v7.0.1

backend/amazon.go

@@ -63,16 +63,14 @@ func (a *AmazonDownloader) getRandomUserAgent() string {
 }
 
 func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (string, error) {
-	// Rate limiting: max 10 requests per minute (song.link API limit)
-	// Reset counter every minute
+
 	now := time.Now()
 	if now.Sub(a.apiCallResetTime) >= time.Minute {
 		a.apiCallCount = 0
 		a.apiCallResetTime = now
 	}
 
-	// If we've hit the limit, wait until the next minute
-	if a.apiCallCount >= 9 { // Use 9 to be safe (limit is 10)
+	if a.apiCallCount >= 9 {
 		waitTime := time.Minute - now.Sub(a.apiCallResetTime)
 		if waitTime > 0 {
 			fmt.Printf("Rate limit reached, waiting %v...\n", waitTime.Round(time.Second))
@@ -82,10 +80,9 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 		}
 	}
 
-	// Add delay between requests (6 seconds = 10 requests per minute)
 	if !a.lastAPICallTime.IsZero() {
 		timeSinceLastCall := now.Sub(a.lastAPICallTime)
-		minDelay := 7 * time.Second // 7 seconds to be safe
+		minDelay := 7 * time.Second
 		if timeSinceLastCall < minDelay {
 			waitTime := minDelay - timeSinceLastCall
 			fmt.Printf("Rate limiting: waiting %v...\n", waitTime.Round(time.Second))
@@ -93,7 +90,6 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 		}
 	}
 
-	// Decode base64 API URL
 	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL3RyYWNrLw==")
 	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyTrackID)
 
@@ -109,7 +105,6 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 
 	fmt.Println("Getting Amazon URL...")
 
-	// Retry logic for rate limit errors
 	maxRetries := 3
 	var resp *http.Response
 	for i := 0; i < maxRetries; i++ {
@@ -118,11 +113,10 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 			return "", fmt.Errorf("failed to get Amazon URL: %w", err)
 		}
 
-		// Update rate limit tracking
 		a.lastAPICallTime = time.Now()
 		a.apiCallCount++
 
-		if resp.StatusCode == 429 { // Too Many Requests
+		if resp.StatusCode == 429 {
 			resp.Body.Close()
 			if i < maxRetries-1 {
 				waitTime := 15 * time.Second
@@ -142,7 +136,6 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 	}
 	defer resp.Body.Close()
 
-	// Read body first to handle encoding issues and provide better error messages
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return "", fmt.Errorf("failed to read response body: %w", err)
@@ -154,7 +147,7 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 
 	var songLinkResp SongLinkResponse
 	if err := json.Unmarshal(body, &songLinkResp); err != nil {
-		// Truncate body for error message (max 200 chars)
+
 		bodyStr := string(body)
 		if len(bodyStr) > 200 {
 			bodyStr = bodyStr[:200] + "..."
@@ -169,7 +162,6 @@ func (a *AmazonDownloader) GetAmazonURLFromSpotify(spotifyTrackID string) (strin
 
 	amazonURL := amazonLink.URL
 
-	// Convert album URL to track URL if needed
 	if strings.Contains(amazonURL, "trackAsin=") {
 		parts := strings.Split(amazonURL, "trackAsin=")
 		if len(parts) > 1 {
@@ -188,12 +180,11 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 
 	for _, region := range a.regions {
 		fmt.Printf("\nTrying region: %s...\n", region)
-		// Decode base64 service URL
+
 		serviceBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly8=")
 		serviceDomain, _ := base64.StdEncoding.DecodeString("LmRvdWJsZWRvdWJsZS50b3A=")
 		baseURL := fmt.Sprintf("%s%s%s", string(serviceBase), region, string(serviceDomain))
 
-		// Step 1: Submit download request
 		encodedURL := url.QueryEscape(amazonURL)
 		submitURL := fmt.Sprintf("%s/dl?url=%s", baseURL, encodedURL)
 
@@ -234,7 +225,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 		downloadID := submitResp.ID
 		fmt.Printf("Download ID: %s\n", downloadID)
 
-		// Step 2: Poll for completion
 		statusURL := fmt.Sprintf("%s/dl/%s", baseURL, downloadID)
 		fmt.Println("Waiting for download to complete...")
 
@@ -276,7 +266,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 			if status.Status == "done" {
 				fmt.Println("\nDownload ready!")
 
-				// Build download URL
 				fileURL := status.URL
 				if strings.HasPrefix(fileURL, "./") {
 					fileURL = fmt.Sprintf("%s/%s", baseURL, fileURL[2:])
@@ -289,7 +278,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 
 				fmt.Printf("Downloading: %s - %s\n", artist, trackName)
 
-				// Download file
 				downloadReq, err := http.NewRequest("GET", fileURL, nil)
 				if err != nil {
 					lastError = fmt.Errorf("failed to create download request: %w", err)
@@ -310,7 +298,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 					break
 				}
 
-				// Generate filename
 				fileName := fmt.Sprintf("%s - %s.flac", artist, trackName)
 				for _, char := range `<>:"/\|?*` {
 					fileName = strings.ReplaceAll(fileName, string(char), "")
@@ -319,7 +306,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 
 				filePath := filepath.Join(outputDir, fileName)
 
-				// Save file
 				out, err := os.Create(filePath)
 				if err != nil {
 					lastError = fmt.Errorf("failed to create file: %w", err)
@@ -328,7 +314,7 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 				defer out.Close()
 
 				fmt.Println("Downloading...")
-				// Use progress writer to track download
+
 				pw := NewProgressWriter(out)
 				_, err = io.Copy(pw, fileResp.Body)
 				if err != nil {
@@ -336,7 +322,6 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 					return "", fmt.Errorf("failed to write file: %w", err)
 				}
 
-				// Print final size
 				fmt.Printf("\rDownloaded: %.2f MB (Complete)\n", float64(pw.GetTotal())/(1024*1024))
 				fmt.Println("Download complete!")
 				return filePath, nil
@@ -349,7 +334,7 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 				lastError = fmt.Errorf("processing failed: %s", errorMsg)
 				break
 			} else {
-				// Still processing
+
 				friendlyStatus := status.FriendlyStatus
 				if friendlyStatus == "" {
 					friendlyStatus = status.Status
@@ -372,15 +357,14 @@ func (a *AmazonDownloader) DownloadFromService(amazonURL, outputDir string) (str
 	return "", fmt.Errorf("all regions failed. Last error: %v", lastError)
 }
 
-func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyISRC string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool) (string, error) {
-	// Create output directory if needed
+func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string) (string, error) {
+
 	if outputDir != "." {
 		if err := os.MkdirAll(outputDir, 0755); err != nil {
 			return "", fmt.Errorf("failed to create output directory: %w", err)
 		}
 	}
 
-	// Check if file with expected name already exists (Amazon doesn't provide ISRC before download)
 	if spotifyTrackName != "" && spotifyArtistName != "" {
 		expectedFilename := BuildExpectedFilename(spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, filenameFormat, includeTrackNumber, position, spotifyDiscNumber, false)
 		expectedPath := filepath.Join(outputDir, expectedFilename)
@@ -393,29 +377,24 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 
 	fmt.Printf("Using Amazon URL: %s\n", amazonURL)
 
-	// Download from service
 	filePath, err := a.DownloadFromService(amazonURL, outputDir)
 	if err != nil {
 		return "", err
 	}
 
-	// Rename file based on Spotify metadata
 	if spotifyTrackName != "" && spotifyArtistName != "" {
 		safeArtist := sanitizeFilename(spotifyArtistName)
 		safeTitle := sanitizeFilename(spotifyTrackName)
 		safeAlbum := sanitizeFilename(spotifyAlbumName)
 		safeAlbumArtist := sanitizeFilename(spotifyAlbumArtist)
 
-		// Extract year from release date
 		year := ""
 		if len(spotifyReleaseDate) >= 4 {
 			year = spotifyReleaseDate[:4]
 		}
 
-		// Build filename based on format settings
 		var newFilename string
 
-		// Check if format is a template (contains {})
 		if strings.Contains(filenameFormat, "{") {
 			newFilename = filenameFormat
 			newFilename = strings.ReplaceAll(newFilename, "{title}", safeTitle)
@@ -424,34 +403,31 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 			newFilename = strings.ReplaceAll(newFilename, "{album_artist}", safeAlbumArtist)
 			newFilename = strings.ReplaceAll(newFilename, "{year}", year)
 
-			// Handle disc number
 			if spotifyDiscNumber > 0 {
 				newFilename = strings.ReplaceAll(newFilename, "{disc}", fmt.Sprintf("%d", spotifyDiscNumber))
 			} else {
 				newFilename = strings.ReplaceAll(newFilename, "{disc}", "")
 			}
 
-			// Handle track number - if position is 0, remove {track} and surrounding separators
 			if position > 0 {
 				newFilename = strings.ReplaceAll(newFilename, "{track}", fmt.Sprintf("%02d", position))
 			} else {
-				// Remove {track} with common separators
+
 				newFilename = regexp.MustCompile(`\{track\}\.\s*`).ReplaceAllString(newFilename, "")
 				newFilename = regexp.MustCompile(`\{track\}\s*-\s*`).ReplaceAllString(newFilename, "")
 				newFilename = regexp.MustCompile(`\{track\}\s*`).ReplaceAllString(newFilename, "")
 			}
 		} else {
-			// Legacy format support
+
 			switch filenameFormat {
 			case "artist-title":
 				newFilename = fmt.Sprintf("%s - %s", safeArtist, safeTitle)
 			case "title":
 				newFilename = safeTitle
-			default: // "title-artist"
+			default:
 				newFilename = fmt.Sprintf("%s - %s", safeTitle, safeArtist)
 			}
 
-			// Add track number prefix if enabled (legacy behavior)
 			if includeTrackNumber && position > 0 {
 				newFilename = fmt.Sprintf("%02d. %s", position, newFilename)
 			}
@@ -460,7 +436,6 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 		newFilename = newFilename + ".flac"
 		newFilePath := filepath.Join(outputDir, newFilename)
 
-		// Rename file
 		if err := os.Rename(filePath, newFilePath); err != nil {
 			fmt.Printf("Warning: Failed to rename file: %v\n", err)
 		} else {
@@ -469,11 +444,10 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 		}
 	}
 
-	// Embed Spotify metadata (replace Amazon's embedded metadata)
 	fmt.Println("Embedding Spotify metadata...")
 
 	coverPath := ""
-	// Download Spotify cover (with max resolution if enabled)
+
 	if spotifyCoverURL != "" {
 		coverPath = filePath + ".cover.jpg"
 		coverClient := NewCoverClient()
@@ -486,27 +460,24 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 		}
 	}
 
-	// Determine track number to embed
-	// Use Spotify track number (album track number) if available, otherwise use position
 	trackNumberToEmbed := spotifyTrackNumber
 	if trackNumberToEmbed == 0 {
-		trackNumberToEmbed = position // Fallback to playlist position
-	}
-	if trackNumberToEmbed == 0 {
-		trackNumberToEmbed = 1 // Default to track 1 for single track downloads without track number
+		trackNumberToEmbed = 1
 	}
 
-	// Build metadata from Spotify
 	metadata := Metadata{
 		Title:       spotifyTrackName,
 		Artist:      spotifyArtistName,
 		Album:       spotifyAlbumName,
 		AlbumArtist: spotifyAlbumArtist,
-		Date:        spotifyReleaseDate, // Recorded date (full date YYYY-MM-DD)
+		Date:        spotifyReleaseDate,
 		TrackNumber: trackNumberToEmbed,
-		TotalTracks: spotifyTotalTracks, // Total tracks in album from Spotify
-		DiscNumber:  spotifyDiscNumber,  // Disc number from Spotify
-		ISRC:        spotifyISRC,        // Use ISRC from Spotify
+		TotalTracks: spotifyTotalTracks,
+		DiscNumber:  spotifyDiscNumber,
+		TotalDiscs:  spotifyTotalDiscs,
+		URL:         spotifyURL,
+		Copyright:   spotifyCopyright,
+		Publisher:   spotifyPublisher,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 	}
 
@@ -521,12 +492,12 @@ func (a *AmazonDownloader) DownloadByURL(amazonURL, outputDir, filenameFormat st
 	return filePath, nil
 }
 
-func (a *AmazonDownloader) DownloadBySpotifyID(spotifyTrackID, outputDir, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyISRC string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool) (string, error) {
-	// Get Amazon URL from Spotify track ID
+func (a *AmazonDownloader) DownloadBySpotifyID(spotifyTrackID, outputDir, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL string, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, embedMaxQualityCover bool, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string) (string, error) {
+
 	amazonURL, err := a.GetAmazonURLFromSpotify(spotifyTrackID)
 	if err != nil {
 		return "", err
 	}
 
-	return a.DownloadByURL(amazonURL, outputDir, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyISRC, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, embedMaxQualityCover)
+	return a.DownloadByURL(amazonURL, outputDir, filenameFormat, includeTrackNumber, position, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate, spotifyCoverURL, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks, embedMaxQualityCover, spotifyTotalDiscs, spotifyCopyright, spotifyPublisher, spotifyURL)
 }

backend/analysis.go

@@ -9,7 +9,6 @@ import (
 	mewflac "github.com/mewkiz/flac"
 )
 
-// AnalysisResult contains the audio analysis data
 type AnalysisResult struct {
 	FilePath      string        `json:"file_path"`
 	FileSize      int64         `json:"file_size"`
@@ -25,19 +24,16 @@ type AnalysisResult struct {
 	Spectrum      *SpectrumData `json:"spectrum,omitempty"`
 }
 
-// AnalyzeTrack performs audio analysis on a FLAC file
 func AnalyzeTrack(filepath string) (*AnalysisResult, error) {
 	if !fileExists(filepath) {
 		return nil, fmt.Errorf("file does not exist: %s", filepath)
 	}
 
-	// Get file size
 	fileInfo, err := os.Stat(filepath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get file info: %w", err)
 	}
 
-	// Parse FLAC file
 	f, err := flac.ParseFile(filepath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse FLAC file: %w", err)
@@ -48,68 +44,55 @@ func AnalyzeTrack(filepath string) (*AnalysisResult, error) {
 		FileSize: fileInfo.Size(),
 	}
 
-	// Extract basic audio properties from STREAMINFO block
 	if len(f.Meta) > 0 {
 		streamInfo := f.Meta[0]
 		if streamInfo.Type == flac.StreamInfo {
-			// Read STREAMINFO data
+
 			data := streamInfo.Data
 			if len(data) >= 18 {
-				// Sample rate (bits 10-29 of bytes 10-13)
+
 				result.SampleRate = uint32(data[10])<<12 | uint32(data[11])<<4 | uint32(data[12])>>4
 
-				// Channels (bits 30-32 of byte 12)
 				result.Channels = ((data[12] >> 1) & 0x07) + 1
 
-				// Bits per sample (bits 33-37 of bytes 12-13)
 				result.BitsPerSample = ((data[12]&0x01)<<4 | data[13]>>4) + 1
 
-				// Total samples (bits 38-73 of bytes 13-17)
 				result.TotalSamples = uint64(data[13]&0x0F)<<32 |
 					uint64(data[14])<<24 |
 					uint64(data[15])<<16 |
 					uint64(data[16])<<8 |
 					uint64(data[17])
 
-				// Calculate duration
 				if result.SampleRate > 0 {
 					result.Duration = float64(result.TotalSamples) / float64(result.SampleRate)
 				}
 
-				// Read min/max frame size and block size for additional analysis
-				// Min block size (bytes 0-1)
-				// Max block size (bytes 2-3)
-				// These can give us hints about encoding quality
 			}
 		}
 	}
 
-	// Analyze spectrum and calculate real audio metrics
 	spectrum, err := AnalyzeSpectrum(filepath)
 	if err != nil {
-		// Log error but continue
+
 		fmt.Printf("Warning: failed to analyze spectrum: %v\n", err)
 	} else {
 		result.Spectrum = spectrum
-		// Calculate dynamic range, peak, and RMS from decoded samples
+
 		calculateRealAudioMetrics(result, filepath)
 	}
 
-	// Set bit depth
 	result.BitDepth = fmt.Sprintf("%d-bit", result.BitsPerSample)
 
 	return result, nil
 }
 
-// calculateRealAudioMetrics calculates actual dynamic range, peak, and RMS from decoded audio
 func calculateRealAudioMetrics(result *AnalysisResult, filepath string) {
-	// Decode FLAC to get actual samples
+
 	samples, err := decodeFLACForMetrics(filepath)
 	if err != nil {
 		return
 	}
 
-	// Calculate peak amplitude
 	var peak float64
 	var sumSquares float64
 
@@ -124,20 +107,16 @@ func calculateRealAudioMetrics(result *AnalysisResult, filepath string) {
 		sumSquares += sample * sample
 	}
 
-	// Convert peak to dB (reference: 1.0 = 0 dBFS)
 	peakDB := 20.0 * math.Log10(peak)
 	result.PeakAmplitude = peakDB
 
-	// Calculate RMS (Root Mean Square)
 	rms := math.Sqrt(sumSquares / float64(len(samples)))
 	rmsDB := 20.0 * math.Log10(rms)
 	result.RMSLevel = rmsDB
 
-	// Dynamic range is the difference between peak and RMS
 	result.DynamicRange = peakDB - rmsDB
 }
 
-// decodeFLACForMetrics decodes FLAC file and returns normalized samples for metric calculation
 func decodeFLACForMetrics(filepath string) ([]float64, error) {
 	stream, err := mewflac.ParseFile(filepath)
 	if err != nil {
@@ -145,24 +124,20 @@ func decodeFLACForMetrics(filepath string) ([]float64, error) {
 	}
 	defer stream.Close()
 
-	// Limit samples to prevent memory issues (10 million samples = ~3.8 minutes at 44.1kHz)
 	maxSamples := 10000000
 	samples := make([]float64, 0, maxSamples)
 
-	// Read all audio frames
 	for {
 		frame, err := stream.ParseNext()
 		if err != nil {
 			break
 		}
 
-		// Get samples from first channel (mono or left channel)
 		var channelSamples []int32
 		if len(frame.Subframes) > 0 {
 			channelSamples = frame.Subframes[0].Samples
 		}
 
-		// Normalize samples to -1.0 to 1.0 range
 		maxVal := float64(int64(1) << (stream.Info.BitsPerSample - 1))
 		for _, sample := range channelSamples {
 			if len(samples) >= maxSamples {

backend/config.go

@@ -6,13 +6,12 @@ import (
 )
 
 func GetDefaultMusicPath() string {
-	// Get user's home directory
+
 	homeDir, err := os.UserHomeDir()
 	if err != nil {
-		// Fallback to Public Music if can't get home dir
+
 		return "C:\\Users\\Public\\Music"
 	}
 
-	// Return path to user's Music folder
 	return filepath.Join(homeDir, "Music")
 }

backend/cover.go

@@ -12,12 +12,10 @@ import (
 )
 
 const (
-	// Spotify image size codes
-	spotifySize640 = "ab67616d0000b273" // 640x640
-	spotifySizeMax = "ab67616d000082c1" // Max resolution
+	spotifySize640 = "ab67616d0000b273"
+	spotifySizeMax = "ab67616d000082c1"
 )
 
-// CoverDownloadRequest represents a request to download cover art
 type CoverDownloadRequest struct {
 	CoverURL       string `json:"cover_url"`
 	TrackName      string `json:"track_name"`
@@ -32,7 +30,6 @@ type CoverDownloadRequest struct {
 	DiscNumber     int    `json:"disc_number"`
 }
 
-// CoverDownloadResponse represents the response from cover download
 type CoverDownloadResponse struct {
 	Success       bool   `json:"success"`
 	Message       string `json:"message"`
@@ -41,26 +38,36 @@ type CoverDownloadResponse struct {
 	AlreadyExists bool   `json:"already_exists,omitempty"`
 }
 
-// CoverClient handles cover art downloading
+type HeaderDownloadRequest struct {
+	HeaderURL  string `json:"header_url"`
+	ArtistName string `json:"artist_name"`
+	OutputDir  string `json:"output_dir"`
+}
+
+type HeaderDownloadResponse struct {
+	Success       bool   `json:"success"`
+	Message       string `json:"message"`
+	File          string `json:"file,omitempty"`
+	Error         string `json:"error,omitempty"`
+	AlreadyExists bool   `json:"already_exists,omitempty"`
+}
+
 type CoverClient struct {
 	httpClient *http.Client
 }
 
-// NewCoverClient creates a new cover client
 func NewCoverClient() *CoverClient {
 	return &CoverClient{
 		httpClient: &http.Client{Timeout: 30 * time.Second},
 	}
 }
 
-// buildCoverFilename builds the cover filename based on settings (same as track filename)
 func buildCoverFilename(trackName, artistName, albumName, albumArtist, releaseDate, filenameFormat string, includeTrackNumber bool, position, discNumber int) string {
 	safeTitle := sanitizeFilename(trackName)
 	safeArtist := sanitizeFilename(artistName)
 	safeAlbum := sanitizeFilename(albumName)
 	safeAlbumArtist := sanitizeFilename(albumArtist)
 
