rewrite

internal/codec/codec.go

@@ -0,0 +1,50 @@
+package codec
+
+import (
+	"image"
+	"io"
+
+	"github.com/coalaura/ffwebp/internal/opts"
+	"github.com/urfave/cli/v3"
+)
+
+type Codec interface {
+	Name() string
+
+	Flags([]cli.Flag) []cli.Flag
+	Extensions() []string
+
+	Sniff(io.ReaderAt) (int, error)
+	Decode(io.Reader) (image.Image, error)
+	Encode(io.Writer, image.Image, opts.Common) error
+}
+
+var codecs = map[string]Codec{}
+
+func Register(c Codec) {
+	codecs[c.Name()] = c
+}
+
+func Flags(flags []cli.Flag) []cli.Flag {
+	for _, codec := range codecs {
+		flags = codec.Flags(flags)
+	}
+
+	return flags
+}
+
+func Get(name string) (Codec, bool) {
+	c, ok := codecs[name]
+
+	return c, ok
+}
+
+func All() []Codec {
+	out := make([]Codec, 0, len(codecs))
+
+	for _, c := range codecs {
+		out = append(out, c)
+	}
+
+	return out
+}

internal/codec/detect.go

@@ -0,0 +1,72 @@
+package codec
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"path/filepath"
+	"strings"
+)
+
+func Sniff(reader io.Reader) (Codec, io.Reader, error) {
+	buf, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	ra := bytes.NewReader(buf)
+
+	var (
+		guess Codec
+		best  int
+	)
+
+	for _, codec := range codecs {
+		confidence, err := codec.Sniff(ra)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		if confidence > best {
+			best = confidence
+			guess = codec
+		}
+	}
+
+	if guess == nil {
+		return nil, nil, errors.New("unknown format")
+	}
+
+	return guess, bytes.NewReader(buf), nil
+}
+
+func Detect(output, override string) (Codec, error) {
+	if override != "" {
+		codec, ok := codecs[override]
+		if !ok {
+			return nil, fmt.Errorf("unsupported output codec: %q", override)
+		}
+
+		return codec, nil
+	}
+
+	if output == "-" {
+		return nil, errors.New("missing codec for output")
+	}
+
+	ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(output), "."))
+	if ext == "" {
+		return nil, fmt.Errorf("output filename %q has no extension", output)
+	}
+
+	for _, codec := range codecs {
+		for _, alias := range codec.Extensions() {
+			if ext == strings.ToLower(alias) {
+				return codec, nil
+			}
+		}
+	}
+
+	return nil, fmt.Errorf("unsupported or unknown file extension: %q", ext)
+}

internal/codec/jpeg/jpeg.go

@@ -0,0 +1,56 @@
+package jpeg
+
+import (
+	"bytes"
+	"image"
+	"image/jpeg"
+	"io"
+
+	"github.com/coalaura/ffwebp/internal/codec"
+	"github.com/coalaura/ffwebp/internal/opts"
+	"github.com/urfave/cli/v3"
+)
+
+type impl struct{}
+
+func init() {
+	codec.Register(impl{})
+}
+
+func (impl) Name() string {
+	return "jpeg"
+}
+
+func (impl) Extensions() []string {
+	return []string{"jpg", "jpeg", "jpe"}
+}
+
+func (impl) Flags(flags []cli.Flag) []cli.Flag {
+	return flags
+}
+
+func (impl) Sniff(reader io.ReaderAt) (int, error) {
+	marker := []byte{0xFF, 0xD8, 0xFF}
+
+	buf := make([]byte, 3)
+
+	if _, err := reader.ReadAt(buf, 0); err != nil {
+		return 0, err
+	}
+
+	if bytes.Equal(buf, marker) {
+		return 100, nil
+	}
+
+	return 0, nil
+}
+
+func (impl) Decode(reader io.Reader) (image.Image, error) {
+	return jpeg.Decode(reader)
+}
+
+func (impl) Encode(writer io.Writer, img image.Image, options opts.Common) error {
+	return jpeg.Encode(writer, img, &jpeg.Options{
+		Quality: options.Quality,
+	})
+}