Add a Room database for Artists, Indexes and MusicFolders.

* There is one database for each Server
* Index items are saved with a "musicFolderId" prop, which makes it possible to filter the database by musicFolder without necessarily having to query the server for it.
* Databases for new Servers are created on the fly
* If the user removes a server, the respective database is deleted.

core/domain/build.gradle

@@ -1,7 +1,14 @@
-apply from: bootstrap.kotlinModule
+apply from: bootstrap.androidModule
+apply plugin: 'kotlin-kapt'
 
 ext {
     jacocoExclude = [
             '**/domain/**'
     ]
 }
+
+dependencies {
+    implementation androidSupport.roomRuntime
+    implementation androidSupport.roomKtx
+    kapt androidSupport.room
+}

core/domain/src/main/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.moire.ultrasonic.subsonic.domain">
+</manifest>

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/Artist.kt

@@ -1,18 +1,17 @@
 package org.moire.ultrasonic.domain
 
-import java.io.Serializable
+import androidx.room.Entity
+import androidx.room.PrimaryKey
 
+@Entity(tableName = "artists")
 data class Artist(
-    override var id: String? = null,
+    @PrimaryKey override var id: String,
     override var name: String? = null,
-    var index: String? = null,
-    var coverArt: String? = null,
-    var albumCount: Long? = null,
-    var closeness: Int = 0
-) : Serializable, GenericEntry(), Comparable<Artist> {
-    companion object {
-        private const val serialVersionUID = -5790532593784846982L
-    }
+    override var index: String? = null,
+    override var coverArt: String? = null,
+    override var albumCount: Long? = null,
+    override var closeness: Int = 0
+) : ArtistOrIndex(id), Comparable<Artist> {
 
     override fun compareTo(other: Artist): Int {
         when {

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/ArtistOrIndex.kt

@@ -0,0 +1,18 @@
+package org.moire.ultrasonic.domain
+
+import androidx.room.Ignore
+
+open class ArtistOrIndex(
+    @Ignore
+    override var id: String,
+    @Ignore
+    override var name: String? = null,
+    @Ignore
+    open var index: String? = null,
+    @Ignore
+    open var coverArt: String? = null,
+    @Ignore
+    open var albumCount: Long? = null,
+    @Ignore
+    open var closeness: Int = 0
+) : GenericEntry()

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/GenericEntry.kt

@@ -1,8 +1,12 @@
 package org.moire.ultrasonic.domain
 
-abstract class GenericEntry {
-    // TODO: Should be non-null!
-    abstract val id: String?
+import androidx.room.Ignore
+
+open class GenericEntry {
+    // TODO Should be non-null!
+    @Ignore
+    open val id: String? = null
+    @Ignore
     open val name: String? = null
 
     // These are just a formality and will never be called,

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/Genre.kt

@@ -1,11 +1,14 @@
 package org.moire.ultrasonic.domain
 
+import androidx.room.Entity
+import androidx.room.PrimaryKey
 import java.io.Serializable
 
+@Entity
 data class Genre(
-    val name: String,
-    val index: String
-) : Serializable {
+    @PrimaryKey val index: String,
+    override val name: String
+) : Serializable, GenericEntry() {
     companion object {
         private const val serialVersionUID = -3943025175219134028L
     }

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/Index.kt

@@ -0,0 +1,15 @@
+package org.moire.ultrasonic.domain
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+@Entity(tableName = "indexes")
+data class Index(
+    @PrimaryKey override var id: String,
+    override var name: String? = null,
+    override var index: String? = null,
+    override var coverArt: String? = null,
+    override var albumCount: Long? = null,
+    override var closeness: Int = 0,
+    var musicFolderId: String? = null
+) : ArtistOrIndex(id)

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/Indexes.kt

@@ -1,14 +0,0 @@
-package org.moire.ultrasonic.domain
-
-import java.io.Serializable
-
-data class Indexes(
-    val lastModified: Long,
-    val ignoredArticles: String,
-    val shortcuts: MutableList<Artist> = mutableListOf(),
-    val artists: MutableList<Artist> = mutableListOf()
-) : Serializable {
-    companion object {
-        private const val serialVersionUID = 8156117238598414701L
-    }
-}

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/MusicDirectory.kt

@@ -1,5 +1,7 @@
 package org.moire.ultrasonic.domain
 
+import androidx.room.Entity
+import androidx.room.PrimaryKey
 import java.io.Serializable
 import java.util.Date
 
@@ -35,8 +37,9 @@ class MusicDirectory {
         return children.filter { it.isDirectory && includeDirs || !it.isDirectory && includeFiles }
     }
 
+    @Entity
     data class Entry(
-        override var id: String,
+        @PrimaryKey override var id: String,
         var parent: String? = null,
         var isDirectory: Boolean = false,
         var title: String? = null,

core/domain/src/main/kotlin/org/moire/ultrasonic/domain/MusicFolder.kt

@@ -1,9 +1,13 @@
 package org.moire.ultrasonic.domain
 
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
 /**
  * Represents a top level directory in which music or other media is stored.
  */
+@Entity(tableName = "music_folders")
 data class MusicFolder(
-    override val id: String,
+    @PrimaryKey override val id: String,
     override val name: String
 ) : GenericEntry()

gradle_scripts/android-module-bootstrap.gradle

@@ -1,9 +1,11 @@
+/**
+ * This module provides a base for for submodules which depend on the Android runtime
+ */
 apply plugin: 'com.android.library'
 apply plugin: 'kotlin-android'
 apply plugin: 'jacoco'
 apply from: "${project.rootDir}/gradle_scripts/code_quality.gradle"
 