-	// Extract year from release date (format: YYYY-MM-DD or YYYY)
 	year := ""
 	if len(releaseDate) >= 4 {
 		year = releaseDate[:4]
@@ -68,7 +75,6 @@ func buildCoverFilename(trackName, artistName, albumName, albumArtist, releaseDa
 
 	var filename string
 
-	// Check if format is a template (contains {})
 	if strings.Contains(filenameFormat, "{") {
 		filename = filenameFormat
 		filename = strings.ReplaceAll(filename, "{title}", safeTitle)
@@ -77,72 +83,58 @@ func buildCoverFilename(trackName, artistName, albumName, albumArtist, releaseDa
 		filename = strings.ReplaceAll(filename, "{album_artist}", safeAlbumArtist)
 		filename = strings.ReplaceAll(filename, "{year}", year)
 
-		// Handle disc number
 		if discNumber > 0 {
 			filename = strings.ReplaceAll(filename, "{disc}", fmt.Sprintf("%d", discNumber))
 		} else {
 			filename = strings.ReplaceAll(filename, "{disc}", "")
 		}
 
-		// Handle track number - if position is 0, remove {track} and surrounding separators
 		if position > 0 {
 			filename = strings.ReplaceAll(filename, "{track}", fmt.Sprintf("%02d", position))
 		} else {
-			// Remove {track} with common separators
+
 			filename = regexp.MustCompile(`\{track\}\.\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*-\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*`).ReplaceAllString(filename, "")
 		}
 	} else {
-		// Legacy format support
+
 		switch filenameFormat {
 		case "artist-title":
 			filename = fmt.Sprintf("%s - %s", safeArtist, safeTitle)
+		case "title-artist":
+			filename = fmt.Sprintf("%s - %s", safeTitle, safeArtist)
 		case "title":
 			filename = safeTitle
-		default: // "title-artist"
+		default:
 			filename = fmt.Sprintf("%s - %s", safeTitle, safeArtist)
 		}
 
-		// Add track number prefix if enabled (legacy behavior)
 		if includeTrackNumber && position > 0 {
-			filename = fmt.Sprintf("%02d. %s", position, filename)
+			filename = fmt.Sprintf("%02d - %s", position, filename)
 		}
 	}
 
-	return filename + ".jpg"
+	return filename + ".cover.jpg"
 }
 
-// getMaxResolutionURL converts a Spotify cover URL to max resolution
-// Falls back to original URL if max resolution is not available
-func (c *CoverClient) getMaxResolutionURL(coverURL string) string {
-	// Try to convert to max resolution
-	if strings.Contains(coverURL, spotifySize640) {
-		maxURL := strings.Replace(coverURL, spotifySize640, spotifySizeMax, 1)
-		// Check if max resolution URL is available
-		resp, err := c.httpClient.Head(maxURL)
-		if err == nil && resp.StatusCode == http.StatusOK {
-			return maxURL
-		}
+func (c *CoverClient) getMaxResolutionURL(imageURL string) string {
+	if strings.Contains(imageURL, spotifySize640) {
+		return strings.Replace(imageURL, spotifySize640, spotifySizeMax, 1)
 	}
-	// Return original URL as fallback
-	return coverURL
+	return imageURL
 }
 
-// DownloadCoverToPath downloads cover art from URL to a specific path
-// If embedMaxQualityCover is true, it will try to get max resolution
 func (c *CoverClient) DownloadCoverToPath(coverURL, outputPath string, embedMaxQualityCover bool) error {
 	if coverURL == "" {
 		return fmt.Errorf("cover URL is required")
 	}
 
-	// Use max quality URL if setting is enabled
 	downloadURL := coverURL
 	if embedMaxQualityCover {
 		downloadURL = c.getMaxResolutionURL(coverURL)
 	}
 
-	// Download cover image
 	resp, err := c.httpClient.Get(downloadURL)
 	if err != nil {
 		return fmt.Errorf("failed to download cover: %v", err)
@@ -153,14 +145,12 @@ func (c *CoverClient) DownloadCoverToPath(coverURL, outputPath string, embedMaxQ
 		return fmt.Errorf("failed to download cover: HTTP %d", resp.StatusCode)
 	}
 
-	// Create file
 	file, err := os.Create(outputPath)
 	if err != nil {
 		return fmt.Errorf("failed to create file: %v", err)
 	}
 	defer file.Close()
 
-	// Write content to file
 	_, err = io.Copy(file, resp.Body)
 	if err != nil {
 		return fmt.Errorf("failed to write cover file: %v", err)
@@ -169,7 +159,6 @@ func (c *CoverClient) DownloadCoverToPath(coverURL, outputPath string, embedMaxQ
 	return nil
 }
 
-// DownloadCover downloads cover art for a single track
 func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadResponse, error) {
 	if req.CoverURL == "" {
 		return &CoverDownloadResponse{
@@ -178,7 +167,6 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 		}, fmt.Errorf("cover URL is required")
 	}
 
-	// Create output directory if it doesn't exist
 	outputDir := req.OutputDir
 	if outputDir == "" {
 		outputDir = GetDefaultMusicPath()
@@ -193,15 +181,13 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 		}, err
 	}
 
-	// Generate filename using same format as track
 	filenameFormat := req.FilenameFormat
 	if filenameFormat == "" {
-		filenameFormat = "title-artist" // default
+		filenameFormat = "title-artist"
 	}
 	filename := buildCoverFilename(req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, filenameFormat, req.TrackNumber, req.Position, req.DiscNumber)
 	filePath := filepath.Join(outputDir, filename)
 
-	// Check if file already exists
 	if fileInfo, err := os.Stat(filePath); err == nil && fileInfo.Size() > 0 {
 		return &CoverDownloadResponse{
 			Success:       true,
@@ -211,10 +197,8 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 		}, nil
 	}
 
-	// Try to get max resolution URL, fallback to original
 	downloadURL := c.getMaxResolutionURL(req.CoverURL)
 
-	// Download cover image
 	resp, err := c.httpClient.Get(downloadURL)
 	if err != nil {
 		return &CoverDownloadResponse{
@@ -231,7 +215,6 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 		}, fmt.Errorf("HTTP %d", resp.StatusCode)
 	}
 
-	// Create file
 	file, err := os.Create(filePath)
 	if err != nil {
 		return &CoverDownloadResponse{
@@ -241,7 +224,6 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 	}
 	defer file.Close()
 
-	// Write content to file
 	_, err = io.Copy(file, resp.Body)
 	if err != nil {
 		return &CoverDownloadResponse{
@@ -256,3 +238,278 @@ func (c *CoverClient) DownloadCover(req CoverDownloadRequest) (*CoverDownloadRes
 		File:    filePath,
 	}, nil
 }
+
+func (c *CoverClient) DownloadHeader(req HeaderDownloadRequest) (*HeaderDownloadResponse, error) {
+	if req.HeaderURL == "" {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   "Header URL is required",
+		}, fmt.Errorf("header URL is required")
+	}
+
+	if req.ArtistName == "" {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   "Artist name is required",
+		}, fmt.Errorf("artist name is required")
+	}
+
+	outputDir := req.OutputDir
+	if outputDir == "" {
+		outputDir = GetDefaultMusicPath()
+	} else {
+		outputDir = NormalizePath(outputDir)
+	}
+
+	artistFolder := filepath.Join(outputDir, sanitizeFilename(req.ArtistName))
+	if err := os.MkdirAll(artistFolder, 0755); err != nil {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create artist folder: %v", err),
+		}, err
+	}
+
+	filename := sanitizeFilename(req.ArtistName) + "_Header.jpg"
+	filePath := filepath.Join(artistFolder, filename)
+
+	if fileInfo, err := os.Stat(filePath); err == nil && fileInfo.Size() > 0 {
+		return &HeaderDownloadResponse{
+			Success:       true,
+			Message:       "Header file already exists",
+			File:          filePath,
+			AlreadyExists: true,
+		}, nil
+	}
+
+	resp, err := c.httpClient.Get(req.HeaderURL)
+	if err != nil {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download header: %v", err),
+		}, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download header: HTTP %d", resp.StatusCode),
+		}, fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	file, err := os.Create(filePath)
+	if err != nil {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create file: %v", err),
+		}, err
+	}
+	defer file.Close()
+
+	_, err = io.Copy(file, resp.Body)
+	if err != nil {
+		return &HeaderDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to write header file: %v", err),
+		}, err
+	}
+
+	return &HeaderDownloadResponse{
+		Success: true,
+		Message: "Header downloaded successfully",
+		File:    filePath,
+	}, nil
+}
+
+type GalleryImageDownloadRequest struct {
+	ImageURL   string `json:"image_url"`
+	ArtistName string `json:"artist_name"`
+	ImageIndex int    `json:"image_index"`
+	OutputDir  string `json:"output_dir"`
+}
+
+type GalleryImageDownloadResponse struct {
+	Success       bool   `json:"success"`
+	Message       string `json:"message"`
+	File          string `json:"file,omitempty"`
+	Error         string `json:"error,omitempty"`
+	AlreadyExists bool   `json:"already_exists,omitempty"`
+}
+
+func (c *CoverClient) DownloadGalleryImage(req GalleryImageDownloadRequest) (*GalleryImageDownloadResponse, error) {
+	if req.ImageURL == "" {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   "Image URL is required",
+		}, fmt.Errorf("image URL is required")
+	}
+
+	if req.ArtistName == "" {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   "Artist name is required",
+		}, fmt.Errorf("artist name is required")
+	}
+
+	outputDir := req.OutputDir
+	if outputDir == "" {
+		outputDir = GetDefaultMusicPath()
+	} else {
+		outputDir = NormalizePath(outputDir)
+	}
+
+	artistFolder := filepath.Join(outputDir, sanitizeFilename(req.ArtistName))
+	if err := os.MkdirAll(artistFolder, 0755); err != nil {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create artist folder: %v", err),
+		}, err
+	}
+
+	filename := sanitizeFilename(req.ArtistName) + fmt.Sprintf("_Gallery_%d.jpg", req.ImageIndex+1)
+	filePath := filepath.Join(artistFolder, filename)
+
+	if fileInfo, err := os.Stat(filePath); err == nil && fileInfo.Size() > 0 {
+		return &GalleryImageDownloadResponse{
+			Success:       true,
+			Message:       "Gallery image file already exists",
+			File:          filePath,
+			AlreadyExists: true,
+		}, nil
+	}
+
+	resp, err := c.httpClient.Get(req.ImageURL)
+	if err != nil {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download gallery image: %v", err),
+		}, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download gallery image: HTTP %d", resp.StatusCode),
+		}, fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	file, err := os.Create(filePath)
+	if err != nil {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create file: %v", err),
+		}, err
+	}
+	defer file.Close()
+
+	_, err = io.Copy(file, resp.Body)
+	if err != nil {
+		return &GalleryImageDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to write gallery image file: %v", err),
+		}, err
+	}
+
+	return &GalleryImageDownloadResponse{
+		Success: true,
+		Message: "Gallery image downloaded successfully",
+		File:    filePath,
+	}, nil
+}
+
+type AvatarDownloadRequest struct {
+	AvatarURL  string `json:"avatar_url"`
+	ArtistName string `json:"artist_name"`
+	OutputDir  string `json:"output_dir"`
+}
+
+type AvatarDownloadResponse struct {
+	Success       bool   `json:"success"`
+	Message       string `json:"message"`
+	File          string `json:"file,omitempty"`
+	Error         string `json:"error,omitempty"`
+	AlreadyExists bool   `json:"already_exists,omitempty"`
+}
+
+func (c *CoverClient) DownloadAvatar(req AvatarDownloadRequest) (*AvatarDownloadResponse, error) {
+	if req.AvatarURL == "" {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   "Avatar URL is required",
+		}, fmt.Errorf("avatar URL is required")
+	}
+
+	if req.ArtistName == "" {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   "Artist name is required",
+		}, fmt.Errorf("artist name is required")
+	}
+
+	outputDir := req.OutputDir
+	if outputDir == "" {
+		outputDir = GetDefaultMusicPath()
+	} else {
+		outputDir = NormalizePath(outputDir)
+	}
+
+	artistFolder := filepath.Join(outputDir, sanitizeFilename(req.ArtistName))
+	if err := os.MkdirAll(artistFolder, 0755); err != nil {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create artist folder: %v", err),
+		}, err
+	}
+
+	filename := sanitizeFilename(req.ArtistName) + "_Avatar.jpg"
+	filePath := filepath.Join(artistFolder, filename)
+
+	if fileInfo, err := os.Stat(filePath); err == nil && fileInfo.Size() > 0 {
+		return &AvatarDownloadResponse{
+			Success:       true,
+			Message:       "Avatar file already exists",
+			File:          filePath,
+			AlreadyExists: true,
+		}, nil
+	}
+
+	resp, err := c.httpClient.Get(req.AvatarURL)
+	if err != nil {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download avatar: %v", err),
+		}, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to download avatar: HTTP %d", resp.StatusCode),
+		}, fmt.Errorf("HTTP %d", resp.StatusCode)
+	}
+
+	file, err := os.Create(filePath)
+	if err != nil {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to create file: %v", err),
+		}, err
+	}
+	defer file.Close()
+
+	_, err = io.Copy(file, resp.Body)
+	if err != nil {
+		return &AvatarDownloadResponse{
+			Success: false,
+			Error:   fmt.Sprintf("failed to write avatar file: %v", err),
+		}, err
+	}
+
+	return &AvatarDownloadResponse{
+		Success: true,
+		Message: "Avatar downloaded successfully",
+		File:    filePath,
+	}, nil
+}

backend/ffmpeg.go

@@ -13,11 +13,11 @@ import (
 	"runtime"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/ulikunitz/xz"
 )
 
-// decodeBase64 decodes a base64 encoded string
 func decodeBase64(encoded string) (string, error) {
 	decoded, err := base64.StdEncoding.DecodeString(encoded)
 	if err != nil {
@@ -26,14 +26,12 @@ func decodeBase64(encoded string) (string, error) {
 	return string(decoded), nil
 }
 
-// ValidateExecutable checks if the path points to a valid, safe executable
 func ValidateExecutable(path string) error {
 	cleanedPath := filepath.Clean(path)
 	if cleanedPath == "" {
 		return fmt.Errorf("empty path")
 	}
 
-	// Ensure path is absolute
 	if !filepath.IsAbs(cleanedPath) {
 		return fmt.Errorf("path must be absolute: %s", path)
 	}
@@ -47,14 +45,12 @@ func ValidateExecutable(path string) error {
 		return fmt.Errorf("path is a directory: %s", path)
 	}
 
-	// Check executable permission on Unix
 	if runtime.GOOS != "windows" {
 		if info.Mode()&0111 == 0 {
 			return fmt.Errorf("file is not executable: %s", path)
 		}
 	}
 
-	// Validate filename allowlist
 	base := filepath.Base(cleanedPath)
 	validNames := map[string]bool{
 		"ffmpeg":      true,
@@ -76,7 +72,6 @@ const (
 	ffprobeMacOSURL  = "aHR0cHM6Ly9ldmVybWVldC5jeC9mZm1wZWcvZ2V0cmVsZWFzZS9mZnByb2JlL3ppcA=="
 )
 
-// GetFFmpegDir returns the directory where ffmpeg should be stored
 func GetFFmpegDir() (string, error) {
 	homeDir, err := os.UserHomeDir()
 	if err != nil {
@@ -85,7 +80,6 @@ func GetFFmpegDir() (string, error) {
 	return filepath.Join(homeDir, ".spotiflac"), nil
 }
 
-// GetFFmpegPath returns the full path to the ffmpeg executable
 func GetFFmpegPath() (string, error) {
 	ffmpegDir, err := GetFFmpegDir()
 	if err != nil {
@@ -100,7 +94,6 @@ func GetFFmpegPath() (string, error) {
 	return filepath.Join(ffmpegDir, ffmpegName), nil
 }
 
-// GetFFprobePath returns the full path to the ffprobe executable in app directory
 func GetFFprobePath() (string, error) {
 	ffmpegDir, err := GetFFmpegDir()
 	if err != nil {
@@ -120,7 +113,6 @@ func GetFFprobePath() (string, error) {
 	return "", fmt.Errorf("ffprobe not found in app directory")
 }
 
-// IsFFprobeInstalled checks if ffprobe is installed in the app directory
 func IsFFprobeInstalled() (bool, error) {
 	ffprobePath, err := GetFFprobePath()
 	if err != nil {
@@ -131,14 +123,12 @@ func IsFFprobeInstalled() (bool, error) {
 		return false, nil
 	}
 
-	// Verify it's executable
 	cmd := exec.Command(ffprobePath, "-version")
 	setHideWindow(cmd)
 	err = cmd.Run()
 	return err == nil, nil
 }
 
-// IsFFmpegInstalled checks if ffmpeg is installed in the app directory
 func IsFFmpegInstalled() (bool, error) {
 	ffmpegPath, err := GetFFmpegPath()
 	if err != nil {
@@ -149,33 +139,35 @@ func IsFFmpegInstalled() (bool, error) {
 		return false, nil
 	}
 
-	// Verify it's executable
 	cmd := exec.Command(ffmpegPath, "-version")
-	// Hide console window on Windows
+
 	setHideWindow(cmd)
 	err = cmd.Run()
 	return err == nil, nil
 }
 
-// DownloadFFmpeg downloads and extracts ffmpeg to the app directory
 func DownloadFFmpeg(progressCallback func(int)) error {
+
+	SetDownloadProgress(0)
+	SetDownloadSpeed(0)
+	SetDownloading(true)
+	defer SetDownloading(false)
+
 	ffmpegDir, err := GetFFmpegDir()
 	if err != nil {
 		return err
 	}
 
-	// Create directory if it doesn't exist
 	if err := os.MkdirAll(ffmpegDir, 0755); err != nil {
 		return fmt.Errorf("failed to create ffmpeg directory: %w", err)
 	}
 
-	// For macOS, download ffmpeg and ffprobe separately (only if not already installed)
 	if runtime.GOOS == "darwin" {
 		ffmpegInstalled, _ := IsFFmpegInstalled()
 		ffprobeInstalled, _ := IsFFprobeInstalled()
 
 		if !ffmpegInstalled && !ffprobeInstalled {
-			// Download both
+
 			ffmpegURL, _ := decodeBase64(ffmpegMacOSURL)
 			fmt.Printf("[FFmpeg] Downloading ffmpeg from: %s\n", ffmpegURL)
 			if err := downloadAndExtract(ffmpegURL, ffmpegDir, progressCallback, 0, 50); err != nil {
@@ -188,14 +180,14 @@ func DownloadFFmpeg(progressCallback func(int)) error {
 				return fmt.Errorf("failed to download ffprobe: %w", err)
 			}
 		} else if !ffmpegInstalled {
-			// Only download ffmpeg
+
 			ffmpegURL, _ := decodeBase64(ffmpegMacOSURL)
 			fmt.Printf("[FFmpeg] Downloading ffmpeg from: %s\n", ffmpegURL)
 			if err := downloadAndExtract(ffmpegURL, ffmpegDir, progressCallback, 0, 100); err != nil {
 				return err
 			}
 		} else if !ffprobeInstalled {
-			// Only download ffprobe
+
 			ffprobeURL, _ := decodeBase64(ffprobeMacOSURL)
 			fmt.Printf("[FFmpeg] Downloading ffprobe from: %s\n", ffprobeURL)
 			if err := downloadAndExtract(ffprobeURL, ffmpegDir, progressCallback, 0, 100); err != nil {
@@ -205,7 +197,6 @@ func DownloadFFmpeg(progressCallback func(int)) error {
 		return nil
 	}
 
-	// For Windows/Linux: single archive contains both ffmpeg and ffprobe
 	var encodedURL string
 	switch runtime.GOOS {
 	case "windows":
@@ -216,7 +207,6 @@ func DownloadFFmpeg(progressCallback func(int)) error {
 		return fmt.Errorf("unsupported operating system: %s", runtime.GOOS)
 	}
 
-	// Decode URL
 	url, err := decodeBase64(encodedURL)
 	if err != nil {
 		return fmt.Errorf("failed to decode ffmpeg URL: %w", err)
@@ -231,9 +221,8 @@ func DownloadFFmpeg(progressCallback func(int)) error {
 	return nil
 }
 
-// downloadAndExtract downloads a file and extracts it
 func downloadAndExtract(url, destDir string, progressCallback func(int), progressStart, progressEnd int) error {
-	// Create temporary file for download
+
 	tmpFile, err := os.CreateTemp("", "ffmpeg-*")
 	if err != nil {
 		return fmt.Errorf("failed to create temp file: %w", err)
@@ -241,7 +230,6 @@ func downloadAndExtract(url, destDir string, progressCallback func(int), progres
 	defer os.Remove(tmpFile.Name())
 	defer tmpFile.Close()
 
-	// Download the file
 	resp, err := http.Get(url)
 	if err != nil {
 		return fmt.Errorf("failed to download: %w", err)
@@ -254,8 +242,16 @@ func downloadAndExtract(url, destDir string, progressCallback func(int), progres
 
 	totalSize := resp.ContentLength
 	var downloaded int64
+	lastTime := time.Now()
+	var lastBytes int64
+
+	if totalSize > 0 {
+		totalSizeMB := float64(totalSize) / (1024 * 1024)
+		fmt.Printf("[FFmpeg] Total size: %.2f MB\n", totalSizeMB)
+	} else {
+		fmt.Printf("[FFmpeg] Downloading... (size unknown)\n")
+	}
 
