Files
SpotiFLAC-Mobile/go_backend/lyrics_apple.go

306 lines
8.3 KiB
Go

package gobackend
import (
"encoding/json"
"fmt"
"io"
"math"
"net/http"
"net/url"
"strings"
"time"
)
// AppleMusicClient fetches lyrics from Apple Music.
// Uses Paxsenix endpoints for search and lyrics.
type AppleMusicClient struct {
httpClient *http.Client
}
type appleMusicSearchResult struct {
ID string `json:"id"`
SongName string `json:"songName"`
ArtistName string `json:"artistName"`
AlbumName string `json:"albumName"`
Duration int `json:"duration"`
}
// PaxResponse represents the lyrics proxy response for word-by-word / line lyrics
type paxResponse struct {
Type string `json:"type"` // "Syllable" or "Line"
Content []paxLyrics `json:"content"` // List of lyric lines
}
type paxLyrics struct {
Text []paxLyricDetail `json:"text"`
Timestamp int `json:"timestamp"`
OppositeTurn bool `json:"oppositeTurn"`
Background bool `json:"background"`
BackgroundText []paxLyricDetail `json:"backgroundText"`
EndTime int `json:"endtime"`
}
type paxLyricDetail struct {
Text string `json:"text"`
Part bool `json:"part"`
Timestamp *int `json:"timestamp"`
EndTime *int `json:"endtime"`
}
func NewAppleMusicClient() *AppleMusicClient {
return &AppleMusicClient{
httpClient: NewMetadataHTTPClient(20 * time.Second),
}
}
func selectBestAppleMusicSearchResult(results []appleMusicSearchResult, trackName, artistName string, durationSec float64) *appleMusicSearchResult {
if len(results) == 0 {
return nil
}
normalizedTrack := strings.ToLower(strings.TrimSpace(simplifyTrackName(trackName)))
normalizedArtist := strings.ToLower(strings.TrimSpace(normalizeArtistName(artistName)))
if normalizedArtist == "" {
normalizedArtist = strings.ToLower(strings.TrimSpace(artistName))
}
bestIndex := 0
bestScore := -1
for i := range results {
result := &results[i]
score := 0
candidateTrack := strings.ToLower(strings.TrimSpace(simplifyTrackName(result.SongName)))
candidateArtist := strings.ToLower(strings.TrimSpace(normalizeArtistName(result.ArtistName)))
switch {
case candidateTrack == normalizedTrack:
score += 50
case strings.Contains(candidateTrack, normalizedTrack) || strings.Contains(normalizedTrack, candidateTrack):
score += 25
}
switch {
case candidateArtist == normalizedArtist:
score += 60
case strings.Contains(candidateArtist, normalizedArtist) || strings.Contains(normalizedArtist, candidateArtist):
score += 30
}
if durationSec > 0 && result.Duration > 0 {
diff := math.Abs(float64(result.Duration)/1000.0 - durationSec)
if diff <= durationToleranceSec {
score += 20
}
}
if score > bestScore {
bestScore = score
bestIndex = i
}
}
return &results[bestIndex]
}
// SearchSong searches for a song on Apple Music and returns its ID.
func (c *AppleMusicClient) SearchSong(trackName, artistName string, durationSec float64) (string, error) {
query := trackName + " " + artistName
if strings.TrimSpace(query) == "" {
return "", fmt.Errorf("empty search query")
}
encodedQuery := url.QueryEscape(query)
searchURL := fmt.Sprintf("https://lyrics.paxsenix.org/apple-music/search?q=%s", encodedQuery)
req, err := http.NewRequest("GET", searchURL, nil)
if err != nil {
return "", fmt.Errorf("failed to create request: %w", err)
}
req.Header.Set("User-Agent", getRandomUserAgent())
req.Header.Set("Accept", "application/json")
resp, err := c.httpClient.Do(req)
if err != nil {
return "", fmt.Errorf("apple music search failed: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return "", fmt.Errorf("apple music search returned HTTP %d", resp.StatusCode)
}
var searchResp []appleMusicSearchResult
if err := json.NewDecoder(resp.Body).Decode(&searchResp); err != nil {
return "", fmt.Errorf("failed to decode apple music response: %w", err)
}
best := selectBestAppleMusicSearchResult(searchResp, trackName, artistName, durationSec)
if best == nil || strings.TrimSpace(best.ID) == "" {
return "", fmt.Errorf("no songs found on apple music")
}
return strings.TrimSpace(best.ID), nil
}
// FetchLyricsByID fetches lyrics from the paxsenix proxy using Apple Music song ID.
