feat(coupon): 添加优惠券领取功能

- 新增 CouponClaimRequest 和 CouponClaimResult 类用于处理优惠券领取请求和结果
- 在 ICouponService 接口中添加 claimCoupon 方法
- 在 CouponServiceImpl 中实现 claimCoupon 方法，包括参数验证、优惠券查询、库存检查、记录创建等步骤
- 优化日志记录和异常处理

src/main/java/com/ycwl/basic/pricing/service/ICouponService.java

@@ -3,6 +3,8 @@ package com.ycwl.basic.pricing.service;
 import com.ycwl.basic.pricing.dto.CouponInfo;
 import com.ycwl.basic.pricing.dto.CouponUseRequest;
 import com.ycwl.basic.pricing.dto.CouponUseResult;
+import com.ycwl.basic.pricing.dto.CouponClaimRequest;
+import com.ycwl.basic.pricing.dto.CouponClaimResult;
 import com.ycwl.basic.pricing.dto.ProductItem;
 import com.ycwl.basic.pricing.entity.PriceCouponConfig;
 
@@ -59,4 +61,12 @@ public interface ICouponService {
      * @return 可用优惠券列表
      */
     List<CouponInfo> getUserAvailableCoupons(Long userId);
+    
+    /**
+     * 领取优惠券（内部调用方法）
+     * 
+     * @param request 领取请求
+     * @return 领取结果
+     */
+    CouponClaimResult claimCoupon(CouponClaimRequest request);
 }

src/main/java/com/ycwl/basic/pricing/service/impl/CouponServiceImpl.java

@@ -196,4 +196,90 @@ public class CouponServiceImpl implements ICouponService {
         info.setActualDiscountAmount(actualDiscountAmount);
         return info;
     }
+    
+    @Override
+    @Transactional
+    public CouponClaimResult claimCoupon(CouponClaimRequest request) {
+        log.info("开始领取优惠券: userId={}, couponId={}, scenicId={}", 
+                request.getUserId(), request.getCouponId(), request.getScenicId());
+        
+        try {
+            // 1. 参数验证
+            if (request.getUserId() == null || request.getCouponId() == null) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_INVALID_PARAMS, "用户ID和优惠券ID不能为空");
+            }
+            
+            // 2. 查询优惠券配置
+            PriceCouponConfig coupon = couponConfigMapper.selectById(request.getCouponId());
+            if (coupon == null || coupon.getDeleted() == 1) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_COUPON_NOT_FOUND, "优惠券不存在");
+            }
+            
+            // 3. 检查优惠券是否启用
+            if (!Boolean.TRUE.equals(coupon.getIsActive())) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_COUPON_INACTIVE, "优惠券已停用");
+            }
+            
+            // 4. 检查优惠券有效期
+            LocalDateTime now = LocalDateTime.now();
+            if (coupon.getValidFrom() != null && now.isBefore(coupon.getValidFrom())) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_COUPON_EXPIRED, "优惠券尚未生效");
+            }
+            if (coupon.getValidUntil() != null && now.isAfter(coupon.getValidUntil())) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_COUPON_EXPIRED, "优惠券已过期");
+            }
+            
+            // 5. 检查库存（如果有总量限制）
+            if (coupon.getTotalQuantity() != null && coupon.getUsedQuantity() != null) {
+                if (coupon.getUsedQuantity() >= coupon.getTotalQuantity()) {
+                    return CouponClaimResult.failure(CouponClaimResult.ERROR_COUPON_OUT_OF_STOCK, "优惠券已领完");
+                }
+            }
+            
+            // 6. 检查用户是否已经领取过该优惠券
+            PriceCouponClaimRecord existingRecord = couponClaimRecordMapper.selectUserCouponRecord(
+                    request.getUserId(), request.getCouponId());
+            if (existingRecord != null) {
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_ALREADY_CLAIMED, "您已经领取过该优惠券");
+            }
+            
+            // 7. 创建领取记录
+            Date claimTime = new Date();
+            PriceCouponClaimRecord claimRecord = new PriceCouponClaimRecord();
+            claimRecord.setCouponId(request.getCouponId());
+            claimRecord.setUserId(request.getUserId());
+            claimRecord.setClaimTime(claimTime);
+            claimRecord.setStatus(CouponStatus.CLAIMED);
+            claimRecord.setScenicId(request.getScenicId());
+            claimRecord.setCreateTime(claimTime);
+            claimRecord.setUpdateTime(claimTime);
+            claimRecord.setDeleted(0);
+            
+            // 8. 插入领取记录
+            int insertResult = couponClaimRecordMapper.insert(claimRecord);
+            if (insertResult <= 0) {
+                log.error("插入优惠券领取记录失败: userId={}, couponId={}", 
+                        request.getUserId(), request.getCouponId());
+                return CouponClaimResult.failure(CouponClaimResult.ERROR_SYSTEM_ERROR, "领取失败，请稍后重试");
+            }
+            
+            // 9. 更新优惠券已使用数量（如果有总量限制）
+            if (coupon.getTotalQuantity() != null) {
+                int updatedUsedQuantity = (coupon.getUsedQuantity() == null ? 0 : coupon.getUsedQuantity()) + 1;
+                coupon.setUsedQuantity(updatedUsedQuantity);
+                couponConfigMapper.updateById(coupon);
+            }
+            
+            log.info("优惠券领取成功: userId={}, couponId={}, claimRecordId={}", 
+                    request.getUserId(), request.getCouponId(), claimRecord.getId());
+            
+            // 10. 返回成功结果
+            return CouponClaimResult.success(claimRecord, coupon.getCouponName());
+            
+        } catch (Exception e) {
+            log.error("领取优惠券失败: userId={}, couponId={}", 
+                    request.getUserId(), request.getCouponId(), e);
+            return CouponClaimResult.failure(CouponClaimResult.ERROR_SYSTEM_ERROR, "系统错误，领取失败：" + e.getMessage());
+        }
+    }
 }