-	// Create a progress reader
 	buf := make([]byte, 32*1024)
 	for {
 		n, err := resp.Body.Read(buf)
@@ -265,12 +261,46 @@ func downloadAndExtract(url, destDir string, progressCallback func(int), progres
 				return fmt.Errorf("failed to write to temp file: %w", writeErr)
 			}
 			downloaded += int64(n)
+
+			mbDownloaded := float64(downloaded) / (1024 * 1024)
+			now := time.Now()
+			timeDiff := now.Sub(lastTime).Seconds()
+			var speedMBps float64
+
+			if timeDiff > 0.1 {
+				bytesDiff := float64(downloaded - lastBytes)
+				speedMBps = (bytesDiff / (1024 * 1024)) / timeDiff
+				lastTime = now
+				lastBytes = downloaded
+			}
+
+			SetDownloadProgress(mbDownloaded)
+			if speedMBps > 0 {
+				SetDownloadSpeed(speedMBps)
+			}
+
 			if totalSize > 0 && progressCallback != nil {
-				// Scale progress between progressStart and progressEnd
 				rawProgress := float64(downloaded) / float64(totalSize)
 				scaledProgress := progressStart + int(rawProgress*float64(progressEnd-progressStart))
 				progressCallback(scaledProgress)
 			}
+
+			if totalSize > 0 {
+				percent := float64(downloaded) * 100 / float64(totalSize)
+				if speedMBps > 0 {
+					fmt.Printf("\r[FFmpeg] Downloading: %.2f MB / %.2f MB (%.1f%%) - %.2f MB/s",
+						mbDownloaded, float64(totalSize)/(1024*1024), percent, speedMBps)
+				} else {
+					fmt.Printf("\r[FFmpeg] Downloading: %.2f MB / %.2f MB (%.1f%%)",
+						mbDownloaded, float64(totalSize)/(1024*1024), percent)
+				}
+			} else {
+				if speedMBps > 0 {
+					fmt.Printf("\r[FFmpeg] Downloading: %.2f MB - %.2f MB/s", mbDownloaded, speedMBps)
+				} else {
+					fmt.Printf("\r[FFmpeg] Downloading: %.2f MB", mbDownloaded)
+				}
+			}
 		}
 		if err == io.EOF {
 			break
@@ -282,16 +312,20 @@ func downloadAndExtract(url, destDir string, progressCallback func(int), progres
 
 	tmpFile.Close()
 
-	fmt.Printf("[FFmpeg] Download complete, extracting...\n")
+	if totalSize > 0 {
+		fmt.Printf("\r[FFmpeg] Download complete: %.2f MB / %.2f MB (100%%)          \n",
+			float64(downloaded)/(1024*1024), float64(totalSize)/(1024*1024))
+	} else {
+		fmt.Printf("\r[FFmpeg] Download complete: %.2f MB          \n", float64(downloaded)/(1024*1024))
+	}
+	fmt.Printf("[FFmpeg] Extracting...\n")
 
-	// Extract the archive based on file type
 	if strings.HasSuffix(url, ".tar.xz") || runtime.GOOS == "linux" {
 		return extractTarXz(tmpFile.Name(), destDir)
 	}
 	return extractZip(tmpFile.Name(), destDir)
 }
 
-// extractZip extracts ffmpeg and ffprobe from a zip archive (skips ffplay)
 func extractZip(zipPath, destDir string) error {
 	r, err := zip.OpenReader(zipPath)
 	if err != nil {
@@ -323,7 +357,7 @@ func extractZip(zipPath, destDir string) error {
 			destPath = filepath.Join(destDir, ffprobeName)
 			foundFFprobe = true
 		} else {
-			// Skip ffplay and other files
+
 			continue
 		}
 
@@ -351,7 +385,6 @@ func extractZip(zipPath, destDir string) error {
 		fmt.Printf("[FFmpeg] Extracted to: %s\n", destPath)
 	}
 
-	// At least one of ffmpeg or ffprobe should be found
 	if !foundFFmpeg && !foundFFprobe {
 		return fmt.Errorf("neither ffmpeg nor ffprobe found in archive")
 	}
@@ -366,7 +399,6 @@ func extractZip(zipPath, destDir string) error {
 	return nil
 }
 
-// extractTarXz extracts ffmpeg and ffprobe from a tar.xz archive (skips ffplay)
 func extractTarXz(tarXzPath, destDir string) error {
 	file, err := os.Open(tarXzPath)
 	if err != nil {
@@ -409,7 +441,7 @@ func extractTarXz(tarXzPath, destDir string) error {
 			destPath = filepath.Join(destDir, ffprobeName)
 			foundFFprobe = true
 		} else {
-			// Skip ffplay and other files
+
 			continue
 		}
 
@@ -430,7 +462,6 @@ func extractTarXz(tarXzPath, destDir string) error {
 		fmt.Printf("[FFmpeg] Extracted to: %s\n", destPath)
 	}
 
-	// At least one of ffmpeg or ffprobe should be found
 	if !foundFFmpeg && !foundFFprobe {
 		return fmt.Errorf("neither ffmpeg nor ffprobe found in archive")
 	}
@@ -445,15 +476,13 @@ func extractTarXz(tarXzPath, destDir string) error {
 	return nil
 }
 
-// ConvertAudioRequest represents a request to convert audio files
 type ConvertAudioRequest struct {
 	InputFiles   []string `json:"input_files"`
-	OutputFormat string   `json:"output_format"` // mp3, m4a
-	Bitrate      string   `json:"bitrate"`       // e.g., "320k", "256k", "192k", "128k" (ignored for ALAC)
-	Codec        string   `json:"codec"`         // For m4a: "aac" (lossy) or "alac" (lossless). Default: "aac"
+	OutputFormat string   `json:"output_format"`
+	Bitrate      string   `json:"bitrate"`
+	Codec        string   `json:"codec"`
 }
 
-// ConvertAudioResult represents the result of a single file conversion
 type ConvertAudioResult struct {
 	InputFile  string `json:"input_file"`
 	OutputFile string `json:"output_file"`
@@ -461,7 +490,6 @@ type ConvertAudioResult struct {
 	Error      string `json:"error,omitempty"`
 }
 
-// ConvertAudio converts audio files using ffmpeg while preserving metadata
 func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 	ffmpegPath, err := GetFFmpegPath()
 	if err != nil {
@@ -481,7 +509,6 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 	var wg sync.WaitGroup
 	var mu sync.Mutex
 
-	// Convert files in parallel
 	for i, inputFile := range req.InputFiles {
 		wg.Add(1)
 		go func(idx int, inputFile string) {
@@ -491,16 +518,13 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 				InputFile: inputFile,
 			}
 
-			// Get input file info
 			inputExt := strings.ToLower(filepath.Ext(inputFile))
 			baseName := strings.TrimSuffix(filepath.Base(inputFile), inputExt)
 			inputDir := filepath.Dir(inputFile)
 
-			// Determine output directory: same as input file location + subfolder (MP3 or M4A)
 			outputFormatUpper := strings.ToUpper(req.OutputFormat)
 			outputDir := filepath.Join(inputDir, outputFormatUpper)
 
-			// Create output directory if it doesn't exist
 			if err := os.MkdirAll(outputDir, 0755); err != nil {
 				result.Error = fmt.Sprintf("failed to create output directory: %v", err)
 				result.Success = false
@@ -510,11 +534,9 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 				return
 			}
 
-			// Determine output path
 			outputExt := "." + strings.ToLower(req.OutputFormat)
 			outputFile := filepath.Join(outputDir, baseName+outputExt)
 
-			// Skip if same format
 			if inputExt == outputExt {
 				result.Error = "Input and output formats are the same"
 				result.Success = false
@@ -526,9 +548,14 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 
 			result.OutputFile = outputFile
 
-			// Extract cover art and lyrics from input file before conversion
 			var coverArtPath string
 			var lyrics string
+			var inputMetadata Metadata
+
+			inputMetadata, err = ExtractFullMetadataFromFile(inputFile)
+			if err != nil {
+				fmt.Printf("[FFmpeg] Warning: Failed to extract metadata from %s: %v\n", inputFile, err)
+			}
 
 			coverArtPath, _ = ExtractCoverArt(inputFile)
 			lyrics, err = ExtractLyrics(inputFile)
@@ -540,49 +567,42 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 				fmt.Printf("[FFmpeg] No lyrics found in %s\n", inputFile)
 			}
 
-			// Build ffmpeg command
+			inputMetadata.Lyrics = lyrics
+
 			args := []string{
 				"-i", inputFile,
-				"-y", // Overwrite output
+				"-y",
 			}
 
-			// Add codec and bitrate based on output format
 			switch req.OutputFormat {
 			case "mp3":
 				args = append(args,
 					"-codec:a", "libmp3lame",
 					"-b:a", req.Bitrate,
-					"-map", "0:a", // Map audio stream
-					"-map_metadata", "0", // Copy all metadata
-					"-id3v2_version", "3", // Use ID3v2.3 for better compatibility
+					"-map", "0:a",
+					"-id3v2_version", "3",
 				)
-				// Map video stream if exists (for cover art)
-				args = append(args, "-map", "0:v?", "-c:v", "copy")
 			case "m4a":
-				// Determine codec: ALAC (lossless) or AAC (lossy)
+
 				codec := req.Codec
 				if codec == "" {
-					codec = "aac" // Default to AAC for backward compatibility
+					codec = "aac"
 				}
 
 				if codec == "alac" {
-					// ALAC - Apple Lossless (no bitrate needed)
+
 					args = append(args,
 						"-codec:a", "alac",
-						"-map", "0:a", // Map audio stream
-						"-map_metadata", "0", // Copy all metadata
+						"-map", "0:a",
 					)
 				} else {
-					// AAC - lossy with bitrate
+
 					args = append(args,
 						"-codec:a", "aac",
 						"-b:a", req.Bitrate,
-						"-map", "0:a", // Map audio stream
-						"-map_metadata", "0", // Copy all metadata
+						"-map", "0:a",
 					)
 				}
-				// Map video stream for cover art in M4A
-				args = append(args, "-map", "0:v?", "-c:v", "copy", "-disposition:v:0", "attached_pic")
 			}
 
 			args = append(args, outputFile)
@@ -590,7 +610,7 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 			fmt.Printf("[FFmpeg] Converting: %s -> %s\n", inputFile, outputFile)
 
 			cmd := exec.Command(ffmpegPath, args...)
-			// Hide console window on Windows
+
 			setHideWindow(cmd)
 			output, err := cmd.CombinedOutput()
 			if err != nil {
@@ -599,21 +619,17 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 				mu.Lock()
 				results[idx] = result
 				mu.Unlock()
-				// Clean up temp cover art file if exists
+
 				if coverArtPath != "" {
 					os.Remove(coverArtPath)
 				}
 				return
 			}
 
-			// Embed cover art and lyrics after conversion if they were extracted
-			if coverArtPath != "" {
-				if err := EmbedCoverArtOnly(outputFile, coverArtPath); err != nil {
-					fmt.Printf("[FFmpeg] Warning: Failed to embed cover art: %v\n", err)
-				} else {
-					fmt.Printf("[FFmpeg] Cover art embedded successfully\n")
-				}
-				os.Remove(coverArtPath) // Clean up temp file
+			if err := EmbedMetadataToConvertedFile(outputFile, inputMetadata, coverArtPath); err != nil {
+				fmt.Printf("[FFmpeg] Warning: Failed to embed metadata: %v\n", err)
+			} else {
+				fmt.Printf("[FFmpeg] Metadata embedded successfully\n")
 			}
 
 			if lyrics != "" {
@@ -624,6 +640,10 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 				}
 			}
 
+			if coverArtPath != "" {
+				os.Remove(coverArtPath)
+			}
+
 			result.Success = true
 			fmt.Printf("[FFmpeg] Successfully converted: %s\n", outputFile)
 
@@ -637,7 +657,6 @@ func ConvertAudio(req ConvertAudioRequest) ([]ConvertAudioResult, error) {
 	return results, nil
 }
 
-// GetAudioInfo returns information about an audio file
 type AudioFileInfo struct {
 	Path     string `json:"path"`
 	Filename string `json:"filename"`
@@ -645,7 +664,6 @@ type AudioFileInfo struct {
 	Size     int64  `json:"size"`
 }
 
-// GetAudioFileInfo gets information about an audio file
 func GetAudioFileInfo(filePath string) (*AudioFileInfo, error) {
 	info, err := os.Stat(filePath)
 	if err != nil {

backend/ffmpeg_unix.go

@@ -7,8 +7,6 @@ import (
 	"os/exec"
 )
 
-// setHideWindow is a no-op on non-Windows platforms
 func setHideWindow(cmd *exec.Cmd) {
-	// No-op on Unix-like systems
-}
 
+}

backend/ffmpeg_windows.go

@@ -8,10 +8,8 @@ import (
 	"syscall"
 )
 
-// setHideWindow sets HideWindow attribute for Windows processes
 func setHideWindow(cmd *exec.Cmd) {
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		HideWindow: true,
 	}
 }
-

backend/file_dialog.go

@@ -6,7 +6,6 @@ import (
 	"github.com/wailsapp/wails/v2/pkg/runtime"
 )
 
-// SelectMultipleFiles opens a file dialog to select multiple audio files
 func SelectMultipleFiles(ctx context.Context) ([]string, error) {
 	files, err := runtime.OpenMultipleFilesDialog(ctx, runtime.OpenDialogOptions{
 		Title: "Select Audio Files",
@@ -39,7 +38,6 @@ func SelectMultipleFiles(ctx context.Context) ([]string, error) {
 	return files, nil
 }
 
-// SelectOutputDirectory opens a directory dialog to select output folder
 func SelectOutputDirectory(ctx context.Context) (string, error) {
 	dir, err := runtime.OpenDirectoryDialog(ctx, runtime.OpenDialogOptions{
 		Title: "Select Output Directory",
@@ -49,4 +47,3 @@ func SelectOutputDirectory(ctx context.Context) (string, error) {
 	}
 	return dir, nil
 }
-

backend/filemanager.go

@@ -14,7 +14,6 @@ import (
 	"github.com/go-flac/go-flac"
 )
 
-// FileInfo represents information about a file or folder
 type FileInfo struct {
 	Name     string     `json:"name"`
 	Path     string     `json:"path"`
@@ -23,7 +22,6 @@ type FileInfo struct {
 	Children []FileInfo `json:"children,omitempty"`
 }
 
-// AudioMetadata represents metadata read from an audio file
 type AudioMetadata struct {
 	Title       string `json:"title"`
 	Artist      string `json:"artist"`
@@ -34,7 +32,6 @@ type AudioMetadata struct {
 	Year        string `json:"year"`
 }
 
-// RenamePreview represents a preview of file rename operation
 type RenamePreview struct {
 	OldPath  string        `json:"old_path"`
 	OldName  string        `json:"old_name"`
@@ -44,7 +41,6 @@ type RenamePreview struct {
 	Metadata AudioMetadata `json:"metadata"`
 }
 
-// RenameResult represents the result of a rename operation
 type RenameResult struct {
 	OldPath string `json:"old_path"`
 	NewPath string `json:"new_path"`
@@ -52,7 +48,6 @@ type RenameResult struct {
 	Error   string `json:"error,omitempty"`
 }
 
-// ListDirectory lists files and folders in a directory
 func ListDirectory(dirPath string) ([]FileInfo, error) {
 	entries, err := os.ReadDir(dirPath)
 	if err != nil {
@@ -73,7 +68,6 @@ func ListDirectory(dirPath string) ([]FileInfo, error) {
 			Size:  info.Size(),
 		}
 
-		// If it's a directory, recursively list its contents
 		if entry.IsDir() {
 			children, err := ListDirectory(fileInfo.Path)
 			if err == nil {
@@ -87,13 +81,12 @@ func ListDirectory(dirPath string) ([]FileInfo, error) {
 	return result, nil
 }
 
-// ListAudioFiles lists only audio files (flac, mp3, m4a) in a directory recursively
 func ListAudioFiles(dirPath string) ([]FileInfo, error) {
 	var result []FileInfo
 
 	err := filepath.Walk(dirPath, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
-			return nil // Skip files with errors
+			return nil
 		}
 
 		if info.IsDir() {
@@ -120,7 +113,6 @@ func ListAudioFiles(dirPath string) ([]FileInfo, error) {
 	return result, nil
 }
 
-// ReadAudioMetadata reads metadata from an audio file
 func ReadAudioMetadata(filePath string) (*AudioMetadata, error) {
 	if !fileExists(filePath) {
 		return nil, fmt.Errorf("file does not exist")
@@ -140,7 +132,6 @@ func ReadAudioMetadata(filePath string) (*AudioMetadata, error) {
 	}
 }
 
-// readFlacMetadata reads metadata from a FLAC file
 func readFlacMetadata(filePath string) (*AudioMetadata, error) {
 	f, err := flac.ParseFile(filePath)
 	if err != nil {
@@ -192,7 +183,6 @@ func readFlacMetadata(filePath string) (*AudioMetadata, error) {
 	return metadata, nil
 }
 
-// readMp3Metadata reads metadata from an MP3 file
 func readMp3Metadata(filePath string) (*AudioMetadata, error) {
 	tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
 	if err != nil {
@@ -207,14 +197,12 @@ func readMp3Metadata(filePath string) (*AudioMetadata, error) {
 		Year:   tag.Year(),
 	}
 
-	// Get Album Artist (TPE2)
 	if frames := tag.GetFrames("TPE2"); len(frames) > 0 {
 		if textFrame, ok := frames[0].(id3v2.TextFrame); ok {
 			metadata.AlbumArtist = textFrame.Text
 		}
 	}
 
-	// Get Track Number
 	if frames := tag.GetFrames(tag.CommonID("Track number/Position in set")); len(frames) > 0 {
 		if textFrame, ok := frames[0].(id3v2.TextFrame); ok {
 			trackStr := strings.Split(textFrame.Text, "/")[0]
@@ -224,7 +212,6 @@ func readMp3Metadata(filePath string) (*AudioMetadata, error) {
 		}
 	}
 
-	// Get Disc Number
 	if frames := tag.GetFrames(tag.CommonID("Part of a set")); len(frames) > 0 {
 		if textFrame, ok := frames[0].(id3v2.TextFrame); ok {
 			discStr := strings.Split(textFrame.Text, "/")[0]
@@ -237,7 +224,6 @@ func readMp3Metadata(filePath string) (*AudioMetadata, error) {
 	return metadata, nil
 }
 
-// readMetadataWithFFprobe reads metadata from any audio file using ffprobe
 func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 	ffprobePath, err := GetFFprobePath()
 	if err != nil {
@@ -248,7 +234,6 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 		return nil, fmt.Errorf("invalid ffprobe executable: %w", err)
 	}
 
-	// Use ffprobe to get metadata in JSON format (both format and stream tags)
 	cmd := exec.Command(ffprobePath,
 		"-v", "quiet",
 		"-print_format", "json",
@@ -257,7 +242,6 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 		filePath,
 	)
 
-	// Hide console window on Windows
 	setHideWindow(cmd)
 
 	output, err := cmd.Output()
@@ -265,7 +249,6 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 		return nil, err
 	}
 
-	// Parse JSON output
 	var result struct {
 		Format struct {
 			Tags map[string]string `json:"tags"`
@@ -281,22 +264,18 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 
 	metadata := &AudioMetadata{}
 
-	// Merge tags from format and streams (format tags take priority)
 	allTags := make(map[string]string)
 
-	// First add stream tags
 	for _, stream := range result.Streams {
 		for key, value := range stream.Tags {
 			allTags[strings.ToLower(key)] = value
 		}
 	}
 
-	// Then add format tags (overwrite stream tags)
 	for key, value := range result.Format.Tags {
 		allTags[strings.ToLower(key)] = value
 	}
 
-	// Parse tags
 	for key, value := range allTags {
 		switch key {
 		case "title":
@@ -308,7 +287,7 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 		case "album_artist", "albumartist":
 			metadata.AlbumArtist = value
 		case "track":
-			// Format might be "4" or "4/12"
+
 			trackStr := strings.Split(value, "/")[0]
 			if num, err := strconv.Atoi(trackStr); err == nil {
 				metadata.TrackNumber = num
@@ -328,7 +307,6 @@ func readMetadataWithFFprobe(filePath string) (*AudioMetadata, error) {
 	return metadata, nil
 }
 
-// readM4aMetadata reads metadata from an M4A file using ffprobe
 func readM4aMetadata(filePath string) (*AudioMetadata, error) {
 	metadata, err := readMetadataWithFFprobe(filePath)
 	if err != nil {
@@ -337,7 +315,6 @@ func readM4aMetadata(filePath string) (*AudioMetadata, error) {
 	return metadata, nil
 }
 
-// GenerateFilename generates a new filename based on metadata and format template
 func GenerateFilename(metadata *AudioMetadata, format string, ext string) string {
 	if metadata == nil {
 		return ""
@@ -345,38 +322,32 @@ func GenerateFilename(metadata *AudioMetadata, format string, ext string) string
 
 	result := format
 
-	// Extract year (first 4 characters only)
 	year := metadata.Year
 	if len(year) >= 4 {
 		year = year[:4]
 	}
 
-	// Replace placeholders
 	result = strings.ReplaceAll(result, "{title}", sanitizeFilenameForRename(metadata.Title))
 	result = strings.ReplaceAll(result, "{artist}", sanitizeFilenameForRename(metadata.Artist))
 	result = strings.ReplaceAll(result, "{album}", sanitizeFilenameForRename(metadata.Album))
 	result = strings.ReplaceAll(result, "{album_artist}", sanitizeFilenameForRename(metadata.AlbumArtist))
 	result = strings.ReplaceAll(result, "{year}", sanitizeFilenameForRename(year))
 
-	// Track number with padding
 	if metadata.TrackNumber > 0 {
 		result = strings.ReplaceAll(result, "{track}", fmt.Sprintf("%02d", metadata.TrackNumber))
 	} else {
 		result = strings.ReplaceAll(result, "{track}", "")
 	}
 
