feat: Enable downloading of song lyrics for offline viewing

app/src/main/java/com/cappielloantonio/tempo/database/AppDatabase.java

@@ -12,6 +12,7 @@ import com.cappielloantonio.tempo.database.converter.DateConverters;
 import com.cappielloantonio.tempo.database.dao.ChronologyDao;
 import com.cappielloantonio.tempo.database.dao.DownloadDao;
 import com.cappielloantonio.tempo.database.dao.FavoriteDao;
+import com.cappielloantonio.tempo.database.dao.LyricsDao;
 import com.cappielloantonio.tempo.database.dao.PlaylistDao;
 import com.cappielloantonio.tempo.database.dao.QueueDao;
 import com.cappielloantonio.tempo.database.dao.RecentSearchDao;
@@ -20,6 +21,7 @@ import com.cappielloantonio.tempo.database.dao.SessionMediaItemDao;
 import com.cappielloantonio.tempo.model.Chronology;
 import com.cappielloantonio.tempo.model.Download;
 import com.cappielloantonio.tempo.model.Favorite;
+import com.cappielloantonio.tempo.model.LyricsCache;
 import com.cappielloantonio.tempo.model.Queue;
 import com.cappielloantonio.tempo.model.RecentSearch;
 import com.cappielloantonio.tempo.model.Server;
@@ -28,9 +30,9 @@ import com.cappielloantonio.tempo.subsonic.models.Playlist;
 
 @UnstableApi
 @Database(
-        version = 11,
+        version = 12,
-        entities = {Queue.class, Server.class, RecentSearch.class, Download.class, Chronology.class, Favorite.class, SessionMediaItem.class, Playlist.class},
+        entities = {Queue.class, Server.class, RecentSearch.class, Download.class, Chronology.class, Favorite.class, SessionMediaItem.class, Playlist.class, LyricsCache.class},
-        autoMigrations = {@AutoMigration(from = 10, to = 11)}
+        autoMigrations = {@AutoMigration(from = 10, to = 11), @AutoMigration(from = 11, to = 12)}
 )
 @TypeConverters({DateConverters.class})
 public abstract class AppDatabase extends RoomDatabase {
@@ -62,4 +64,6 @@ public abstract class AppDatabase extends RoomDatabase {
     public abstract SessionMediaItemDao sessionMediaItemDao();
 
     public abstract PlaylistDao playlistDao();
+
+    public abstract LyricsDao lyricsDao();
 }

app/src/main/java/com/cappielloantonio/tempo/database/dao/LyricsDao.java

@@ -0,0 +1,24 @@
+package com.cappielloantonio.tempo.database.dao;
+
+import androidx.lifecycle.LiveData;
+import androidx.room.Dao;
+import androidx.room.Insert;
+import androidx.room.OnConflictStrategy;
+import androidx.room.Query;
+
+import com.cappielloantonio.tempo.model.LyricsCache;
+
+@Dao
+public interface LyricsDao {
+    @Query("SELECT * FROM lyrics_cache WHERE song_id = :songId")
+    LyricsCache getOne(String songId);
+
+    @Query("SELECT * FROM lyrics_cache WHERE song_id = :songId")
+    LiveData<LyricsCache> observeOne(String songId);
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    void insert(LyricsCache lyricsCache);
+
+    @Query("DELETE FROM lyrics_cache WHERE song_id = :songId")
+    void delete(String songId);
+}

app/src/main/java/com/cappielloantonio/tempo/model/LyricsCache.kt

@@ -0,0 +1,25 @@
+package com.cappielloantonio.tempo.model
+
+import androidx.annotation.Keep
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import kotlin.jvm.JvmOverloads
+
+@Keep
+@Entity(tableName = "lyrics_cache")
+data class LyricsCache @JvmOverloads constructor(
+    @PrimaryKey
+    @ColumnInfo(name = "song_id")
+    var songId: String,
+    @ColumnInfo(name = "artist")
+    var artist: String? = null,
+    @ColumnInfo(name = "title")
+    var title: String? = null,
+    @ColumnInfo(name = "lyrics")
+    var lyrics: String? = null,
+    @ColumnInfo(name = "structured_lyrics")
+    var structuredLyrics: String? = null,
+    @ColumnInfo(name = "updated_at")
+    var updatedAt: Long = System.currentTimeMillis()
+)

