Add offline song download feature

android/app/src/main/AndroidManifest.xml

@@ -8,6 +8,11 @@
 
     <uses-permission android:name="android.permission.READ_MEDIA_AUDIO" />
 
+    <!-- Permissions for foreground download service -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+
     <queries>
         <intent>
             <action android:name="android.intent.action.OPEN_DOCUMENT_TREE" />
@@ -101,6 +106,12 @@
             android:authorities="${applicationId}.androidx-startup"
             tools:node="remove"></provider>
 
+        <!-- Download Service -->
+        <service
+            android:name="com.simplecityapps.playback.download.DownloadService"
+            android:exported="false"
+            android:foregroundServiceType="dataSync" />
+
     </application>
 
 </manifest>

android/app/src/main/java/com/simplecityapps/shuttle/di/RepositoryModule.kt

@@ -3,6 +3,7 @@ package com.simplecityapps.shuttle.di
 import android.content.Context
 import com.simplecityapps.localmediaprovider.local.data.room.DatabaseProvider
 import com.simplecityapps.localmediaprovider.local.data.room.database.MediaDatabase
+import com.simplecityapps.localmediaprovider.local.data.room.repository.DownloadRepositoryImpl
 import com.simplecityapps.localmediaprovider.local.repository.LocalAlbumArtistRepository
 import com.simplecityapps.localmediaprovider.local.repository.LocalAlbumRepository
 import com.simplecityapps.localmediaprovider.local.repository.LocalGenreRepository
@@ -11,6 +12,7 @@ import com.simplecityapps.localmediaprovider.local.repository.LocalSongRepositor
 import com.simplecityapps.mediaprovider.MediaImporter
 import com.simplecityapps.mediaprovider.repository.albums.AlbumRepository
 import com.simplecityapps.mediaprovider.repository.artists.AlbumArtistRepository
+import com.simplecityapps.mediaprovider.repository.downloads.DownloadRepository
 import com.simplecityapps.mediaprovider.repository.genres.GenreRepository
 import com.simplecityapps.mediaprovider.repository.playlists.PlaylistRepository
 import com.simplecityapps.mediaprovider.repository.songs.SongRepository
@@ -76,4 +78,10 @@ class RepositoryModule {
         songRepository: SongRepository,
         @AppCoroutineScope appCoroutineScope: CoroutineScope
     ): GenreRepository = LocalGenreRepository(appCoroutineScope, songRepository)
+
+    @Provides
+    @Singleton
+    fun provideDownloadRepository(
+        database: MediaDatabase
+    ): DownloadRepository = DownloadRepositoryImpl(database.downloadDao())
 }

android/app/src/main/java/com/simplecityapps/shuttle/ui/screens/downloads/DownloadHelper.kt

@@ -0,0 +1,89 @@
+package com.simplecityapps.shuttle.ui.screens.downloads
+
+import android.content.Context
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Download
+import androidx.compose.material.icons.filled.DownloadDone
+import androidx.compose.ui.graphics.vector.ImageVector
+import com.simplecityapps.shuttle.model.DownloadState
+import com.simplecityapps.shuttle.model.Song
+
+/**
+ * Helper object for download-related UI functionality
+ */
+object DownloadHelper {
+
+    /**
+     * Get the appropriate icon for a song's download state
+     */
+    fun getDownloadIcon(downloadState: DownloadState): ImageVector {
+        return when (downloadState) {
+            DownloadState.COMPLETED -> Icons.Default.DownloadDone
+            else -> Icons.Default.Download
+        }
+    }
+
+    /**
+     * Get the download action text for a song's download state
+     */
+    fun getDownloadActionText(downloadState: DownloadState): String {
+        return when (downloadState) {
+            DownloadState.NONE -> "Download"
+            DownloadState.QUEUED -> "Queued for download"
+            DownloadState.DOWNLOADING -> "Downloading..."
+            DownloadState.PAUSED -> "Resume download"
+            DownloadState.COMPLETED -> "Downloaded"
+            DownloadState.FAILED -> "Retry download"
+        }
+    }
+
+    /**
+     * Check if a song can be downloaded (is from a remote provider)
+     */
+    fun canDownload(song: Song): Boolean {
+        return song.mediaProvider.remote
+    }
+
+    /**
+     * Format download size for display
+     */
+    fun formatDownloadSize(bytes: Long): String {
+        return when {
+            bytes == 0L -> "Unknown size"
+            bytes < 1024 -> "$bytes B"
+            bytes < 1024 * 1024 -> String.format("%.1f KB", bytes / 1024.0)
+            bytes < 1024 * 1024 * 1024 -> String.format("%.1f MB", bytes / (1024.0 * 1024.0))
+            else -> String.format("%.2f GB", bytes / (1024.0 * 1024.0 * 1024.0))
+        }
+    }
+
+    /**
+     * Get download status message
+     */
+    fun getDownloadStatusMessage(downloadState: DownloadState, progress: Float, downloadedBytes: Long, totalBytes: Long): String {
+        return when (downloadState) {
+            DownloadState.NONE -> "Not downloaded"
+            DownloadState.QUEUED -> "Waiting to download..."
+            DownloadState.DOWNLOADING -> {
+                val percentage = (progress * 100).toInt()
+                if (totalBytes > 0) {
+                    "$percentage% (${formatDownloadSize(downloadedBytes)} / ${formatDownloadSize(totalBytes)})"
+                } else {
+                    "$percentage%"
+                }
+            }
+            DownloadState.PAUSED -> {
+                val percentage = (progress * 100).toInt()
+                "Paused at $percentage%"
+            }
+            DownloadState.COMPLETED -> {
+                if (totalBytes > 0) {
+                    "Downloaded (${formatDownloadSize(totalBytes)})"
+                } else {
+                    "Downloaded"
+                }
+            }
+            DownloadState.FAILED -> "Download failed"
+        }
+    }
+}

