Refactor GetPost and ListPosts logic to use time.Time for timestamps; convert to Unix milliseconds and improve error handling

app/internal/logic/listpostslogic.go

@@ -9,6 +9,7 @@ import (
 	"git.cialloo.com/CiallooWeb/Blog/app/internal/types"
 
 	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/lib/pq"
 	"github.com/zeromicro/go-zero/core/logx"
 )
 
@@ -28,35 +29,65 @@ func NewListPostsLogic(ctx context.Context, svcCtx *svc.ServiceContext) *ListPos
 }
 
 func (l *ListPostsLogic) ListPosts(req *types.ListPostsReq) (resp *types.ListPostsResp, err error) {
-	// Set default values
+	// Determine pagination parameters with sane defaults.
 	page := req.Page
 	if page < 1 {
 		page = 1
 	}
+
 	pageSize := req.PageSize
 	if pageSize < 1 || pageSize > 100 {
-		pageSize = 10 // Default page size
+		pageSize = 10
 	}
+
 	offset := (page - 1) * pageSize
 
-	// Build query with optional tag filter
-	var countQuery string
-	var postsQuery string
-	var args []interface{}
+	var (
+		rows       *sql.Rows
+		totalCount int
+	)
 
-	if len(req.TagIds) > 0 {
-		// Filter by tags - posts that have ALL specified tags
-		countQuery = `
-			SELECT COUNT(DISTINCT p.id)
+	if len(req.TagIds) == 0 {
+		countQuery := `SELECT COUNT(*) FROM posts`
+		if err = l.svcCtx.DB.QueryRowContext(l.ctx, countQuery).Scan(&totalCount); err != nil {
+			l.Errorf("Failed to get total count: %v", err)
+			return nil, err
+		}
+
+		postsQuery := `
+			SELECT 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
-			HAVING COUNT(DISTINCT ph.hashtag_id) = $2
+			ORDER BY p.created_at DESC
+			LIMIT $1 OFFSET $2
 		`
 
-		postsQuery = `
-			SELECT DISTINCT p.id, p.title, p.created_at, p.updated_at, p.cover_id
+		rows, err = l.svcCtx.DB.QueryContext(l.ctx, postsQuery, pageSize, offset)
+		if err != nil {
+			l.Errorf("Failed to get posts: %v", err)
+			return nil, err
+		}
+	} else {
+		tagArray := pq.Array(req.TagIds)
+
+		countQuery := `
+			SELECT COUNT(*)
+			FROM (
+				SELECT 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
+			) filtered_posts
+		`
+
+		if err = l.svcCtx.DB.QueryRowContext(l.ctx, countQuery, tagArray, len(req.TagIds)).Scan(&totalCount); err != nil {
+			l.Errorf("Failed to get filtered total count: %v", err)
+			return nil, err
+		}
+
+		postsQuery := `
+			SELECT 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)
@@ -66,83 +97,47 @@ func (l *ListPostsLogic) ListPosts(req *types.ListPostsReq) (resp *types.ListPos
 			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
-	if len(req.TagIds) > 0 {
-		// Count posts matching tag filter
-		rows, err := l.svcCtx.DB.QueryContext(l.ctx, countQuery, req.TagIds, len(req.TagIds))
+		rows, err = l.svcCtx.DB.QueryContext(l.ctx, postsQuery, tagArray, len(req.TagIds), pageSize, offset)
 		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)
+			l.Errorf("Failed to get filtered posts: %v", err)
 			return nil, err
 		}
 	}
 
-	// Get posts with pagination
-	rows, err := l.svcCtx.DB.QueryContext(l.ctx, postsQuery, args...)
-	if err != nil {
-		l.Errorf("Failed to get posts: %v", err)
-		return nil, err
-	}
 	defer rows.Close()
 
-	posts := []types.ListPostsRespPosts{}
+	posts := make([]types.ListPostsRespPosts, 0)
 	for rows.Next() {
-		var post types.ListPostsRespPosts
-		var coverID sql.NullInt64
-		var createdAt, updatedAt time.Time
+		var (
+			post      types.ListPostsRespPosts
+			coverID   sql.NullInt64
+			createdAt time.Time
+			updatedAt time.Time
+		)
 
-		err := rows.Scan(&post.PostId, &post.Title, &createdAt, &updatedAt, &coverID)
-		if err != nil {
-			l.Errorf("Failed to scan post: %v", err)
+		if scanErr := rows.Scan(&post.PostId, &post.Title, &createdAt, &updatedAt, &coverID); scanErr != nil {
+			l.Errorf("Failed to scan post: %v", scanErr)
 			continue
 		}
 
-		// Convert timestamps to Unix milliseconds
 		post.CreatedAt = createdAt.UnixMilli()
 		post.UpdatedAt = updatedAt.UnixMilli()
 
-		// If cover image exists, get its URL
 		if coverID.Valid {
-			coverQuery := `SELECT file_key FROM files WHERE id = $1`
+			const coverQuery = `SELECT file_key FROM files WHERE id = $1`
 			var fileKey string
-			err = l.svcCtx.DB.QueryRowContext(l.ctx, coverQuery, coverID.Int64).Scan(&fileKey)
-			if err == nil {
-				// Generate presigned URL for cover image
+
+			if queryErr := l.svcCtx.DB.QueryRowContext(l.ctx, coverQuery, coverID.Int64).Scan(&fileKey); queryErr == nil {
 				expiration := time.Duration(l.svcCtx.Config.S3.PresignedURLExpiration) * time.Second
 				presignClient := s3.NewPresignClient(l.svcCtx.S3Client)
 				getObjectInput := &s3.GetObjectInput{
 					Bucket: &l.svcCtx.Config.S3.Bucket,
 					Key:    &fileKey,
 				}
-				presignedReq, err := presignClient.PresignGetObject(l.ctx, getObjectInput, func(opts *s3.PresignOptions) {
+
+				if presignedReq, presignErr := presignClient.PresignGetObject(l.ctx, getObjectInput, func(opts *s3.PresignOptions) {
 					opts.Expires = expiration
-				})
-				if err == nil {
+				}); presignErr == nil {
 					post.CoverImageUrl = presignedReq.URL
 				}
 			}
@@ -151,6 +146,11 @@ func (l *ListPostsLogic) ListPosts(req *types.ListPostsReq) (resp *types.ListPos
 		posts = append(posts, post)
 	}
 
+	if rowsErr := rows.Err(); rowsErr != nil {
+		l.Errorf("Error while iterating posts: %v", rowsErr)
+		return nil, rowsErr
+	}
+
 	return &types.ListPostsResp{
 		Posts:      posts,
 		TotalCount: totalCount,