-
 android {
     compileSdkVersion versions.compileSdk
 

gradle_scripts/kotlin-module-bootstrap.gradle

@@ -1,5 +1,8 @@
-apply plugin: 'java-library'
+/**
+ * This module provides a base for for pure kotlin modules
+ */
 apply plugin: 'kotlin'
+apply plugin: 'kotlin-kapt'
 apply plugin: 'jacoco'
 apply from: "${project.rootDir}/gradle_scripts/code_quality.gradle"
 

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/ActiveServerProvider.kt

@@ -1,5 +1,6 @@
 package org.moire.ultrasonic.data
 
+import androidx.room.Room
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
@@ -7,6 +8,7 @@ import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withContext
 import org.moire.ultrasonic.R
 import org.moire.ultrasonic.app.UApp
+import org.moire.ultrasonic.di.DB_FILENAME
 import org.moire.ultrasonic.service.MusicServiceFactory.resetMusicService
 import org.moire.ultrasonic.util.Constants
 import org.moire.ultrasonic.util.Util
@@ -20,6 +22,8 @@ class ActiveServerProvider(
     private val repository: ServerSettingDao
 ) {
     private var cachedServer: ServerSetting? = null
+    private var cachedDatabase: MetaDatabase? = null
+    private var cachedServerId: Int? = null
 
     /**
      * Get the settings of the current Active Server
@@ -82,6 +86,33 @@ class ActiveServerProvider(
         }
     }
 
+    @Synchronized
+    fun getActiveMetaDatabase(): MetaDatabase {
+        val activeServer = getActiveServerId()
+
+        if (activeServer == cachedServerId && cachedDatabase != null) {
+            return cachedDatabase!!
+        }
+
+        Timber.i("Switching to new database, id:$activeServer")
+        cachedServerId = activeServer
+        val db = Room.databaseBuilder(
+            UApp.applicationContext(),
+            MetaDatabase::class.java,
+            METADATA_DB + cachedServerId
+        )
+            .fallbackToDestructiveMigrationOnDowngrade()
+            .build()
+        return db
+    }
+
+    @Synchronized
+    fun deleteMetaDatabase(id: Int) {
+        cachedDatabase?.close()
+        UApp.applicationContext().deleteDatabase(METADATA_DB + id)
+        Timber.i("Deleted metadataBase, id:$id")
+    }
+
     /**
      * Sets the minimum Subsonic API version of the current server.
      */
@@ -130,6 +161,9 @@ class ActiveServerProvider(
     }
 
     companion object {
+
+        const val METADATA_DB = "$DB_FILENAME-meta-"
+
         /**
          * Queries if the Active Server is the "Offline" mode of Ultrasonic
          * @return True, if the "Offline" mode is selected

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/AppDatabase.kt

@@ -6,7 +6,8 @@ import androidx.room.migration.Migration
 import androidx.sqlite.db.SupportSQLiteDatabase
 
 /**
- * Room Database to be used to store data for Ultrasonic
+ * Room Database to be used to store global data for the whole app.
+ * This could be settings or data that are not specific to any remote music database
  */
 @Database(entities = [ServerSetting::class], version = 3)
 abstract class AppDatabase : RoomDatabase() {

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/ArtistsDao.kt

@@ -0,0 +1,31 @@
+package org.moire.ultrasonic.data
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import org.moire.ultrasonic.domain.Artist
+
+@Dao
+interface ArtistsDao {
+    /**
+     * Insert a list in the database. If the item already exists, replace it.
+     *
+     * @param objects the items to be inserted.
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    @JvmSuppressWildcards
+    fun set(objects: List<Artist>)
+
+    /**
+     * Clear the whole database
+     */
+    @Query("DELETE FROM artists")
+    fun clear()
+
+    /**
+     * Get all artists
+     */
+    @Query("SELECT * FROM artists")
+    fun get(): List<Artist>
+}

