From ea1d78ed589a7e21e81f52c510922534a61d20bf Mon Sep 17 00:00:00 2001
From: Drew Weymouth <dweymouth@gmail.com>
Date: Tue, 5 Mar 2024 08:53:57 -0800
Subject: [PATCH] add LyricsProvider / GetLyrics

---
 backend/mediaprovider/mediaprovider.go        |  4 ++
 backend/mediaprovider/model.go                | 12 +++++
 .../subsonic/subsonicmediaprovider.go         | 48 +++++++++++++++++++
 3 files changed, 64 insertions(+)

diff --git a/backend/mediaprovider/mediaprovider.go b/backend/mediaprovider/mediaprovider.go
index f7fe0b1..fde5fb7 100644
--- a/backend/mediaprovider/mediaprovider.go
+++ b/backend/mediaprovider/mediaprovider.go
@@ -154,6 +154,10 @@ type SupportsSharing interface {
 	CanShareArtists() bool
 }
 
+type LyricsProvider interface {
+	GetLyrics(track *Track) (*Lyrics, error)
+}
+
 type JukeboxProvider interface {
 	JukeboxStart() error
 	JukeboxStop() error
diff --git a/backend/mediaprovider/model.go b/backend/mediaprovider/model.go
index ac4201a..d7a820f 100644
--- a/backend/mediaprovider/model.go
+++ b/backend/mediaprovider/model.go
@@ -120,6 +120,18 @@ type PlaylistWithTracks struct {
 	Tracks []*Track
 }
 
+type Lyrics struct {
+	Title  string
+	Artist string
+	Synced bool
+	Lines  []LyricLine
+}
+
+type LyricLine struct {
+	Text  string
+	Start float64 // seconds
+}
+
 type ContentType int
 
 const (
diff --git a/backend/mediaprovider/subsonic/subsonicmediaprovider.go b/backend/mediaprovider/subsonic/subsonicmediaprovider.go
index 5c858eb..4470bf7 100644
--- a/backend/mediaprovider/subsonic/subsonicmediaprovider.go
+++ b/backend/mediaprovider/subsonic/subsonicmediaprovider.go
@@ -6,6 +6,7 @@ import (
 	"io"
 	"math"
 	"net/url"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -345,6 +346,53 @@ func (s *subsonicMediaProvider) RescanLibrary() error {
 	return err
 }
 
+// LyricsProvider interface
+var _ mediaprovider.LyricsProvider = (*subsonicMediaProvider)(nil)
+
+func (s *subsonicMediaProvider) GetLyrics(track *mediaprovider.Track) (*mediaprovider.Lyrics, error) {
+	ext, err := s.client.GetOpenSubsonicExtensions()
+	supportsSynced := err == nil &&
+		slices.ContainsFunc(ext, func(ext *subsonic.OpenSubsonicExtension) bool {
+			return ext.Name == subsonic.SongLyricsExtension
+		})
+	if supportsSynced {
+		lyrics, err := s.client.GetLyricsBySongId(track.ID)
+		if err != nil || len(lyrics.StructuredLyrics) == 0 {
+			return nil, err
+		}
+		lyric := lyrics.StructuredLyrics[0]
+		mpLyrics := &mediaprovider.Lyrics{
+			Title:  lyric.DisplayTitle,
+			Artist: lyric.DisplayArtist,
+			Synced: lyric.Synced,
+		}
+		for _, line := range lyric.Lines {
+			mpLyrics.Lines = append(mpLyrics.Lines, mediaprovider.LyricLine{
+				Text:  line.Text,
+				Start: float64(line.Start) / 1000,
+			})
+		}
+		return mpLyrics, nil
+	}
+	// fallback to legacy getLyrics endpoint
+	lyrics, err := s.client.GetLyrics(track.Name, track.ArtistNames[0])
+	if err != nil || lyrics == nil || lyrics.Text == "" {
+		return nil, err
+	}
+	mpLyrics := &mediaprovider.Lyrics{
+		Title:  lyrics.Title,
+		Artist: lyrics.Artist,
+		Synced: false,
+	}
+	lines := strings.Split(lyrics.Text, "\n")
+	for _, line := range lines {
+		mpLyrics.Lines = append(mpLyrics.Lines, mediaprovider.LyricLine{
+			Text: line,
+		})
+	}
+	return mpLyrics, nil
+}
+
 func toTrack(ch *subsonic.Child) *mediaprovider.Track {
 	if ch == nil {
 		return nil