❮ Fixed v2.Frame.toBytes(), some functions looks better now ❯

util/conversion.go

@@ -35,7 +35,7 @@ func BytesToIntSynchsafe(gBytes []byte) uint32 {
 // Finally understood with the help of: https://github.com/bogem/id3v2/blob/master/size.go ,
 // thank you very much !
 func IntToBytesSynchsafe(gInt uint32) []byte {
-	synchsafeIBytes := make([]byte, 4)
+	var synchsafeIBytes []byte
 
 	// skip 4 0`ed bits
 	gInt = gInt << 4
@@ -71,15 +71,22 @@ func ToStringLossy(gBytes []byte) string {
 	return strings.ToValidUTF8(string(runes), "")
 }
 
+const (
+	EncodingISO8859 byte = iota
+	EncodingUTF16BOM
+	EncodingUTF16
+	EncodingUTF8
+)
+
 // Decodes the given frame`s contents
 func DecodeText(fContents []byte) string {
 	textEncoding := fContents[0] // the first byte is the encoding
 
 	switch textEncoding {
-	case 0:
+	case EncodingISO8859:
 		// ISO-8859-1
 		return ToStringLossy(fContents[1:])
-	case 1:
+	case EncodingUTF16BOM:
 		// UTF-16 with BOM
 		encoding := euni.UTF16(euni.BigEndian, euni.ExpectBOM)
 		decoder := encoding.NewDecoder()
@@ -92,7 +99,7 @@ func DecodeText(fContents []byte) string {
 
 		return string(decodedBytes)
 
-	case 2:
+	case EncodingUTF16:
 		// UTF-16
 		encoding := euni.UTF16(euni.BigEndian, euni.IgnoreBOM)
 		decoder := encoding.NewDecoder()
@@ -105,7 +112,7 @@ func DecodeText(fContents []byte) string {
 
 		return string(decodedBytes)
 
-	case 3:
+	case EncodingUTF8:
 		// UTF-8
 		return ToStringLossy(fContents[1:])
 	}

util/conversion_test.go

@@ -37,6 +37,9 @@ func TestIntToBytesSynchsafe(t *testing.T) {
 
 	for _, testInt := range testInts {
 		synchSafeBytes := IntToBytesSynchsafe(testInt)
+		if len(synchSafeBytes) != 4 {
+			t.Errorf("IntToBytesSynchsafe failed: expected len to be %d; got %d", 4, len(synchSafeBytes))
+		}
 
 		synchsafeInt := BytesToIntSynchsafe(synchSafeBytes)
 

v2/frame.go

@@ -268,62 +268,66 @@ func (f *Frame) Text() string {
 	return util.DecodeText(f.Contents)
 }
 
-func v23FlagsToBytes(v23f FrameFlags) []byte {
-	var flags = []byte{0, 0}
+func frameFlagsToBytes(ff FrameFlags, version string) []byte {
+	var flagBytes = []byte{0, 0}
+
+	switch version {
+	case V2_2:
+		return nil
 
-	if v23f.TagAlterPreservation {
-		flags[0] = util.SetBit(flags[0], 8)
+	case V2_3:
+		if ff.TagAlterPreservation {
+			flagBytes[0] = util.SetBit(flagBytes[0], 8)
 		}
-	if v23f.FileAlterPreservation {
-		flags[0] = util.SetBit(flags[0], 7)
+		if ff.FileAlterPreservation {
+			flagBytes[0] = util.SetBit(flagBytes[0], 7)
 		}
-	if v23f.ReadOnly {
-		flags[0] = util.SetBit(flags[0], 6)
+		if ff.ReadOnly {
+			flagBytes[0] = util.SetBit(flagBytes[0], 6)
 		}
 
-	if v23f.Compressed {
-		flags[1] = util.SetBit(flags[1], 8)
-	}
-	if v23f.Encrypted {
-		flags[1] = util.SetBit(flags[1], 7)
+		if ff.Compressed {
+			flagBytes[1] = util.SetBit(flagBytes[1], 8)
 		}
-	if v23f.InGroup {
-		flags[1] = util.SetBit(flags[1], 6)
+		if ff.Encrypted {
+			flagBytes[1] = util.SetBit(flagBytes[1], 7)
 		}
-
-	return flags
+		if ff.InGroup {
+			flagBytes[1] = util.SetBit(flagBytes[1], 6)
 		}
+		return flagBytes
 