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/BasicDaos.kt

@@ -0,0 +1,146 @@
+package org.moire.ultrasonic.data
+
+import androidx.room.Dao
+import androidx.room.Delete
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Transaction
+import androidx.room.Update
+import org.moire.ultrasonic.domain.Index
+import org.moire.ultrasonic.domain.MusicFolder
+
+@Dao
+interface MusicFoldersDao : GenericDao<MusicFolder> {
+    /**
+     * Clear the whole database
+     */
+    @Query("DELETE FROM music_folders")
+    fun clear()
+
+    /**
+     * Get all folders
+     */
+    @Query("SELECT * FROM music_folders")
+    fun get(): List<MusicFolder>
+}
+
+@Dao
+interface IndexDao : GenericDao<Index> {
+
+    /**
+     * Clear the whole database
+     */
+    @Query("DELETE FROM indexes")
+    fun clear()
+
+    /**
+     * Get all indexes
+     */
+    @Query("SELECT * FROM indexes")
+    fun get(): List<Index>
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    fun insertAll(vararg indexes: Index)
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    fun insertArray(arr: Array<Index>)
+
+    /**
+     * Get all indexes for a specific folder id
+     */
+    @Query("SELECT * FROM indexes where musicFolderId LIKE :musicFolderId")
+    fun get(musicFolderId: String): List<Index>
+
+    /**
+     * Upserts (insert or update) an object to the database
+     *
+     * @param obj the object to upsert
+     */
+    @Transaction
+    @JvmSuppressWildcards
+    fun upsert(obj: Index) {
+        val id = insertIgnoring(obj)
+        if (id == -1L) {
+            update(obj)
+        }
+    }
+
+    /**
+     * Upserts (insert or update) a list of objects
+     *
+     * @param objList the object to be upserted
+     */
+    @Transaction
+    @JvmSuppressWildcards
+    fun upsert(objList: List<Index>) {
+        val insertResult = insertIgnoring(objList)
+        val updateList: MutableList<Index> = ArrayList()
+        for (i in insertResult.indices) {
+            if (insertResult[i] == -1L) {
+                updateList.add(objList[i])
+            }
+        }
+        if (updateList.isNotEmpty()) {
+            update(updateList)
+        }
+    }
+}
+
+interface GenericDao<T> {
+    /**
+     * Replaces the list with a new collection
+     *
+     * @param objects the items to be inserted.
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    @JvmSuppressWildcards
+    fun set(objects: List<T>)
+
+    /**
+     * Insert an object in the database.
+     *
+     * @param obj the object to be inserted.
+     * @return The SQLite row id
+     */
+    @Insert(onConflict = OnConflictStrategy.IGNORE)
+    @JvmSuppressWildcards
+    fun insertIgnoring(obj: T): Long
+
+    /**
+     * Insert an array of objects in the database.
+     *
+     * @param obj the objects to be inserted.
+     * @return The SQLite row ids
+     */
+    @Insert(onConflict = OnConflictStrategy.IGNORE)
+    @JvmSuppressWildcards
+    fun insertIgnoring(obj: List<T>?): List<Long>
+
+    /**
+     * Update an object from the database.
+     *
+     * @param obj the object to be updated
+     */
+    @Update
+    @JvmSuppressWildcards
+    fun update(obj: T)
+
+    /**
+     * Update an array of objects from the database.
+     *
+     * @param obj the object to be updated
+     */
+    @Update
+    @JvmSuppressWildcards
+    fun update(obj: List<T>?)
+
+    /**
+     * Delete an object from the database
+     *
+     * @param obj the object to be deleted
+     */
+    @Delete
+    @JvmSuppressWildcards
+    fun delete(obj: T)
+}

ultrasonic/src/main/kotlin/org/moire/ultrasonic/data/MetaDatabase.kt

@@ -0,0 +1,19 @@
+package org.moire.ultrasonic.data
+
+import androidx.room.Database
+import androidx.room.RoomDatabase
+import org.moire.ultrasonic.domain.Artist
+import org.moire.ultrasonic.domain.Index
+import org.moire.ultrasonic.domain.MusicFolder
+
+@Database(
+    entities = [Artist::class, Index::class, MusicFolder::class],
+    version = 1
+)
+abstract class MetaDatabase : RoomDatabase() {
+    abstract fun artistsDao(): ArtistsDao
+
+    abstract fun musicFoldersDao(): MusicFoldersDao
+
+    abstract fun indexDao(): IndexDao
+}

ultrasonic/src/main/kotlin/org/moire/ultrasonic/di/MusicServiceModule.kt

@@ -65,7 +65,7 @@ val musicServiceModule = module {
     single { SubsonicAPIClient(get(), get()) }
 
     single<MusicService>(named(ONLINE_MUSIC_SERVICE)) {
-        CachedMusicService(RESTMusicService(get(), get(), get()))
+        CachedMusicService(RESTMusicService(get(), get()))
     }
 
     single<MusicService>(named(OFFLINE_MUSIC_SERVICE)) {

ultrasonic/src/main/kotlin/org/moire/ultrasonic/domain/APIArtistConverter.kt

@@ -5,12 +5,20 @@ package org.moire.ultrasonic.domain
 
 import org.moire.ultrasonic.api.subsonic.models.Artist as APIArtist
 
+// When we like to convert to an Artist
 fun APIArtist.toDomainEntity(): Artist = Artist(
     id = this@toDomainEntity.id,
     coverArt = this@toDomainEntity.coverArt,
     name = this@toDomainEntity.name
 )
 
+// When we like to convert to an index (eg. a single directory).
+fun APIArtist.toIndexEntity(): Index = Index(
+    id = this@toIndexEntity.id,
+    coverArt = this@toIndexEntity.coverArt,
+    name = this@toIndexEntity.name
+)
+
 fun APIArtist.toMusicDirectoryDomainEntity(): MusicDirectory = MusicDirectory().apply {
     name = this@toMusicDirectoryDomainEntity.name
     addAll(this@toMusicDirectoryDomainEntity.albumsList.map { it.toDomainEntity() })

ultrasonic/src/main/kotlin/org/moire/ultrasonic/domain/APIIndexesConverter.kt

@@ -3,15 +3,37 @@
 @file:JvmName("APIIndexesConverter")
 package org.moire.ultrasonic.domain
 
-import org.moire.ultrasonic.api.subsonic.models.Index
+import org.moire.ultrasonic.api.subsonic.models.Index as APIIndex
 import org.moire.ultrasonic.api.subsonic.models.Indexes as APIIndexes
 
-fun APIIndexes.toDomainEntity(): Indexes = Indexes(
-    this.lastModified, this.ignoredArticles,
-    this.shortcutList.map { it.toDomainEntity() }.toMutableList(),
-    this.indexList.foldIndexToArtistList().toMutableList()
+fun APIIndexes.toArtistList(): List<Artist> {
+    val list = this.shortcutList.map { it.toDomainEntity() }.toMutableList()
+    list.addAll(this.indexList.foldIndexToArtistList())
+    return list
+}
+
+fun APIIndexes.toIndexList(musicFolderId: String?): List<Index> {
+    val list = this.shortcutList.map { it.toIndexEntity() }.toMutableList()
+    list.addAll(this.indexList.foldIndexToIndexList(musicFolderId))
+    return list
+}
+
+private fun List<APIIndex>.foldIndexToArtistList(): List<Artist> = this.fold(
+    listOf(),
+    { acc, index ->
+        acc + index.artists.map {
+            it.toDomainEntity()
+        }
+    }
 )
 