app/src/main/java/com/cappielloantonio/tempo/repository/LyricsRepository.java

@@ -0,0 +1,92 @@
+package com.cappielloantonio.tempo.repository;
+
+import androidx.lifecycle.LiveData;
+
+import com.cappielloantonio.tempo.database.AppDatabase;
+import com.cappielloantonio.tempo.database.dao.LyricsDao;
+import com.cappielloantonio.tempo.model.LyricsCache;
+
+public class LyricsRepository {
+    private final LyricsDao lyricsDao = AppDatabase.getInstance().lyricsDao();
+
+    public LyricsCache getLyrics(String songId) {
+        GetLyricsThreadSafe getLyricsThreadSafe = new GetLyricsThreadSafe(lyricsDao, songId);
+        Thread thread = new Thread(getLyricsThreadSafe);
+        thread.start();
+
+        try {
+            thread.join();
+            return getLyricsThreadSafe.getLyrics();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+
+        return null;
+    }
+
+    public LiveData<LyricsCache> observeLyrics(String songId) {
+        return lyricsDao.observeOne(songId);
+    }
+
+    public void insert(LyricsCache lyricsCache) {
+        InsertThreadSafe insert = new InsertThreadSafe(lyricsDao, lyricsCache);
+        Thread thread = new Thread(insert);
+        thread.start();
+    }
+
+    public void delete(String songId) {
+        DeleteThreadSafe delete = new DeleteThreadSafe(lyricsDao, songId);
+        Thread thread = new Thread(delete);
+        thread.start();
+    }
+
+    private static class GetLyricsThreadSafe implements Runnable {
+        private final LyricsDao lyricsDao;
+        private final String songId;
+        private LyricsCache lyricsCache;
+
+        public GetLyricsThreadSafe(LyricsDao lyricsDao, String songId) {
+            this.lyricsDao = lyricsDao;
+            this.songId = songId;
+        }
+
+        @Override
+        public void run() {
+            lyricsCache = lyricsDao.getOne(songId);
+        }
+
+        public LyricsCache getLyrics() {
+            return lyricsCache;
+        }
+    }
+
+    private static class InsertThreadSafe implements Runnable {
+        private final LyricsDao lyricsDao;
+        private final LyricsCache lyricsCache;
+
+        public InsertThreadSafe(LyricsDao lyricsDao, LyricsCache lyricsCache) {
+            this.lyricsDao = lyricsDao;
+            this.lyricsCache = lyricsCache;
+        }
+
+        @Override
+        public void run() {
+            lyricsDao.insert(lyricsCache);
+        }
+    }
+
+    private static class DeleteThreadSafe implements Runnable {
+        private final LyricsDao lyricsDao;
+        private final String songId;
+
+        public DeleteThreadSafe(LyricsDao lyricsDao, String songId) {
+            this.lyricsDao = lyricsDao;
+            this.songId = songId;
+        }
+
+        @Override
+        public void run() {
+            lyricsDao.delete(songId);
+        }
+    }
+}

app/src/main/java/com/cappielloantonio/tempo/ui/fragment/PlayerLyricsFragment.java

@@ -4,15 +4,16 @@ import android.annotation.SuppressLint;
 import android.content.ComponentName;
 import android.os.Bundle;
 import android.os.Handler;
+import android.text.Layout;
 import android.text.Spannable;
 import android.text.SpannableString;
-import android.text.Layout;
+import android.text.TextUtils;
 import android.text.style.ForegroundColorSpan;
-import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.WindowManager;
+import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -29,10 +30,10 @@ import com.cappielloantonio.tempo.service.MediaService;
 import com.cappielloantonio.tempo.subsonic.models.Line;
 import com.cappielloantonio.tempo.subsonic.models.LyricsList;
 import com.cappielloantonio.tempo.util.MusicUtil;
-import com.cappielloantonio.tempo.util.OpenSubsonicExtensionsUtil;
 import com.cappielloantonio.tempo.util.Preferences;
 import com.cappielloantonio.tempo.viewmodel.PlayerBottomSheetViewModel;
 import com.google.common.util.concurrent.ListenableFuture;
+import com.google.android.material.button.MaterialButton;
 import com.google.common.util.concurrent.MoreExecutors;
 
 import java.util.List;
@@ -48,6 +49,9 @@ public class PlayerLyricsFragment extends Fragment {
     private MediaBrowser mediaBrowser;
     private Handler syncLyricsHandler;
     private Runnable syncLyricsRunnable;
+    private String currentLyrics;
+    private LyricsList currentLyricsList;
+    private String currentDescription;
 
