feat: Implement notification service and integrate with user interactions

- Added notification service to handle sending and listing notifications.
- Integrated notification sending on user follow and order payment events.
- Updated user service to include fetching followed tenants.
- Enhanced content service to manage access control for content assets.
- Implemented logic for listing content topics based on genre.
- Updated creator service to manage content updates and pricing.
- Improved order service to include detailed order information and notifications.
- Added tests for notification CRUD operations and order details.

backend/app/services/content.go

@@ -102,11 +102,14 @@ func (s *content) Get(ctx context.Context, id string) (*content_dto.ContentDetai
 		return nil, errorx.ErrDatabaseError.WithCause(err)
 	}
 
-	// Interaction status
+	// Interaction & Access status
 	isLiked := false
 	isFavorited := false
+	hasAccess := false
+
 	if userID := ctx.Value(consts.CtxKeyUser); userID != nil {
 		uid := cast.ToInt64(userID)
+		// Interaction
 		isLiked, _ = models.UserContentActionQuery.WithContext(ctx).
 			Where(models.UserContentActionQuery.UserID.Eq(uid),
 				models.UserContentActionQuery.ContentID.Eq(cid),
@@ -117,16 +120,46 @@ func (s *content) Get(ctx context.Context, id string) (*content_dto.ContentDetai
 				models.UserContentActionQuery.ContentID.Eq(cid),
 				models.UserContentActionQuery.Type.Eq("favorite")).
 			Exists()
+
+		// Access Check
+		if item.UserID == uid {
+			hasAccess = true // Owner
+		} else {
+			// Check Purchase
+			exists, _ := models.ContentAccessQuery.WithContext(ctx).
+				Where(models.ContentAccessQuery.UserID.Eq(uid),
+					models.ContentAccessQuery.ContentID.Eq(cid),
+					models.ContentAccessQuery.Status.Eq(consts.ContentAccessStatusActive)).
+				Exists()
+			if exists {
+				hasAccess = true
+			}
+		}
+	}
+
+	// Filter Assets based on Access
+	var accessibleAssets []*models.ContentAsset
+	for _, ca := range item.ContentAssets {
+		if hasAccess {
+			accessibleAssets = append(accessibleAssets, ca)
+		} else {
+			// If no access, only allow Preview and Cover
+			if ca.Role == consts.ContentAssetRolePreview || ca.Role == consts.ContentAssetRoleCover {
+				accessibleAssets = append(accessibleAssets, ca)
+			}
+		}
 	}
 
 	detail := &content_dto.ContentDetail{
 		ContentItem: s.toContentItemDTO(&item),
 		Description: item.Description,
 		Body:        item.Body,
-		MediaUrls:   s.toMediaURLs(item.ContentAssets),
+		MediaUrls:   s.toMediaURLs(accessibleAssets),
 		IsLiked:     isLiked,
 		IsFavorited: isFavorited,
 	}
+	// Pass IsPurchased/HasAccess info to frontend?
+	detail.ContentItem.IsPurchased = hasAccess // Update DTO field logic if needed. IsPurchased usually means "Bought". Owner implies access but not necessarily purchased. But for UI "Play" button, IsPurchased=true is fine.
 
 	return detail, nil
 }
@@ -224,7 +257,13 @@ func (s *content) LikeComment(ctx context.Context, id string) error {
 	uid := cast.ToInt64(userID)
 	cmid := cast.ToInt64(id)
 
-	return models.Q.Transaction(func(tx *models.Query) error {
+	// Fetch comment for author
+	cm, err := models.CommentQuery.WithContext(ctx).Where(models.CommentQuery.ID.Eq(cmid)).First()
+	if err != nil {
+		return errorx.ErrRecordNotFound
+	}
+
+	err = models.Q.Transaction(func(tx *models.Query) error {
 		exists, _ := tx.UserCommentAction.WithContext(ctx).
 			Where(tx.UserCommentAction.UserID.Eq(uid), tx.UserCommentAction.CommentID.Eq(cmid), tx.UserCommentAction.Type.Eq("like")).
 			Exists()
@@ -240,6 +279,14 @@ func (s *content) LikeComment(ctx context.Context, id string) error {
 		_, err := tx.Comment.WithContext(ctx).Where(tx.Comment.ID.Eq(cmid)).UpdateSimple(tx.Comment.Likes.Add(1))
 		return err
 	})
+	if err != nil {
+		return err
+	}
+
+	if Notification != nil {
+		_ = Notification.Send(ctx, cm.UserID, "interaction", "评论点赞", "有人点赞了您的评论")
+	}
+	return nil
 }
 
 func (s *content) GetLibrary(ctx context.Context) ([]user_dto.ContentItem, error) {
@@ -309,8 +356,56 @@ func (s *content) RemoveLike(ctx context.Context, contentId string) error {
 }
 