android/app/src/main/java/com/simplecityapps/shuttle/ui/screens/downloads/DownloadsContract.kt

@@ -0,0 +1,31 @@
+package com.simplecityapps.shuttle.ui.screens.downloads
+
+import com.simplecityapps.localmediaprovider.local.data.room.entity.DownloadData
+import com.simplecityapps.shuttle.model.Song
+import com.simplecityapps.shuttle.ui.common.mvp.BaseContract
+
+interface DownloadsContract {
+
+    sealed class Event {
+        data class SongClicked(val song: Song) : Event()
+        data class RemoveDownload(val song: Song) : Event()
+        data class PauseDownload(val song: Song) : Event()
+        data class ResumeDownload(val song: Song) : Event()
+        object RemoveAllDownloads : Event()
+        object NavigateBack : Event()
+    }
+
+    interface View : BaseContract.View<Presenter, Event> {
+        fun setData(downloads: List<DownloadData>, songs: List<Song>)
+        fun showLoadError(error: Error)
+        fun setLoadingState(loading: Boolean)
+    }
+
+    interface Presenter : BaseContract.Presenter<View> {
+        fun loadDownloads()
+        fun removeDownload(song: Song)
+        fun pauseDownload(song: Song)
+        fun resumeDownload(song: Song)
+        fun removeAllDownloads()
+    }
+}

android/app/src/main/java/com/simplecityapps/shuttle/ui/screens/downloads/DownloadsPresenter.kt

@@ -0,0 +1,93 @@
+package com.simplecityapps.shuttle.ui.screens.downloads
+
+import com.simplecityapps.localmediaprovider.local.data.room.entity.DownloadData
+import com.simplecityapps.mediaprovider.repository.downloads.DownloadRepository
+import com.simplecityapps.mediaprovider.repository.songs.SongQuery
+import com.simplecityapps.mediaprovider.repository.songs.SongRepository
+import com.simplecityapps.playback.download.DownloadUseCase
+import com.simplecityapps.shuttle.model.Song
+import com.simplecityapps.shuttle.ui.common.mvp.BasePresenter
+import javax.inject.Inject
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.firstOrNull
+import kotlinx.coroutines.launch
+import timber.log.Timber
+
+class DownloadsPresenter @Inject constructor(
+    private val downloadRepository: DownloadRepository,
+    private val songRepository: SongRepository,
+    private val downloadUseCase: DownloadUseCase
+) : BasePresenter<DownloadsContract.View>(),
+    DownloadsContract.Presenter {
+
+    override fun bindView(view: DownloadsContract.View) {
+        super.bindView(view)
+        loadDownloads()
+    }
+
+    override fun loadDownloads() {
+        launch {
+            try {
+                view?.setLoadingState(true)
+
+                combine(
+                    downloadRepository.observeAllDownloads(),
+                    songRepository.getSongs(SongQuery.All())
+                ) { downloads, songs ->
+                    Pair(downloads, songs)
+                }.collect { (downloads, songs) ->
+                    view?.setData(downloads, songs ?: emptyList())
+                    view?.setLoadingState(false)
+                }
+            } catch (e: Exception) {
+                Timber.e(e, "Failed to load downloads")
+                view?.showLoadError(Error.LoadFailed(e))
+                view?.setLoadingState(false)
+            }
+        }
+    }
+
+    override fun removeDownload(song: Song) {
+        launch {
+            try {
+                downloadUseCase.removeDownload(song)
+            } catch (e: Exception) {
+                Timber.e(e, "Failed to remove download")
+            }
+        }
+    }
+
+    override fun pauseDownload(song: Song) {
+        launch {
+            try {
+                downloadUseCase.pauseDownload(song)
+            } catch (e: Exception) {
+                Timber.e(e, "Failed to pause download")
+            }
+        }
+    }
+
+    override fun resumeDownload(song: Song) {
+        launch {
+            try {
+                downloadUseCase.resumeDownload(song)
+            } catch (e: Exception) {
+                Timber.e(e, "Failed to resume download")
+            }
+        }
+    }
+
+    override fun removeAllDownloads() {
+        launch {
+            try {
+                downloadUseCase.removeAllDownloads()
+            } catch (e: Exception) {
+                Timber.e(e, "Failed to remove all downloads")
+            }
+        }
+    }
+
+    sealed class Error {
+        data class LoadFailed(val error: Throwable) : Error()
+    }
+}