METANOIA/metadata/toc.go

package metadata

import (
	"crypto/sha1"
	"encoding/base64"
	"fmt"
	"strconv"
	"strings"
	"time"
)

const TocPregap = 150
const SectorsPerSecond = 75
const DataTrackGap = 11400
const BytesPerSector = 2352
const CDChannels = 2
const Int16SamplesPerSector = BytesPerSector / (2 * CDChannels)
const CDSampleRate = Int16SamplesPerSector * SectorsPerSecond

//TOC includes a list, index 0 being total sectors/end, then start times follow, with TocPregap added
type TOC []int

var specialBase64Encoding = base64.NewEncoding("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789._").WithPadding('-')

func NewTOCFromString(toc string, split ...string) (r TOC) {
	sep := " "
	if len(split) > 0 {
		sep = split[0]
	}
	for _, i := range strings.Split(toc, sep) {
		item, err := strconv.Atoi(i)
		if err == nil {
			r = append(r, item)
		}
	}
	return
}
func NewTOCFromCTDBString(toc string) (r TOC) {
	t := NewTOCFromString(toc)

	r = append(r, t[len(t)-1]+TocPregap)
	for i := 0; i < len(t)-1; i++ {
		r = append(r, t[i]+TocPregap)
	}
	return
}
func NewTOCFromCTDB2String(toc string) (r TOC) {
	t := NewTOCFromString(toc, ":")

	r = append(r, t[len(t)-1]+TocPregap)
	for i := 0; i < len(t)-1; i++ {
		r = append(r, t[i]+TocPregap)
	}
	return
}

func (t TOC) GetTrackNumber() int {
	return len(t) - 1
}

func (t TOC) GetDuration() time.Duration {
	return (time.Second * time.Duration(t[0]-t[1])) / SectorsPerSecond
}

func (t TOC) GetTrackDuration(index int) time.Duration {
	if index < 0 || index > len(t)-2 {
		return 0
	} else if index == len(t)-2 {
		return (time.Second * time.Duration(t[0]-t[index+1])) / SectorsPerSecond
	} else {
		return (time.Second * time.Duration(t[index+2]-t[index+1])) / SectorsPerSecond
	}
}

func (t TOC) CTDBString() string {
	toc := make([]string, 0, len(t))
	for _, o := range t[1:] {
		toc = append(toc, fmt.Sprintf("%d", o-TocPregap))
	}
	toc = append(toc, fmt.Sprintf("%d", t[0]-TocPregap))

	return strings.Join(toc, ":")
}

func (t TOC) CDDBString() string {
	return fmt.Sprintf("%s %d %s %d", t.GetCDDB1(), t.GetTrackNumber(), t[1:].String(), int(t.GetDuration().Seconds()))
}

func (t TOC) MusicBrainzString() string {
	return fmt.Sprintf("1 %d %s", t.GetTrackNumber(), t.String())
}

func (t TOC) String() string {
	toc := make([]string, 0, len(t))
	for _, o := range t {
		toc = append(toc, fmt.Sprintf("%d", o))
	}
	return strings.Join(toc, " ")
}

func (t TOC) GetCDDB1() CDDB1 {

	length := uint32(t.GetDuration().Seconds())
	checksum := uint32(0)
	for i := 1; i < len(t); i++ {
		n := uint32(t[i] / SectorsPerSecond)
		for n > 0 {
			checksum += n % 10
			n /= 10
		}
	}

	return CDDB1(uint32((len(t)-1)&0xFF) | ((length & 0xFFFF) << 8) | ((checksum % 255) << 24))
}

func (t TOC) GetDiscID() DiscID {

	hasher := sha1.New()

	hasher.Write([]byte(fmt.Sprintf("%02X", 1)))
	hasher.Write([]byte(fmt.Sprintf("%02X", len(t)-1)))

	for i := 0; i < 100; i++ {
		if i < len(t) { //tracks+lead-out
			hasher.Write([]byte(fmt.Sprintf("%08X", t[i])))
		} else {
			hasher.Write([]byte(fmt.Sprintf("%08X", 0)))
		}
	}

	result := hasher.Sum([]byte{})
	return DiscID(specialBase64Encoding.EncodeToString(result))
}

func (t TOC) GetTocID() TocID {

	hasher := sha1.New()

	for i := 2; i < len(t); i++ {
		hasher.Write([]byte(fmt.Sprintf("%08X", t[i]-t[1])))
	}
	hasher.Write([]byte(fmt.Sprintf("%08X", t[0]-t[1])))
	for i := len(t) - 1; i < 100; i++ {
		hasher.Write([]byte(fmt.Sprintf("%08X", 0)))
	}

	result := hasher.Sum([]byte{})
	return TocID(specialBase64Encoding.EncodeToString(result))
}

func (t TOC) GetAccurateRipData() (byte, uint32, uint32, CDDB1) {

	var TrackOffsetsAdded uint32
	var TrackOffsetsMultiplied uint32
	var num uint32
	for i := 1; i < len(t); i++ {
		start := uint32(t[i] - TocPregap)
		TrackOffsetsAdded += start
		if start < 1 {
			start = 1
		}
		num++
		TrackOffsetsMultiplied += start * num
	}
	TrackOffsetsAdded += uint32(t[0] - TocPregap)
	num++
	TrackOffsetsMultiplied += uint32(t[0]-TocPregap) * num

	return byte(t.GetTrackNumber()), TrackOffsetsAdded, TrackOffsetsMultiplied, t.GetCDDB1()
}

func (t TOC) Equals(o TOC) bool {
	if len(t) != len(o) {
		return false
	}

	for i, d := range t {
		if o[i] != d {
			return false
		}
	}

	return true
}