added points to sale and logic backend

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

@@ -5,6 +5,7 @@ import jakarta.validation.constraints.NotEmpty;
 import jakarta.validation.constraints.NotNull;
 import java.util.List;
 import java.util.Objects;
+import java.math.BigDecimal;
 
 public class SaleRequest {
     @NotNull(message = "Store ID is required")
@@ -28,6 +29,10 @@ public class SaleRequest {
 
     private Long cartId;
 
+    private Integer pointsUsed;
+
+    private BigDecimal pointsDiscountAmount;
+
     public Long getStoreId() {
         return storeId;
     }
@@ -100,6 +105,22 @@ public class SaleRequest {
         this.cartId = cartId;
     }
 
+    public Integer getPointsUsed() {
+        return pointsUsed;
+    }
+
+    public void setPointsUsed(Integer pointsUsed) {
+        this.pointsUsed = pointsUsed;
+    }
+
+    public BigDecimal getPointsDiscountAmount() {
+        return pointsDiscountAmount;
+    }
+
+    public void setPointsDiscountAmount(BigDecimal pointsDiscountAmount) {
+        this.pointsDiscountAmount = pointsDiscountAmount;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

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

@@ -19,6 +19,8 @@ public class SaleResponse {
     private BigDecimal couponDiscountAmount;
     private BigDecimal employeeDiscountAmount;
     private Integer pointsEarned;
+    private Integer pointsUsed;
+    private BigDecimal pointsDiscountAmount;
     private String channel;
     private Long couponId;
     private Long cartId;
@@ -135,6 +137,22 @@ public class SaleResponse {
         this.pointsEarned = pointsEarned;
     }
 
+    public Integer getPointsUsed() {
+        return pointsUsed;
+    }
+
+    public void setPointsUsed(Integer pointsUsed) {
+        this.pointsUsed = pointsUsed;
+    }
+
+    public BigDecimal getPointsDiscountAmount() {
+        return pointsDiscountAmount;
+    }
+
+    public void setPointsDiscountAmount(BigDecimal pointsDiscountAmount) {
+        this.pointsDiscountAmount = pointsDiscountAmount;
+    }
+
     public String getChannel() {
         return channel;
     }

backend/src/main/java/com/petshop/backend/entity/Sale.java

@@ -69,6 +69,12 @@ public class Sale {
     @Column(nullable = false)
     private Integer pointsEarned = 0;
 
+    @Column(nullable = false)
+    private Integer pointsUsed = 0;
+
+    @Column(nullable = false, precision = 10, scale = 2)
+    private BigDecimal pointsDiscountAmount = BigDecimal.ZERO;
+
     @OneToMany(mappedBy = "sale", cascade = CascadeType.ALL)
     private List<SaleItem> items = new ArrayList<>();
 
@@ -211,6 +217,22 @@ public class Sale {
         this.pointsEarned = pointsEarned;
     }
 
+    public Integer getPointsUsed() {
+        return pointsUsed;
+    }
+
+    public void setPointsUsed(Integer pointsUsed) {
+        this.pointsUsed = pointsUsed;
+    }
+
+    public BigDecimal getPointsDiscountAmount() {
+        return pointsDiscountAmount;
+    }
+
+    public void setPointsDiscountAmount(BigDecimal pointsDiscountAmount) {
+        this.pointsDiscountAmount = pointsDiscountAmount;
+    }
+
     public List<SaleItem> getItems() {
         return items;
     }

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

@@ -152,9 +152,33 @@ public class SaleService {
                 saleItems.add(saleItem);
                 subtotalAmount = subtotalAmount.add(itemTotal);
             }
-            subtotalAmount = subtotalAmount.negate();
+
-            sale.setSubtotalAmount(subtotalAmount);
+            Sale originalSale = sale.getOriginalSale();
-            sale.setTotalAmount(subtotalAmount);
+            BigDecimal originalSubtotal = originalSale.getSubtotalAmount() != null
+                    ? originalSale.getSubtotalAmount()
+                    : originalSale.getItems().stream()
+                            .map(i -> i.getUnitPrice().multiply(BigDecimal.valueOf(Math.abs(i.getQuantity()))))
+                            .reduce(BigDecimal.ZERO, BigDecimal::add);
+
+            BigDecimal refundRatio = originalSubtotal.compareTo(BigDecimal.ZERO) != 0
+                    ? subtotalAmount.divide(originalSubtotal, 10, RoundingMode.HALF_UP)
+                    : BigDecimal.ONE;
+
+            BigDecimal refundTotal = originalSale.getTotalAmount().abs()
+                    .multiply(refundRatio).setScale(2, RoundingMode.HALF_UP);
+
+            sale.setSubtotalAmount(subtotalAmount.negate());
+            sale.setTotalAmount(refundTotal.negate());
+
+            User refundCustomer = customer != null ? customer : originalSale.getCustomer();
+            if (refundCustomer != null) {
+                int pointsToRestore = BigDecimal.valueOf(originalSale.getPointsUsed())
+                        .multiply(refundRatio).setScale(0, RoundingMode.FLOOR).intValue();
+                int pointsToDeduct = BigDecimal.valueOf(originalSale.getPointsEarned())
+                        .multiply(refundRatio).setScale(0, RoundingMode.FLOOR).intValue();
+                refundCustomer.setLoyaltyPoints(refundCustomer.getLoyaltyPoints() + pointsToRestore - pointsToDeduct);
+                userRepository.save(refundCustomer);
+            }
         } else {
             for (var itemRequest : request.getItems()) {
                 Product product = productRepository.findById(itemRequest.getProdId())
@@ -188,10 +212,23 @@ public class SaleService {
             BigDecimal couponDiscount = calculateCouponDiscount(sale.getCoupon(), subtotalAmount);
             sale.setCouponDiscountAmount(couponDiscount);
 