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
@@ -66,6 +70,7 @@ public class PlayerLyricsFragment extends Fragment {
         super.onViewCreated(view, savedInstanceState);
 
         initPanelContent();
+        observeDownloadState();
     }
 
     @Override
@@ -101,12 +106,26 @@ public class PlayerLyricsFragment extends Fragment {
     public void onDestroyView() {
         super.onDestroyView();
         bind = null;
+        currentLyrics = null;
+        currentLyricsList = null;
+        currentDescription = null;
     }
 
     private void initOverlay() {
         bind.syncLyricsTapButton.setOnClickListener(view -> {
             playerBottomSheetViewModel.changeSyncLyricsState();
         });
+
+        bind.downloadLyricsButton.setOnClickListener(view -> {
+            boolean saved = playerBottomSheetViewModel.downloadCurrentLyrics();
+            if (getContext() != null) {
+                Toast.makeText(
+                        requireContext(),
+                        saved ? R.string.player_lyrics_download_success : R.string.player_lyrics_download_failure,
+                        Toast.LENGTH_SHORT
+                ).show();
+            }
+        });
     }
 
     private void initializeBrowser() {
@@ -136,50 +155,91 @@ public class PlayerLyricsFragment extends Fragment {
     }
 
     private void initPanelContent() {
-        if (OpenSubsonicExtensionsUtil.isSongLyricsExtensionAvailable()) {
+        playerBottomSheetViewModel.getLiveLyrics().observe(getViewLifecycleOwner(), lyrics -> {
-            playerBottomSheetViewModel.getLiveLyricsList().observe(getViewLifecycleOwner(), lyricsList -> {
+            currentLyrics = lyrics;
-                setPanelContent(null, lyricsList);
+            updatePanelContent();
-            });
+        });
-        } else {
+
-            playerBottomSheetViewModel.getLiveLyrics().observe(getViewLifecycleOwner(), lyrics -> {
+        playerBottomSheetViewModel.getLiveLyricsList().observe(getViewLifecycleOwner(), lyricsList -> {
-                setPanelContent(lyrics, null);
+            currentLyricsList = lyricsList;
-            });
+            updatePanelContent();
-        }
+        });
+
+        playerBottomSheetViewModel.getLiveDescription().observe(getViewLifecycleOwner(), description -> {
+            currentDescription = description;
+            updatePanelContent();
+        });
     }
 
-    private void setPanelContent(String lyrics, LyricsList lyricsList) {
+    private void observeDownloadState() {
-        playerBottomSheetViewModel.getLiveDescription().observe(getViewLifecycleOwner(), description -> {
+        playerBottomSheetViewModel.getLyricsCachedState().observe(getViewLifecycleOwner(), cached -> {
             if (bind != null) {
-                bind.nowPlayingSongLyricsSrollView.smoothScrollTo(0, 0);
+                MaterialButton downloadButton = (MaterialButton) bind.downloadLyricsButton;
-
+                if (cached != null && cached) {
-                if (lyrics != null && !lyrics.trim().equals("")) {
+                    downloadButton.setIconResource(R.drawable.ic_done);
-                    bind.nowPlayingSongLyricsTextView.setText(MusicUtil.getReadableLyrics(lyrics));
+                    downloadButton.setContentDescription(getString(R.string.player_lyrics_downloaded_content_description));
-                    bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
-                    bind.emptyDescriptionImageView.setVisibility(View.GONE);
-                    bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
-                    bind.syncLyricsTapButton.setVisibility(View.GONE);
-                } else if (lyricsList != null && lyricsList.getStructuredLyrics() != null) {
-                    setSyncLirics(lyricsList);
-                    bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
-                    bind.emptyDescriptionImageView.setVisibility(View.GONE);
-                    bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
-                    bind.syncLyricsTapButton.setVisibility(View.VISIBLE);
-                } else if (description != null && !description.trim().equals("")) {
-                    bind.nowPlayingSongLyricsTextView.setText(MusicUtil.getReadableLyrics(description));
-                    bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
-                    bind.emptyDescriptionImageView.setVisibility(View.GONE);
-                    bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
-                    bind.syncLyricsTapButton.setVisibility(View.GONE);
                 } else {
-                    bind.nowPlayingSongLyricsTextView.setVisibility(View.GONE);
+                    downloadButton.setIconResource(R.drawable.ic_download);
-                    bind.emptyDescriptionImageView.setVisibility(View.VISIBLE);
+                    downloadButton.setContentDescription(getString(R.string.player_lyrics_download_content_description));
-                    bind.titleEmptyDescriptionLabel.setVisibility(View.VISIBLE);
-                    bind.syncLyricsTapButton.setVisibility(View.GONE);
                 }
             }
         });
     }
 