-	// Disc number
 	if metadata.DiscNumber > 0 {
 		result = strings.ReplaceAll(result, "{disc}", fmt.Sprintf("%d", metadata.DiscNumber))
 	} else {
 		result = strings.ReplaceAll(result, "{disc}", "")
 	}
 
-	// Clean up multiple spaces and trim
 	result = strings.TrimSpace(result)
 	result = strings.Join(strings.Fields(result), " ")
 
-	// Remove leading/trailing separators
 	result = strings.Trim(result, " -._")
 
 	if result == "" {
@@ -386,9 +357,8 @@ func GenerateFilename(metadata *AudioMetadata, format string, ext string) string
 	return result + ext
 }
 
-// sanitizeFilenameForRename removes invalid characters from filename (for rename operations)
 func sanitizeFilenameForRename(name string) string {
-	// Remove characters that are invalid in filenames
+
 	invalid := []string{"<", ">", ":", "\"", "/", "\\", "|", "?", "*"}
 	result := name
 	for _, char := range invalid {
@@ -397,7 +367,6 @@ func sanitizeFilenameForRename(name string) string {
 	return strings.TrimSpace(result)
 }
 
-// PreviewRename generates a preview of rename operations
 func PreviewRename(files []string, format string) []RenamePreview {
 	var previews []RenamePreview
 
@@ -434,7 +403,6 @@ func PreviewRename(files []string, format string) []RenamePreview {
 	return previews
 }
 
-// GetFileSizes returns file sizes for a list of file paths
 func GetFileSizes(files []string) map[string]int64 {
 	result := make(map[string]int64)
 	for _, filePath := range files {
@@ -446,7 +414,6 @@ func GetFileSizes(files []string) map[string]int64 {
 	return result
 }
 
-// RenameFiles renames files based on their metadata
 func RenameFiles(files []string, format string) []RenameResult {
 	var results []RenameResult
 
@@ -476,7 +443,6 @@ func RenameFiles(files []string, format string) []RenameResult {
 		newPath := filepath.Join(filepath.Dir(filePath), newName)
 		result.NewPath = newPath
 
-		// Check if new path already exists (and is different from old path)
 		if newPath != filePath {
 			if _, err := os.Stat(newPath); err == nil {
 				result.Error = "File already exists"
@@ -486,7 +452,6 @@ func RenameFiles(files []string, format string) []RenameResult {
 			}
 		}
 
-		// Rename the file
 		if err := os.Rename(filePath, newPath); err != nil {
 			result.Error = err.Error()
 			result.Success = false

backend/filename.go

@@ -9,15 +9,13 @@ import (
 	"unicode/utf8"
 )
 
-// BuildExpectedFilename builds the expected filename based on track metadata and settings
 func BuildExpectedFilename(trackName, artistName, albumName, albumArtist, releaseDate, filenameFormat string, includeTrackNumber bool, position, discNumber int, useAlbumTrackNumber bool) string {
-	// Sanitize track name and artist name
+
 	safeTitle := sanitizeFilename(trackName)
 	safeArtist := sanitizeFilename(artistName)
 	safeAlbum := sanitizeFilename(albumName)
 	safeAlbumArtist := sanitizeFilename(albumArtist)
 
-	// Extract year from release date (format: YYYY-MM-DD or YYYY)
 	year := ""
 	if len(releaseDate) >= 4 {
 		year = releaseDate[:4]
@@ -25,7 +23,6 @@ func BuildExpectedFilename(trackName, artistName, albumName, albumArtist, releas
 
 	var filename string
 
-	// Check if format is a template (contains {})
 	if strings.Contains(filenameFormat, "{") {
 		filename = filenameFormat
 		filename = strings.ReplaceAll(filename, "{title}", safeTitle)
@@ -34,34 +31,31 @@ func BuildExpectedFilename(trackName, artistName, albumName, albumArtist, releas
 		filename = strings.ReplaceAll(filename, "{album_artist}", safeAlbumArtist)
 		filename = strings.ReplaceAll(filename, "{year}", year)
 
-		// Handle disc number
 		if discNumber > 0 {
 			filename = strings.ReplaceAll(filename, "{disc}", fmt.Sprintf("%d", discNumber))
 		} else {
 			filename = strings.ReplaceAll(filename, "{disc}", "")
 		}
 
-		// Handle track number - if position is 0, remove {track} and surrounding separators
 		if position > 0 {
 			filename = strings.ReplaceAll(filename, "{track}", fmt.Sprintf("%02d", position))
 		} else {
-			// Remove {track} with common separators like ". " or " - " or ". "
+
 			filename = regexp.MustCompile(`\{track\}\.\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*-\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*`).ReplaceAllString(filename, "")
 		}
 	} else {
-		// Legacy format support
+
 		switch filenameFormat {
 		case "artist-title":
 			filename = fmt.Sprintf("%s - %s", safeArtist, safeTitle)
 		case "title":
 			filename = safeTitle
-		default: // "title-artist"
+		default:
 			filename = fmt.Sprintf("%s - %s", safeTitle, safeArtist)
 		}
 
-		// Add track number prefix if enabled (legacy behavior)
 		if includeTrackNumber && position > 0 {
 			filename = fmt.Sprintf("%02d. %s", position, filename)
 		}
@@ -70,109 +64,81 @@ func BuildExpectedFilename(trackName, artistName, albumName, albumArtist, releas
 	return filename + ".flac"
 }
 
-// sanitizeFilename removes invalid characters from filename
 func sanitizeFilename(name string) string {
-	// Replace forward slash with space (more natural than underscore)
+
 	sanitized := strings.ReplaceAll(name, "/", " ")
 
-	// Remove other invalid filesystem characters (replace with space)
 	re := regexp.MustCompile(`[<>:"\\|?*]`)
 	sanitized = re.ReplaceAllString(sanitized, " ")
 
-	// Remove control characters (0x00-0x1F, 0x7F)
 	var result strings.Builder
 	for _, r := range sanitized {
-		// Keep printable characters and valid Unicode characters
-		// Remove control characters, but keep spaces, tabs, newlines for now
+
 		if r < 0x20 && r != 0x09 && r != 0x0A && r != 0x0D {
 			continue
 		}
 		if r == 0x7F {
 			continue
 		}
-		// Remove emoji and other symbols that might cause issues
-		// Keep letters, numbers, and common punctuation
+
 		if unicode.IsControl(r) && r != 0x09 && r != 0x0A && r != 0x0D {
 			continue
 		}
-		// Remove emoji ranges (most emoji are in these ranges)
-		if (r >= 0x1F300 && r <= 0x1F9FF) || // Miscellaneous Symbols and Pictographs, Emoticons
-			(r >= 0x2600 && r <= 0x26FF) || // Miscellaneous Symbols
-			(r >= 0x2700 && r <= 0x27BF) || // Dingbats
-			(r >= 0xFE00 && r <= 0xFE0F) || // Variation Selectors
-			(r >= 0x1F900 && r <= 0x1F9FF) || // Supplemental Symbols and Pictographs
-			(r >= 0x1F600 && r <= 0x1F64F) || // Emoticons
-			(r >= 0x1F680 && r <= 0x1F6FF) || // Transport and Map Symbols
-			(r >= 0x1F1E0 && r <= 0x1F1FF) { // Regional Indicator Symbols (flags)
-			continue
-		}
+
 		result.WriteRune(r)
 	}
 
 	sanitized = result.String()
 	sanitized = strings.TrimSpace(sanitized)
 
-	// Remove leading/trailing dots and spaces (Windows doesn't allow these)
 	sanitized = strings.Trim(sanitized, ". ")
 
-	// Normalize consecutive spaces to single space
 	re = regexp.MustCompile(`\s+`)
 	sanitized = re.ReplaceAllString(sanitized, " ")
 
-	// Normalize consecutive underscores to single underscore
 	re = regexp.MustCompile(`_+`)
 	sanitized = re.ReplaceAllString(sanitized, "_")
 
-	// Remove leading/trailing underscores and spaces
 	sanitized = strings.Trim(sanitized, "_ ")
 
 	if sanitized == "" {
 		return "Unknown"
 	}
 
-	// Ensure the result is valid UTF-8
 	if !utf8.ValidString(sanitized) {
-		// If invalid UTF-8, try to fix it
+
 		sanitized = strings.ToValidUTF8(sanitized, "_")
 	}
 
 	return sanitized
 }
 
-// NormalizePath only normalizes path separators without modifying folder names
-// Use this for user-provided paths that already exist on the filesystem
 func NormalizePath(folderPath string) string {
-	// Normalize all forward slashes to backslashes on Windows
+
 	return strings.ReplaceAll(folderPath, "/", string(filepath.Separator))
 }
 
-// SanitizeFolderPath sanitizes each component of a folder path and normalizes separators
-// Use this only for NEW folders being created (artist names, album names, etc.)
 func SanitizeFolderPath(folderPath string) string {
-	// Normalize all forward slashes to backslashes on Windows
+
 	normalizedPath := strings.ReplaceAll(folderPath, "/", string(filepath.Separator))
 
-	// Detect separator
 	sep := string(filepath.Separator)
 
-	// Split path into components
 	parts := strings.Split(normalizedPath, sep)
 	sanitizedParts := make([]string, 0, len(parts))
 
 	for i, part := range parts {
-		// Keep drive letter intact on Windows (e.g., "C:")
+
 		if i == 0 && len(part) == 2 && part[1] == ':' {
 			sanitizedParts = append(sanitizedParts, part)
 			continue
 		}
 
-		// Keep empty first part for absolute paths on Unix (e.g., "/Users/...")
 		if i == 0 && part == "" {
 			sanitizedParts = append(sanitizedParts, part)
 			continue
 		}
 
-		// Sanitize each folder name (but don't replace / or \ since we already normalized)
 		sanitized := sanitizeFolderName(part)
 		if sanitized != "" {
 			sanitizedParts = append(sanitizedParts, sanitized)
@@ -182,8 +148,7 @@ func SanitizeFolderPath(folderPath string) string {
 	return strings.Join(sanitizedParts, sep)
 }
 
-// sanitizeFolderName removes invalid characters from a single folder name
 func sanitizeFolderName(name string) string {
-	// Use the same sanitization as filename
+
 	return sanitizeFilename(name)
 }

backend/folder.go

@@ -14,7 +14,7 @@ func OpenFolderInExplorer(path string) error {
 	switch runtime.GOOS {
 	case "windows":
 		cmd = exec.Command("explorer", path)
-	case "darwin": // macOS
+	case "darwin":
 		cmd = exec.Command("open", path)
 	case "linux":
 		cmd = exec.Command("xdg-open", path)
@@ -26,7 +26,7 @@ func OpenFolderInExplorer(path string) error {
 }
 
 func SelectFolderDialog(ctx context.Context, defaultPath string) (string, error) {
-	// If defaultPath is empty, use default music path
+
 	if defaultPath == "" {
 		defaultPath = GetDefaultMusicPath()
 	}
@@ -41,7 +41,6 @@ func SelectFolderDialog(ctx context.Context, defaultPath string) (string, error)
 		return "", err
 	}
 
-	// If user cancelled, selectedPath will be empty
 	if selectedPath == "" {
 		return "", nil
 	}
@@ -69,7 +68,6 @@ func SelectFileDialog(ctx context.Context) (string, error) {
 		return "", err
 	}
 
-	// If user cancelled, selectedFile will be empty
 	if selectedFile == "" {
 		return "", nil
 	}

backend/lyrics.go

@@ -14,7 +14,6 @@ import (
 	"time"
 )
 
-// LRCLibResponse represents the LRCLIB API response
 type LRCLibResponse struct {
 	ID           int     `json:"id"`
 	Name         string  `json:"name"`
@@ -27,21 +26,18 @@ type LRCLibResponse struct {
 	SyncedLyrics string  `json:"syncedLyrics"`
 }
 
-// LyricsLine represents a single line of lyrics
 type LyricsLine struct {
 	StartTimeMs string `json:"startTimeMs"`
 	Words       string `json:"words"`
 	EndTimeMs   string `json:"endTimeMs"`
 }
 
-// LyricsResponse represents the API response
 type LyricsResponse struct {
 	Error    bool         `json:"error"`
 	SyncType string       `json:"syncType"`
 	Lines    []LyricsLine `json:"lines"`
 }
 
-// LyricsDownloadRequest represents a request to download lyrics
 type LyricsDownloadRequest struct {
 	SpotifyID           string `json:"spotify_id"`
 	TrackName           string `json:"track_name"`
@@ -57,7 +53,6 @@ type LyricsDownloadRequest struct {
 	DiscNumber          int    `json:"disc_number"`
 }
 
-// LyricsDownloadResponse represents the response from lyrics download
 type LyricsDownloadResponse struct {
 	Success       bool   `json:"success"`
 	Message       string `json:"message"`
@@ -66,27 +61,28 @@ type LyricsDownloadResponse struct {
 	AlreadyExists bool   `json:"already_exists,omitempty"`
 }
 
-// LyricsClient handles lyrics fetching
 type LyricsClient struct {
 	httpClient *http.Client
 }
 
-// NewLyricsClient creates a new lyrics client
 func NewLyricsClient() *LyricsClient {
 	return &LyricsClient{
 		httpClient: &http.Client{Timeout: 15 * time.Second},
 	}
 }
 
-// FetchLyricsWithMetadata fetches lyrics using track name and artist from LRCLIB
-func (c *LyricsClient) FetchLyricsWithMetadata(trackName, artistName string) (*LyricsResponse, error) {
-	// Try LRCLIB API
+func (c *LyricsClient) FetchLyricsWithMetadata(trackName, artistName string, duration int) (*LyricsResponse, error) {
+
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9scmNsaWIubmV0L2FwaS9nZXQ/YXJ0aXN0X25hbWU9")
 	apiURL := fmt.Sprintf("%s%s&track_name=%s",
 		string(apiBase),
 		url.QueryEscape(artistName),
 		url.QueryEscape(trackName))
 
+	if duration > 0 {
+		apiURL = fmt.Sprintf("%s&duration=%d", apiURL, duration)
+	}
+
 	resp, err := c.httpClient.Get(apiURL)
 	if err != nil {
 		return nil, fmt.Errorf("failed to fetch from LRCLIB: %v", err)
@@ -107,11 +103,9 @@ func (c *LyricsClient) FetchLyricsWithMetadata(trackName, artistName string) (*L
 		return nil, fmt.Errorf("failed to parse LRCLIB response: %v", err)
 	}
 
-	// Convert LRCLIB response to our LyricsResponse format
 	return c.convertLRCLibToLyricsResponse(&lrcLibResp), nil
 }
 
-// convertLRCLibToLyricsResponse converts LRCLIB response to our standard format
 func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *LyricsResponse {
 	resp := &LyricsResponse{
 		Error:    false,
@@ -119,7 +113,6 @@ func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *Ly
 		Lines:    []LyricsLine{},
 	}
 
-	// Prefer synced lyrics, fall back to plain
 	lyricsText := lrcLib.SyncedLyrics
 	if lyricsText == "" {
 		lyricsText = lrcLib.PlainLyrics
@@ -131,7 +124,6 @@ func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *Ly
 		return resp
 	}
 
-	// Parse synced lyrics format [mm:ss.xx] text
 	lines := strings.Split(lyricsText, "\n")
 	for _, line := range lines {
 		line = strings.TrimSpace(line)
@@ -139,14 +131,12 @@ func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *Ly
 			continue
 		}
 
-		// Check if line has timestamp [mm:ss.xx]
 		if strings.HasPrefix(line, "[") && len(line) > 10 {
 			closeBracket := strings.Index(line, "]")
 			if closeBracket > 0 {
 				timestamp := line[1:closeBracket]
 				words := strings.TrimSpace(line[closeBracket+1:])
 
-				// Convert [mm:ss.xx] to milliseconds
 				ms := lrcTimestampToMs(timestamp)
 				resp.Lines = append(resp.Lines, LyricsLine{
 					StartTimeMs: fmt.Sprintf("%d", ms),
@@ -156,9 +146,8 @@ func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *Ly
 			}
 		}
 
-		// Plain lyrics line (no timestamp)
 		resp.Lines = append(resp.Lines, LyricsLine{
-			StartTimeMs: "0",
+			StartTimeMs: "",
 			Words:       line,
 		})
 	}
@@ -166,10 +155,9 @@ func (c *LyricsClient) convertLRCLibToLyricsResponse(lrcLib *LRCLibResponse) *Ly
 	return resp
 }
 
-// lrcTimestampToMs converts LRC timestamp [mm:ss.xx] to milliseconds
 func lrcTimestampToMs(timestamp string) int64 {
 	var minutes, seconds, centiseconds int64
-	// Try parsing mm:ss.xx format
+
 	n, _ := fmt.Sscanf(timestamp, "%d:%d.%d", &minutes, &seconds, &centiseconds)
 	if n >= 2 {
 		return minutes*60*1000 + seconds*1000 + centiseconds*10
@@ -177,7 +165,6 @@ func lrcTimestampToMs(timestamp string) int64 {
 	return 0
 }
 
-// FetchLyricsFromLRCLibSearch fetches lyrics using LRCLIB search API
 func (c *LyricsClient) FetchLyricsFromLRCLibSearch(trackName, artistName string) (*LyricsResponse, error) {
 	query := fmt.Sprintf("%s %s", artistName, trackName)
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9scmNsaWIubmV0L2FwaS9zZWFyY2g/cT0=")
@@ -207,7 +194,6 @@ func (c *LyricsClient) FetchLyricsFromLRCLibSearch(trackName, artistName string)
 		return nil, fmt.Errorf("no results found")
 	}
 
-	// Find best match - prefer one with synced lyrics
 	var best *LRCLibResponse
 	for i := range results {
 		if results[i].SyncedLyrics != "" {
@@ -226,41 +212,37 @@ func (c *LyricsClient) FetchLyricsFromLRCLibSearch(trackName, artistName string)
 	return c.convertLRCLibToLyricsResponse(best), nil
 }
 
-// simplifyTrackName removes common suffixes like "(feat. X)", "(Remastered)", etc.
 func simplifyTrackName(name string) string {
-	// Remove content in parentheses
+
 	if idx := strings.Index(name, "("); idx > 0 {
 		name = strings.TrimSpace(name[:idx])
 	}
-	// Remove content after " - " (like "From the Motion Picture")
+
 	if idx := strings.Index(name, " - "); idx > 0 {
 		name = strings.TrimSpace(name[:idx])
 	}
 	return name
 }
 
-// FetchLyricsAllSources tries all LRCLIB sources to get lyrics
-func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName string) (*LyricsResponse, string, error) {
-	// 1. Try LRCLIB exact match
-	resp, err := c.FetchLyricsWithMetadata(trackName, artistName)
+func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName string, duration int) (*LyricsResponse, string, error) {
+
+	resp, err := c.FetchLyricsWithMetadata(trackName, artistName, duration)
 	if err == nil && resp != nil && !resp.Error && len(resp.Lines) > 0 {
 		return resp, "LRCLIB", nil
 	}
 	fmt.Printf("   LRCLIB exact: %v\n", err)
 
-	// 2. Try LRCLIB search
 	resp, err = c.FetchLyricsFromLRCLibSearch(trackName, artistName)
 	if err == nil && resp != nil && !resp.Error && len(resp.Lines) > 0 {
 		return resp, "LRCLIB Search", nil
 	}
 	fmt.Printf("   LRCLIB search: %v\n", err)
 
-	// 3. Try with simplified track name (remove parentheses, subtitles)
 	simplifiedTrack := simplifyTrackName(trackName)
 	if simplifiedTrack != trackName {
 		fmt.Printf("   Trying simplified name: %s\n", simplifiedTrack)
 
-		resp, err = c.FetchLyricsWithMetadata(simplifiedTrack, artistName)
+		resp, err = c.FetchLyricsWithMetadata(simplifiedTrack, artistName, duration)
 		if err == nil && resp != nil && !resp.Error && len(resp.Lines) > 0 {
 			return resp, "LRCLIB (simplified)", nil
 		}
@@ -274,31 +256,31 @@ func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName st
 	return nil, "", fmt.Errorf("lyrics not found in any source")
 }
 
-// ConvertToLRC converts lyrics response to LRC format
 func (c *LyricsClient) ConvertToLRC(lyrics *LyricsResponse, trackName, artistName string) string {
 	var sb strings.Builder
 
-	// Add metadata
 	sb.WriteString(fmt.Sprintf("[ti:%s]\n", trackName))
 	sb.WriteString(fmt.Sprintf("[ar:%s]\n", artistName))
 	sb.WriteString("[by:SpotiFlac]\n")
 	sb.WriteString("\n")
 
-	// Add lyrics lines
 	for _, line := range lyrics.Lines {
 		if line.Words == "" {
 			continue
 		}
 
-		// Convert milliseconds to LRC timestamp format [mm:ss.xx]
-		timestamp := msToLRCTimestamp(line.StartTimeMs)
-		sb.WriteString(fmt.Sprintf("%s%s\n", timestamp, line.Words))
+		if line.StartTimeMs == "" {
+			sb.WriteString(fmt.Sprintf("%s\n", line.Words))
+		} else {
+
+			timestamp := msToLRCTimestamp(line.StartTimeMs)
+			sb.WriteString(fmt.Sprintf("%s%s\n", timestamp, line.Words))
+		}
 	}
 
 	return sb.String()
 }
 
-// msToLRCTimestamp converts milliseconds string to LRC timestamp format [mm:ss.xx]
 func msToLRCTimestamp(msStr string) string {
 	var ms int64
 	fmt.Sscanf(msStr, "%d", &ms)
@@ -311,14 +293,12 @@ func msToLRCTimestamp(msStr string) string {
 	return fmt.Sprintf("[%02d:%02d.%02d]", minutes, seconds, centiseconds)
 }
 