 func (s *content) ListTopics(ctx context.Context) ([]content_dto.Topic, error) {
-	// topics usually hardcoded or from a dedicated table
-	return []content_dto.Topic{}, nil
+	var results []struct {
+		Genre string
+		Count int
+	}
+	err := models.ContentQuery.WithContext(ctx).UnderlyingDB().
+		Model(&models.Content{}).
+		Where("status = ?", consts.ContentStatusPublished).
+		Select("genre, count(*) as count").
+		Group("genre").
+		Scan(&results).Error
+
+	if err != nil {
+		return nil, errorx.ErrDatabaseError.WithCause(err)
+	}
+
+	var topics []content_dto.Topic
+	for i, r := range results {
+		if r.Genre == "" {
+			continue
+		}
+
+		// Fetch latest content in this genre to get a cover
+		var c models.Content
+		models.ContentQuery.WithContext(ctx).
+			Where(models.ContentQuery.Genre.Eq(r.Genre), models.ContentQuery.Status.Eq(consts.ContentStatusPublished)).
+			Order(models.ContentQuery.PublishedAt.Desc()).
+			UnderlyingDB().
+			Preload("ContentAssets").
+			Preload("ContentAssets.Asset").
+			First(&c)
+
+		cover := ""
+		for _, ca := range c.ContentAssets {
+			if (ca.Role == consts.ContentAssetRoleCover || ca.Role == consts.ContentAssetRoleMain) && ca.Asset != nil {
+				cover = Common.GetAssetURL(ca.Asset.ObjectKey)
+				if ca.Role == consts.ContentAssetRoleCover {
+					break // Prefer cover
+				}
+			}
+		}
+
+		topics = append(topics, content_dto.Topic{
+			ID:    cast.ToString(i + 1), // Use index as ID for aggregation results
+			Title: r.Genre,
+			Tag:   r.Genre,
+			Count: r.Count,
+			Cover: cover,
+		})
+	}
+	return topics, nil
 }
 
 // Helpers
@@ -337,7 +432,7 @@ func (s *content) toContentItemDTO(item *models.Content) content_dto.ContentItem
 		}
 		// Cover
 		if asset.Role == consts.ContentAssetRoleCover {
-			dto.Cover = "http://mock/" + asset.Asset.ObjectKey
+			dto.Cover = Common.GetAssetURL(asset.Asset.ObjectKey)
 		}
 		// Type detection
 		switch asset.Asset.Type {
@@ -352,7 +447,7 @@ func (s *content) toContentItemDTO(item *models.Content) content_dto.ContentItem
 	if dto.Cover == "" && len(item.ContentAssets) > 0 {
 		for _, asset := range item.ContentAssets {
 			if asset.Asset != nil && asset.Asset.Type == consts.MediaAssetTypeImage {
-				dto.Cover = "http://mock/" + asset.Asset.ObjectKey
+				dto.Cover = Common.GetAssetURL(asset.Asset.ObjectKey)
 				break
 			}
 		}
@@ -373,7 +468,7 @@ func (s *content) toMediaURLs(assets []*models.ContentAsset) []content_dto.Media
 	var urls []content_dto.MediaURL
 	for _, ca := range assets {
 		if ca.Asset != nil {
-			url := "http://mock/" + ca.Asset.ObjectKey
+			url := Common.GetAssetURL(ca.Asset.ObjectKey)
 			urls = append(urls, content_dto.MediaURL{
 				Type: string(ca.Asset.Type),
 				URL:  url,
@@ -391,7 +486,13 @@ func (s *content) addInteract(ctx context.Context, contentId, typ string) error
 	uid := cast.ToInt64(userID)
 	cid := cast.ToInt64(contentId)
 
-	return models.Q.Transaction(func(tx *models.Query) error {
+	// Fetch content for author
+	c, err := models.ContentQuery.WithContext(ctx).Where(models.ContentQuery.ID.Eq(cid)).Select(models.ContentQuery.UserID, models.ContentQuery.Title).First()
+	if err != nil {
+		return errorx.ErrRecordNotFound
+	}
+
+	err = models.Q.Transaction(func(tx *models.Query) error {
 		exists, _ := tx.UserContentAction.WithContext(ctx).
 			Where(tx.UserContentAction.UserID.Eq(uid), tx.UserContentAction.ContentID.Eq(cid), tx.UserContentAction.Type.Eq(typ)).
 			Exists()
@@ -410,6 +511,20 @@ func (s *content) addInteract(ctx context.Context, contentId, typ string) error
 		}
 		return nil
 	})
+	if err != nil {
+		return err
+	}
+
+	if Notification != nil {
+		actionName := "互动"
+		if typ == "like" {
+			actionName = "点赞"
+		} else if typ == "favorite" {
+			actionName = "收藏"
+		}
+		_ = Notification.Send(ctx, c.UserID, "interaction", "新的"+actionName, "有人"+actionName+"了您的作品: "+c.Title)
+	}
+	return nil
 }
 
 func (s *content) removeInteract(ctx context.Context, contentId, typ string) error {