-private fun List<Index>.foldIndexToArtistList(): List<Artist> = this.fold(
-    listOf(), { acc, index -> acc + index.artists.map { it.toDomainEntity() } }
+private fun List<APIIndex>.foldIndexToIndexList(musicFolderId: String?): List<Index> = this.fold(
+    listOf(),
+    { acc, index ->
+        acc + index.artists.map {
+            val ret = it.toIndexEntity()
+            ret.musicFolderId = musicFolderId
+            ret
+        }
+    }
 )

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/ArtistListFragment.kt

@@ -4,13 +4,13 @@ import android.os.Bundle
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.LiveData
 import org.moire.ultrasonic.R
-import org.moire.ultrasonic.domain.Artist
+import org.moire.ultrasonic.domain.ArtistOrIndex
 import org.moire.ultrasonic.util.Constants
 
 /**
  * Displays the list of Artists from the media library
  */
-class ArtistListFragment : GenericListFragment<Artist, ArtistRowAdapter>() {
+class ArtistListFragment : GenericListFragment<ArtistOrIndex, ArtistRowAdapter>() {
 
     /**
      * The ViewModel to use to get the data
@@ -41,7 +41,7 @@ class ArtistListFragment : GenericListFragment<Artist, ArtistRowAdapter>() {
     /**
      * The central function to pass a query to the model and return a LiveData object
      */
-    override fun getLiveData(args: Bundle?): LiveData<List<Artist>> {
+    override fun getLiveData(args: Bundle?): LiveData<List<ArtistOrIndex>> {
         val refresh = args?.getBoolean(Constants.INTENT_EXTRA_NAME_REFRESH) ?: false
         return listModel.getItems(refresh, refreshListView!!)
     }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/ArtistListModel.kt

@@ -23,19 +23,19 @@ import android.os.Bundle
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
-import org.moire.ultrasonic.domain.Artist
+import org.moire.ultrasonic.domain.ArtistOrIndex
 import org.moire.ultrasonic.service.MusicService
 
 /**
  * Provides ViewModel which contains the list of available Artists
  */
 class ArtistListModel(application: Application) : GenericListModel(application) {
-    private val artists: MutableLiveData<List<Artist>> = MutableLiveData(listOf())
+    private val artists: MutableLiveData<List<ArtistOrIndex>> = MutableLiveData(listOf())
 
     /**
      * Retrieves all available Artists in a LiveData
      */
-    fun getItems(refresh: Boolean, swipe: SwipeRefreshLayout): LiveData<List<Artist>> {
+    fun getItems(refresh: Boolean, swipe: SwipeRefreshLayout): LiveData<List<ArtistOrIndex>> {
         // Don't reload the data if navigating back to the view that was active before.
         // This way, we keep the scroll position
         if (artists.value!!.isEmpty() || refresh) {
@@ -55,14 +55,14 @@ class ArtistListModel(application: Application) : GenericListModel(application)
 
         val musicFolderId = activeServer.musicFolderId
 
-        val result = if (!isOffline && useId3Tags)
-            musicService.getArtists(refresh)
-        else musicService.getIndexes(musicFolderId, refresh)
+        val result: List<ArtistOrIndex>
 
-        val retrievedArtists: MutableList<Artist> =
-            ArrayList(result.shortcuts.size + result.artists.size)
-        retrievedArtists.addAll(result.shortcuts)
-        retrievedArtists.addAll(result.artists)
-        artists.postValue(retrievedArtists)
+        if (!isOffline && useId3Tags) {
+            result = musicService.getArtists(refresh)
+        } else {
+            result = musicService.getIndexes(musicFolderId, refresh)
+        }
+
+        artists.postValue(result.toMutableList())
     }
 }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/ArtistRowAdapter.kt

@@ -13,7 +13,7 @@ import androidx.recyclerview.widget.RecyclerView
 import com.simplecityapps.recyclerview_fastscroll.views.FastScrollRecyclerView.SectionedAdapter
 import java.text.Collator
 import org.moire.ultrasonic.R
-import org.moire.ultrasonic.domain.Artist
+import org.moire.ultrasonic.domain.ArtistOrIndex
 import org.moire.ultrasonic.domain.MusicDirectory
 import org.moire.ultrasonic.imageloader.ImageLoader
 import org.moire.ultrasonic.util.Util
@@ -22,12 +22,12 @@ import org.moire.ultrasonic.util.Util
  * Creates a Row in a RecyclerView which contains the details of an Artist
  */
 class ArtistRowAdapter(
-    artistList: List<Artist>,
-    onItemClick: (Artist) -> Unit,
-    onContextMenuClick: (MenuItem, Artist) -> Boolean,
+    artistList: List<ArtistOrIndex>,
+    onItemClick: (ArtistOrIndex) -> Unit,
+    onContextMenuClick: (MenuItem, ArtistOrIndex) -> Boolean,
     private val imageLoader: ImageLoader,
     onMusicFolderUpdate: (String?) -> Unit
-) : GenericRowAdapter<Artist>(
+) : GenericRowAdapter<ArtistOrIndex>(
     onItemClick,
     onContextMenuClick,
     onMusicFolderUpdate
@@ -43,7 +43,7 @@ class ArtistRowAdapter(
     /**
      * Sets the data to be displayed in the RecyclerView
      */
-    override fun setData(data: List<Artist>) {
+    override fun setData(data: List<ArtistOrIndex>) {
         itemList = data.sortedWith(compareBy(Collator.getInstance()) { t -> t.name })
         super.notifyDataSetChanged()
     }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/GenericListModel.kt