+    private void updatePanelContent() {
+        if (bind == null) {
+            return;
+        }
+
+        bind.nowPlayingSongLyricsSrollView.smoothScrollTo(0, 0);
+
+        if (hasStructuredLyrics(currentLyricsList)) {
+            setSyncLirics(currentLyricsList);
+            bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
+            bind.emptyDescriptionImageView.setVisibility(View.GONE);
+            bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
+            bind.syncLyricsTapButton.setVisibility(View.VISIBLE);
+            bind.downloadLyricsButton.setVisibility(View.VISIBLE);
+            bind.downloadLyricsButton.setEnabled(true);
+        } else if (hasText(currentLyrics)) {
+            bind.nowPlayingSongLyricsTextView.setText(MusicUtil.getReadableLyrics(currentLyrics));
+            bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
+            bind.emptyDescriptionImageView.setVisibility(View.GONE);
+            bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
+            bind.syncLyricsTapButton.setVisibility(View.GONE);
+            bind.downloadLyricsButton.setVisibility(View.VISIBLE);
+            bind.downloadLyricsButton.setEnabled(true);
+        } else if (hasText(currentDescription)) {
+            bind.nowPlayingSongLyricsTextView.setText(MusicUtil.getReadableLyrics(currentDescription));
+            bind.nowPlayingSongLyricsTextView.setVisibility(View.VISIBLE);
+            bind.emptyDescriptionImageView.setVisibility(View.GONE);
+            bind.titleEmptyDescriptionLabel.setVisibility(View.GONE);
+            bind.syncLyricsTapButton.setVisibility(View.GONE);
+            bind.downloadLyricsButton.setVisibility(View.GONE);
+            bind.downloadLyricsButton.setEnabled(false);
+        } else {
+            bind.nowPlayingSongLyricsTextView.setVisibility(View.GONE);
+            bind.emptyDescriptionImageView.setVisibility(View.VISIBLE);
+            bind.titleEmptyDescriptionLabel.setVisibility(View.VISIBLE);
+            bind.syncLyricsTapButton.setVisibility(View.GONE);
+            bind.downloadLyricsButton.setVisibility(View.GONE);
+            bind.downloadLyricsButton.setEnabled(false);
+        }
+    }
+
+    private boolean hasText(String value) {
+        return value != null && !value.trim().isEmpty();
+    }
+
+    private boolean hasStructuredLyrics(LyricsList lyricsList) {
+        return lyricsList != null
+                && lyricsList.getStructuredLyrics() != null
+                && !lyricsList.getStructuredLyrics().isEmpty()
+                && lyricsList.getStructuredLyrics().get(0) != null
+                && lyricsList.getStructuredLyrics().get(0).getLine() != null
+                && !lyricsList.getStructuredLyrics().get(0).getLine().isEmpty();
+    }
+
     @SuppressLint("DefaultLocale")
     private void setSyncLirics(LyricsList lyricsList) {
         if (lyricsList.getStructuredLyrics() != null && !lyricsList.getStructuredLyrics().isEmpty() && lyricsList.getStructuredLyrics().get(0).getLine() != null) {
@@ -198,28 +258,28 @@ public class PlayerLyricsFragment extends Fragment {
 
     private void defineProgressHandler() {
         playerBottomSheetViewModel.getLiveLyricsList().observe(getViewLifecycleOwner(), lyricsList -> {
-            if (lyricsList != null) {
+            if (!hasStructuredLyrics(lyricsList)) {
-
-                if (lyricsList.getStructuredLyrics() != null && lyricsList.getStructuredLyrics().get(0) != null && !lyricsList.getStructuredLyrics().get(0).getSynced()) {
-                    releaseHandler();
-                    return;
-                }
-
-                syncLyricsHandler = new Handler();
-                syncLyricsRunnable = () -> {
-                    if (syncLyricsHandler != null) {
-                        if (bind != null) {
-                            displaySyncedLyrics();
-                        }
-
-                        syncLyricsHandler.postDelayed(syncLyricsRunnable, 250);
-                    }
-                };
-
-                syncLyricsHandler.postDelayed(syncLyricsRunnable, 250);
-            } else {
                 releaseHandler();
+                return;
             }
+
+            if (!lyricsList.getStructuredLyrics().get(0).getSynced()) {
+                releaseHandler();
+                return;
+            }
+
+            syncLyricsHandler = new Handler();
+            syncLyricsRunnable = () -> {
+                if (syncLyricsHandler != null) {
+                    if (bind != null) {
+                        displaySyncedLyrics();
+                    }
+
+                    syncLyricsHandler.postDelayed(syncLyricsRunnable, 250);
+                }
+            };
+
+            syncLyricsHandler.postDelayed(syncLyricsRunnable, 250);
         });
     }
 
