feat: filebrowser with encfs

img/service.go

@@ -0,0 +1,244 @@
+//go:generate go-enum --sql --marshal --file $GOFILE
+package img
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"image"
+	"io"
+
+	"github.com/disintegration/imaging"
+	"github.com/dsoprea/go-exif/v3"
+	"github.com/marusama/semaphore/v2"
+
+	exifcommon "github.com/dsoprea/go-exif/v3/common"
+)
+
+// ErrUnsupportedFormat means the given image format is not supported.
+var ErrUnsupportedFormat = errors.New("unsupported image format")
+
+// Service
+type Service struct {
+	sem semaphore.Semaphore
+}
+
+func New(workers int) *Service {
+	return &Service{
+		sem: semaphore.New(workers),
+	}
+}
+
+// Format is an image file format.
+/*
+ENUM(
+jpeg
+png
+gif
+tiff
+bmp
+)
+*/
+type Format int
+
+func (x Format) toImaging() imaging.Format {
+	switch x {
+	case FormatJpeg:
+		return imaging.JPEG
+	case FormatPng:
+		return imaging.PNG
+	case FormatGif:
+		return imaging.GIF
+	case FormatTiff:
+		return imaging.TIFF
+	case FormatBmp:
+		return imaging.BMP
+	default:
+		return imaging.JPEG
+	}
+}
+
+/*
+ENUM(
+high
+medium
+low
+)
+*/
+type Quality int
+
+func (x Quality) resampleFilter() imaging.ResampleFilter {
+	switch x {
+	case QualityHigh:
+		return imaging.Lanczos
+	case QualityMedium:
+		return imaging.Box
+	case QualityLow:
+		return imaging.NearestNeighbor
+	default:
+		return imaging.Box
+	}
+}
+
+/*
+ENUM(
+fit
+fill
+)
+*/
+type ResizeMode int
+
+func (s *Service) FormatFromExtension(ext string) (Format, error) {
+	format, err := imaging.FormatFromExtension(ext)
+	if err != nil {
+		return -1, ErrUnsupportedFormat
+	}
+	switch format {
+	case imaging.JPEG:
+		return FormatJpeg, nil
+	case imaging.PNG:
+		return FormatPng, nil
+	case imaging.GIF:
+		return FormatGif, nil
+	case imaging.TIFF:
+		return FormatTiff, nil
+	case imaging.BMP:
+		return FormatBmp, nil
+	}
+	return -1, ErrUnsupportedFormat
+}
+
+type resizeConfig struct {
+	format     Format
+	resizeMode ResizeMode
+	quality    Quality
+}
+
+type Option func(*resizeConfig)
+
+func WithFormat(format Format) Option {
+	return func(config *resizeConfig) {
+		config.format = format
+	}
+}
+
+func WithMode(mode ResizeMode) Option {
+	return func(config *resizeConfig) {
+		config.resizeMode = mode
+	}
+}
+
+func WithQuality(quality Quality) Option {
+	return func(config *resizeConfig) {
+		config.quality = quality
+	}
+}
+
+func (s *Service) Resize(ctx context.Context, in io.Reader, width, height int, out io.Writer, options ...Option) error {
+	if err := s.sem.Acquire(ctx, 1); err != nil {
+		return err
+	}
+	defer s.sem.Release(1)
+
+	format, wrappedReader, err := s.detectFormat(in)
+	if err != nil {
+		return err
+	}
+
+	config := resizeConfig{
+		format:     format,
+		resizeMode: ResizeModeFit,
+		quality:    QualityMedium,
+	}
+	for _, option := range options {
+		option(&config)
+	}
+
+	if config.quality == QualityLow && format == FormatJpeg {
+		thm, newWrappedReader, errThm := getEmbeddedThumbnail(wrappedReader)
+		wrappedReader = newWrappedReader
+		if errThm == nil {
+			_, err = out.Write(thm)
+			if err == nil {
+				return nil
+			}
+		}
+	}
+
+	img, err := imaging.Decode(wrappedReader, imaging.AutoOrientation(true))
+	if err != nil {
+		return err
+	}
+
+	switch config.resizeMode {
+	case ResizeModeFill:
+		img = imaging.Fill(img, width, height, imaging.Center, config.quality.resampleFilter())
+	case ResizeModeFit:
+		fallthrough //nolint:gocritic
+	default:
+		img = imaging.Fit(img, width, height, config.quality.resampleFilter())
+	}
+
+	return imaging.Encode(out, img, config.format.toImaging())
+}
+
+func (s *Service) detectFormat(in io.Reader) (Format, io.Reader, error) {
+	buf := &bytes.Buffer{}
+	r := io.TeeReader(in, buf)
+
+	_, imgFormat, err := image.DecodeConfig(r)
+	if err != nil {
+		return 0, nil, fmt.Errorf("%s: %w", err.Error(), ErrUnsupportedFormat)
+	}
+
+	format, err := ParseFormat(imgFormat)
+	if err != nil {
+		return 0, nil, ErrUnsupportedFormat
+	}
+
+	return format, io.MultiReader(buf, in), nil
+}
+
+func getEmbeddedThumbnail(in io.Reader) ([]byte, io.Reader, error) {
+	buf := &bytes.Buffer{}
+	r := io.TeeReader(in, buf)
+	wrappedReader := io.MultiReader(buf, in)
+
+	offset := 0
+	offsets := []int{12, 30}
+	head := make([]byte, 0xffff) //nolint:gomnd
+
+	_, err := r.Read(head)
+	if err != nil {
+		return nil, wrappedReader, err
+	}
+
+	for _, offset = range offsets {
+		if _, err = exif.ParseExifHeader(head[offset:]); err == nil {
+			break
+		}
+	}
+
+	if err != nil {
+		return nil, wrappedReader, err
+	}
+
+	im, err := exifcommon.NewIfdMappingWithStandard()
+	if err != nil {
+		return nil, wrappedReader, err
+	}
+
+	_, index, err := exif.Collect(im, exif.NewTagIndex(), head[offset:])
+	if err != nil {
+		return nil, wrappedReader, err
+	}
+
+	ifd := index.RootIfd.NextIfd()
+	if ifd == nil {
+		return nil, wrappedReader, exif.ErrNoThumbnail
+	}
+
+	thm, err := ifd.Thumbnail()
+	return thm, wrappedReader, err
+}