@@ -45,7 +45,7 @@ open class GenericListModel(application: Application) :
         return true
     }
 
-    internal val musicFolders: MutableLiveData<List<MusicFolder>> = MutableLiveData()
+    internal val musicFolders: MutableLiveData<List<MusicFolder>> = MutableLiveData(listOf())
 
     /**
      * Helper function to check online status

ultrasonic/src/main/kotlin/org/moire/ultrasonic/fragment/ServerSelectorFragment.kt

@@ -8,7 +8,6 @@ import android.view.ViewGroup
 import android.widget.AdapterView
 import android.widget.ListView
 import androidx.fragment.app.Fragment
-import androidx.lifecycle.Observer
 import androidx.navigation.fragment.findNavController
 import com.google.android.material.floatingactionbutton.FloatingActionButton
 import kotlinx.coroutines.Dispatchers
@@ -104,7 +103,7 @@ class ServerSelectorFragment : Fragment() {
         val serverList = serverSettingsModel.getServerList()
         serverList.observe(
             this,
-            Observer { t ->
+            { t ->
                 serverRowAdapter!!.setData(t.toTypedArray())
             }
         )
@@ -141,10 +140,16 @@ class ServerSelectorFragment : Fragment() {
                 dialog.dismiss()
 
                 val activeServerIndex = activeServerProvider.getActiveServer().index
+                val id = ActiveServerProvider.getActiveServerId()
+
                 // If the currently active server is deleted, go offline
                 if (index == activeServerIndex) setActiveServer(-1)
 
                 serverSettingsModel.deleteItem(index)
+
+                // Clear the metadata cache
+                activeServerProvider.deleteMetaDatabase(id)
+
                 Timber.i("Server deleted: $index")
             }
             .setNegativeButton(R.string.common_cancel) { dialog, _ ->

ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/CachedMusicService.kt

@@ -11,10 +11,12 @@ import java.util.concurrent.TimeUnit
 import org.koin.core.component.KoinComponent
 import org.koin.core.component.inject
 import org.moire.ultrasonic.data.ActiveServerProvider
+import org.moire.ultrasonic.data.MetaDatabase
+import org.moire.ultrasonic.domain.Artist
 import org.moire.ultrasonic.domain.Bookmark
 import org.moire.ultrasonic.domain.ChatMessage
 import org.moire.ultrasonic.domain.Genre
-import org.moire.ultrasonic.domain.Indexes
+import org.moire.ultrasonic.domain.Index
 import org.moire.ultrasonic.domain.JukeboxStatus
 import org.moire.ultrasonic.domain.Lyrics
 import org.moire.ultrasonic.domain.MusicDirectory
@@ -33,19 +35,24 @@ import org.moire.ultrasonic.util.Util
 @Suppress("TooManyFunctions")
 class CachedMusicService(private val musicService: MusicService) : MusicService, KoinComponent {
     private val activeServerProvider: ActiveServerProvider by inject()
+    private var metaDatabase: MetaDatabase = activeServerProvider.getActiveMetaDatabase()
+
+    // Old style TimeLimitedCache
+    private val cachedMusicDirectories: LRUCache<String, TimeLimitedCache<MusicDirectory?>>
+    private val cachedArtist: LRUCache<String, TimeLimitedCache<MusicDirectory?>>
+    private val cachedAlbum: LRUCache<String, TimeLimitedCache<MusicDirectory?>>
+    private val cachedUserInfo: LRUCache<String, TimeLimitedCache<UserInfo?>>
+    private val cachedLicenseValid = TimeLimitedCache<Boolean>(120, TimeUnit.SECONDS)
+    private val cachedPlaylists = TimeLimitedCache<List<Playlist>?>(3600, TimeUnit.SECONDS)
+    private val cachedPodcastsChannels =
+        TimeLimitedCache<List<PodcastsChannel>?>(3600, TimeUnit.SECONDS)
+    private val cachedGenres = TimeLimitedCache<List<Genre>>(10 * 3600, TimeUnit.SECONDS)
+
+    // New Room Database
+    private var cachedArtists = metaDatabase.artistsDao()
+    private var cachedIndexes = metaDatabase.indexDao()
+    private val cachedMusicFolders = metaDatabase.musicFoldersDao()
 
-    private val cachedMusicDirectories: LRUCache<String?, TimeLimitedCache<MusicDirectory?>>
-    private val cachedArtist: LRUCache<String?, TimeLimitedCache<MusicDirectory?>>
-    private val cachedAlbum: LRUCache<String?, TimeLimitedCache<MusicDirectory?>>
-    private val cachedUserInfo: LRUCache<String?, TimeLimitedCache<UserInfo?>>
-    private val cachedLicenseValid = TimeLimitedCache<Boolean>(expiresAfter = 10, TimeUnit.MINUTES)
-    private val cachedIndexes = TimeLimitedCache<Indexes?>()
-    private val cachedArtists = TimeLimitedCache<Indexes?>()
-    private val cachedPlaylists = TimeLimitedCache<List<Playlist>?>()
-    private val cachedPodcastsChannels = TimeLimitedCache<List<PodcastsChannel>>()
-    private val cachedMusicFolders =
-        TimeLimitedCache<List<MusicFolder>?>(10, TimeUnit.HOURS)
-    private val cachedGenres = TimeLimitedCache<List<Genre>?>(10, TimeUnit.HOURS)
     private var restUrl: String? = null
     private var cachedMusicFolderId: String? = null
 
