Fix duplicate download insert: handle NULL columns in download scan, check by torrent ID, enrich MonitorAlbum response, recover orphaned downloads on startup

internal/database/download_repository.go

@@ -16,8 +16,8 @@ type Download struct {
 	Quality      string
 	State        string
 	QbitHash     string
-	SavePath     string
-	ErrorMessage string
+	SavePath     *string
+	ErrorMessage *string
 	QueuedAt     time.Time
 	StartedAt    *time.Time
 	CompletedAt  *time.Time
@@ -107,6 +107,19 @@ func (r *DownloadRepository) GetByAlbumID(ctx context.Context, albumID string) (
 	return downloads, nil
 }
 
+func (r *DownloadRepository) GetActiveByTorrentID(ctx context.Context, torrentID string) (*Download, error) {
+	d := &Download{}
+	err := r.pool.QueryRow(ctx,
+		`SELECT id, torrent_id, album_id, format, quality, state, qbit_hash, save_path, error_message, queued_at, started_at, completed_at, created_at, updated_at
+		 FROM downloads WHERE torrent_id = $1 AND state NOT IN ('failed')
+		 ORDER BY created_at DESC LIMIT 1`, torrentID,
+	).Scan(&d.ID, &d.TorrentID, &d.AlbumID, &d.Format, &d.Quality, &d.State, &d.QbitHash, &d.SavePath, &d.ErrorMessage, &d.QueuedAt, &d.StartedAt, &d.CompletedAt, &d.CreatedAt, &d.UpdatedAt)
+	if err != nil {
+		return nil, fmt.Errorf("getting active download by torrent: %w", err)
+	}
+	return d, nil
+}
+
 func (r *DownloadRepository) GetActive(ctx context.Context) ([]*Download, error) {
 	rows, err := r.pool.Query(ctx,
 		`SELECT id, torrent_id, album_id, format, quality, state, qbit_hash, save_path, error_message, queued_at, started_at, completed_at, created_at, updated_at

internal/service.go

@@ -170,7 +170,7 @@ func (service *MusicAgregatorService) buildAlbumsForArtist(ctx context.Context,
 					State:    best.State,
 					Format:   best.Format,
 					Quality:  best.Quality,
-					SavePath: best.SavePath,
+					SavePath: derefStr(best.SavePath),
 				}
 			}
 		} else {
@@ -228,7 +228,7 @@ func (service *MusicAgregatorService) GetAlbum(ctx context.Context, req *pb.GetA
 			State:    best.State,
 			Format:   best.Format,
 			Quality:  best.Quality,
-			SavePath: best.SavePath,
+			SavePath: derefStr(best.SavePath),
 		}
 	}
 
@@ -514,14 +514,10 @@ func (service *MusicAgregatorService) saveTorrentAndDownload(ctx context.Context
 		return
 	}
 
-	existingDownloads, err := service.downloads.GetByAlbumID(ctx, dbAlbumID)
-	if err == nil {
-		for _, d := range existingDownloads {
-			if d.TorrentID == savedTorrent.ID && d.State != "failed" {
-				log.Info().Str("hash", best.rel.InfoHash).Str("state", d.State).Msg("active download already exists, skipping")
-				return
-			}
-		}
+	existingDownload, err := service.downloads.GetActiveByTorrentID(ctx, savedTorrent.ID)
+	if err == nil && existingDownload != nil {
+		log.Info().Str("hash", best.rel.InfoHash).Str("state", existingDownload.State).Msg("active download already exists, skipping")
+		return
 	}
 
 	download := &database.Download{
@@ -647,7 +643,7 @@ func (service *MusicAgregatorService) buildAlbumDetail(ctx context.Context, dbAl
 			State:    best.State,
 			Format:   best.Format,
 			Quality:  best.Quality,
-			SavePath: best.SavePath,
+			SavePath: derefStr(best.SavePath),
 		}
 	}
 
@@ -667,6 +663,13 @@ func toProtoMonitorState(state database.MonitorState) pb.MonitorState {
 	}
 }
 
+func derefStr(s *string) string {
+	if s == nil {
+		return ""
+	}
+	return *s
+}
+
 func downloadTorrentData(url string) ([]byte, error) {
 	client := &http.Client{Timeout: 30 * time.Second}
 	resp, err := client.Get(url)