@@ -227,7 +287,7 @@ public class PlayerLyricsFragment extends Fragment {
         LyricsList lyricsList = playerBottomSheetViewModel.getLiveLyricsList().getValue();
         int timestamp = (int) (mediaBrowser.getCurrentPosition());
 
-        if (lyricsList != null && lyricsList.getStructuredLyrics() != null && !lyricsList.getStructuredLyrics().isEmpty() && lyricsList.getStructuredLyrics().get(0).getLine() != null) {
+        if (hasStructuredLyrics(lyricsList)) {
             StringBuilder lyricsBuilder = new StringBuilder();
             List<Line> lines = lyricsList.getStructuredLyrics().get(0).getLine();
 

app/src/main/java/com/cappielloantonio/tempo/ui/fragment/SettingsFragment.java

@@ -116,6 +116,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
         actionChangeDownloadStorage();
         actionDeleteDownloadStorage();
         actionKeepScreenOn();
+        actionAutoDownloadLyrics();
 
         bindMediaService();
         actionAppEqualizer();
@@ -357,6 +358,21 @@ public class SettingsFragment extends PreferenceFragmentCompat {
         });
     }
 
+    private void actionAutoDownloadLyrics() {
+        SwitchPreference preference = findPreference("auto_download_lyrics");
+        if (preference == null) {
+            return;
+        }
+
+        preference.setChecked(Preferences.isAutoDownloadLyricsEnabled());
+        preference.setOnPreferenceChangeListener((pref, newValue) -> {
+            if (newValue instanceof Boolean) {
+                Preferences.setAutoDownloadLyricsEnabled((Boolean) newValue);
+            }
+            return true;
+        });
+    }
+
     private void getScanStatus() {
         settingViewModel.getScanStatus(new ScanCallback() {
             @Override

app/src/main/java/com/cappielloantonio/tempo/util/Preferences.kt

@@ -46,6 +46,7 @@ object Preferences {
     private const val ROUNDED_CORNER_SIZE = "rounded_corner_size"
     private const val PODCAST_SECTION_VISIBILITY = "podcast_section_visibility"
     private const val RADIO_SECTION_VISIBILITY = "radio_section_visibility"
+    private const val AUTO_DOWNLOAD_LYRICS = "auto_download_lyrics"
     private const val MUSIC_DIRECTORY_SECTION_VISIBILITY = "music_directory_section_visibility"
     private const val REPLAY_GAIN_MODE = "replay_gain_mode"
     private const val AUDIO_TRANSCODE_PRIORITY = "audio_transcode_priority"
@@ -163,6 +164,24 @@ object Preferences {
         App.getInstance().preferences.edit().putString(OPEN_SUBSONIC_EXTENSIONS, Gson().toJson(extension)).apply()
     }
 
+    @JvmStatic
+    fun isAutoDownloadLyricsEnabled(): Boolean {
+        val preferences = App.getInstance().preferences
+
+        if (preferences.contains(AUTO_DOWNLOAD_LYRICS)) {
+            return preferences.getBoolean(AUTO_DOWNLOAD_LYRICS, false)
+        }
+
+        return false
+    }
+
+    @JvmStatic
+    fun setAutoDownloadLyricsEnabled(isEnabled: Boolean) {
+        App.getInstance().preferences.edit()
+            .putBoolean(AUTO_DOWNLOAD_LYRICS, isEnabled)
+            .apply()
+    }
+
     @JvmStatic
     fun getLocalAddress(): String? {
         return App.getInstance().preferences.getString(LOCAL_ADDRESS, null)

app/src/main/java/com/cappielloantonio/tempo/viewmodel/PlayerBottomSheetViewModel.java