@@ -72,41 +79,51 @@ class CachedMusicService(private val musicService: MusicService) : MusicService,
         if (refresh) {
             cachedMusicFolders.clear()
         }
+        var result = cachedMusicFolders.get()
 
-        val cache = cachedMusicFolders.get()
-        if (cache != null) return cache
-
-        val result = musicService.getMusicFolders(refresh)
-        cachedMusicFolders.set(result)
-
+        if (result.isEmpty()) {
+            result = musicService.getMusicFolders(refresh)
+            cachedMusicFolders.set(result)
+        }
         return result
     }
 
     @Throws(Exception::class)
-    override fun getIndexes(musicFolderId: String?, refresh: Boolean): Indexes {
+    override fun getIndexes(musicFolderId: String?, refresh: Boolean): List<Index> {
         checkSettingsChanged()
+
         if (refresh) {
             cachedIndexes.clear()
-            cachedMusicFolders.clear()
             cachedMusicDirectories.clear()
         }
-        var result = cachedIndexes.get()
-        if (result == null) {
-            result = musicService.getIndexes(musicFolderId, refresh)
-            cachedIndexes.set(result)
+
+        var indexes: List<Index>
+
+        if (musicFolderId == null) {
+            indexes = cachedIndexes.get()
+        } else {
+            indexes = cachedIndexes.get(musicFolderId)
         }
-        return result
+
+        if (indexes.isEmpty()) {
+            indexes = musicService.getIndexes(musicFolderId, refresh)
+            cachedIndexes.upsert(indexes)
+        }
+
+        return indexes
     }
 
     @Throws(Exception::class)
-    override fun getArtists(refresh: Boolean): Indexes {
+    override fun getArtists(refresh: Boolean): List<Artist> {
         checkSettingsChanged()
         if (refresh) {
             cachedArtists.clear()
         }
         var result = cachedArtists.get()
-        if (result == null) {
+
+        if (result.isEmpty()) {
             result = musicService.getArtists(refresh)
+            cachedArtist.clear()
             cachedArtists.set(result)
         }
         return result
@@ -296,19 +313,26 @@ class CachedMusicService(private val musicService: MusicService) : MusicService,
         return musicService.setJukeboxGain(gain)
     }
 
+    @Synchronized
     private fun checkSettingsChanged() {
         val newUrl = activeServerProvider.getRestUrl(null)
         val newFolderId = activeServerProvider.getActiveServer().musicFolderId
         if (!Util.equals(newUrl, restUrl) || !Util.equals(cachedMusicFolderId, newFolderId)) {
-            cachedMusicFolders.clear()
+            // Switch database
+            metaDatabase = activeServerProvider.getActiveMetaDatabase()
+            cachedArtists = metaDatabase.artistsDao()
+            cachedIndexes = metaDatabase.indexDao()
+
+            // Clear in memory caches
             cachedMusicDirectories.clear()
             cachedLicenseValid.clear()
-            cachedIndexes.clear()
             cachedPlaylists.clear()
             cachedGenres.clear()
             cachedAlbum.clear()
             cachedArtist.clear()
             cachedUserInfo.clear()
+
+            // Set the cache keys
             restUrl = newUrl
             cachedMusicFolderId = newFolderId
         }
@@ -330,7 +354,7 @@ class CachedMusicService(private val musicService: MusicService) : MusicService,
     }
 
     @Throws(Exception::class)
-    override fun getGenres(refresh: Boolean): List<Genre>? {
+    override fun getGenres(refresh: Boolean): List<Genre> {
         checkSettingsChanged()
         if (refresh) {
             cachedGenres.clear()
@@ -338,11 +362,11 @@ class CachedMusicService(private val musicService: MusicService) : MusicService,
         var result = cachedGenres.get()
         if (result == null) {
             result = musicService.getGenres(refresh)
-            cachedGenres.set(result)
+            cachedGenres.set(result!!)
         }
 
-        val sorted = result?.toMutableList()
-        sorted?.sortWith { genre, genre2 ->
+        val sorted = result.toMutableList()
+        sorted.sortWith { genre, genre2 ->
             genre.name.compareTo(
                 genre2.name,
                 ignoreCase = true

ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/MusicService.kt

@@ -7,10 +7,11 @@
 package org.moire.ultrasonic.service
 
 import java.io.InputStream
+import org.moire.ultrasonic.domain.Artist
 import org.moire.ultrasonic.domain.Bookmark
 import org.moire.ultrasonic.domain.ChatMessage
 import org.moire.ultrasonic.domain.Genre
-import org.moire.ultrasonic.domain.Indexes
+import org.moire.ultrasonic.domain.Index
 import org.moire.ultrasonic.domain.JukeboxStatus
 import org.moire.ultrasonic.domain.Lyrics
 import org.moire.ultrasonic.domain.MusicDirectory
@@ -46,10 +47,10 @@ interface MusicService {
     fun getMusicFolders(refresh: Boolean): List<MusicFolder>
 
     @Throws(Exception::class)
-    fun getIndexes(musicFolderId: String?, refresh: Boolean): Indexes
+    fun getIndexes(musicFolderId: String?, refresh: Boolean): List<Index>
 
     @Throws(Exception::class)
-    fun getArtists(refresh: Boolean): Indexes
+    fun getArtists(refresh: Boolean): List<Artist>
 
     @Throws(Exception::class)
     fun getMusicDirectory(id: String, name: String?, refresh: Boolean): MusicDirectory

ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/OfflineMusicService.kt

@@ -28,7 +28,7 @@ import org.moire.ultrasonic.domain.Artist
 import org.moire.ultrasonic.domain.Bookmark
 import org.moire.ultrasonic.domain.ChatMessage
 import org.moire.ultrasonic.domain.Genre
-import org.moire.ultrasonic.domain.Indexes
+import org.moire.ultrasonic.domain.Index
 import org.moire.ultrasonic.domain.JukeboxStatus
 import org.moire.ultrasonic.domain.Lyrics
 import org.moire.ultrasonic.domain.MusicDirectory
@@ -50,21 +50,21 @@ import timber.log.Timber
 class OfflineMusicService : MusicService, KoinComponent {
     private val activeServerProvider: ActiveServerProvider by inject()
 
-    override fun getIndexes(musicFolderId: String?, refresh: Boolean): Indexes {
-        val artists: MutableList<Artist> = ArrayList()
+    override fun getIndexes(musicFolderId: String?, refresh: Boolean): List<Index> {
+        val indexes: MutableList<Index> = ArrayList()
         val root = FileUtil.getMusicDirectory()
         for (file in FileUtil.listFiles(root)) {
             if (file.isDirectory) {
-                val artist = Artist()
-                artist.id = file.path
-                artist.index = file.name.substring(0, 1)
-                artist.name = file.name
-                artists.add(artist)
+                val index = Index(file.path)
+                index.id = file.path
+                index.index = file.name.substring(0, 1)
+                index.name = file.name
+                indexes.add(index)
             }
         }
         val ignoredArticlesString = "The El La Los Las Le Les"
         val ignoredArticles = COMPILE.split(ignoredArticlesString)
-        artists.sortWith { lhsArtist, rhsArtist ->
+        indexes.sortWith { lhsArtist, rhsArtist ->
             var lhs = lhsArtist.name!!.lowercase(Locale.ROOT)
             var rhs = rhsArtist.name!!.lowercase(Locale.ROOT)
             val lhs1 = lhs[0]
@@ -92,7 +92,7 @@ class OfflineMusicService : MusicService, KoinComponent {
             lhs.compareTo(rhs)
         }
 
-        return Indexes(0L, ignoredArticlesString, artists = artists)
+        return indexes
     }
 
     override fun getMusicDirectory(
@@ -127,8 +127,7 @@ class OfflineMusicService : MusicService, KoinComponent {
             val artistName = artistFile.name
             if (artistFile.isDirectory) {
                 if (matchCriteria(criteria, artistName).also { closeness = it } > 0) {
-                    val artist = Artist()
-                    artist.id = artistFile.path
+                    val artist = Artist(artistFile.path)
                     artist.index = artistFile.name.substring(0, 1)
                     artist.name = artistName
                     artist.closeness = closeness
@@ -442,7 +441,7 @@ class OfflineMusicService : MusicService, KoinComponent {
     override fun isLicenseValid(): Boolean = true
 
     @Throws(OfflineException::class)
-    override fun getArtists(refresh: Boolean): Indexes {
+    override fun getArtists(refresh: Boolean): List<Artist> {
         throw OfflineException("getArtists isn't available in offline mode")
     }
 

ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/RESTMusicService.kt

@@ -6,9 +6,6 @@
  */
 package org.moire.ultrasonic.service
 
-import java.io.BufferedWriter
-import java.io.File
-import java.io.FileWriter
 import java.io.IOException
 import java.io.InputStream
 import okhttp3.Protocol
@@ -20,15 +17,13 @@ import org.moire.ultrasonic.api.subsonic.models.AlbumListType.Companion.fromName
 import org.moire.ultrasonic.api.subsonic.models.JukeboxAction
 import org.moire.ultrasonic.api.subsonic.throwOnFailure
 import org.moire.ultrasonic.api.subsonic.toStreamResponse
-import org.moire.ultrasonic.cache.PermanentFileStorage
-import org.moire.ultrasonic.cache.serializers.getIndexesSerializer
-import org.moire.ultrasonic.cache.serializers.getMusicFolderListSerializer
 import org.moire.ultrasonic.data.ActiveServerProvider
 import org.moire.ultrasonic.data.ActiveServerProvider.Companion.isOffline
+import org.moire.ultrasonic.domain.Artist
 import org.moire.ultrasonic.domain.Bookmark
 import org.moire.ultrasonic.domain.ChatMessage
 import org.moire.ultrasonic.domain.Genre
-import org.moire.ultrasonic.domain.Indexes
+import org.moire.ultrasonic.domain.Index
 import org.moire.ultrasonic.domain.JukeboxStatus
 import org.moire.ultrasonic.domain.Lyrics
 import org.moire.ultrasonic.domain.MusicDirectory
@@ -39,11 +34,14 @@ import org.moire.ultrasonic.domain.SearchCriteria
 import org.moire.ultrasonic.domain.SearchResult
 import org.moire.ultrasonic.domain.Share
 import org.moire.ultrasonic.domain.UserInfo
+import org.moire.ultrasonic.domain.toArtistList
 import org.moire.ultrasonic.domain.toDomainEntitiesList
 import org.moire.ultrasonic.domain.toDomainEntity
 import org.moire.ultrasonic.domain.toDomainEntityList
+import org.moire.ultrasonic.domain.toIndexList
 import org.moire.ultrasonic.domain.toMusicDirectoryDomainEntity
 import org.moire.ultrasonic.util.FileUtil
+import org.moire.ultrasonic.util.FileUtilKt
 import org.moire.ultrasonic.util.Util
 import timber.log.Timber
 
