Reorganised Vorbis Comment parsing into own type

- Added FileType to Metadata to distinguish between FLAC and OGG
- TODO: fix ALAC files being identified as AAC

flac.go

@@ -6,11 +6,8 @@ package tag
 
 import (
 	"errors"
-	"fmt"
 	"io"
 	"os"
-	"strconv"
-	"strings"
 )
 
 // BlockType is a type which represents an enumeration of valid FLAC blocks
@@ -43,7 +40,7 @@ func ReadFLACTags(r io.ReadSeeker) (Metadata, error) {
 	}
 
 	m := &metadataFLAC{
-		c: make(map[string]string),
+		newMetadataVorbis(),
 	}
 
 	for {
@@ -60,8 +57,7 @@ func ReadFLACTags(r io.ReadSeeker) (Metadata, error) {
 }
 
 type metadataFLAC struct {
-	c map[string]string // the vorbis comments
-	p *Picture
+	*metadataVorbis
 }
 
 func (m *metadataFLAC) readFLACMetadataBlock(r io.ReadSeeker) (last bool, err error) {
@@ -93,205 +89,6 @@ func (m *metadataFLAC) readFLACMetadataBlock(r io.ReadSeeker) (last bool, err er
 	return
 }
 
-func (m *metadataFLAC) readVorbisComment(r io.Reader) error {
-	vendorLen, err := readInt32LittleEndian(r)
-	if err != nil {
-		return err
-	}
-
-	vendor, err := readString(r, vendorLen)
-	if err != nil {
-		return err
-	}
-	m.c["vendor"] = vendor
-
-	commentsLen, err := readInt32LittleEndian(r)
-	if err != nil {
-		return err
-	}
-
-	for i := 0; i < commentsLen; i++ {
-		l, err := readInt32LittleEndian(r)
-		if err != nil {
-			return err
-		}
-		s, err := readString(r, l)
-		if err != nil {
-			return err
-		}
-		k, v, err := parseComment(s)
-		if err != nil {
-			return err
-		}
-		m.c[strings.ToLower(k)] = v
-	}
-	return nil
-}
-
-func (m *metadataFLAC) readPictureBlock(r io.Reader) error {
-	b, err := readInt(r, 4)
-	if err != nil {
-		return err
-	}
-	pictureType, ok := pictureTypes[byte(b)]
-	if !ok {
-		return fmt.Errorf("invalid picture type: %v", b)
-	}
-	mimeLen, err := readInt(r, 4)
-	if err != nil {
-		return err
-	}
-	mime, err := readString(r, mimeLen)
-	if err != nil {
-		return err
-	}
-
-	ext := ""
-	switch mime {
-	case "image/jpeg":
-		ext = "jpg"
-	case "image/png":
-		ext = "png"
-	case "image/gif":
-		ext = "gif"
-	}
-
-	descLen, err := readInt(r, 4)
-	if err != nil {
-		return err
-	}
-	desc, err := readString(r, descLen)
-	if err != nil {
-		return err
-	}
-
-	// We skip width <32>, height <32>, colorDepth <32>, coloresUsed <32>
-	_, err = readInt(r, 4) // width
-	if err != nil {
-		return err
-	}
-	_, err = readInt(r, 4) // height
-	if err != nil {
-		return err
-	}
-	_, err = readInt(r, 4) // color depth
-	if err != nil {
-		return err
-	}
-	_, err = readInt(r, 4) // colors used
-	if err != nil {
-		return err
-	}
-
-	dataLen, err := readInt(r, 4)
-	if err != nil {
-		return err
-	}
-	data := make([]byte, dataLen)
-	_, err = io.ReadFull(r, data)
-	if err != nil {
-		return err
-	}
-
-	m.p = &Picture{
-		Ext:         ext,
-		MIMEType:    mime,
-		Type:        pictureType,
-		Description: desc,
-		Data:        data,
-	}
-	return nil
-}
-
-func parseComment(c string) (k, v string, err error) {
-	kv := strings.SplitN(c, "=", 2)
-	if len(kv) != 2 {
-		err = errors.New("vorbis comment must contain '='")
-		return
-	}
-	k = kv[0]
-	v = kv[1]
-	return
-}
-
-func (m *metadataFLAC) Format() Format {
+func (m *metadataFLAC) FileType() FileType {
 	return FLAC
 }
-
-func (m *metadataFLAC) Raw() map[string]interface{} {
-	raw := make(map[string]interface{}, len(m.c))
-	for k, v := range m.c {
-		raw[k] = v
-	}
-	return raw
-}
-
-func (m *metadataFLAC) Title() string {
-	return m.c["title"]
-}
-
-func (m *metadataFLAC) Artist() string {
-	// PERFORMER
-	// The artist(s) who performed the work. In classical music this would be the
-	// conductor, orchestra, soloists. In an audio book it would be the actor who
-	// did the reading. In popular music this is typically the same as the ARTIST
-	// and is omitted.
-	if m.c["performer"] != "" {
-		return m.c["performer"]
-	}
-	return m.c["artist"]
-}
-
-func (m *metadataFLAC) Album() string {
-	return m.c["album"]
-}
-
-func (m *metadataFLAC) AlbumArtist() string {
-	// This field isn't included in the standard.
-	return ""
-}
-
-func (m *metadataFLAC) Composer() string {
-	// ARTIST
-	// The artist generally considered responsible for the work. In popular music
-	// this is usually the performing band or singer. For classical music it would
-	// be the composer. For an audio book it would be the author of the original text.
-	if m.c["composer"] != "" {
-		return m.c["composer"]
-	}
-	if m.c["performer"] == "" {
-		return ""
-	}
-	return m.c["artist"]
-}
-
-func (m *metadataFLAC) Genre() string {
-	return m.c["genre"]
-}
-
-func (m *metadataFLAC) Year() int {
-	// FIXME: try to parse the date in m.c["date"] to extract this
-	return 0
-}
-
-func (m *metadataFLAC) Track() (int, int) {
-	x, _ := strconv.Atoi(m.c["tracknumber"])
-	// https://wiki.xiph.org/Field_names
-	n, _ := strconv.Atoi(m.c["tracktotal"])
-	return x, n
-}
-
-func (m *metadataFLAC) Disc() (int, int) {
-	// https://wiki.xiph.org/Field_names
-	x, _ := strconv.Atoi(m.c["discnumber"])
-	n, _ := strconv.Atoi(m.c["disctotal"])
-	return x, n
-}
-
-func (m *metadataFLAC) Lyrics() string {
-	return m.c["lyrics"]
-}
-
-func (m *metadataFLAC) Picture() *Picture {
-	return m.p
-}