@@ -2,6 +2,7 @@ package com.cappielloantonio.tempo.viewmodel;
 
 import android.app.Application;
 import android.content.Context;
+import android.text.TextUtils;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.OptIn;
@@ -9,14 +10,17 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.Observer;
 import androidx.media3.common.util.UnstableApi;
 
 import com.cappielloantonio.tempo.interfaces.StarCallback;
 import com.cappielloantonio.tempo.model.Download;
+import com.cappielloantonio.tempo.model.LyricsCache;
 import com.cappielloantonio.tempo.model.Queue;
 import com.cappielloantonio.tempo.repository.AlbumRepository;
 import com.cappielloantonio.tempo.repository.ArtistRepository;
 import com.cappielloantonio.tempo.repository.FavoriteRepository;
+import com.cappielloantonio.tempo.repository.LyricsRepository;
 import com.cappielloantonio.tempo.repository.OpenRepository;
 import com.cappielloantonio.tempo.repository.QueueRepository;
 import com.cappielloantonio.tempo.repository.SongRepository;
@@ -31,6 +35,7 @@ import com.cappielloantonio.tempo.util.MappingUtil;
 import com.cappielloantonio.tempo.util.NetworkUtil;
 import com.cappielloantonio.tempo.util.OpenSubsonicExtensionsUtil;
 import com.cappielloantonio.tempo.util.Preferences;
+import com.google.gson.Gson;
 
 import java.util.Collections;
 import java.util.Date;
@@ -47,14 +52,20 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
     private final QueueRepository queueRepository;
     private final FavoriteRepository favoriteRepository;
     private final OpenRepository openRepository;
+    private final LyricsRepository lyricsRepository;
     private final MutableLiveData<String> lyricsLiveData = new MutableLiveData<>(null);
     private final MutableLiveData<LyricsList> lyricsListLiveData = new MutableLiveData<>(null);
+    private final MutableLiveData<Boolean> lyricsCachedLiveData = new MutableLiveData<>(false);
     private final MutableLiveData<String> descriptionLiveData = new MutableLiveData<>(null);
     private final MutableLiveData<Child> liveMedia = new MutableLiveData<>(null);
     private final MutableLiveData<AlbumID3> liveAlbum = new MutableLiveData<>(null);
     private final MutableLiveData<ArtistID3> liveArtist = new MutableLiveData<>(null);
     private final MutableLiveData<List<Child>> instantMix = new MutableLiveData<>(null);
+    private final Gson gson = new Gson();
     private boolean lyricsSyncState = true;
+    private LiveData<LyricsCache> cachedLyricsSource;
+    private String currentSongId;
+    private final Observer<LyricsCache> cachedLyricsObserver = this::onCachedLyricsChanged;
 
 
     public PlayerBottomSheetViewModel(@NonNull Application application) {
@@ -66,6 +77,7 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
         queueRepository = new QueueRepository();
         favoriteRepository = new FavoriteRepository();
         openRepository = new OpenRepository();
+        lyricsRepository = new LyricsRepository();
     }
 
     public LiveData<List<Queue>> getQueueSong() {
@@ -139,12 +151,49 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
     }
 
     public void refreshMediaInfo(LifecycleOwner owner, Child media) {
+        lyricsLiveData.postValue(null);
+        lyricsListLiveData.postValue(null);
+        lyricsCachedLiveData.postValue(false);
+
+        clearCachedLyricsObserver();
+
+        String songId = media != null ? media.getId() : currentSongId;
+
+        if (TextUtils.isEmpty(songId) || owner == null) {
+            return;
+        }
+
+        currentSongId = songId;
+
+        observeCachedLyrics(owner, songId);
+
+        LyricsCache cachedLyrics = lyricsRepository.getLyrics(songId);
+        if (cachedLyrics != null) {
+            onCachedLyricsChanged(cachedLyrics);
+        }
+
+        if (NetworkUtil.isOffline() || media == null) {
+            return;
+        }
+
         if (OpenSubsonicExtensionsUtil.isSongLyricsExtensionAvailable()) {
-            openRepository.getLyricsBySongId(media.getId()).observe(owner, lyricsListLiveData::postValue);
+            openRepository.getLyricsBySongId(media.getId()).observe(owner, lyricsList -> {
-            lyricsLiveData.postValue(null);
+                lyricsListLiveData.postValue(lyricsList);
+                lyricsLiveData.postValue(null);
+
+                if (shouldAutoDownloadLyrics() && hasStructuredLyrics(lyricsList)) {
+                    saveLyricsToCache(media, null, lyricsList);
+                }
+            });
         } else {
-            songRepository.getSongLyrics(media).observe(owner, lyricsLiveData::postValue);
+            songRepository.getSongLyrics(media).observe(owner, lyrics -> {
-            lyricsListLiveData.postValue(null);
+                lyricsLiveData.postValue(lyrics);
+                lyricsListLiveData.postValue(null);
+
+                if (shouldAutoDownloadLyrics() && !TextUtils.isEmpty(lyrics)) {
+                    saveLyricsToCache(media, lyrics, null);
+                }
+            });
         }
     }
 