-            BigDecimal employeeDiscount = calculateEmployeeDiscount(customer, subtotalAmount.subtract(couponDiscount));
+            BigDecimal pointsDiscount = BigDecimal.ZERO;
+            int pointsUsed = 0;
+            if (customer != null && request.getPointsUsed() != null && request.getPointsUsed() > 0) {
+                if (customer.getLoyaltyPoints() < request.getPointsUsed()) {
+                    throw new BusinessException("Customer does not have enough loyalty points");
+                }
+                pointsUsed = request.getPointsUsed();
+                pointsDiscount = calculatePointsDiscount(pointsUsed);
+                customer.setLoyaltyPoints(customer.getLoyaltyPoints() - pointsUsed);
+            }
+            sale.setPointsUsed(pointsUsed);
+            sale.setPointsDiscountAmount(pointsDiscount);
+
+            BigDecimal employeeDiscount = calculateEmployeeDiscount(customer, subtotalAmount.subtract(couponDiscount).subtract(pointsDiscount));
             sale.setEmployeeDiscountAmount(employeeDiscount);
 
-            BigDecimal finalTotal = subtotalAmount.subtract(couponDiscount).subtract(employeeDiscount);
+            BigDecimal finalTotal = subtotalAmount.subtract(couponDiscount).subtract(pointsDiscount).subtract(employeeDiscount);
             sale.setTotalAmount(finalTotal.max(BigDecimal.ZERO));
 
             sale.setPointsEarned(sale.getTotalAmount().setScale(0, RoundingMode.FLOOR).intValue());
@@ -240,6 +277,10 @@ public class SaleService {
         return discount.min(subtotal).setScale(2, RoundingMode.HALF_UP);
     }
 
+    private BigDecimal calculatePointsDiscount(int pointsUsed) {
+        return new BigDecimal(pointsUsed).divide(new BigDecimal("20"), 2, RoundingMode.HALF_UP);
+    }
+
     private BigDecimal calculateEmployeeDiscount(User customer, BigDecimal remainingAmount) {
         if (customer == null || remainingAmount.compareTo(BigDecimal.ZERO) <= 0) {
             return BigDecimal.ZERO;
@@ -274,6 +315,8 @@ public class SaleService {
         response.setCouponDiscountAmount(sale.getCouponDiscountAmount());
         response.setEmployeeDiscountAmount(sale.getEmployeeDiscountAmount());
         response.setPointsEarned(sale.getPointsEarned());
+        response.setPointsUsed(sale.getPointsUsed());
+        response.setPointsDiscountAmount(sale.getPointsDiscountAmount());
         response.setChannel(sale.getChannel());
         if (sale.getCoupon() != null) {
             response.setCouponId(sale.getCoupon().getCouponId());

backend/src/main/resources/db/migration/V5__add_points_columns_to_sale.sql

@@ -0,0 +1,3 @@
+ALTER TABLE sale
+    ADD COLUMN pointsUsed INT NOT NULL DEFAULT 0,
+    ADD COLUMN pointsDiscountAmount DECIMAL(10, 2) NOT NULL DEFAULT 0.00;

backend/src/main/resources/dev/final-target/final_target_schema.sql

@@ -230,6 +230,8 @@ CREATE TABLE IF NOT EXISTS sale (
     couponDiscountAmount DECIMAL(10, 2) NOT NULL DEFAULT 0.00,
     employeeDiscountAmount DECIMAL(10, 2) NOT NULL DEFAULT 0.00,
     pointsEarned INT NOT NULL DEFAULT 0,
+    pointsUsed INT NOT NULL DEFAULT 0,
+    pointsDiscountAmount DECIMAL(10, 2) NOT NULL DEFAULT 0.00,
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
     CONSTRAINT fk_sale_employee FOREIGN KEY (employeeId) REFERENCES users(id),