-// buildLyricsFilename builds the lyrics filename based on settings (same as track filename)
 func buildLyricsFilename(trackName, artistName, albumName, albumArtist, releaseDate, filenameFormat string, includeTrackNumber bool, position, discNumber int) string {
 	safeTitle := sanitizeFilename(trackName)
 	safeArtist := sanitizeFilename(artistName)
 	safeAlbum := sanitizeFilename(albumName)
 	safeAlbumArtist := sanitizeFilename(albumArtist)
 
-	// Extract year from release date (format: YYYY-MM-DD or YYYY)
 	year := ""
 	if len(releaseDate) >= 4 {
 		year = releaseDate[:4]
@@ -326,7 +306,6 @@ func buildLyricsFilename(trackName, artistName, albumName, albumArtist, releaseD
 
 	var filename string
 
-	// Check if format is a template (contains {})
 	if strings.Contains(filenameFormat, "{") {
 		filename = filenameFormat
 		filename = strings.ReplaceAll(filename, "{title}", safeTitle)
@@ -335,34 +314,31 @@ func buildLyricsFilename(trackName, artistName, albumName, albumArtist, releaseD
 		filename = strings.ReplaceAll(filename, "{album_artist}", safeAlbumArtist)
 		filename = strings.ReplaceAll(filename, "{year}", year)
 
-		// Handle disc number
 		if discNumber > 0 {
 			filename = strings.ReplaceAll(filename, "{disc}", fmt.Sprintf("%d", discNumber))
 		} else {
 			filename = strings.ReplaceAll(filename, "{disc}", "")
 		}
 
-		// Handle track number - if position is 0, remove {track} and surrounding separators
 		if position > 0 {
 			filename = strings.ReplaceAll(filename, "{track}", fmt.Sprintf("%02d", position))
 		} else {
-			// Remove {track} with common separators
+
 			filename = regexp.MustCompile(`\{track\}\.\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*-\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*`).ReplaceAllString(filename, "")
 		}
 	} else {
-		// Legacy format support
+
 		switch filenameFormat {
 		case "artist-title":
 			filename = fmt.Sprintf("%s - %s", safeArtist, safeTitle)
 		case "title":
 			filename = safeTitle
-		default: // "title-artist"
+		default:
 			filename = fmt.Sprintf("%s - %s", safeTitle, safeArtist)
 		}
 
-		// Add track number prefix if enabled (legacy behavior)
 		if includeTrackNumber && position > 0 {
 			filename = fmt.Sprintf("%02d. %s", position, filename)
 		}
@@ -371,7 +347,47 @@ func buildLyricsFilename(trackName, artistName, albumName, albumArtist, releaseD
 	return filename + ".lrc"
 }
 
-// DownloadLyrics downloads lyrics for a single track
+func findAudioFileForLyrics(dir, trackName, artistName string) string {
+
+	safeTitle := sanitizeFilename(trackName)
+	safeArtist := sanitizeFilename(artistName)
+
+	audioExts := []string{".flac", ".mp3", ".m4a", ".FLAC", ".MP3", ".M4A"}
+
+	patterns := []string{
+		fmt.Sprintf("%s - %s", safeTitle, safeArtist),
+		fmt.Sprintf("%s - %s", safeArtist, safeTitle),
+		safeTitle,
+	}
+
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return ""
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+
+		filename := entry.Name()
+		baseName := strings.TrimSuffix(filename, filepath.Ext(filename))
+
+		for _, pattern := range patterns {
+			if strings.HasPrefix(baseName, pattern) || strings.Contains(baseName, pattern) {
+				ext := strings.ToLower(filepath.Ext(filename))
+				for _, audioExt := range audioExts {
+					if ext == strings.ToLower(audioExt) {
+						return filepath.Join(dir, filename)
+					}
+				}
+			}
+		}
+	}
+
+	return ""
+}
+
 func (c *LyricsClient) DownloadLyrics(req LyricsDownloadRequest) (*LyricsDownloadResponse, error) {
 	if req.SpotifyID == "" {
 		return &LyricsDownloadResponse{
@@ -380,7 +396,6 @@ func (c *LyricsClient) DownloadLyrics(req LyricsDownloadRequest) (*LyricsDownloa
 		}, fmt.Errorf("spotify ID is required")
 	}
 
-	// Create output directory if it doesn't exist
 	outputDir := req.OutputDir
 	if outputDir == "" {
 		outputDir = GetDefaultMusicPath()
@@ -395,15 +410,13 @@ func (c *LyricsClient) DownloadLyrics(req LyricsDownloadRequest) (*LyricsDownloa
 		}, err
 	}
 
-	// Generate filename using same format as track
 	filenameFormat := req.FilenameFormat
 	if filenameFormat == "" {
-		filenameFormat = "title-artist" // default
+		filenameFormat = "title-artist"
 	}
 	filename := buildLyricsFilename(req.TrackName, req.ArtistName, req.AlbumName, req.AlbumArtist, req.ReleaseDate, filenameFormat, req.TrackNumber, req.Position, req.DiscNumber)
 	filePath := filepath.Join(outputDir, filename)
 
-	// Check if file already exists
 	if fileInfo, err := os.Stat(filePath); err == nil && fileInfo.Size() > 0 {
 		return &LyricsDownloadResponse{
 			Success:       true,
@@ -413,8 +426,17 @@ func (c *LyricsClient) DownloadLyrics(req LyricsDownloadRequest) (*LyricsDownloa
 		}, nil
 	}
 
-	// Fetch lyrics from LRCLIB
-	lyrics, _, err := c.FetchLyricsAllSources(req.SpotifyID, req.TrackName, req.ArtistName)
+	audioDuration := 0
+	audioFile := findAudioFileForLyrics(outputDir, req.TrackName, req.ArtistName)
+	if audioFile != "" {
+		duration, err := GetAudioDuration(audioFile)
+		if err == nil && duration > 0 {
+			audioDuration = int(duration)
+			fmt.Printf("[DownloadLyrics] Found audio file, duration: %d seconds\n", audioDuration)
+		}
+	}
+
+	lyrics, _, err := c.FetchLyricsAllSources(req.SpotifyID, req.TrackName, req.ArtistName, audioDuration)
 	if err != nil {
 		return &LyricsDownloadResponse{
 			Success: false,
@@ -422,10 +444,8 @@ func (c *LyricsClient) DownloadLyrics(req LyricsDownloadRequest) (*LyricsDownloa
 		}, err
 	}
 
-	// Convert to LRC format
 	lrcContent := c.ConvertToLRC(lyrics, req.TrackName, req.ArtistName)
 
-	// Write LRC file
 	if err := os.WriteFile(filePath, []byte(lrcContent), 0644); err != nil {
 		return &LyricsDownloadResponse{
 			Success: false,

backend/metadata.go

@@ -1,13 +1,13 @@
 package backend
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"os/exec"
 	pathfilepath "path/filepath"
 	"strconv"
 	"strings"
-	"sync"
 
 	id3v2 "github.com/bogem/id3v2/v2"
 	"github.com/go-flac/flacpicture"
@@ -20,12 +20,15 @@ type Metadata struct {
 	Artist      string
 	Album       string
 	AlbumArtist string
-	Date        string // Recorded date (full date YYYY-MM-DD)
-	ReleaseDate string // Release date (full date) - kept for compatibility
+	Date        string
+	ReleaseDate string
 	TrackNumber int
-	TotalTracks int // Total tracks in album
+	TotalTracks int
 	DiscNumber  int
-	ISRC        string
+	TotalDiscs  int
+	URL         string
+	Copyright   string
+	Publisher   string
 	Lyrics      string
 	Description string
 }
@@ -70,15 +73,21 @@ func EmbedMetadata(filepath string, metadata Metadata, coverPath string) error {
 	if metadata.DiscNumber > 0 {
 		_ = cmt.Add("DISCNUMBER", strconv.Itoa(metadata.DiscNumber))
 	}
-	if metadata.ISRC != "" {
-		_ = cmt.Add(flacvorbis.FIELD_ISRC, metadata.ISRC)
+	if metadata.TotalDiscs > 0 {
+		_ = cmt.Add("TOTALDISCS", strconv.Itoa(metadata.TotalDiscs))
+	}
+	if metadata.Copyright != "" {
+		_ = cmt.Add("COPYRIGHT", metadata.Copyright)
+	}
+	if metadata.Publisher != "" {
+		_ = cmt.Add("PUBLISHER", metadata.Publisher)
 	}
 	if metadata.Description != "" {
 		_ = cmt.Add("DESCRIPTION", metadata.Description)
 	}
-	// Lyrics is added last to keep it at the bottom
+
 	if metadata.Lyrics != "" {
-		_ = cmt.Add("LYRICS", metadata.Lyrics) // Or "UNSYNCEDLYRICS" for unsynced
+		_ = cmt.Add("LYRICS", metadata.Lyrics)
 	}
 
 	cmtBlock := cmt.Marshal()
@@ -135,20 +144,17 @@ func fileExists(path string) bool {
 	return err == nil
 }
 
-// extractYear extracts the year from a release date string
-// Handles formats: "YYYY-MM-DD", "YYYY-MM", "YYYY"
 func extractYear(releaseDate string) string {
 	if releaseDate == "" {
 		return ""
 	}
-	// Try to extract year (first 4 digits)
+
 	if len(releaseDate) >= 4 {
 		return releaseDate[:4]
 	}
 	return releaseDate
 }
 
-// EmbedLyricsOnly adds lyrics to a FLAC file while preserving existing metadata
 func EmbedLyricsOnly(filepath string, lyrics string) error {
 	if lyrics == "" {
 		return nil
@@ -171,10 +177,8 @@ func EmbedLyricsOnly(filepath string, lyrics string) error {
 		}
 	}
 
-	// Create new comment block, preserving existing comments
 	cmt := flacvorbis.New()
 
-	// Copy existing comments except LYRICS
 	if existingCmt != nil {
 		for _, comment := range existingCmt.Comments {
 			parts := strings.SplitN(comment, "=", 2)
@@ -187,7 +191,6 @@ func EmbedLyricsOnly(filepath string, lyrics string) error {
 		}
 	}
 
-	// Add lyrics
 	_ = cmt.Add("LYRICS", lyrics)
 
 	cmtBlock := cmt.Marshal()
@@ -204,82 +207,6 @@ func EmbedLyricsOnly(filepath string, lyrics string) error {
 	return nil
 }
 
-// ReadISRCFromFile reads ISRC metadata from a FLAC file
-func ReadISRCFromFile(filepath string) (string, error) {
-	if !fileExists(filepath) {
-		return "", fmt.Errorf("file does not exist")
-	}
-
-	f, err := flac.ParseFile(filepath)
-	if err != nil {
-		return "", fmt.Errorf("failed to parse FLAC file: %w", err)
-	}
-
-	// Find VorbisComment block
-	for _, block := range f.Meta {
-		if block.Type == flac.VorbisComment {
-			cmt, err := flacvorbis.ParseFromMetaDataBlock(*block)
-			if err != nil {
-				continue
-			}
-
-			// Get ISRC field
-			isrcValues, err := cmt.Get(flacvorbis.FIELD_ISRC)
-			if err == nil && len(isrcValues) > 0 {
-				return isrcValues[0], nil
-			}
-		}
-	}
-
-	return "", nil // No ISRC found
-}
-
-// CheckISRCExists checks if a file with the given ISRC already exists in the directory
-func CheckISRCExists(outputDir string, targetISRC string) (string, bool) {
-	if targetISRC == "" {
-		return "", false
-	}
-
-	// Read all .flac files in directory
-	entries, err := os.ReadDir(outputDir)
-	if err != nil {
-		return "", false
-	}
-
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-
-		// Check only .flac files
-		filename := entry.Name()
-		if len(filename) < 5 || filename[len(filename)-5:] != ".flac" {
-			continue
-		}
-
-		filepath := fmt.Sprintf("%s/%s", outputDir, filename)
-
-		// Read ISRC from file (this will fail for corrupted files)
-		isrc, err := ReadISRCFromFile(filepath)
-		if err != nil {
-			// File is corrupted or unreadable, delete it
-			fmt.Printf("Removing corrupted/unreadable file: %s (error: %v)\n", filepath, err)
-			if removeErr := os.Remove(filepath); removeErr != nil {
-				fmt.Printf("Warning: Failed to remove corrupted file %s: %v\n", filepath, removeErr)
-			}
-			continue
-		}
-
-		// Compare ISRC (case-insensitive)
-		if isrc != "" && strings.EqualFold(isrc, targetISRC) {
-			return filepath, true
-		}
-	}
-
-	return "", false
-}
-
-// ExtractCoverArt extracts cover art from an audio file and saves it to a temporary file
 func ExtractCoverArt(filePath string) (string, error) {
 	ext := strings.ToLower(pathfilepath.Ext(filePath))
 
@@ -293,7 +220,6 @@ func ExtractCoverArt(filePath string) (string, error) {
 	}
 }
 
-// extractCoverFromMp3 extracts cover art from MP3 file
 func extractCoverFromMp3(filePath string) (string, error) {
 	tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
 	if err != nil {
@@ -311,7 +237,6 @@ func extractCoverFromMp3(filePath string) (string, error) {
 		return "", fmt.Errorf("invalid picture frame")
 	}
 
-	// Create temporary file
 	tmpFile, err := os.CreateTemp("", "cover-*.jpg")
 	if err != nil {
 		return "", fmt.Errorf("failed to create temp file: %w", err)
@@ -326,7 +251,6 @@ func extractCoverFromMp3(filePath string) (string, error) {
 	return tmpFile.Name(), nil
 }
 
-// extractCoverFromM4AOrFlac extracts cover art from M4A or FLAC file
 func extractCoverFromM4AOrFlac(filePath string) (string, error) {
 	ext := strings.ToLower(pathfilepath.Ext(filePath))
 
@@ -343,7 +267,6 @@ func extractCoverFromM4AOrFlac(filePath string) (string, error) {
 					continue
 				}
 
-				// Create temporary file
 				tmpFile, err := os.CreateTemp("", "cover-*.jpg")
 				if err != nil {
 					return "", fmt.Errorf("failed to create temp file: %w", err)
@@ -361,12 +284,9 @@ func extractCoverFromM4AOrFlac(filePath string) (string, error) {
 		return "", fmt.Errorf("no cover art found")
 	}
 
-	// For M4A, try to extract using ffmpeg or return empty
-	// M4A cover art should be preserved by ffmpeg during conversion
 	return "", nil
 }
 
-// ExtractLyrics extracts lyrics from an audio file
 func ExtractLyrics(filePath string) (string, error) {
 	ext := strings.ToLower(pathfilepath.Ext(filePath))
 
@@ -376,14 +296,13 @@ func ExtractLyrics(filePath string) (string, error) {
 	case ".flac":
 		return extractLyricsFromFlac(filePath)
 	case ".m4a":
-		// M4A lyrics extraction would need different approach
+
 		return "", nil
 	default:
 		return "", fmt.Errorf("unsupported file format: %s", ext)
 	}
 }
 
-// extractLyricsFromMp3 extracts lyrics from MP3 file
 func extractLyricsFromMp3(filePath string) (string, error) {
 	tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
 	if err != nil {
@@ -412,7 +331,6 @@ func extractLyricsFromMp3(filePath string) (string, error) {
 	return uslt.Lyrics, nil
 }
 
-// extractLyricsFromFlac extracts lyrics from FLAC file
 func extractLyricsFromFlac(filePath string) (string, error) {
 	f, err := flac.ParseFile(filePath)
 	if err != nil {
@@ -426,7 +344,6 @@ func extractLyricsFromFlac(filePath string) (string, error) {
 				continue
 			}
 
-			// Search through comments for lyrics
 			for _, comment := range cmt.Comments {
 				parts := strings.SplitN(comment, "=", 2)
 				if len(parts) == 2 {
@@ -445,7 +362,6 @@ func extractLyricsFromFlac(filePath string) (string, error) {
 	return "", nil
 }
 
-// EmbedCoverArtOnly embeds cover art into an audio file
 func EmbedCoverArtOnly(filePath string, coverPath string) error {
 	if coverPath == "" || !fileExists(coverPath) {
 		return nil
@@ -457,16 +373,13 @@ func EmbedCoverArtOnly(filePath string, coverPath string) error {
 	case ".mp3":
 		return embedCoverToMp3(filePath, coverPath)
 	case ".m4a":
-		// M4A cover art should be handled by ffmpeg during conversion
-		// If not, we can try to embed using atomicparsley or similar tool
-		// For now, return nil as ffmpeg should handle it
+
 		return nil
 	default:
 		return fmt.Errorf("unsupported file format: %s", ext)
 	}
 }
 
-// embedCoverToMp3 embeds cover art into MP3 file
 func embedCoverToMp3(filePath string, coverPath string) error {
 	tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
 	if err != nil {
@@ -474,16 +387,13 @@ func embedCoverToMp3(filePath string, coverPath string) error {
 	}
 	defer tag.Close()
 
-	// Remove existing cover art
 	tag.DeleteFrames(tag.CommonID("Attached picture"))
 
-	// Read cover art
 	artwork, err := os.ReadFile(coverPath)
 	if err != nil {
 		return fmt.Errorf("failed to read cover art: %w", err)
 	}
 
-	// Add new cover art
 	pic := id3v2.PictureFrame{
 		Encoding:    id3v2.EncodingUTF8,
 		MimeType:    "image/jpeg",
@@ -500,27 +410,30 @@ func embedCoverToMp3(filePath string, coverPath string) error {
 	return nil
 }
 
-// EmbedLyricsOnlyMP3 adds lyrics to an MP3 file using ID3v2 USLT frame
 func EmbedLyricsOnlyMP3(filepath string, lyrics string) error {
 	if lyrics == "" {
 		return nil
 	}
 
+	validatedLyrics, err := validateLyricsDuration(lyrics, filepath)
+	if err != nil {
+		fmt.Printf("[EmbedLyricsOnlyMP3] Warning: Failed to validate lyrics duration: %v, using original lyrics\n", err)
+		validatedLyrics = lyrics
+	}
+	lyrics = validatedLyrics
+
 	tag, err := id3v2.Open(filepath, id3v2.Options{Parse: true})
 	if err != nil {
 		return fmt.Errorf("failed to open MP3 file: %w", err)
 	}
 	defer tag.Close()
 
-	// Remove existing USLT frames
 	tag.DeleteFrames(tag.CommonID("Unsynchronised lyrics/text transcription"))
 
-	// Add new USLT frame with lyrics
-	// Use UTF-8 encoding for better compatibility with AIMP and other players
 	usltFrame := id3v2.UnsynchronisedLyricsFrame{
-		Encoding:          id3v2.EncodingUTF8, // Use UTF-8 instead of default encoding
+		Encoding:          id3v2.EncodingUTF8,
 		Language:          "eng",
-		ContentDescriptor: "", // Empty descriptor for better compatibility
+		ContentDescriptor: "",
 		Lyrics:            lyrics,
 	}
 	tag.AddUnsynchronisedLyricsFrame(usltFrame)
@@ -532,10 +445,15 @@ func EmbedLyricsOnlyMP3(filepath string, lyrics string) error {
 	return nil
 }
 
-// embedLyricsToM4A adds lyrics to an M4A file using ffmpeg
 func embedLyricsToM4A(filepath string, lyrics string) error {
-	// Use ffmpeg to embed lyrics into M4A file
-	// M4A uses iTunes metadata format with atom '©lyr' for lyrics
+
+	validatedLyrics, err := validateLyricsDuration(lyrics, filepath)
+	if err != nil {
+		fmt.Printf("[embedLyricsToM4A] Warning: Failed to validate lyrics duration: %v, using original lyrics\n", err)
+		validatedLyrics = lyrics
+	}
+	lyrics = validatedLyrics
+
 	ffmpegPath, err := GetFFmpegPath()
 	if err != nil {
 		return fmt.Errorf("ffmpeg not found: %w", err)
@@ -545,18 +463,14 @@ func embedLyricsToM4A(filepath string, lyrics string) error {
 		return fmt.Errorf("invalid ffmpeg executable: %w", err)
 	}
 
-	// Create temporary output file with proper extension so ffmpeg can detect format
 	tmpOutputFile := strings.TrimSuffix(filepath, pathfilepath.Ext(filepath)) + ".tmp" + pathfilepath.Ext(filepath)
 	defer func() {
-		// Only remove if file still exists (rename might have failed)
+
 		if _, err := os.Stat(tmpOutputFile); err == nil {
 			os.Remove(tmpOutputFile)
 		}
 	}()
 
-	// Use ffmpeg to copy file and add lyrics metadata
-	// For M4A, we need to use the correct metadata tag format and specify output format
-	// Use -f ipod for M4A format (iPod format is compatible with M4A)
 	cmd := exec.Command(ffmpegPath,
 		"-i", filepath,
 		"-map", "0",
@@ -564,12 +478,11 @@ func embedLyricsToM4A(filepath string, lyrics string) error {
 		"-metadata", "lyrics-eng="+lyrics,
 		"-metadata", "lyrics="+lyrics,
 		"-codec", "copy",
-		"-f", "ipod", // Explicitly specify M4A/iPod format
-		"-y", // Overwrite
+		"-f", "ipod",
+		"-y",
 		tmpOutputFile,
 	)
 
