Init

util/img.go

@@ -0,0 +1,126 @@
+package util
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"io"
+	"os"
+
+	_ "image/gif"
+	_ "image/png"
+
+	_ "github.com/strukturag/libheif/go/heif"
+	_ "golang.org/x/image/webp"
+)
+
+var (
+	jpegMagic = []byte{0xFF, 0xD8, 0xFF}
+	pngMagic  = []byte{0x89, 0x50, 0x4E, 0x47}
+	gifMagic  = []byte{0x47, 0x49, 0x46}
+	riffMagic = []byte{0x52, 0x49, 0x46, 0x46}
+	webpMagic = []byte{0x57, 0x45, 0x42, 0x50}
+)
+
+func ImgToJPEG(file io.ReadSeeker, outputPath string) error {
+	format, err := DetectImageFormat(file)
+	if err != nil {
+		return fmt.Errorf("failed to detect image format: %w", err)
+	}
+
+	outputFile, err := os.Create(outputPath)
+	if err != nil {
+		return fmt.Errorf("failed to create output file: %w", err)
+	}
+	defer outputFile.Close()
+
+	if format == "jpeg" {
+		if _, err = file.Seek(0, io.SeekStart); err != nil {
+			return fmt.Errorf("failed to reset file position: %w", err)
+		}
+
+		if _, err = io.Copy(outputFile, file); err != nil {
+			os.Remove(outputPath)
+			return fmt.Errorf("failed to copy image: %w", err)
+		}
+		return nil
+	}
+
+	if _, err = file.Seek(0, io.SeekStart); err != nil {
+		return fmt.Errorf("failed to reset file position: %w", err)
+	}
+
+	img, _, err := image.Decode(file)
+	if err != nil {
+		return fmt.Errorf("failed to decode image: %w", err)
+	}
+
+	err = jpeg.Encode(outputFile, img, nil)
+	if err != nil {
+		os.Remove(outputPath)
+		return fmt.Errorf("failed to encode image: %w", err)
+	}
+
+	return nil
+}
+
+func DetectImageFormat(file io.ReadSeeker) (string, error) {
+	header := make([]byte, 12)
+
+	_, err := file.Read(header)
+	if err != nil {
+		return "", fmt.Errorf("failed to read file header: %w", err)
+	}
+	if _, err = file.Seek(0, io.SeekStart); err != nil {
+		return "", fmt.Errorf("failed to reset file position: %w", err)
+	}
+	if len(header) < 12 {
+		return "", ErrFileTooShort
+	}
+	if bytes.HasPrefix(header, jpegMagic) {
+		return "jpeg", nil
+	}
+
+	if bytes.HasPrefix(header, pngMagic) {
+		return "png", nil
+	}
+
+	if bytes.HasPrefix(header, gifMagic) {
+		return "gif", nil
+	}
+
+	if isHEIF(header) {
+		return "heif", nil
+	}
+
+	if bytes.HasPrefix(header, riffMagic) {
+		if bytes.Equal(header[8:12], webpMagic) {
+			return "webp", nil
+		}
+		return "", ErrUnknownRIFF
+	}
+
+	return "", ErrUnsupportedImageFormat
+}
+
+func isHEIF(header []byte) bool {
+	if len(header) < 12 {
+		return false
+	}
+	isHeifHeader := header[0] == 0x00 && header[1] == 0x00 &&
+		header[2] == 0x00 && (header[3] == 0x18 || header[3] == 0x1C) &&
+		bytes.Equal(header[4:8], []byte("ftyp"))
+	if !isHeifHeader {
+		return false
+	}
+	heifBrands := []string{"heic", "heix", "mif1", "msf1"}
+	brand := string(header[8:12])
+
+	for _, b := range heifBrands {
+		if brand == b {
+			return true
+		}
+	}
+	return false
+}