Add tag filtering to ListPosts and enhance ListTags with post count

app/internal/logic/listpostslogic.go

@@ -39,23 +39,71 @@ func (l *ListPostsLogic) ListPosts(req *types.ListPostsReq) (resp *types.ListPos
 	}
 	offset := (page - 1) * pageSize
 
+	// Build query with optional tag filter
+	var countQuery string
+	var postsQuery string
+	var args []interface{}
+
+	if len(req.TagIds) > 0 {
+		// Filter by tags - posts that have ALL specified tags
+		countQuery = `
+			SELECT COUNT(DISTINCT p.id)
+			FROM posts p
+			INNER JOIN post_hashtags ph ON p.id = ph.post_id
+			WHERE ph.hashtag_id = ANY($1)
+			GROUP BY p.id
+			HAVING COUNT(DISTINCT ph.hashtag_id) = $2
+		`
+
+		postsQuery = `
+			SELECT DISTINCT p.id, p.title, p.created_at, p.updated_at, p.cover_id
+			FROM posts p
+			INNER JOIN post_hashtags ph ON p.id = ph.post_id
+			WHERE ph.hashtag_id = ANY($1)
+			GROUP BY p.id, p.title, p.created_at, p.updated_at, p.cover_id
+			HAVING COUNT(DISTINCT ph.hashtag_id) = $2
+			ORDER BY p.created_at DESC
+			LIMIT $3 OFFSET $4
+		`
+
+		args = []interface{}{req.TagIds, len(req.TagIds), pageSize, offset}
+	} else {
+		// No tag filter - get all posts
+		countQuery = `SELECT COUNT(*) FROM posts`
+		postsQuery = `
+			SELECT p.id, p.title, p.created_at, p.updated_at, p.cover_id
+			FROM posts p
+			ORDER BY p.created_at DESC
+			LIMIT $1 OFFSET $2
+		`
+		args = []interface{}{pageSize, offset}
+	}
+
 	// Get total count
 	var totalCount int
-	countQuery := `SELECT COUNT(*) FROM posts`
-	err = l.svcCtx.DB.QueryRowContext(l.ctx, countQuery).Scan(&totalCount)
-	if err != nil {
-		l.Errorf("Failed to get total count: %v", err)
-		return nil, err
+	if len(req.TagIds) > 0 {
+		// Count posts matching tag filter
+		rows, err := l.svcCtx.DB.QueryContext(l.ctx, countQuery, req.TagIds, len(req.TagIds))
+		if err != nil {
+			l.Errorf("Failed to get total count: %v", err)
+			return nil, err
+		}
+		defer rows.Close()
+
+		totalCount = 0
+		for rows.Next() {
+			totalCount++
+		}
+	} else {
+		err = l.svcCtx.DB.QueryRowContext(l.ctx, countQuery).Scan(&totalCount)
+		if err != nil {
+			l.Errorf("Failed to get total count: %v", err)
+			return nil, err
+		}
 	}
 
 	// Get posts with pagination
-	postsQuery := `
-		SELECT p.id, p.title, p.created_at, p.updated_at, p.cover_id
-		FROM posts p
-		ORDER BY p.created_at DESC
-		LIMIT $1 OFFSET $2
-	`
-	rows, err := l.svcCtx.DB.QueryContext(l.ctx, postsQuery, pageSize, offset)
+	rows, err := l.svcCtx.DB.QueryContext(l.ctx, postsQuery, args...)
 	if err != nil {
 		l.Errorf("Failed to get posts: %v", err)
 		return nil, err

app/internal/logic/listtagslogic.go

@@ -25,8 +25,14 @@ func NewListTagsLogic(ctx context.Context, svcCtx *svc.ServiceContext) *ListTags
 }
 
 func (l *ListTagsLogic) ListTags(req *types.ListTagsReq) (resp *types.ListTagsResp, err error) {
-	// Query all hashtags
-	query := `SELECT id, name FROM hashtags ORDER BY name`
+	// Query all hashtags with post count
+	query := `
+		SELECT h.id, h.name, COUNT(ph.post_id) as post_count
+		FROM hashtags h
+		LEFT JOIN post_hashtags ph ON h.id = ph.hashtag_id
+		GROUP BY h.id, h.name
+		ORDER BY h.name
+	`
 	rows, err := l.svcCtx.DB.QueryContext(l.ctx, query)
 	if err != nil {
 		l.Errorf("Failed to get tags: %v", err)
@@ -37,7 +43,7 @@ func (l *ListTagsLogic) ListTags(req *types.ListTagsReq) (resp *types.ListTagsRe
 	var tags []types.ListTagsRespTags
 	for rows.Next() {
 		var tag types.ListTagsRespTags
-		err := rows.Scan(&tag.TagId, &tag.TagName)
+		err := rows.Scan(&tag.TagId, &tag.TagName, &tag.PostCount)
 		if err != nil {
 			l.Errorf("Failed to scan tag: %v", err)
 			continue

app/internal/types/types.go

@@ -53,8 +53,9 @@ type GetPostResp struct {
 }
 
 type ListPostsReq struct {
-	Page     int `json:"page"`     // Page number for pagination (1-based)
-	PageSize int `json:"pageSize"` // Number of posts per page
+	TagIds   []string `json:"tagIds,optional"` // Array of tag IDs to filter posts (optional)
+	Page     int      `json:"page"`            // Page number for pagination (1-based)
+	PageSize int      `json:"pageSize"`        // Number of posts per page
 }
 
 type ListPostsResp struct {
@@ -78,8 +79,9 @@ type ListTagsResp struct {
 }
 
 type ListTagsRespTags struct {
-	TagId   string `json:"tagId"`   // Unique identifier of the tag
-	TagName string `json:"tagName"` // Name of the tag
+	TagId     string `json:"tagId"`     // Unique identifier of the tag
+	TagName   string `json:"tagName"`   // Name of the tag
+	PostCount int    `json:"postCount"` // Number of posts associated with the tag
 }
 
 type PingReq struct {