Download Queue & Progress UI (#123)

* Add download queue tracking and UI integration

Introduces backend support for a download queue with item tracking, status updates, and session statistics. Adds frontend components and hooks for displaying and managing the download queue, including a dialog and toast indicator. Updates download logic to pre-add items to the queue, track progress, and handle completion, skipping, and failure states. Integrates @radix-ui/react-scroll-area for improved UI scrolling.

* Add session stats to DownloadQueue dialog

Introduces session statistics (downloaded amount, speed, and duration) to the DownloadQueue dialog for improved user feedback. Also adjusts dialog sizing for better display and removes the sm:max-w-lg restriction in dialog.tsx for more flexible width.

app.go

@@ -53,6 +53,7 @@ type DownloadRequest struct {
 	SpotifyID           string `json:"spotify_id,omitempty"`             // Spotify track ID
 	ServiceURL          string `json:"service_url,omitempty"`            // Direct service URL (Tidal/Deezer/Amazon) to skip song.link API call
 	Duration            int    `json:"duration,omitempty"`               // Track duration in seconds for better matching
+	ItemID              string `json:"item_id,omitempty"`                // Optional queue item ID for multi-service fallback tracking
 }
 
 // DownloadResponse represents the response structure for download operations
@@ -62,6 +63,7 @@ type DownloadResponse struct {
 	File          string `json:"file,omitempty"`
 	Error         string `json:"error,omitempty"`
 	AlreadyExists bool   `json:"already_exists,omitempty"`
+	ItemID        string `json:"item_id,omitempty"` // Queue item ID for tracking
 }
 
 // GetStreamingURLs fetches all streaming URLs from song.link API
@@ -143,14 +145,30 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 		req.FilenameFormat = "title-artist"
 	}
 
+	// ItemID should always be provided by frontend (created via AddToDownloadQueue)
+	// If not provided, generate one for backwards compatibility
+	itemID := req.ItemID
+	if itemID == "" {
+		itemID = fmt.Sprintf("%s-%d", req.ISRC, time.Now().UnixNano())
+		// Add to queue if no ItemID was provided (legacy support)
+		backend.AddToQueue(itemID, req.TrackName, req.ArtistName, req.AlbumName, req.ISRC)
+	}
+
+	// Mark item as downloading immediately
+	backend.SetDownloading(true)
+	backend.StartDownloadItem(itemID)
+	defer backend.SetDownloading(false)
+
 	// Early check: Check if file with same ISRC already exists
 	if existingFile, exists := backend.CheckISRCExists(req.OutputDir, req.ISRC); exists {
 		fmt.Printf("File with ISRC %s already exists: %s\n", req.ISRC, existingFile)
+		backend.SkipDownloadItem(itemID, existingFile)
 		return DownloadResponse{
 			Success:       true,
 			Message:       "File with same ISRC already exists",
 			File:          existingFile,
 			AlreadyExists: true,
+			ItemID:        itemID,
 		}, nil
 	}
 
@@ -159,20 +177,28 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 		expectedFilename := backend.BuildExpectedFilename(req.TrackName, req.ArtistName, req.FilenameFormat, req.TrackNumber, req.Position, req.UseAlbumTrackNumber)
 		expectedPath := filepath.Join(req.OutputDir, expectedFilename)
 
-		if fileInfo, err := os.Stat(expectedPath); err == nil && fileInfo.Size() > 0 {
-			return DownloadResponse{
-				Success:       true,
-				Message:       "File already exists",
-				File:          expectedPath,
-				AlreadyExists: true,
-			}, nil
+		if fileInfo, err := os.Stat(expectedPath); err == nil && fileInfo.Size() > 100*1024 {
+			// Validate the file by checking if it has valid ISRC metadata
+			if fileISRC, readErr := backend.ReadISRCFromFile(expectedPath); readErr == nil && fileISRC != "" {
+				// File exists and has valid metadata - skip download
+				backend.SkipDownloadItem(itemID, expectedPath)
+				return DownloadResponse{
+					Success:       true,
+					Message:       "File already exists",
+					File:          expectedPath,
+					AlreadyExists: true,
+					ItemID:        itemID,
+				}, nil
+			} else {
+				// File exists but has no valid ISRC metadata - it's corrupted, delete it
+				fmt.Printf("Removing corrupted file (no valid ISRC metadata): %s\n", expectedPath)
+				if removeErr := os.Remove(expectedPath); removeErr != nil {
+					fmt.Printf("Warning: Failed to remove corrupted file %s: %v\n", expectedPath, removeErr)
+				}
+			}
 		}
 	}
 