@@ -153,6 +202,17 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
     }
 
     public void setLiveMedia(LifecycleOwner owner, String mediaType, String mediaId) {
+        currentSongId = mediaId;
+
+        if (!TextUtils.isEmpty(mediaId)) {
+            refreshMediaInfo(owner, null);
+        } else {
+            clearCachedLyricsObserver();
+            lyricsLiveData.postValue(null);
+            lyricsListLiveData.postValue(null);
+            lyricsCachedLiveData.postValue(false);
+        }
+
         if (mediaType != null) {
             switch (mediaType) {
                 case Constants.MEDIA_TYPE_MUSIC:
@@ -162,7 +222,12 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
                 case Constants.MEDIA_TYPE_PODCAST:
                     liveMedia.postValue(null);
                     break;
+                default:
+                    liveMedia.postValue(null);
+                    break;
             }
+        } else {
+            liveMedia.postValue(null);
         }
     }
 
@@ -233,6 +298,105 @@ public class PlayerBottomSheetViewModel extends AndroidViewModel {
         return false;
     }
 
+    private void observeCachedLyrics(LifecycleOwner owner, String songId) {
+        if (TextUtils.isEmpty(songId)) {
+            return;
+        }
+
+        cachedLyricsSource = lyricsRepository.observeLyrics(songId);
+        cachedLyricsSource.observe(owner, cachedLyricsObserver);
+    }
+
+    private void clearCachedLyricsObserver() {
+        if (cachedLyricsSource != null) {
+            cachedLyricsSource.removeObserver(cachedLyricsObserver);
+            cachedLyricsSource = null;
+        }
+    }
+
+    private void onCachedLyricsChanged(LyricsCache lyricsCache) {
+        if (lyricsCache == null) {
+            lyricsCachedLiveData.postValue(false);
+            return;
+        }
+
+        lyricsCachedLiveData.postValue(true);
+
+        if (!TextUtils.isEmpty(lyricsCache.getStructuredLyrics())) {
+            try {
+                LyricsList cachedList = gson.fromJson(lyricsCache.getStructuredLyrics(), LyricsList.class);
+                lyricsListLiveData.postValue(cachedList);
+                lyricsLiveData.postValue(null);
+            } catch (Exception exception) {
+                lyricsListLiveData.postValue(null);
+                lyricsLiveData.postValue(lyricsCache.getLyrics());
+            }
+        } else {
+            lyricsListLiveData.postValue(null);
+            lyricsLiveData.postValue(lyricsCache.getLyrics());
+        }
+    }
+
+    private void saveLyricsToCache(Child media, String lyrics, LyricsList lyricsList) {
+        if (media == null) {
+            return;
+        }
+
+        if ((lyricsList == null || !hasStructuredLyrics(lyricsList)) && TextUtils.isEmpty(lyrics)) {
+            return;
+        }
+
+        LyricsCache lyricsCache = new LyricsCache(media.getId());
+        lyricsCache.setArtist(media.getArtist());
+        lyricsCache.setTitle(media.getTitle());
+        lyricsCache.setUpdatedAt(System.currentTimeMillis());
+
+        if (lyricsList != null && hasStructuredLyrics(lyricsList)) {
+            lyricsCache.setStructuredLyrics(gson.toJson(lyricsList));
+            lyricsCache.setLyrics(null);
+        } else {
+            lyricsCache.setLyrics(lyrics);
+            lyricsCache.setStructuredLyrics(null);
+        }
+
+        lyricsRepository.insert(lyricsCache);
+        lyricsCachedLiveData.postValue(true);
+    }
+
+    private boolean hasStructuredLyrics(LyricsList lyricsList) {
+        return lyricsList != null
+                && lyricsList.getStructuredLyrics() != null
+                && !lyricsList.getStructuredLyrics().isEmpty()
+                && lyricsList.getStructuredLyrics().get(0) != null
+                && lyricsList.getStructuredLyrics().get(0).getLine() != null
+                && !lyricsList.getStructuredLyrics().get(0).getLine().isEmpty();
+    }
+
+    private boolean shouldAutoDownloadLyrics() {
+        return Preferences.isAutoDownloadLyricsEnabled();
+    }
+
+    public boolean downloadCurrentLyrics() {
+        Child media = getLiveMedia().getValue();
+        if (media == null) {
+            return false;
+        }
+
+        LyricsList lyricsList = lyricsListLiveData.getValue();
+        String lyrics = lyricsLiveData.getValue();
+
+        if ((lyricsList == null || !hasStructuredLyrics(lyricsList)) && TextUtils.isEmpty(lyrics)) {
+            return false;
+        }
+
+        saveLyricsToCache(media, lyrics, lyricsList);
+        return true;
+    }
+
+    public LiveData<Boolean> getLyricsCachedState() {
+        return lyricsCachedLiveData;
+    }
+
     public void changeSyncLyricsState() {
         lyricsSyncState = !lyricsSyncState;
     }