-	// Hide console window on Windows
 	setHideWindow(cmd)
 
 	output, err := cmd.CombinedOutput()
@@ -578,7 +491,6 @@ func embedLyricsToM4A(filepath string, lyrics string) error {
 		return fmt.Errorf("ffmpeg failed to embed lyrics: %s - %w", string(output), err)
 	}
 
-	// Replace original file with new file
 	if err := os.Rename(tmpOutputFile, filepath); err != nil {
 		return fmt.Errorf("failed to replace original file: %w", err)
 	}
@@ -587,7 +499,6 @@ func embedLyricsToM4A(filepath string, lyrics string) error {
 	return nil
 }
 
-// EmbedLyricsOnlyUniversal embeds lyrics to MP3, FLAC, or M4A file
 func EmbedLyricsOnlyUniversal(filepath string, lyrics string) error {
 	if lyrics == "" {
 		return nil
@@ -606,85 +517,451 @@ func EmbedLyricsOnlyUniversal(filepath string, lyrics string) error {
 	}
 }
 
-// FileExistenceResult represents the result of checking if a file exists
-type FileExistenceResult struct {
-	ISRC       string `json:"isrc"`
-	Exists     bool   `json:"exists"`
-	FilePath   string `json:"file_path,omitempty"`
-	TrackName  string `json:"track_name,omitempty"`
-	ArtistName string `json:"artist_name,omitempty"`
-}
+func GetAudioDuration(filepath string) (float64, error) {
+	ext := strings.ToLower(pathfilepath.Ext(filepath))
 
-// CheckFilesExistParallel checks if multiple files exist in parallel
-// It builds an ISRC index from the output directory once, then checks all tracks against it
-func CheckFilesExistParallel(outputDir string, tracks []struct {
-	ISRC       string
-	TrackName  string
-	ArtistName string
-}) []FileExistenceResult {
-	results := make([]FileExistenceResult, len(tracks))
-
-	// Build ISRC index from output directory (scan once)
-	isrcIndex := buildISRCIndex(outputDir)
-
-	// Check each track against the index (parallel)
-	var wg sync.WaitGroup
-	for i, track := range tracks {
-		wg.Add(1)
-		go func(idx int, t struct {
-			ISRC       string
-			TrackName  string
-			ArtistName string
-		}) {
-			defer wg.Done()
-
-			result := FileExistenceResult{
-				ISRC:       t.ISRC,
-				TrackName:  t.TrackName,
-				ArtistName: t.ArtistName,
-				Exists:     false,
-			}
-
-			if t.ISRC != "" {
-				if filePath, exists := isrcIndex[strings.ToUpper(t.ISRC)]; exists {
-					result.Exists = true
-					result.FilePath = filePath
-				}
-			}
-
-			results[idx] = result
-		}(i, track)
+	if ext == ".flac" {
+		duration, err := getFlacDuration(filepath)
+		if err == nil && duration > 0 {
+			return duration, nil
+		}
 	}
 
-	wg.Wait()
-	return results
+	return getDurationWithFFprobe(filepath)
 }
 
-// buildISRCIndex scans a directory and builds a map of ISRC -> file path
-func buildISRCIndex(outputDir string) map[string]string {
-	index := make(map[string]string)
+func getFlacDuration(filepath string) (float64, error) {
+	f, err := flac.ParseFile(filepath)
+	if err != nil {
+		return 0, err
+	}
 
-	// Walk directory recursively - only check .flac files for SpotiFLAC
-	pathfilepath.Walk(outputDir, func(path string, info os.FileInfo, err error) error {
-		if err != nil || info.IsDir() {
-			return nil
+	if len(f.Meta) > 0 {
+		streamInfo := f.Meta[0]
+		if streamInfo.Type == flac.StreamInfo {
+			data := streamInfo.Data
+			if len(data) >= 18 {
+
+				sampleRate := uint32(data[10])<<12 | uint32(data[11])<<4 | uint32(data[12])>>4
+
+				totalSamples := uint64(data[13]&0x0F)<<32 |
+					uint64(data[14])<<24 |
+					uint64(data[15])<<16 |
+					uint64(data[16])<<8 |
+					uint64(data[17])
+
+				if sampleRate > 0 {
+					return float64(totalSamples) / float64(sampleRate), nil
+				}
+			}
 		}
+	}
 
-		ext := strings.ToLower(pathfilepath.Ext(path))
-		if ext != ".flac" {
-			return nil
-		}
-
-		// Read ISRC from file
-		isrc, err := ReadISRCFromFile(path)
-		if err != nil || isrc == "" {
-			return nil
-		}
-
-		// Store in index (uppercase for case-insensitive matching)
-		index[strings.ToUpper(isrc)] = path
-		return nil
-	})
-
-	return index
+	return 0, fmt.Errorf("could not extract duration from FLAC file")
+}
+
+func getDurationWithFFprobe(filepath string) (float64, error) {
+	ffprobePath, err := GetFFprobePath()
+	if err != nil {
+		return 0, err
+	}
+
+	if err := ValidateExecutable(ffprobePath); err != nil {
+		return 0, fmt.Errorf("invalid ffprobe executable: %w", err)
+	}
+
+	cmd := exec.Command(ffprobePath,
+		"-v", "quiet",
+		"-print_format", "json",
+		"-show_format",
+		filepath,
+	)
+
+	setHideWindow(cmd)
+
+	output, err := cmd.Output()
+	if err != nil {
+		return 0, err
+	}
+
+	var result struct {
+		Format struct {
+			Duration string `json:"duration"`
+		} `json:"format"`
+	}
+
+	if err := json.Unmarshal(output, &result); err != nil {
+		return 0, err
+	}
+
+	if result.Format.Duration == "" {
+		return 0, fmt.Errorf("duration not found in ffprobe output")
+	}
+
+	duration, err := strconv.ParseFloat(result.Format.Duration, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return duration, nil
+}
+
+func validateLyricsDuration(lyrics string, filepath string) (string, error) {
+
+	duration, err := GetAudioDuration(filepath)
+	if err != nil {
+
+		fmt.Printf("[ValidateLyrics] Warning: Could not get audio duration: %v, skipping validation\n", err)
+		return lyrics, nil
+	}
+
+	if duration <= 0 {
+
+		fmt.Printf("[ValidateLyrics] Warning: Invalid duration (%f seconds), skipping validation\n", duration)
+		return lyrics, nil
+	}
+
+	durationMs := int64(duration * 1000)
+
+	lines := strings.Split(lyrics, "\n")
+	var validLines []string
+
+	for _, line := range lines {
+		trimmedLine := strings.TrimSpace(line)
+		if trimmedLine == "" {
+			validLines = append(validLines, line)
+			continue
+		}
+
+		if strings.HasPrefix(trimmedLine, "[") {
+
+			if strings.Index(trimmedLine, ":") > 0 {
+
+				validLines = append(validLines, line)
+				continue
+			}
+
+			closeBracket := strings.Index(trimmedLine, "]")
+			if closeBracket > 0 {
+				timestampStr := trimmedLine[1:closeBracket]
+
+				ms := parseLRCTimestamp(timestampStr)
+				if ms >= 0 && ms <= durationMs {
+
+					validLines = append(validLines, line)
+				} else {
+
+					fmt.Printf("[ValidateLyrics] Filtered out line with timestamp %s (exceeds duration %d ms): %s\n", timestampStr, durationMs, trimmedLine)
+				}
+			} else {
+
+				validLines = append(validLines, line)
+			}
+		} else {
+
+			validLines = append(validLines, line)
+		}
+	}
+
+	return strings.Join(validLines, "\n"), nil
+}
+
+func parseLRCTimestamp(timestamp string) int64 {
+	var minutes, seconds, centiseconds int64
+	n, _ := fmt.Sscanf(timestamp, "%d:%d.%d", &minutes, &seconds, &centiseconds)
+	if n >= 2 {
+		return minutes*60*1000 + seconds*1000 + centiseconds*10
+	}
+	return -1
+}
+
+func ExtractFullMetadataFromFile(filePath string) (Metadata, error) {
+	var metadata Metadata
+
+	ffprobePath, err := GetFFprobePath()
+	if err != nil {
+		return metadata, err
+	}
+
+	if err := ValidateExecutable(ffprobePath); err != nil {
+		return metadata, fmt.Errorf("invalid ffprobe executable: %w", err)
+	}
+
+	cmd := exec.Command(ffprobePath,
+		"-v", "quiet",
+		"-print_format", "json",
+		"-show_format",
+		"-show_streams",
+		filePath,
+	)
+
+	setHideWindow(cmd)
+
+	output, err := cmd.Output()
+	if err != nil {
+		return metadata, err
+	}
+
+	var result struct {
+		Format struct {
+			Tags map[string]string `json:"tags"`
+		} `json:"format"`
+		Streams []struct {
+			Tags map[string]string `json:"tags"`
+		} `json:"streams"`
+	}
+
+	if err := json.Unmarshal(output, &result); err != nil {
+		return metadata, err
+	}
+
+	allTags := make(map[string]string)
+
+	for _, stream := range result.Streams {
+		for key, value := range stream.Tags {
+			allTags[strings.ToLower(key)] = value
+		}
+	}
+
+	for key, value := range result.Format.Tags {
+		allTags[strings.ToLower(key)] = value
+	}
+
+	for key, value := range allTags {
+		switch key {
+		case "title":
+			metadata.Title = value
+		case "artist":
+			metadata.Artist = value
+		case "album":
+			metadata.Album = value
+		case "album_artist", "albumartist":
+			metadata.AlbumArtist = value
+		case "date", "year":
+			if metadata.Date == "" || len(value) > len(metadata.Date) {
+				metadata.Date = value
+			}
+		case "track":
+
+			parts := strings.Split(value, "/")
+			if len(parts) > 0 {
+				if num, err := strconv.Atoi(parts[0]); err == nil {
+					metadata.TrackNumber = num
+				}
+			}
+			if len(parts) > 1 {
+				if num, err := strconv.Atoi(parts[1]); err == nil {
+					metadata.TotalTracks = num
+				}
+			}
+		case "disc":
+
+			parts := strings.Split(value, "/")
+			if len(parts) > 0 {
+				if num, err := strconv.Atoi(parts[0]); err == nil {
+					metadata.DiscNumber = num
+				}
+			}
+			if len(parts) > 1 {
+				if num, err := strconv.Atoi(parts[1]); err == nil {
+					metadata.TotalDiscs = num
+				}
+			}
+		case "copyright", "tcop":
+			metadata.Copyright = value
+		case "publisher", "tpub", "label":
+			metadata.Publisher = value
+		case "url":
+			metadata.URL = value
+		case "description", "comment":
+			if metadata.Description == "" {
+				metadata.Description = value
+			}
+		}
+	}
+
+	return metadata, nil
+}
+
+func EmbedMetadataToConvertedFile(filePath string, metadata Metadata, coverPath string) error {
+	ext := strings.ToLower(pathfilepath.Ext(filePath))
+
+	switch ext {
+	case ".flac":
+
+		return EmbedMetadata(filePath, metadata, coverPath)
+	case ".mp3":
+		return embedMetadataToMP3(filePath, metadata, coverPath)
+	case ".m4a":
+		return embedMetadataToM4A(filePath, metadata, coverPath)
+	default:
+		return fmt.Errorf("unsupported file format: %s", ext)
+	}
+}
+
+func embedMetadataToMP3(filePath string, metadata Metadata, coverPath string) error {
+	tag, err := id3v2.Open(filePath, id3v2.Options{Parse: true})
+	if err != nil {
+		return fmt.Errorf("failed to open MP3 file: %w", err)
+	}
+	defer tag.Close()
+
+	tag.DeleteFrames("TXXX")
+
+	if metadata.Title != "" {
+		tag.SetTitle(metadata.Title)
+	}
+	if metadata.Artist != "" {
+		tag.SetArtist(metadata.Artist)
+	}
+	if metadata.Album != "" {
+		tag.SetAlbum(metadata.Album)
+	}
+	if metadata.Date != "" {
+		year := metadata.Date
+		if len(year) >= 4 {
+			year = year[:4]
+		}
+		tag.SetYear(year)
+	}
+
+	if metadata.AlbumArtist != "" {
+		tag.DeleteFrames("TPE2")
+		tag.AddTextFrame("TPE2", id3v2.EncodingUTF8, metadata.AlbumArtist)
+	}
+
+	if metadata.TrackNumber > 0 {
+		tag.DeleteFrames(tag.CommonID("Track number/Position in set"))
+		trackStr := strconv.Itoa(metadata.TrackNumber)
+		if metadata.TotalTracks > 0 {
+			trackStr = fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks)
+		}
+		tag.AddTextFrame(tag.CommonID("Track number/Position in set"), id3v2.EncodingUTF8, trackStr)
+	}
+
+	if metadata.DiscNumber > 0 {
+		tag.DeleteFrames(tag.CommonID("Part of a set"))
+		discStr := strconv.Itoa(metadata.DiscNumber)
+		if metadata.TotalDiscs > 0 {
+			discStr = fmt.Sprintf("%d/%d", metadata.DiscNumber, metadata.TotalDiscs)
+		}
+		tag.AddTextFrame(tag.CommonID("Part of a set"), id3v2.EncodingUTF8, discStr)
+	}
+
+	if metadata.Copyright != "" {
+		tag.DeleteFrames("TCOP")
+		tag.AddTextFrame("TCOP", id3v2.EncodingUTF8, metadata.Copyright)
+	}
+
+	if metadata.Publisher != "" {
+		tag.DeleteFrames("TPUB")
+		tag.AddTextFrame("TPUB", id3v2.EncodingUTF8, metadata.Publisher)
+	}
+
+	if coverPath != "" && fileExists(coverPath) {
+
+		tag.DeleteFrames(tag.CommonID("Attached picture"))
+
+		artwork, err := os.ReadFile(coverPath)
+		if err == nil {
+			pic := id3v2.PictureFrame{
+				Encoding:    id3v2.EncodingUTF8,
+				MimeType:    "image/jpeg",
+				PictureType: id3v2.PTFrontCover,
+				Description: "Cover",
+				Picture:     artwork,
+			}
+			tag.AddAttachedPicture(pic)
+		} else {
+			fmt.Printf("[EmbedMetadataToMP3] Warning: Failed to read cover art file: %v\n", err)
+		}
+	}
+
+	if err := tag.Save(); err != nil {
+		return fmt.Errorf("failed to save MP3 tags: %w", err)
+	}
+
+	return nil
+}
+
+func embedMetadataToM4A(filePath string, metadata Metadata, coverPath string) error {
+	ffmpegPath, err := GetFFmpegPath()
+	if err != nil {
+		return fmt.Errorf("ffmpeg not found: %w", err)
+	}
+
+	if err := ValidateExecutable(ffmpegPath); err != nil {
+		return fmt.Errorf("invalid ffmpeg executable: %w", err)
+	}
+
+	args := []string{
+		"-i", filePath,
+		"-y",
+	}
+
+	if coverPath != "" && fileExists(coverPath) {
+		args = append(args, "-i", coverPath)
+		args = append(args, "-map", "0:a", "-map", "1", "-c:a", "copy", "-c:v", "copy", "-disposition:v:0", "attached_pic")
+	} else {
+		args = append(args, "-map", "0", "-codec", "copy")
+	}
+
+	if metadata.Title != "" {
+		args = append(args, "-metadata", "title="+metadata.Title)
+	}
+	if metadata.Artist != "" {
+		args = append(args, "-metadata", "artist="+metadata.Artist)
+	}
+	if metadata.Album != "" {
+		args = append(args, "-metadata", "album="+metadata.Album)
+	}
+	if metadata.AlbumArtist != "" {
+		args = append(args, "-metadata", "album_artist="+metadata.AlbumArtist)
+	}
+	if metadata.Date != "" {
+		args = append(args, "-metadata", "date="+metadata.Date)
+	}
+	if metadata.TrackNumber > 0 {
+		trackStr := strconv.Itoa(metadata.TrackNumber)
+		if metadata.TotalTracks > 0 {
+			trackStr = fmt.Sprintf("%d/%d", metadata.TrackNumber, metadata.TotalTracks)
+		}
+		args = append(args, "-metadata", "track="+trackStr)
+	}
+	if metadata.DiscNumber > 0 {
+		discStr := strconv.Itoa(metadata.DiscNumber)
+		if metadata.TotalDiscs > 0 {
+			discStr = fmt.Sprintf("%d/%d", metadata.DiscNumber, metadata.TotalDiscs)
+		}
+		args = append(args, "-metadata", "disk="+discStr)
+	}
+	if metadata.Copyright != "" {
+		args = append(args, "-metadata", "copyright="+metadata.Copyright)
+	}
+	if metadata.Publisher != "" {
+		args = append(args, "-metadata", "publisher="+metadata.Publisher)
+	}
+
+	tmpOutputFile := strings.TrimSuffix(filePath, pathfilepath.Ext(filePath)) + ".tmp" + pathfilepath.Ext(filePath)
+	defer func() {
+		if _, err := os.Stat(tmpOutputFile); err == nil {
+			os.Remove(tmpOutputFile)
+		}
+	}()
+
+	args = append(args, "-f", "ipod", tmpOutputFile)
+
+	cmd := exec.Command(ffmpegPath, args...)
+	setHideWindow(cmd)
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("ffmpeg failed to embed metadata: %s - %w", string(output), err)
+	}
+
+	if err := os.Rename(tmpOutputFile, filePath); err != nil {
+		return fmt.Errorf("failed to replace original file: %w", err)
+	}
+
+	return nil
 }

backend/progress.go

@@ -7,7 +7,6 @@ import (
 	"time"
 )
 
-// DownloadStatus represents the status of a download item
 type DownloadStatus string
 
 const (
@@ -18,7 +17,6 @@ const (
 	StatusSkipped     DownloadStatus = "skipped"
 )
 
-// DownloadItem represents a single item in the download queue
 type DownloadItem struct {
 	ID           string         `json:"id"`
 	TrackName    string         `json:"track_name"`
@@ -26,16 +24,15 @@ type DownloadItem struct {
 	AlbumName    string         `json:"album_name"`
 	ISRC         string         `json:"isrc"`
 	Status       DownloadStatus `json:"status"`
-	Progress     float64        `json:"progress"`      // MB downloaded
-	TotalSize    float64        `json:"total_size"`    // MB total (if known)
-	Speed        float64        `json:"speed"`         // MB/s
-	StartTime    int64          `json:"start_time"`    // Unix timestamp
-	EndTime      int64          `json:"end_time"`      // Unix timestamp
-	ErrorMessage string         `json:"error_message"` // If failed
-	FilePath     string         `json:"file_path"`     // Final file path
+	Progress     float64        `json:"progress"`
+	TotalSize    float64        `json:"total_size"`
+	Speed        float64        `json:"speed"`
+	StartTime    int64          `json:"start_time"`
+	EndTime      int64          `json:"end_time"`
+	ErrorMessage string         `json:"error_message"`
+	FilePath     string         `json:"file_path"`
 }
 
-// Global progress tracker
 var (
 	currentProgress     float64
 	currentProgressLock sync.RWMutex
@@ -44,7 +41,6 @@ var (
 	currentSpeed        float64
 	speedLock           sync.RWMutex
 
-	// Download queue tracking
 	downloadQueue       []DownloadItem
 	downloadQueueLock   sync.RWMutex
 	currentItemID       string
@@ -55,27 +51,24 @@ var (
 	sessionStartLock    sync.RWMutex
 )
 
-// ProgressInfo represents download progress information
 type ProgressInfo struct {
 	IsDownloading bool    `json:"is_downloading"`
 	MBDownloaded  float64 `json:"mb_downloaded"`
 	SpeedMBps     float64 `json:"speed_mbps"`
 }
 
-// DownloadQueueInfo represents the complete download queue state
 type DownloadQueueInfo struct {
 	IsDownloading    bool           `json:"is_downloading"`
 	Queue            []DownloadItem `json:"queue"`
-	CurrentSpeed     float64        `json:"current_speed"`      // MB/s
-	TotalDownloaded  float64        `json:"total_downloaded"`   // MB this session
-	SessionStartTime int64          `json:"session_start_time"` // Unix timestamp
+	CurrentSpeed     float64        `json:"current_speed"`
+	TotalDownloaded  float64        `json:"total_downloaded"`
+	SessionStartTime int64          `json:"session_start_time"`
 	QueuedCount      int            `json:"queued_count"`
 	CompletedCount   int            `json:"completed_count"`
 	FailedCount      int            `json:"failed_count"`
 	SkippedCount     int            `json:"skipped_count"`
 }
 
-// GetDownloadProgress returns current download progress
 func GetDownloadProgress() ProgressInfo {
 	downloadingLock.RLock()
 	downloading := isDownloading
@@ -96,34 +89,30 @@ func GetDownloadProgress() ProgressInfo {
 	}
 }
 
-// SetDownloadSpeed updates the current download speed
 func SetDownloadSpeed(mbps float64) {
 	speedLock.Lock()
 	currentSpeed = mbps
 	speedLock.Unlock()
 }
 
-// SetDownloadProgress updates the current download progress
 func SetDownloadProgress(mbDownloaded float64) {
 	currentProgressLock.Lock()
 	currentProgress = mbDownloaded
 	currentProgressLock.Unlock()
 }
 
