initial Go port of streamrip

internal/artwork/artwork.go

@@ -0,0 +1,186 @@
+package artwork
+
+import (
+	"context"
+	"crypto/sha1"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	"golang.org/x/image/draw"
+
+	"streamrip-go/internal/config"
+)
+
+type Downloader interface {
+	File(ctx context.Context, sourceURL, outputPath string) error
+	FileNoProgress(ctx context.Context, sourceURL, outputPath string) error
+}
+
+type Result struct {
+	EmbedPath string
+	SavedPath string
+}
+
+var (
+	tempDirsMu sync.Mutex
+	tempDirs   = map[string]struct{}{}
+)
+
+func Prepare(ctx context.Context, dl Downloader, folder string, albumMeta map[string]any, cfg config.ArtworkConfig, forPlaylist bool) (Result, error) {
+	saveArtwork := cfg.SaveArtwork
+	if forPlaylist {
+		saveArtwork = false
+	}
+	if !(cfg.Embed || saveArtwork) {
+		return Result{}, nil
+	}
+
+	imageMap, ok := albumMeta["image"].(map[string]any)
+	if !ok {
+		return Result{}, nil
+	}
+
+	largestURL := pickLargestURL(imageMap)
+	embedURL := pickEmbedURL(imageMap, cfg.EmbedSize)
+	if embedURL == "" {
+		embedURL = largestURL
+	}
+
+	result := Result{}
+	if saveArtwork && largestURL != "" {
+		savedPath := filepath.Join(folder, "cover.jpg")
+		if fileExists(savedPath) {
+			result.SavedPath = savedPath
+		} else if err := dl.FileNoProgress(ctx, largestURL, savedPath); err == nil {
+			if cfg.SavedMaxWidth > 0 {
+				_ = downscaleImage(savedPath, cfg.SavedMaxWidth)
+			}
+			result.SavedPath = savedPath
+		}
+	}
+
+	if cfg.Embed && embedURL != "" {
+		embedDir := filepath.Join(folder, "__artwork")
+		if err := os.MkdirAll(embedDir, 0o755); err == nil {
+			registerTempDir(embedDir)
+			embedPath := filepath.Join(embedDir, embedFilename(embedURL))
+			if fileExists(embedPath) {
+				result.EmbedPath = embedPath
+			} else if err := dl.FileNoProgress(ctx, embedURL, embedPath); err == nil {
+				if cfg.EmbedMaxWidth > 0 {
+					_ = downscaleImage(embedPath, cfg.EmbedMaxWidth)
+				}
+				result.EmbedPath = embedPath
+			}
+		}
+	}
+
+	return result, nil
+}
+
+func CleanupTempDirs() {
+	tempDirsMu.Lock()
+	defer tempDirsMu.Unlock()
+
+	for dir := range tempDirs {
+		_ = os.RemoveAll(dir)
+		delete(tempDirs, dir)
+	}
+}
+
+func registerTempDir(path string) {
+	tempDirsMu.Lock()
+	defer tempDirsMu.Unlock()
+	tempDirs[path] = struct{}{}
+}
+
+func fileExists(path string) bool {
+	st, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+	return !st.IsDir()
+}
+
+func pickLargestURL(image map[string]any) string {
+	for _, key := range []string{"original", "mega", "extralarge", "large", "small", "thumbnail"} {
+		if v := stringAny(image[key]); v != "" {
+			return v
+		}
+	}
+	return ""
+}
+
+func pickEmbedURL(image map[string]any, size string) string {
+	size = strings.ToLower(strings.TrimSpace(size))
+	if size == "" {
+		size = "large"
+	}
+	for _, key := range []string{size, "large", "extralarge", "small", "thumbnail", "original"} {
+		if v := stringAny(image[key]); v != "" {
+			return v
+		}
+	}
+	return ""
+}
+
+func embedFilename(url string) string {
+	s := sha1.Sum([]byte(url))
+	return fmt.Sprintf("cover%x.jpg", s[:8])
+}
+
+func stringAny(v any) string {
+	s, _ := v.(string)
+	return s
+}
+
+func downscaleImage(path string, maxDimension int) error {
+	f, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	img, _, err := image.Decode(f)
+	_ = f.Close()
+	if err != nil {
+		return err
+	}
+
+	b := img.Bounds()
+	w, h := b.Dx(), b.Dy()
+	if w <= 0 || h <= 0 || maxDimension <= 0 {
+		return nil
+	}
+	if w <= maxDimension && h <= maxDimension {
+		return nil
+	}
+
+	newW, newH := w, h
+	if w > h {
+		newW = maxDimension
+		newH = int(float64(h) * (float64(maxDimension) / float64(w)))
+	} else {
+		newH = maxDimension
+		newW = int(float64(w) * (float64(maxDimension) / float64(h)))
+	}
+	if newW <= 0 {
+		newW = 1
+	}
+	if newH <= 0 {
+		newH = 1
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, newW, newH))
+	draw.CatmullRom.Scale(dst, dst.Bounds(), img, b, draw.Over, nil)
+
+	out, err := os.Create(path)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = out.Close() }()
+	return jpeg.Encode(out, dst, &jpeg.Options{Quality: 92})
+}