修复(#75): 按数量查询促销资格

Co-authored-by: multica-agent <github@multica.ai>

internal/logic/common/promoEligibility.go

@@ -53,6 +53,7 @@ func (promoRule) TableName() string {
 type subscribePromo struct {
 	Id          int64     `gorm:"column:id" json:"id"`
 	SubscribeId int64     `gorm:"column:subscribe_id" json:"subscribe_id"`
+	Quantity    int64     `gorm:"column:quantity" json:"quantity"`
 	PromoRuleId int64     `gorm:"column:promo_rule_id" json:"promo_rule_id"`
 	PromoPrice  int64     `gorm:"column:promo_price" json:"promo_price"`
 	CreatedAt   time.Time `gorm:"column:created_at" json:"created_at"`
@@ -77,12 +78,12 @@ type gormPromoEligibilitySource struct {
 	db *gorm.DB
 }
 
-func EvaluatePromo(ctx context.Context, svcCtx *svc.ServiceContext, userID int64, subscribeID int64) (*PromoResult, error) {
+func EvaluatePromo(ctx context.Context, svcCtx *svc.ServiceContext, userID int64, subscribeID int64, quantity int64) (*PromoResult, error) {
 	if svcCtx == nil || svcCtx.DB == nil {
 		return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "service context is empty")
 	}
-	if userID <= 0 || subscribeID <= 0 {
-		return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "user id or subscribe id is empty")
+	if userID <= 0 || subscribeID <= 0 || quantity <= 0 {
+		return nil, errors.Wrapf(xerr.NewErrCode(xerr.InvalidParams), "user id, subscribe id or quantity is empty")
 	}
 
 	rules, err := loadEnabledPromoRules(ctx, svcCtx)
@@ -93,7 +94,7 @@ func EvaluatePromo(ctx context.Context, svcCtx *svc.ServiceContext, userID int64
 		return &PromoResult{}, nil
 	}
 
-	prices, err := loadSubscribePromos(ctx, svcCtx, subscribeID)
+	prices, err := loadSubscribePromos(ctx, svcCtx, subscribeID, quantity)
 	if err != nil {
 		return nil, err
 	}
@@ -292,16 +293,14 @@ func loadEnabledPromoRules(ctx context.Context, svcCtx *svc.ServiceContext) ([]p
 	return rules, nil
 }
 
-func loadSubscribePromos(ctx context.Context, svcCtx *svc.ServiceContext, subscribeID int64) ([]subscribePromo, error) {
-	cacheKey := fmt.Sprintf("%s%d", promoSubscribeCachePrefix, subscribeID)
+func loadSubscribePromos(ctx context.Context, svcCtx *svc.ServiceContext, subscribeID int64, quantity int64) ([]subscribePromo, error) {
+	cacheKey := fmt.Sprintf("%s%d:%d", promoSubscribeCachePrefix, subscribeID, quantity)
 	if cached, ok := getPromoCache[[]subscribePromo](ctx, svcCtx, cacheKey); ok {
 		return cached, nil
 	}
 
 	var promos []subscribePromo
-	if err := svcCtx.DB.WithContext(ctx).
-		Model(&subscribePromo{}).
-		Where("subscribe_id = ?", subscribeID).
+	if err := subscribePromoQuery(svcCtx.DB.WithContext(ctx), subscribeID, quantity).
 		Find(&promos).Error; err != nil {
 		return nil, errors.Wrapf(xerr.NewErrCode(xerr.DatabaseQueryError), "query subscribe promos failed")
 	}
@@ -310,6 +309,12 @@ func loadSubscribePromos(ctx context.Context, svcCtx *svc.ServiceContext, subscr
 	return promos, nil
 }
 
+func subscribePromoQuery(db *gorm.DB, subscribeID int64, quantity int64) *gorm.DB {
+	return db.
+		Model(&subscribePromo{}).
+		Where("subscribe_id = ? AND quantity = ?", subscribeID, quantity)
+}
+
 func getPromoCache[T any](ctx context.Context, svcCtx *svc.ServiceContext, key string) (T, bool) {
 	var zero T
 	if svcCtx == nil || svcCtx.Redis == nil {