-// SetDownloading sets the downloading state
 func SetDownloading(downloading bool) {
 	downloadingLock.Lock()
 	isDownloading = downloading
 	downloadingLock.Unlock()
 
 	if !downloading {
-		// Reset progress when download completes
+
 		SetDownloadProgress(0)
 		SetDownloadSpeed(0)
 	}
 }
 
-// ProgressWriter wraps an io.Writer and reports download progress
 type ProgressWriter struct {
 	writer      io.Writer
 	total       int64
@@ -131,7 +120,7 @@ type ProgressWriter struct {
 	startTime   int64
 	lastTime    int64
 	lastBytes   int64
-	itemID      string // Track which download item this belongs to
+	itemID      string
 }
 
 func NewProgressWriter(writer io.Writer) *ProgressWriter {
@@ -147,7 +136,6 @@ func NewProgressWriter(writer io.Writer) *ProgressWriter {
 	}
 }
 
-// NewProgressWriterWithID creates a progress writer with an item ID for queue tracking
 func NewProgressWriterWithID(writer io.Writer, itemID string) *ProgressWriter {
 	pw := NewProgressWriter(writer)
 	pw.itemID = itemID
@@ -162,13 +150,11 @@ func (pw *ProgressWriter) Write(p []byte) (int, error) {
 	n, err := pw.writer.Write(p)
 	pw.total += int64(n)
 
-	// Report progress every 256KB for smoother updates
 	if pw.total-pw.lastPrinted >= 256*1024 {
 		mbDownloaded := float64(pw.total) / (1024 * 1024)
 
-		// Calculate speed (MB/s)
 		now := getCurrentTimeMillis()
-		timeDiff := float64(now-pw.lastTime) / 1000.0 // seconds
+		timeDiff := float64(now-pw.lastTime) / 1000.0
 		bytesDiff := float64(pw.total - pw.lastBytes)
 
 		var speedMBps float64
@@ -180,10 +166,8 @@ func (pw *ProgressWriter) Write(p []byte) (int, error) {
 			fmt.Printf("\rDownloaded: %.2f MB", mbDownloaded)
 		}
 
-		// Update global progress
 		SetDownloadProgress(mbDownloaded)
 
-		// Update individual item progress if we have an item ID
 		if pw.itemID != "" {
 			UpdateItemProgress(pw.itemID, mbDownloaded, speedMBps)
 		}
@@ -200,9 +184,6 @@ func (pw *ProgressWriter) GetTotal() int64 {
 	return pw.total
 }
 
-// Queue management functions
-
-// AddToQueue adds a new item to the download queue
 func AddToQueue(id, trackName, artistName, albumName, isrc string) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -223,7 +204,6 @@ func AddToQueue(id, trackName, artistName, albumName, isrc string) {
 
 	downloadQueue = append(downloadQueue, item)
 
-	// Initialize session start time if this is the first item
 	sessionStartLock.Lock()
 	if sessionStartTime == 0 {
 		sessionStartTime = time.Now().Unix()
@@ -231,7 +211,6 @@ func AddToQueue(id, trackName, artistName, albumName, isrc string) {
 	sessionStartLock.Unlock()
 }
 
-// StartDownloadItem marks an item as currently downloading
 func StartDownloadItem(id string) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -250,7 +229,6 @@ func StartDownloadItem(id string) {
 	currentItemLock.Unlock()
 }
 
-// UpdateItemProgress updates the progress of the current download item
 func UpdateItemProgress(id string, progress, speed float64) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -264,14 +242,12 @@ func UpdateItemProgress(id string, progress, speed float64) {
 	}
 }
 
-// GetCurrentItemID returns the ID of the currently downloading item
 func GetCurrentItemID() string {
 	currentItemLock.RLock()
 	defer currentItemLock.RUnlock()
 	return currentItemID
 }
 
-// CompleteDownloadItem marks an item as completed
 func CompleteDownloadItem(id, filePath string, finalSize float64) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -284,7 +260,6 @@ func CompleteDownloadItem(id, filePath string, finalSize float64) {
 			downloadQueue[i].Progress = finalSize
 			downloadQueue[i].TotalSize = finalSize
 
-			// Add to total downloaded
 			totalDownloadedLock.Lock()
 			totalDownloaded += finalSize
 			totalDownloadedLock.Unlock()
@@ -293,7 +268,6 @@ func CompleteDownloadItem(id, filePath string, finalSize float64) {
 	}
 }
 
-// FailDownloadItem marks an item as failed
 func FailDownloadItem(id, errorMsg string) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -308,7 +282,6 @@ func FailDownloadItem(id, errorMsg string) {
 	}
 }
 
-// SkipDownloadItem marks an item as skipped (already exists)
 func SkipDownloadItem(id, filePath string) {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -323,9 +296,8 @@ func SkipDownloadItem(id, filePath string) {
 	}
 }
 
-// GetDownloadQueue returns the complete download queue state
 func GetDownloadQueue() DownloadQueueInfo {
-	// Auto-reset session if all downloads are complete
+
 	ResetSessionIfComplete()
 
 	downloadQueueLock.RLock()
@@ -347,7 +319,6 @@ func GetDownloadQueue() DownloadQueueInfo {
 	sessionStart := sessionStartTime
 	sessionStartLock.RUnlock()
 
-	// Count statuses
 	var queued, completed, failed, skipped int
 	for _, item := range downloadQueue {
 		switch item.Status {
@@ -362,7 +333,6 @@ func GetDownloadQueue() DownloadQueueInfo {
 		}
 	}
 
-	// Create a copy of the queue
 	queueCopy := make([]DownloadItem, len(downloadQueue))
 	copy(queueCopy, downloadQueue)
 
@@ -379,12 +349,10 @@ func GetDownloadQueue() DownloadQueueInfo {
 	}
 }
 
-// ClearDownloadQueue clears all completed, failed, and skipped items from the queue
 func ClearDownloadQueue() {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
 
-	// Keep only queued and downloading items
 	newQueue := make([]DownloadItem, 0)
 	for _, item := range downloadQueue {
 		if item.Status == StatusQueued || item.Status == StatusDownloading {
@@ -394,7 +362,6 @@ func ClearDownloadQueue() {
 	downloadQueue = newQueue
 }
 
-// ClearAllDownloads clears the entire queue and resets session stats
 func ClearAllDownloads() {
 	downloadQueueLock.Lock()
 	downloadQueue = []DownloadItem{}
@@ -412,13 +379,10 @@ func ClearAllDownloads() {
 	currentItemID = ""
 	currentItemLock.Unlock()
 
-	// Reset current progress and speed
 	SetDownloadProgress(0)
 	SetDownloadSpeed(0)
 }
 
-// CancelAllQueuedItems marks all queued items as skipped (cancelled)
-// This is called when user stops a download or when batch download completes
 func CancelAllQueuedItems() {
 	downloadQueueLock.Lock()
 	defer downloadQueueLock.Unlock()
@@ -432,8 +396,6 @@ func CancelAllQueuedItems() {
 	}
 }
 
-// ResetSessionIfComplete resets session stats if no active or queued downloads
-// Note: Does NOT clear the queue - items remain visible for history
 func ResetSessionIfComplete() {
 	downloadQueueLock.RLock()
 	hasActiveOrQueued := false
@@ -445,8 +407,6 @@ func ResetSessionIfComplete() {
 	}
 	downloadQueueLock.RUnlock()
 
-	// If no active or queued items, reset session stats
-	// But keep the queue items for history visibility
 	if !hasActiveOrQueued {
 		sessionStartLock.Lock()
 		sessionStartTime = 0

backend/qobuz.go

@@ -78,7 +78,7 @@ func NewQobuzDownloader() *QobuzDownloader {
 }
 
 func (q *QobuzDownloader) SearchByISRC(isrc string) (*QobuzTrack, error) {
-	// Decode base64 API URL
+
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly93d3cucW9idXouY29tL2FwaS5qc29uLzAuMi90cmFjay9zZWFyY2g/cXVlcnk9")
 	url := fmt.Sprintf("%s%s&limit=1&app_id=%s", string(apiBase), isrc, q.appID)
 
@@ -93,7 +93,7 @@ func (q *QobuzDownloader) SearchByISRC(isrc string) (*QobuzTrack, error) {
 	}
 
 	var searchResp QobuzSearchResponse
-	// Read body first to handle encoding issues
+
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response body: %w", err)
@@ -104,7 +104,7 @@ func (q *QobuzDownloader) SearchByISRC(isrc string) (*QobuzTrack, error) {
 	}
 
 	if err := json.Unmarshal(body, &searchResp); err != nil {
-		// Truncate body for error message (max 200 chars)
+
 		bodyStr := string(body)
 		if len(bodyStr) > 200 {
 			bodyStr = bodyStr[:200] + "..."
@@ -120,20 +120,17 @@ func (q *QobuzDownloader) SearchByISRC(isrc string) (*QobuzTrack, error) {
 }
 
 func (q *QobuzDownloader) GetDownloadURL(trackID int64, quality string) (string, error) {
-	// Map quality to Qobuz quality code
-	// Qobuz uses: 5 (MP3 320), 6 (FLAC 16-bit), 7 (FLAC 24-bit), 27 (Hi-Res)
-	qualityCode := quality // Use the provided quality parameter
+
+	qualityCode := quality
 	if qualityCode == "" {
-		qualityCode = "6" // Default to FLAC 16-bit if not specified
+		qualityCode = "6"
 	}
 
 	fmt.Printf("Getting download URL for track ID: %d with requested quality: %s\n", trackID, qualityCode)
 	fmt.Printf("Quality codes: 6=FLAC 16-bit, 7=FLAC 24-bit, 27=Hi-Res\n")
 
-	// Decode base64 API URLs
 	primaryBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9kYWIueWVldC5zdS9hcGkvc3RyZWFtP3RyYWNrSWQ9")
 
-	// Try primary API first
 	primaryURL := fmt.Sprintf("%s%d&quality=%s", string(primaryBase), trackID, qualityCode)
 	fmt.Printf("Qobuz API URL: %s\n", primaryURL)
 
@@ -154,7 +151,6 @@ func (q *QobuzDownloader) GetDownloadURL(trackID int64, quality string) (string,
 		resp.Body.Close()
 	}
 
-	// Fallback to secondary API
 	fmt.Println("Primary API failed, trying fallback...")
 	fallbackBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9kYWJtdXNpYy54eXovYXBpL3N0cmVhbT90cmFja0lkPQ==")
 	fallbackURL := fmt.Sprintf("%s%d&quality=%s", string(fallbackBase), trackID, qualityCode)
@@ -184,7 +180,7 @@ func (q *QobuzDownloader) GetDownloadURL(trackID int64, quality string) (string,
 
 	var streamResp QobuzStreamResponse
 	if err := json.Unmarshal(body, &streamResp); err != nil {
-		// Truncate body for error message (max 200 chars)
+
 		bodyStr := string(body)
 		if len(bodyStr) > 200 {
 			bodyStr = bodyStr[:200] + "..."
@@ -202,10 +198,9 @@ func (q *QobuzDownloader) GetDownloadURL(trackID int64, quality string) (string,
 
 func (q *QobuzDownloader) DownloadFile(url, filepath string) error {
 	fmt.Println("Starting file download...")
-	// Use a separate client with a longer timeout. The default client's 60s limit
-	// causes downloads to fail on slow connections or for large Hi-Res files.
+
 	downloadClient := &http.Client{
-		Timeout: 5 * time.Minute, // 5 minutes for large files
+		Timeout: 5 * time.Minute,
 	}
 
 	resp, err := downloadClient.Get(url)
@@ -226,14 +221,13 @@ func (q *QobuzDownloader) DownloadFile(url, filepath string) error {
 	defer out.Close()
 
 	fmt.Println("Downloading...")
-	// Use progress writer to track download
+
 	pw := NewProgressWriter(out)
 	_, err = io.Copy(pw, resp.Body)
 	if err != nil {
 		return fmt.Errorf("failed to write file: %w", err)
 	}
 
-	// Print final size
 	fmt.Printf("\rDownloaded: %.2f MB (Complete)\n", float64(pw.GetTotal())/(1024*1024))
 	return nil
 }
@@ -266,19 +260,16 @@ func (q *QobuzDownloader) DownloadCoverArt(coverURL, filepath string) error {
 func buildQobuzFilename(title, artist, album, albumArtist, releaseDate string, trackNumber, discNumber int, format string, includeTrackNumber bool, position int, useAlbumTrackNumber bool) string {
 	var filename string
 
-	// Determine track number to use
 	numberToUse := position
 	if useAlbumTrackNumber && trackNumber > 0 {
 		numberToUse = trackNumber
 	}
 
-	// Extract year from release date (format: YYYY-MM-DD or YYYY)
 	year := ""
 	if len(releaseDate) >= 4 {
 		year = releaseDate[:4]
 	}
 
-	// Check if format is a template (contains {})
 	if strings.Contains(format, "{") {
 		filename = format
 		filename = strings.ReplaceAll(filename, "{title}", title)
@@ -287,34 +278,31 @@ func buildQobuzFilename(title, artist, album, albumArtist, releaseDate string, t
 		filename = strings.ReplaceAll(filename, "{album_artist}", albumArtist)
 		filename = strings.ReplaceAll(filename, "{year}", year)
 
-		// Handle disc number
 		if discNumber > 0 {
 			filename = strings.ReplaceAll(filename, "{disc}", fmt.Sprintf("%d", discNumber))
 		} else {
 			filename = strings.ReplaceAll(filename, "{disc}", "")
 		}
 
-		// Handle track number - if numberToUse is 0, remove {track} and surrounding separators
 		if numberToUse > 0 {
 			filename = strings.ReplaceAll(filename, "{track}", fmt.Sprintf("%02d", numberToUse))
 		} else {
-			// Remove {track} with common separators
+
 			filename = regexp.MustCompile(`\{track\}\.\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*-\s*`).ReplaceAllString(filename, "")
 			filename = regexp.MustCompile(`\{track\}\s*`).ReplaceAllString(filename, "")
 		}
 	} else {
-		// Legacy format support
+
 		switch format {
 		case "artist-title":
 			filename = fmt.Sprintf("%s - %s", artist, title)
 		case "title":
 			filename = title
-		default: // "title-artist"
+		default:
 			filename = fmt.Sprintf("%s - %s", title, artist)
 		}
 
-		// Add track number prefix if enabled (legacy behavior)
 		if includeTrackNumber && position > 0 {
 			filename = fmt.Sprintf("%02d. %s", numberToUse, filename)
 		}
@@ -323,22 +311,20 @@ func buildQobuzFilename(title, artist, album, albumArtist, releaseDate string, t
 	return filename + ".flac"
 }
 
-func (q *QobuzDownloader) DownloadByISRC(isrc, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int) (string, error) {
-	fmt.Printf("Fetching track info for ISRC: %s\n", isrc)
+func (q *QobuzDownloader) DownloadByISRC(deezerISRC, outputDir, quality, filenameFormat string, includeTrackNumber bool, position int, spotifyTrackName, spotifyArtistName, spotifyAlbumName, spotifyAlbumArtist, spotifyReleaseDate string, useAlbumTrackNumber bool, spotifyCoverURL string, embedMaxQualityCover bool, spotifyTrackNumber, spotifyDiscNumber, spotifyTotalTracks int, spotifyTotalDiscs int, spotifyCopyright, spotifyPublisher, spotifyURL string) (string, error) {
+	fmt.Printf("Fetching track info for ISRC: %s\n", deezerISRC)
 
-	// Create output directory if it doesn't exist
 	if outputDir != "." {
 		if err := os.MkdirAll(outputDir, 0755); err != nil {
 			return "", fmt.Errorf("failed to create output directory: %w", err)
 		}
 	}
 
-	track, err := q.SearchByISRC(isrc)
+	track, err := q.SearchByISRC(deezerISRC)
 	if err != nil {
 		return "", err
 	}
 
-	// All metadata from Spotify - no fallback to Qobuz
 	artists := spotifyArtistName
 	trackTitle := spotifyTrackName
 	albumTitle := spotifyAlbumName
@@ -362,7 +348,6 @@ func (q *QobuzDownloader) DownloadByISRC(isrc, outputDir, quality, filenameForma
 		return "", fmt.Errorf("received empty download URL")
 	}
 
-	// Show partial URL for security
 	urlPreview := downloadURL
 	if len(downloadURL) > 60 {
 		urlPreview = downloadURL[:60] + "..."
@@ -374,13 +359,6 @@ func (q *QobuzDownloader) DownloadByISRC(isrc, outputDir, quality, filenameForma
 	safeAlbum := sanitizeFilename(albumTitle)
 	safeAlbumArtist := sanitizeFilename(spotifyAlbumArtist)
 
-	// Check if file with same ISRC already exists (use Spotify ISRC)
-	if existingFile, exists := CheckISRCExists(outputDir, isrc); exists {
-		fmt.Printf("File with ISRC %s already exists: %s\n", isrc, existingFile)
-		return "EXISTS:" + existingFile, nil
-	}
-
-	// Build filename based on format settings (use Spotify track number)
 	filename := buildQobuzFilename(safeTitle, safeArtist, safeAlbum, safeAlbumArtist, spotifyReleaseDate, spotifyTrackNumber, spotifyDiscNumber, filenameFormat, includeTrackNumber, position, useAlbumTrackNumber)
 	filepath := filepath.Join(outputDir, filename)
 
@@ -397,7 +375,7 @@ func (q *QobuzDownloader) DownloadByISRC(isrc, outputDir, quality, filenameForma
 	fmt.Printf("Downloaded: %s\n", filepath)
 
 	coverPath := ""
-	// Use Spotify cover URL (with max resolution if enabled) - all metadata from Spotify
+
 	if spotifyCoverURL != "" {
 		coverPath = filepath + ".cover.jpg"
 		coverClient := NewCoverClient()
@@ -412,23 +390,24 @@ func (q *QobuzDownloader) DownloadByISRC(isrc, outputDir, quality, filenameForma
 
 	fmt.Println("Embedding metadata and cover art...")
 
-	// Determine track number to embed - ALL from Spotify
 	trackNumberToEmbed := spotifyTrackNumber
-	if position > 0 && !useAlbumTrackNumber {
-		trackNumberToEmbed = position // Use playlist position
+	if trackNumberToEmbed == 0 {
+		trackNumberToEmbed = 1
 	}
 
-	// ALL metadata from Spotify
 	metadata := Metadata{
 		Title:       trackTitle,
 		Artist:      artists,
 		Album:       albumTitle,
 		AlbumArtist: spotifyAlbumArtist,
-		Date:        spotifyReleaseDate, // Recorded date (full date YYYY-MM-DD)
+		Date:        spotifyReleaseDate,
 		TrackNumber: trackNumberToEmbed,
-		TotalTracks: spotifyTotalTracks, // Total tracks in album from Spotify
-		DiscNumber:  spotifyDiscNumber,  // Disc number from Spotify
-		ISRC:        isrc,               // ISRC from Spotify (passed as parameter)
+		TotalTracks: spotifyTotalTracks,
+		DiscNumber:  spotifyDiscNumber,
+		TotalDiscs:  spotifyTotalDiscs,
+		URL:         spotifyURL,
+		Copyright:   spotifyCopyright,
+		Publisher:   spotifyPublisher,
 		Description: "https://github.com/afkarxyz/SpotiFLAC",
 	}
 

backend/romaji.go

@@ -5,7 +5,6 @@ import (
 	"unicode"
 )
 
-// Hiragana to Romaji mapping
 var hiraganaToRomaji = map[rune]string{
 	'あ': "a", 'い': "i", 'う': "u", 'え': "e", 'お': "o",
 	'か': "ka", 'き': "ki", 'く': "ku", 'け': "ke", 'こ': "ko",
@@ -17,20 +16,19 @@ var hiraganaToRomaji = map[rune]string{
 	'や': "ya", 'ゆ': "yu", 'よ': "yo",
 	'ら': "ra", 'り': "ri", 'る': "ru", 'れ': "re", 'ろ': "ro",
 	'わ': "wa", 'を': "wo", 'ん': "n",
-	// Dakuten (voiced)
+
 	'が': "ga", 'ぎ': "gi", 'ぐ': "gu", 'げ': "ge", 'ご': "go",
 	'ざ': "za", 'じ': "ji", 'ず': "zu", 'ぜ': "ze", 'ぞ': "zo",
 	'だ': "da", 'ぢ': "ji", 'づ': "zu", 'で': "de", 'ど': "do",
 	'ば': "ba", 'び': "bi", 'ぶ': "bu", 'べ': "be", 'ぼ': "bo",
-	// Handakuten (semi-voiced)
+
 	'ぱ': "pa", 'ぴ': "pi", 'ぷ': "pu", 'ぺ': "pe", 'ぽ': "po",
-	// Small characters
+
 	'ゃ': "ya", 'ゅ': "yu", 'ょ': "yo",
-	'っ': "", // Double consonant marker
+	'っ': "",
 	'ぁ': "a", 'ぃ': "i", 'ぅ': "u", 'ぇ': "e", 'ぉ': "o",
 }
 