-func v24FlagsToBytes(v24f FrameFlags) []byte {
-	var flagBytes = []byte{0, 0}
-
-	if v24f.TagAlterPreservation {
+	case V2_4:
+		if ff.TagAlterPreservation {
 			flagBytes[0] = util.SetBit(flagBytes[0], 7)
 		}
-	if v24f.FileAlterPreservation {
+		if ff.FileAlterPreservation {
 			flagBytes[0] = util.SetBit(flagBytes[0], 6)
 		}
-	if v24f.ReadOnly {
+		if ff.ReadOnly {
 			flagBytes[0] = util.SetBit(flagBytes[0], 5)
 		}
 
-	if v24f.InGroup {
+		if ff.InGroup {
 			flagBytes[1] = util.SetBit(flagBytes[1], 7)
 		}
-	if v24f.Compressed {
+		if ff.Compressed {
 			flagBytes[1] = util.SetBit(flagBytes[1], 4)
 		}
-	if v24f.Encrypted {
+		if ff.Encrypted {
 			flagBytes[1] = util.SetBit(flagBytes[1], 3)
 		}
-	if v24f.Unsyrchronised {
+		if ff.Unsyrchronised {
 			flagBytes[1] = util.SetBit(flagBytes[1], 2)
 		}
-	if v24f.HasDataLengthIndicator {
+		if ff.HasDataLengthIndicator {
 			flagBytes[1] = util.SetBit(flagBytes[1], 1)
 		}
-
 		return flagBytes
+
+	default:
+		return nil
+	}
 }
 
 // Converts frame to ready-to-write bytes
@@ -337,17 +341,13 @@ func (f *Frame) toBytes(version string) []byte {
 	buff.Write(util.IntToBytesSynchsafe(f.Header.Size))
 
 	// flags
-	var flagBytes []byte
-	switch version {
-	case V2_2:
-		break
-	case V2_3:
-		flagBytes = v23FlagsToBytes(f.Header.Flags)
-		buff.Write(flagBytes)
-	case V2_4:
-		flagBytes = v24FlagsToBytes(f.Header.Flags)
+	flagBytes := frameFlagsToBytes(f.Header.Flags, version)
+	if flagBytes != nil {
 		buff.Write(flagBytes)
 	}
 
+	// contents
+	buff.Write(f.Contents)
+
 	return buff.Bytes()
 }

v2/frame_test.go

@@ -49,3 +49,54 @@ func TestReadNextFrame(t *testing.T) {
 			"2006", secondFrame.Contents)
 	}
 }
+
+func TestFrameFlagsToBytes(t *testing.T) {
+	testFlags := FrameFlags{
+		TagAlterPreservation: true,
+		ReadOnly:             true,
+	}
+
+	versions := []string{V2_2, V2_3, V2_4}
+
+	for _, version := range versions {
+		flagBytes := frameFlagsToBytes(testFlags, version)
+		if version == V2_2 && flagBytes != nil {
+			t.Errorf("frameFlagsToBytes failed: V2_2, expected flagbytes to be nil; got %v", flagBytes)
+		}
+		if version != V2_2 && len(flagBytes) != 2 {
+			t.Errorf("frameFlagsToBytes failed: expected flagbytes to be len of 2; got %v", len(flagBytes))
+		}
+	}
+}
+
+func TestFrameToBytes(t *testing.T) {
+	testframe := Frame{
+		Header: FrameHeader{
+			ID:    "TEST",
+			Flags: FrameFlags{}, // all false
+			Size:  4,
+		},
+		Contents: []byte{util.EncodingUTF8, 60, 60, 60}, // 60 == <
+	}
+
+	frameBytes := testframe.toBytes(V2_4)
+
+	// t.Errorf("%+v", frameBytes)
+	// 84 69 83 84 0 0 0 4 0 0 3 60 60 60
+
+	// 84 69 83 84 - id (4)
+	// 0 0 - flags (2)
+	// 0 4 0 0 - size (4)
+	// header - 4 + 4 + 2 = 10 bytes (success)
+	// 3 60 60 60 - contents
+
+	if len(frameBytes)-int(testframe.Header.Size) != HEADERSIZE {
+		t.Errorf("FrameToBytes failed: expected header size to be %d; got %d",
+			HEADERSIZE, len(frameBytes)-int(testframe.Header.Size))
+	}
+
+	if util.DecodeText(frameBytes[10:]) != "<<<" {
+		t.Errorf("FrameToBytes failed: expected contents to be %v; got %v",
+			testframe.Contents, frameBytes[10:])
+	}
+}