+                .map(item -> new CartItemResponse(
+                        item.getCartItemId(),
+                        item.getProduct().getProdId(),
+                        item.getProduct().getProdName(),
+                        item.getProduct().getImageUrl(),
+                        item.getUnitPrice(),
+                        item.getQuantity(),
+                        item.getUnitPrice().multiply(BigDecimal.valueOf(item.getQuantity()))
+                ))
+                .toList();
+
+        CartResponse response = new CartResponse();
+        response.setCartId(cart.getCartId());
+        response.setStoreId(cart.getStore() != null ? cart.getStore().getStoreId() : null);
+        response.setCartStatus(cart.getCartStatus());
+        response.setItems(itemResponses);
+        response.setSubtotalAmount(cart.getSubtotalAmount());
+        response.setDiscountAmount(cart.getDiscountAmount());
+        response.setTotalAmount(cart.getTotalAmount());
+        response.setCouponCode(cart.getCoupon() != null ? cart.getCoupon().getCouponCode() : null);
+        
+        return response;
+    }
+}

backend/src/main/resources/application.yml

@@ -50,6 +50,9 @@ jwt:
   secret: ${JWT_SECRET:change_me_please_make_this_at_least_32_characters_long_for_security}
   expiration: ${JWT_EXPIRATION:86400000}
 
+stripe:
+  secret-key: ${STRIPE_SECRET_KEY:}
+
 logging:
   level:
     com.petshop: ${LOG_LEVEL:INFO}