-// Katakana to Romaji mapping
 var katakanaToRomaji = map[rune]string{
 	'ア': "a", 'イ': "i", 'ウ': "u", 'エ': "e", 'オ': "o",
 	'カ': "ka", 'キ': "ki", 'ク': "ku", 'ケ': "ke", 'コ': "ko",
@@ -42,23 +40,22 @@ var katakanaToRomaji = map[rune]string{
 	'ヤ': "ya", 'ユ': "yu", 'ヨ': "yo",
 	'ラ': "ra", 'リ': "ri", 'ル': "ru", 'レ': "re", 'ロ': "ro",
 	'ワ': "wa", 'ヲ': "wo", 'ン': "n",
-	// Dakuten (voiced)
+
 	'ガ': "ga", 'ギ': "gi", 'グ': "gu", 'ゲ': "ge", 'ゴ': "go",
 	'ザ': "za", 'ジ': "ji", 'ズ': "zu", 'ゼ': "ze", 'ゾ': "zo",
 	'ダ': "da", 'ヂ': "ji", 'ヅ': "zu", 'デ': "de", 'ド': "do",
 	'バ': "ba", 'ビ': "bi", 'ブ': "bu", 'ベ': "be", 'ボ': "bo",
-	// Handakuten (semi-voiced)
+
 	'パ': "pa", 'ピ': "pi", 'プ': "pu", 'ペ': "pe", 'ポ': "po",
-	// Small characters
+
 	'ャ': "ya", 'ュ': "yu", 'ョ': "yo",
-	'ッ': "", // Double consonant marker
+	'ッ': "",
 	'ァ': "a", 'ィ': "i", 'ゥ': "u", 'ェ': "e", 'ォ': "o",
-	// Extended katakana
-	'ー': "", // Long vowel mark
+
+	'ー': "",
 	'ヴ': "vu",
 }
 
-// Combination mappings for きゃ, しゃ, etc.
 var combinationHiragana = map[string]string{
 	"きゃ": "kya", "きゅ": "kyu", "きょ": "kyo",
 	"しゃ": "sha", "しゅ": "shu", "しょ": "sho",
@@ -85,13 +82,12 @@ var combinationKatakana = map[string]string{
 	"ジャ": "ja", "ジュ": "ju", "ジョ": "jo",
 	"ビャ": "bya", "ビュ": "byu", "ビョ": "byo",
 	"ピャ": "pya", "ピュ": "pyu", "ピョ": "pyo",
-	// Extended combinations
+
 	"ティ": "ti", "ディ": "di", "トゥ": "tu", "ドゥ": "du",
 	"ファ": "fa", "フィ": "fi", "フェ": "fe", "フォ": "fo",
 	"ウィ": "wi", "ウェ": "we", "ウォ": "wo",
 }
 
-// ContainsJapanese checks if a string contains Japanese characters
 func ContainsJapanese(s string) bool {
 	for _, r := range s {
 		if isHiragana(r) || isKatakana(r) || isKanji(r) {
@@ -110,12 +106,10 @@ func isKatakana(r rune) bool {
 }
 
 func isKanji(r rune) bool {
-	return (r >= 0x4E00 && r <= 0x9FFF) || // CJK Unified Ideographs
-		(r >= 0x3400 && r <= 0x4DBF) // CJK Unified Ideographs Extension A
+	return (r >= 0x4E00 && r <= 0x9FFF) ||
+		(r >= 0x3400 && r <= 0x4DBF)
 }
 
-// JapaneseToRomaji converts Japanese text (hiragana/katakana) to romaji
-// Note: Kanji cannot be converted without a dictionary, so they are kept as-is
 func JapaneseToRomaji(text string) string {
 	if !ContainsJapanese(text) {
 		return text
@@ -126,7 +120,7 @@ func JapaneseToRomaji(text string) string {
 	i := 0
 
 	for i < len(runes) {
-		// Check for っ/ッ (double consonant)
+
 		if i < len(runes)-1 && (runes[i] == 'っ' || runes[i] == 'ッ') {
 			nextRomaji := ""
 			if romaji, ok := hiraganaToRomaji[runes[i+1]]; ok {
@@ -135,13 +129,12 @@ func JapaneseToRomaji(text string) string {
 				nextRomaji = romaji
 			}
 			if len(nextRomaji) > 0 {
-				result.WriteByte(nextRomaji[0]) // Double the first consonant
+				result.WriteByte(nextRomaji[0])
 			}
 			i++
 			continue
 		}
 
-		// Check for two-character combinations
 		if i < len(runes)-1 {
 			combo := string(runes[i : i+2])
 			if romaji, ok := combinationHiragana[combo]; ok {
@@ -156,17 +149,16 @@ func JapaneseToRomaji(text string) string {
 			}
 		}
 
-		// Single character conversion
 		r := runes[i]
 		if romaji, ok := hiraganaToRomaji[r]; ok {
 			result.WriteString(romaji)
 		} else if romaji, ok := katakanaToRomaji[r]; ok {
 			result.WriteString(romaji)
 		} else if isKanji(r) {
-			// Keep kanji as-is (would need dictionary for proper conversion)
+
 			result.WriteRune(r)
 		} else {
-			// Keep other characters (punctuation, spaces, etc.)
+
 			result.WriteRune(r)
 		}
 		i++
@@ -175,21 +167,17 @@ func JapaneseToRomaji(text string) string {
 	return result.String()
 }
 
-// BuildSearchQuery creates a search query from track name and artist
-// Converts Japanese to romaji if present
 func BuildSearchQuery(trackName, artistName string) string {
-	// Convert Japanese to romaji
+
 	trackRomaji := JapaneseToRomaji(trackName)
 	artistRomaji := JapaneseToRomaji(artistName)
 
-	// Clean up the query - remove special characters that might interfere with search
 	trackClean := cleanSearchQuery(trackRomaji)
 	artistClean := cleanSearchQuery(artistRomaji)
 
 	return strings.TrimSpace(artistClean + " " + trackClean)
 }
 
-// cleanSearchQuery removes special characters that might interfere with search
 func cleanSearchQuery(s string) string {
 	var result strings.Builder
 	for _, r := range s {
@@ -202,21 +190,19 @@ func cleanSearchQuery(s string) string {
 	return strings.TrimSpace(result.String())
 }
 
-// cleanToASCII removes all non-ASCII characters and keeps only letters, numbers, spaces
-// This is useful for creating search queries that work better with Tidal's search
 func cleanToASCII(s string) string {
 	var result strings.Builder
 	for _, r := range s {
-		// Keep only ASCII letters, numbers, spaces, and basic punctuation
+
 		if (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') ||
 			(r >= '0' && r <= '9') || r == ' ' || r == '-' || r == '\'' {
 			result.WriteRune(r)
 		} else if r == ',' || r == '.' {
-			// Convert punctuation to space
+
 			result.WriteRune(' ')
 		}
 	}
-	// Clean up multiple spaces
+
 	cleaned := strings.Join(strings.Fields(result.String()), " ")
 	return strings.TrimSpace(cleaned)
 }

backend/songlink.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 )
 
@@ -22,7 +23,6 @@ type SongLinkURLs struct {
 	AmazonURL string `json:"amazon_url"`
 }
 
-// TrackAvailability represents the availability of a track on different platforms
 type TrackAvailability struct {
 	SpotifyID string `json:"spotify_id"`
 	Tidal     bool   `json:"tidal"`
@@ -43,14 +43,13 @@ func NewSongLinkClient() *SongLinkClient {
 }
 
 func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLinkURLs, error) {
-	// Rate limiting: max 10 requests per minute (song.link API limit)
+
 	now := time.Now()
 	if now.Sub(s.apiCallResetTime) >= time.Minute {
 		s.apiCallCount = 0
 		s.apiCallResetTime = now
 	}
 
-	// If we've hit the limit, wait until the next minute
 	if s.apiCallCount >= 9 {
 		waitTime := time.Minute - now.Sub(s.apiCallResetTime)
 		if waitTime > 0 {
@@ -61,7 +60,6 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 		}
 	}
 
-	// Add delay between requests (7 seconds to be safe)
 	if !s.lastAPICallTime.IsZero() {
 		timeSinceLastCall := now.Sub(s.lastAPICallTime)
 		minDelay := 7 * time.Second
@@ -72,7 +70,6 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 		}
 	}
 
-	// Decode base64 API URL
 	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL3RyYWNrLw==")
 	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyTrackID)
 
@@ -86,7 +83,6 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 
 	fmt.Println("Getting streaming URLs from song.link...")
 
-	// Retry logic for rate limit errors
 	maxRetries := 3
 	var resp *http.Response
 	for i := 0; i < maxRetries; i++ {
@@ -95,7 +91,6 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 			return nil, fmt.Errorf("failed to get URLs: %w", err)
 		}
 
-		// Update rate limit tracking
 		s.lastAPICallTime = time.Now()
 		s.apiCallCount++
 
@@ -124,7 +119,7 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 			URL string `json:"url"`
 		} `json:"linksByPlatform"`
 	}
-	// Read body first to handle encoding issues
+
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response body: %w", err)
@@ -135,7 +130,7 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 	}
 
 	if err := json.Unmarshal(body, &songLinkResp); err != nil {
-		// Truncate body for error message (max 200 chars)
+
 		bodyStr := string(body)
 		if len(bodyStr) > 200 {
 			bodyStr = bodyStr[:200] + "..."
@@ -145,23 +140,20 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 
 	urls := &SongLinkURLs{}
 
-	// Extract Tidal URL
 	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
 		urls.TidalURL = tidalLink.URL
 		fmt.Printf("✓ Tidal URL found\n")
 	}
 
-	// Extract Amazon URL
 	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
 		amazonURL := amazonLink.URL
-		// Convert album URL to track URL if needed
+
 		if len(amazonURL) > 0 {
 			urls.AmazonURL = amazonURL
 			fmt.Printf("✓ Amazon URL found\n")
 		}
 	}
 
-	// Check if at least one URL was found
 	if urls.TidalURL == "" && urls.AmazonURL == "" {
 		return nil, fmt.Errorf("no streaming URLs found")
 	}
@@ -169,16 +161,14 @@ func (s *SongLinkClient) GetAllURLsFromSpotify(spotifyTrackID string) (*SongLink
 	return urls, nil
 }
 
-// CheckTrackAvailability checks the availability of a track on different platforms
 func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc string) (*TrackAvailability, error) {
-	// Rate limiting: max 10 requests per minute (song.link API limit)
+
 	now := time.Now()
 	if now.Sub(s.apiCallResetTime) >= time.Minute {
 		s.apiCallCount = 0
 		s.apiCallResetTime = now
 	}
 
-	// If we've hit the limit, wait until the next minute
 	if s.apiCallCount >= 9 {
 		waitTime := time.Minute - now.Sub(s.apiCallResetTime)
 		if waitTime > 0 {
@@ -189,7 +179,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		}
 	}
 
-	// Add delay between requests (7 seconds to be safe)
 	if !s.lastAPICallTime.IsZero() {
 		timeSinceLastCall := now.Sub(s.lastAPICallTime)
 		minDelay := 7 * time.Second
@@ -200,7 +189,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		}
 	}
 
-	// Decode base64 API URL
 	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL3RyYWNrLw==")
 	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyTrackID)
 
@@ -214,7 +202,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 
 	fmt.Printf("Checking availability for track: %s\n", spotifyTrackID)
 
-	// Retry logic for rate limit errors
 	maxRetries := 3
 	var resp *http.Response
 	for i := 0; i < maxRetries; i++ {
@@ -223,7 +210,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 			return nil, fmt.Errorf("failed to check availability: %w", err)
 		}
 
-		// Update rate limit tracking
 		s.lastAPICallTime = time.Now()
 		s.apiCallCount++
 
@@ -252,7 +238,7 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 			URL string `json:"url"`
 		} `json:"linksByPlatform"`
 	}
-	// Read body first to handle encoding issues
+
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response body: %w", err)
@@ -263,7 +249,7 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 	}
 
 	if err := json.Unmarshal(body, &songLinkResp); err != nil {
-		// Truncate body for error message (max 200 chars)
+
 		bodyStr := string(body)
 		if len(bodyStr) > 200 {
 			bodyStr = bodyStr[:200] + "..."
@@ -275,33 +261,33 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		SpotifyID: spotifyTrackID,
 	}
 
-	// Check Tidal
 	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
 		availability.Tidal = true
 		availability.TidalURL = tidalLink.URL
 	}
 
-	// Check Amazon
 	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
 		availability.Amazon = true
 		availability.AmazonURL = amazonLink.URL
 	}
 
-	// Check Qobuz using ISRC (song.link doesn't support Qobuz)
-	if isrc != "" {
-		qobuzAvailable := checkQobuzAvailability(isrc)
-		availability.Qobuz = qobuzAvailable
+	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
+		deezerURL := deezerLink.URL
+
+		deezerISRC, err := GetDeezerISRC(deezerURL)
+		if err == nil && deezerISRC != "" {
+			qobuzAvailable := checkQobuzAvailability(deezerISRC)
+			availability.Qobuz = qobuzAvailable
+		}
 	}
 
 	return availability, nil
 }
 
-// checkQobuzAvailability checks if a track is available on Qobuz using ISRC
 func checkQobuzAvailability(isrc string) bool {
 	client := &http.Client{Timeout: 10 * time.Second}
 	appID := "798273057"
 
-	// Decode base64 API URL
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly93d3cucW9idXouY29tL2FwaS5qc29uLzAuMi90cmFjay9zZWFyY2g/cXVlcnk9")
 	searchURL := fmt.Sprintf("%s%s&limit=1&app_id=%s", string(apiBase), isrc, appID)
 
@@ -326,3 +312,139 @@ func checkQobuzAvailability(isrc string) bool {
 
 	return searchResp.Tracks.Total > 0
 }
+
+func (s *SongLinkClient) GetDeezerURLFromSpotify(spotifyTrackID string) (string, error) {
+
+	now := time.Now()
+	if now.Sub(s.apiCallResetTime) >= time.Minute {
+		s.apiCallCount = 0
+		s.apiCallResetTime = now
+	}
+
+	if s.apiCallCount >= 9 {
+		waitTime := time.Minute - now.Sub(s.apiCallResetTime)
+		if waitTime > 0 {
+			fmt.Printf("Rate limit reached, waiting %v...\n", waitTime.Round(time.Second))
+			time.Sleep(waitTime)
+			s.apiCallCount = 0
+			s.apiCallResetTime = time.Now()
+		}
+	}
+
+	if !s.lastAPICallTime.IsZero() {
+		timeSinceLastCall := now.Sub(s.lastAPICallTime)
+		minDelay := 7 * time.Second
+		if timeSinceLastCall < minDelay {
+			waitTime := minDelay - timeSinceLastCall
+			fmt.Printf("Rate limiting: waiting %v...\n", waitTime.Round(time.Second))
+			time.Sleep(waitTime)
+		}
+	}
+
+	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL3RyYWNrLw==")
+	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyTrackID)
+
+	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9hcGkuc29uZy5saW5rL3YxLWFscGhhLjEvbGlua3M/dXJsPQ==")
+	apiURL := fmt.Sprintf("%s%s", string(apiBase), url.QueryEscape(spotifyURL))
+
+	req, err := http.NewRequest("GET", apiURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create request: %w", err)
+	}
+
+	fmt.Println("Getting Deezer URL from song.link...")
+
+	maxRetries := 3
+	var resp *http.Response
+	for i := 0; i < maxRetries; i++ {
+		resp, err = s.client.Do(req)
+		if err != nil {
+			return "", fmt.Errorf("failed to get Deezer URL: %w", err)
+		}
+
+		s.lastAPICallTime = time.Now()
+		s.apiCallCount++
+
+		if resp.StatusCode == 429 {
+			resp.Body.Close()
+			if i < maxRetries-1 {
+				waitTime := 15 * time.Second
+				fmt.Printf("Rate limited by API, waiting %v before retry...\n", waitTime)
+				time.Sleep(waitTime)
+				continue
+			}
+			return "", fmt.Errorf("API rate limit exceeded after %d retries", maxRetries)
+		}
+
+		if resp.StatusCode != 200 {
+			resp.Body.Close()
+			return "", fmt.Errorf("API returned status %d", resp.StatusCode)
+		}
+
+		break
+	}
+	defer resp.Body.Close()
+
+	var songLinkResp struct {
+		LinksByPlatform map[string]struct {
+			URL string `json:"url"`
+		} `json:"linksByPlatform"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&songLinkResp); err != nil {
+		return "", fmt.Errorf("failed to decode response: %w", err)
+	}
+
+	deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]
+	if !ok || deezerLink.URL == "" {
+		return "", fmt.Errorf("deezer link not found")
+	}
+
+	deezerURL := deezerLink.URL
+	fmt.Printf("Found Deezer URL: %s\n", deezerURL)
+	return deezerURL, nil
+}
+
+func GetDeezerISRC(deezerURL string) (string, error) {
+
+	var trackID string
+	if strings.Contains(deezerURL, "/track/") {
+		parts := strings.Split(deezerURL, "/track/")
+		if len(parts) > 1 {
+			trackID = strings.Split(parts[1], "?")[0]
+			trackID = strings.TrimSpace(trackID)
+		}
+	}
+
+	if trackID == "" {
+		return "", fmt.Errorf("could not extract track ID from Deezer URL: %s", deezerURL)
+	}
+
+	apiURL := fmt.Sprintf("https://api.deezer.com/track/%s", trackID)
+
+	client := &http.Client{Timeout: 10 * time.Second}
+	resp, err := client.Get(apiURL)
+	if err != nil {
+		return "", fmt.Errorf("failed to call Deezer API: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return "", fmt.Errorf("Deezer API returned status %d", resp.StatusCode)
+	}
+
+	var deezerTrack struct {
+		ID    int64  `json:"id"`
+		ISRC  string `json:"isrc"`
+		Title string `json:"title"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&deezerTrack); err != nil {
+		return "", fmt.Errorf("failed to decode Deezer API response: %w", err)
+	}
+
+	if deezerTrack.ISRC == "" {
+		return "", fmt.Errorf("ISRC not found in Deezer API response for track %s", trackID)
+	}
+
+	fmt.Printf("Found ISRC from Deezer: %s (track: %s)\n", deezerTrack.ISRC, deezerTrack.Title)
+	return deezerTrack.ISRC, nil
+}

backend/spectrum.go

@@ -8,7 +8,6 @@ import (
 	"github.com/mewkiz/flac"
 )
 
-// SpectrumData contains frequency spectrum information
 type SpectrumData struct {
 	TimeSlices []TimeSlice `json:"time_slices"`
 	SampleRate int         `json:"sample_rate"`
@@ -17,15 +16,13 @@ type SpectrumData struct {
 	MaxFreq    float64     `json:"max_freq"`
 }
 
-// TimeSlice represents spectrum data at a point in time
 type TimeSlice struct {
 	Time       float64   `json:"time"`
 	Magnitudes []float64 `json:"magnitudes"`
 }
 
-// AnalyzeSpectrum decodes FLAC file and performs FFT analysis
 func AnalyzeSpectrum(filepath string) (*SpectrumData, error) {
-	// Open FLAC file
+
 	stream, err := flac.ParseFile(filepath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse FLAC: %w", err)
@@ -36,7 +33,6 @@ func AnalyzeSpectrum(filepath string) (*SpectrumData, error) {
 	sampleRate := int(info.SampleRate)
 	channels := int(info.NChannels)
 
-	// Read audio samples
 	samples, err := readSamples(stream, channels)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read samples: %w", err)
@@ -46,28 +42,23 @@ func AnalyzeSpectrum(filepath string) (*SpectrumData, error) {
 		return nil, fmt.Errorf("no audio samples found")
 	}
 
-	// Calculate spectrum
 	return calculateSpectrum(samples, sampleRate), nil
 }
 
-// readSamples reads and decodes audio samples from FLAC stream
 func readSamples(stream *flac.Stream, channels int) ([]float64, error) {
 	var allSamples []float64
-	maxSamples := 10 * 1024 * 1024 // Limit to ~10 million samples to avoid memory issues
+	maxSamples := 10 * 1024 * 1024
 
-	// Decode frames
 	for {
 		frame, err := stream.ParseNext()
 		if err != nil {
-			// End of stream
+
 			break
 		}
 
-		// Convert samples to float64 and mix channels to mono
 		for i := 0; i < frame.Subframes[0].NSamples; i++ {
 			var sample float64
 
-			// Mix all channels to mono by averaging
 			for ch := 0; ch < channels; ch++ {
 				sample += float64(frame.Subframes[ch].Samples[i])
 			}
@@ -75,7 +66,6 @@ func readSamples(stream *flac.Stream, channels int) ([]float64, error) {
 
 			allSamples = append(allSamples, sample)
 
-			// Limit sample count
 			if len(allSamples) >= maxSamples {
 				return allSamples, nil
 			}
@@ -85,7 +75,6 @@ func readSamples(stream *flac.Stream, channels int) ([]float64, error) {
 	return allSamples, nil
 }
 
-// calculateSpectrum performs FFT analysis on audio samples
 func calculateSpectrum(samples []float64, sampleRate int) *SpectrumData {
 	fftSize := 8192
 	numTimeSlices := 300
@@ -140,7 +129,6 @@ func calculateSpectrum(samples []float64, sampleRate int) *SpectrumData {
 	}
 }
 
-// applyHannWindow applies Hann window to reduce spectral leakage
 func applyHannWindow(samples []float64) []float64 {
 	n := len(samples)
 	windowed := make([]float64, n)
@@ -153,7 +141,6 @@ func applyHannWindow(samples []float64) []float64 {
 	return windowed
 }
 
-// fft performs Fast Fourier Transform using Cooley-Tukey algorithm
 func fft(samples []float64) []complex128 {
 	n := len(samples)
 
@@ -165,7 +152,6 @@ func fft(samples []float64) []complex128 {
 	return fftRecursive(x)
 }
 
-// fftRecursive performs recursive FFT
 func fftRecursive(x []complex128) []complex128 {
 	n := len(x)