From 2f7034fae238b1ccda0c99e5c1a0651379a498b9 Mon Sep 17 00:00:00 2001
From: benya <benya@daemonlord.ru>
Date: Thu, 2 Apr 2026 22:43:11 +0300
Subject: [PATCH] feat: extract embedded album artwork during scans

Add a dedicated artwork cache directory and save embedded album art from audio tags during library scans. Prefer embedded artwork for album cover resolution while keeping sidecar image files as the fallback path.
---
 .env.example                |  1 +
 cmd/server/main.go          |  2 +-
 internal/config/config.go   |  2 ++
 internal/scanner/service.go | 51 ++++++++++++++++++++++++++++++++++---
 4 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/.env.example b/.env.example
index c2c9fc2..edbcad8 100644
--- a/.env.example
+++ b/.env.example
@@ -2,6 +2,7 @@ APP_ENV=development
 SERVER_HOST=0.0.0.0
 SERVER_PORT=4040
 DATABASE_PATH=./data/app.db
+ARTWORK_CACHE_DIR=./data/artwork
 MEDIA_ROOT=./media
 CORS_ORIGINS=http://localhost:5173
 DEFAULT_ADMIN_USERNAME=demo
diff --git a/cmd/server/main.go b/cmd/server/main.go
index 88ceca4..5cde936 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -33,7 +33,7 @@ func main() {
 		log.Fatalf("database seed failed: %v", err)
 	}
 
-	scanService := scanner.NewService(database, cfg.MediaRoot)
+	scanService := scanner.NewService(database, cfg.MediaRoot, cfg.ArtworkCacheDir)
 	if scanService.HasMediaFiles() {
 		if result, err := scanService.Scan(ctx); err != nil {
 			log.Printf("startup scan failed: %v", err)
diff --git a/internal/config/config.go b/internal/config/config.go
index 8593312..39b55e5 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -7,6 +7,7 @@ type Config struct {
 	ServerHost   string
 	ServerPort   string
 	DatabasePath string
+	ArtworkCacheDir string
 	MediaRoot    string
 	CORSOrigins  string
 	DefaultAdminUsername string
@@ -19,6 +20,7 @@ func Load() Config {
 		ServerHost:   getenv("SERVER_HOST", "0.0.0.0"),
 		ServerPort:   getenv("SERVER_PORT", "4040"),
 		DatabasePath: getenv("DATABASE_PATH", "./data/app.db"),
+		ArtworkCacheDir: getenv("ARTWORK_CACHE_DIR", "./data/artwork"),
 		MediaRoot:    getenv("MEDIA_ROOT", "./media"),
 		CORSOrigins:  getenv("CORS_ORIGINS", "http://localhost:5173"),
 		DefaultAdminUsername: getenv("DEFAULT_ADMIN_USERNAME", "demo"),
diff --git a/internal/scanner/service.go b/internal/scanner/service.go
index 1f4edbb..3f6342c 100644
--- a/internal/scanner/service.go
+++ b/internal/scanner/service.go
@@ -38,6 +38,7 @@ type Result struct {
 type Service struct {
 	db        *sql.DB
 	mediaRoot string
+	artworkRoot string
 	mu        sync.RWMutex
 	status    Status
 }
@@ -78,8 +79,8 @@ type scannedTrack struct {
 	ContentType  string
 }
 
-func NewService(db *sql.DB, mediaRoot string) *Service {
-	return &Service{db: db, mediaRoot: mediaRoot}
+func NewService(db *sql.DB, mediaRoot, artworkRoot string) *Service {
+	return &Service{db: db, mediaRoot: mediaRoot, artworkRoot: artworkRoot}
 }
 
 func (s *Service) HasMediaFiles() bool {
@@ -327,7 +328,13 @@ func (s *Service) scanFile(path string) (scannedItem, error) {
 	artistID := hashID("artist", artistName)
 	albumID := hashID("album", artistName, albumTitle, fmt.Sprintf("%d", year))
 	trackID := hashID("track", path)
-	coverArt := findCoverArt(filepath.Dir(path))
+	coverArt := ""
+	if err == nil {
+		coverArt = s.extractEmbeddedCoverArt(metadata, albumID)
+	}
+	if coverArt == "" {
+		coverArt = findCoverArt(filepath.Dir(path))
+	}
 
 	return scannedItem{
 		artist: scannedArtist{
@@ -417,6 +424,44 @@ func findCoverArt(dir string) string {
 	return ""
 }
 
+func (s *Service) extractEmbeddedCoverArt(metadata tag.Metadata, albumID string) string {
+	if metadata == nil {
+		return ""
+	}
+
+	picture := metadata.Picture()
+	if picture == nil || len(picture.Data) == 0 {
+		return ""
+	}
+
+	if s.artworkRoot == "" {
+		return ""
+	}
+
+	if err := os.MkdirAll(s.artworkRoot, 0o755); err != nil {
+		return ""
+	}
+
+	filename := albumID + coverExtension(picture.MIMEType)
+	path := filepath.Join(s.artworkRoot, filename)
+	if err := os.WriteFile(path, picture.Data, 0o644); err != nil {
+		return ""
+	}
+
+	return path
+}
+
+func coverExtension(mimeType string) string {
+	switch strings.ToLower(mimeType) {
+	case "image/png":
+		return ".png"
+	case "image/webp":
+		return ".webp"
+	default:
+		return ".jpg"
+	}
+}
+
 func (s *Service) tryMarkStarted() bool {
 	s.mu.Lock()
 	defer s.mu.Unlock()