move: 后端

backend/internal/video/like_service.go

@@ -0,0 +1,66 @@
+package video
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"github.com/go-sql-driver/mysql"
+	"gorm.io/gorm"
+)
+
+type LikeService struct {
+	repo      *LikeRepository
+	VideoRepo *VideoRepository
+}
+
+func NewLikeService(repo *LikeRepository, videoRepo *VideoRepository) *LikeService {
+	return &LikeService{repo: repo, VideoRepo: videoRepo}
+}
+
+func isDupKey(err error) bool {
+	var me *mysql.MySQLError
+	return errors.As(err, &me) && me.Number == 1062
+}
+
+func (s *LikeService) Like(ctx context.Context, like *Like) error {
+	like.CreatedAt = time.Now()
+	return s.repo.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		if err := tx.Select("id").First(&Video{}, like.VideoID).Error; err != nil {
+			if errors.Is(err, gorm.ErrRecordNotFound) {
+				return errors.New("video not found")
+			}
+			return err
+		}
+		if err := tx.Create(like).Error; err != nil {
+			if isDupKey(err) {
+				return errors.New("user has liked this video")
+			}
+			return err
+		}
+		if err := tx.Model(&Video{}).Where("id = ?", like.VideoID).
+			UpdateColumn("likes_count", gorm.Expr("likes_count + 1")).Error; err != nil {
+			return err
+		}
+		return nil
+	})
+}
+
+func (s *LikeService) Unlike(ctx context.Context, like *Like) error {
+	return s.repo.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		del := tx.Where("video_id = ? AND account_id = ?", like.VideoID, like.AccountID).Delete(&Like{})
+		if del.Error != nil {
+			return del.Error
+		}
+		if del.RowsAffected == 0 {
+			return errors.New("user has not liked this video")
+		}
+
+		return tx.Model(&Video{}).Where("id = ?", like.VideoID).
+			UpdateColumn("likes_count", gorm.Expr("GREATEST(likes_count - 1, 0)")).Error
+	})
+}
+
+func (s *LikeService) IsLiked(ctx context.Context, videoID, accountID uint) (bool, error) {
+	return s.repo.IsLiked(ctx, videoID, accountID)
+}