refactor: use io.Reader instead of custom method

algo/common/common.go

@@ -1,13 +1,13 @@
 package common
 
-import "context"
+import (
+	"context"
+	"io"
+)
 
 type Decoder interface {
 	Validate() error
-	Decode() error
-	GetAudioData() []byte
-	GetAudioExt() string
-	GetMeta() Meta
+	io.Reader
 }
 
 type CoverImageGetter interface {
@@ -19,3 +19,7 @@ type Meta interface {
 	GetTitle() string
 	GetAlbum() string
 }
+
+type StreamDecoder interface {
+	Decrypt(buf []byte, offset int)
+}

algo/common/dispatch.go

@@ -1,11 +1,12 @@
 package common
 
 import (
+	"io"
 	"path/filepath"
 	"strings"
 )
 
-type NewDecoderFunc func([]byte) Decoder
+type NewDecoderFunc func(rd io.ReadSeeker) Decoder
 
 type decoderItem struct {
 	noop    bool

algo/common/raw.go

@@ -2,21 +2,32 @@ package common
 
 import (
 	"errors"
+	"fmt"
+	"io"
 	"strings"
 )
 
 type RawDecoder struct {
-	file     []byte
+	rd io.ReadSeeker
+
 	audioExt string
 }
 
-func NewRawDecoder(file []byte) Decoder {
-	return &RawDecoder{file: file}
+func NewRawDecoder(rd io.ReadSeeker) Decoder {
+	return &RawDecoder{rd: rd}
 }
 
 func (d *RawDecoder) Validate() error {
+	header := make([]byte, 16)
+	if _, err := io.ReadFull(d.rd, header); err != nil {
+		return fmt.Errorf("read file header failed: %v", err)
+	}
+	if _, err := d.rd.Seek(0, io.SeekStart); err != nil {
+		return fmt.Errorf("seek file failed: %v", err)
+	}
+
 	for ext, sniffer := range snifferRegistry {
-		if sniffer(d.file) {
+		if sniffer(header) {
 			d.audioExt = strings.ToLower(ext)
 			return nil
 		}
@@ -24,20 +35,8 @@ func (d *RawDecoder) Validate() error {
 	return errors.New("audio doesn't recognized")
 }
 
-func (d RawDecoder) Decode() error {
-	return nil
-}
-
-func (d RawDecoder) GetAudioData() []byte {
-	return d.file
-}
-
-func (d RawDecoder) GetAudioExt() string {
-	return d.audioExt
-}
-
-func (d RawDecoder) GetMeta() Meta {
-	return nil
+func (d *RawDecoder) Read(p []byte) (n int, err error) {
+	return d.rd.Read(p)
 }
 
 func init() {