app/src/main/res/layout/inner_fragment_player_lyrics.xml

@@ -51,7 +51,25 @@
             app:layout_constraintTop_toTopOf="parent" />
     </androidx.core.widget.NestedScrollView>
 
-    <Button
+    <com.google.android.material.button.MaterialButton
+        android:id="@+id/download_lyrics_button"
+        style="@style/Widget.Material3.Button.TonalButton.Icon"
+        android:layout_width="48dp"
+        android:layout_height="48dp"
+        android:layout_margin="16dp"
+        android:alpha="0.7"
+        android:contentDescription="@string/player_lyrics_download_content_description"
+        android:insetLeft="0dp"
+        android:insetTop="0dp"
+        android:insetRight="0dp"
+        android:insetBottom="0dp"
+        android:visibility="gone"
+        app:cornerRadius="64dp"
+        app:icon="@drawable/ic_download"
+        app:layout_constraintBottom_toTopOf="@+id/sync_lyrics_tap_button"
+        app:layout_constraintEnd_toEndOf="@+id/now_playing_song_lyrics_sroll_view" />
+
+    <com.google.android.material.button.MaterialButton
         android:id="@+id/sync_lyrics_tap_button"
         style="@style/Widget.Material3.Button.TonalButton.Icon"
         android:layout_width="48dp"

app/src/main/res/values/strings.xml

@@ -199,6 +199,10 @@
     <string name="player_playback_speed">%1$.2fx</string>
     <string name="player_queue_clean_all_button">Clean play queue</string>
     <string name="player_queue_save_queue_success">Saved play queue</string>
+    <string name="player_lyrics_download_content_description">Download lyrics for offline playback</string>
+    <string name="player_lyrics_downloaded_content_description">Lyrics downloaded for offline playback</string>
+    <string name="player_lyrics_download_success">Lyrics saved for offline playback.</string>
+    <string name="player_lyrics_download_failure">Lyrics are not available to download.</string>
     <string name="player_server_priority">Server Priority</string>
     <string name="player_unknown_format">Unknown format</string>
     <string name="player_transcoding">Transcoding</string>
@@ -327,6 +331,8 @@
     <string name="settings_queue_syncing_title">Sync play queue for this user [Not Fully Baked]</string>
     <string name="settings_radio">Show radio</string>
     <string name="settings_radio_summary">If enabled, show the radio section. Restart the app for it to take full effect.</string>
+    <string name="settings_auto_download_lyrics">Auto download lyrics</string>
+    <string name="settings_auto_download_lyrics_summary">Automatically save lyrics when they are available so they can be shown while offline.</string>
     <string name="settings_replay_gain">Set replay gain mode</string>
     <string name="settings_rounded_corner">Rounded corners</string>
     <string name="settings_rounded_corner_size">Corners size</string>

app/src/main/res/xml/global_preferences.xml

@@ -86,6 +86,12 @@
             android:summary="@string/settings_radio_summary"
             android:key="radio_section_visibility" />
 
+        <SwitchPreference
+            android:title="@string/settings_auto_download_lyrics"
+            android:defaultValue="false"
+            android:summary="@string/settings_auto_download_lyrics_summary"
+            android:key="auto_download_lyrics" />
+
         <SwitchPreference
             android:title="@string/settings_music_directory"
             android:defaultValue="true"