func (c *AppleMusicClient) FetchLyricsByID(songID string) (string, error) {
lyricsURL := fmt.Sprintf("https://lyrics.paxsenix.org/apple-music/lyrics?id=%s", songID)
req, err := http.NewRequest("GET", lyricsURL, nil)
if err != nil {
return "", fmt.Errorf("failed to create request: %w", err)
}
req.Header.Set("User-Agent", getRandomUserAgent())
resp, err := c.httpClient.Do(req)
if err != nil {
return "", fmt.Errorf("apple music lyrics fetch failed: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return "", fmt.Errorf("apple music lyrics proxy returned HTTP %d", resp.StatusCode)
}
bodyBytes, err := io.ReadAll(resp.Body)
if err != nil {
return "", fmt.Errorf("failed to read lyrics response: %w", err)
}
bodyStr := strings.TrimSpace(string(bodyBytes))
if bodyStr == "" {
return "", fmt.Errorf("empty lyrics response from apple music")
}
return bodyStr, nil
}
func formatPaxLyricsToLRC(rawJSON string, multiPersonWordByWord bool) (string, error) {
var paxResp paxResponse
if err := json.Unmarshal([]byte(rawJSON), &paxResp); err == nil && paxResp.Content != nil {
return formatPaxContent(paxResp.Type, paxResp.Content, multiPersonWordByWord), nil
}
var directLyrics []paxLyrics
if err := json.Unmarshal([]byte(rawJSON), &directLyrics); err == nil && len(directLyrics) > 0 {
return formatPaxContent("Syllable", directLyrics, multiPersonWordByWord), nil
}
return "", fmt.Errorf("failed to parse pax lyrics response")
}
func appendPaxLyricDetail(builder *strings.Builder, details []paxLyricDetail) {
lastStart := ""
for _, syllable := range details {
if syllable.Timestamp != nil {
start := fmt.Sprintf("<%s>", msToLRCTimestampInline(int64(*syllable.Timestamp)))
if start != lastStart {
builder.WriteString(start)
lastStart = start
}
}
builder.WriteString(syllable.Text)
if !syllable.Part {
builder.WriteString(" ")
}
if syllable.EndTime != nil {
builder.WriteString(fmt.Sprintf("<%s>", msToLRCTimestampInline(int64(*syllable.EndTime))))
}
}
}
func formatPaxContent(lyricsType string, content []paxLyrics, multiPersonWordByWord bool) string {
var sb strings.Builder
for i, line := range content {
if i > 0 {
sb.WriteString("\n")
}
timestamp := msToLRCTimestamp(int64(line.Timestamp))
if strings.EqualFold(lyricsType, "Syllable") {
sb.WriteString(timestamp)
if multiPersonWordByWord {
if line.OppositeTurn {
sb.WriteString("v2:")
} else {
sb.WriteString("v1:")
}
}
appendPaxLyricDetail(&sb, line.Text)
if line.Background && multiPersonWordByWord && len(line.BackgroundText) > 0 {
sb.WriteString("\n[bg:")
appendPaxLyricDetail(&sb, line.BackgroundText)
sb.WriteString("]")
}
} else {
if len(line.Text) > 0 {
sb.WriteString(timestamp)
sb.WriteString(line.Text[0].Text)
}
}
}
return strings.TrimSpace(sb.String())
}
// FetchLyrics searches Apple Music and returns parsed LyricsResponse.
func (c *AppleMusicClient) FetchLyrics(
trackName,
artistName string,
durationSec float64,
multiPersonWordByWord bool,
) (*LyricsResponse, error) {
songID, err := c.SearchSong(trackName, artistName, durationSec)
if err != nil {
return nil, err
}
rawLyrics, err := c.FetchLyricsByID(songID)
if err != nil {
return nil, err
}
if errMsg, isErrorPayload := detectLyricsErrorPayload(rawLyrics); isErrorPayload {
return nil, fmt.Errorf("apple music proxy returned non-lyric payload: %s", errMsg)
}
// Try to parse as pax format (word-by-word or line)
lrcText, err := formatPaxLyricsToLRC(rawLyrics, multiPersonWordByWord)
if err != nil {
// If pax parsing fails, try to parse as direct LRC text
lrcText = rawLyrics
}
lines := parseSyncedLyrics(lrcText)
if len(lines) > 0 {
return &LyricsResponse{
Lines: lines,
SyncType: "LINE_SYNCED",
Provider: "Apple Music",
Source: "Apple Music",
}, nil
}
// Fall back to plain text if no timestamps found
resultLines := plainTextLyricsLines(lrcText)
if len(resultLines) > 0 {
return &LyricsResponse{
Lines: resultLines,
SyncType: "UNSYNCED",
Provider: "Apple Music",
Source: "Apple Music",
}, nil
}
return nil, fmt.Errorf("no lyrics found on apple music")
}