-	// Set downloading state
-	backend.SetDownloading(true)
-	defer backend.SetDownloading(false)
-
 	switch req.Service {
 	case "amazon":
 		downloader := backend.NewAmazonDownloader()
@@ -243,9 +269,23 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 	}
 
 	if err != nil {
+		// Clean up any partial/corrupted file that was created during failed download
+		if filename != "" && !strings.HasPrefix(filename, "EXISTS:") {
+			// Check if file exists and delete it
+			if _, statErr := os.Stat(filename); statErr == nil {
+				fmt.Printf("Removing corrupted/partial file after failed download: %s\n", filename)
+				if removeErr := os.Remove(filename); removeErr != nil {
+					fmt.Printf("Warning: Failed to remove corrupted file %s: %v\n", filename, removeErr)
+				}
+			}
+		}
+
+		// Don't mark as failed in backend - let the frontend handle it
+		// Frontend will call MarkDownloadItemFailed after all services are tried
 		return DownloadResponse{
 			Success: false,
 			Error:   fmt.Sprintf("Download failed: %v", err),
+			ItemID:  itemID,
 		}, err
 	}
 
@@ -259,6 +299,16 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 	message := "Download completed successfully"
 	if alreadyExists {
 		message = "File already exists"
+		backend.SkipDownloadItem(itemID, filename)
+	} else {
+		// Get file size for completed download
+		if fileInfo, statErr := os.Stat(filename); statErr == nil {
+			finalSize := float64(fileInfo.Size()) / (1024 * 1024) // Convert to MB
+			backend.CompleteDownloadItem(itemID, filename, finalSize)
+		} else {
+			// Fallback: mark as completed without size
+			backend.CompleteDownloadItem(itemID, filename, 0)
+		}
 	}
 
 	return DownloadResponse{
@@ -266,6 +316,7 @@ func (a *App) DownloadTrack(req DownloadRequest) (DownloadResponse, error) {
 		Message:       message,
 		File:          filename,
 		AlreadyExists: alreadyExists,
+		ItemID:        itemID,
 	}, nil
 }
 
@@ -305,6 +356,38 @@ func (a *App) GetDownloadProgress() backend.ProgressInfo {
 	return backend.GetDownloadProgress()
 }
 
+// GetDownloadQueue returns the complete download queue state
+func (a *App) GetDownloadQueue() backend.DownloadQueueInfo {
+	return backend.GetDownloadQueue()
+}
+
+// ClearCompletedDownloads clears completed, failed, and skipped items from the queue
+func (a *App) ClearCompletedDownloads() {
+	backend.ClearDownloadQueue()
+}
+
+// ClearAllDownloads clears the entire queue and resets session stats
+func (a *App) ClearAllDownloads() {
+	backend.ClearAllDownloads()
+}
+
+// AddToDownloadQueue adds a new item to the download queue and returns its ID
+func (a *App) AddToDownloadQueue(isrc, trackName, artistName, albumName string) string {
+	itemID := fmt.Sprintf("%s-%d", isrc, time.Now().UnixNano())
+	backend.AddToQueue(itemID, trackName, artistName, albumName, isrc)
+	return itemID
+}
+
+// MarkDownloadItemFailed marks a download item as failed
+func (a *App) MarkDownloadItemFailed(itemID, errorMsg string) {
+	backend.FailDownloadItem(itemID, errorMsg)
+}
+
+// CancelAllQueuedItems marks all queued items as cancelled/skipped
+func (a *App) CancelAllQueuedItems() {
+	backend.CancelAllQueuedItems()
+}
+
 // Quit closes the application
 func (a *App) Quit() {
 	// You can add cleanup logic here if needed