@@ -53,7 +51,6 @@ import timber.log.Timber
 @Suppress("LargeClass")
 open class RESTMusicService(
     val subsonicAPIClient: SubsonicAPIClient,
-    private val fileStorage: PermanentFileStorage,
     private val activeServerProvider: ActiveServerProvider
 ) : MusicService {
 
@@ -77,49 +74,31 @@ open class RESTMusicService(
     override fun getMusicFolders(
         refresh: Boolean
     ): List<MusicFolder> {
-        val cachedMusicFolders = fileStorage.load(
-            MUSIC_FOLDER_STORAGE_NAME, getMusicFolderListSerializer()
-        )
-
-        if (cachedMusicFolders != null && !refresh) return cachedMusicFolders
-
         val response = API.getMusicFolders().execute().throwOnFailure()
 
-        val musicFolders = response.body()!!.musicFolders.toDomainEntityList()
-        fileStorage.store(MUSIC_FOLDER_STORAGE_NAME, musicFolders, getMusicFolderListSerializer())
-
-        return musicFolders
+        return response.body()!!.musicFolders.toDomainEntityList()
     }
 
+    /**
+     *  Retrieves the artists for a given music folder     *
+     */
     @Throws(Exception::class)
     override fun getIndexes(
         musicFolderId: String?,
         refresh: Boolean
-    ): Indexes {
-        val indexName = INDEXES_STORAGE_NAME + (musicFolderId ?: "")
-
-        val cachedIndexes = fileStorage.load(indexName, getIndexesSerializer())
-        if (cachedIndexes != null && !refresh) return cachedIndexes
-
+    ): List<Index> {
         val response = API.getIndexes(musicFolderId, null).execute().throwOnFailure()
 
-        val indexes = response.body()!!.indexes.toDomainEntity()
-        fileStorage.store(indexName, indexes, getIndexesSerializer())
-        return indexes
+        return response.body()!!.indexes.toIndexList(musicFolderId)
     }
 
     @Throws(Exception::class)
     override fun getArtists(
         refresh: Boolean
-    ): Indexes {
-        val cachedArtists = fileStorage.load(ARTISTS_STORAGE_NAME, getIndexesSerializer())
-        if (cachedArtists != null && !refresh) return cachedArtists
-
+    ): List<Artist> {
         val response = API.getArtists(null).execute().throwOnFailure()
 
-        val indexes = response.body()!!.indexes.toDomainEntity()
-        fileStorage.store(ARTISTS_STORAGE_NAME, indexes, getIndexesSerializer())
-        return indexes
+        return response.body()!!.indexes.toArtistList()
     }
 
     @Throws(Exception::class)
@@ -186,11 +165,11 @@ open class RESTMusicService(
         criteria: SearchCriteria
     ): SearchResult {
         return try {
-            if (
-                !isOffline() &&
-                Util.getShouldUseId3Tags()
-            ) search3(criteria)
-            else search2(criteria)
+            if (!isOffline() && Util.getShouldUseId3Tags()) {
+                search3(criteria)
+            } else {
+                search2(criteria)
+            }
         } catch (ignored: ApiNotSupportedException) {
             // Ensure backward compatibility with REST 1.3.
             searchOld(criteria)
@@ -262,28 +241,7 @@ open class RESTMusicService(
             activeServerProvider.getActiveServer().name, name
         )
 
-        val fw = FileWriter(playlistFile)
-        val bw = BufferedWriter(fw)
-
-        try {
-            fw.write("#EXTM3U\n")
-            for (e in playlist.getChildren()) {
-                var filePath = FileUtil.getSongFile(e).absolutePath
-
-                if (!File(filePath).exists()) {
-                    val ext = FileUtil.getExtension(filePath)
-                    val base = FileUtil.getBaseName(filePath)
-                    filePath = "$base.complete.$ext"
-                }
-                fw.write(filePath + "\n")
-            }
-        } catch (e: IOException) {
-            Timber.w("Failed to save playlist: %s", name)
-            throw e
-        } finally {
-            bw.close()
-            fw.close()
-        }
+        FileUtilKt.savePlaylist(playlistFile, playlist, name)
     }
 
     @Throws(Exception::class)
@@ -711,10 +669,4 @@ open class RESTMusicService(
             activeServerProvider.setMinimumApiVersion(it.restApiVersion)
         }
     }
-
-    companion object {
-        private const val MUSIC_FOLDER_STORAGE_NAME = "music_folder"
-        private const val INDEXES_STORAGE_NAME = "indexes"
-        private const val ARTISTS_STORAGE_NAME = "artists"
-    }
 }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/util/FileUtilKt.kt

@@ -0,0 +1,47 @@
+/*
+ * FileUtil.kt
+ * Copyright (C) 2009-2021 Ultrasonic developers
+ *
+ * Distributed under terms of the GNU GPLv3 license.
+ */
+
+package org.moire.ultrasonic.util
+
+import java.io.BufferedWriter
+import java.io.File
+import java.io.FileWriter
+import java.io.IOException
+import org.moire.ultrasonic.domain.MusicDirectory
+import timber.log.Timber
+
+// TODO: Convert FileUtil.java and merge into here.
+object FileUtilKt {
+    fun savePlaylist(
+        playlistFile: File?,
+        playlist: MusicDirectory,
+        name: String
+    ) {
+        val fw = FileWriter(playlistFile)
+        val bw = BufferedWriter(fw)
+
+        try {
+            fw.write("#EXTM3U\n")
+            for (e in playlist.getChildren()) {
+                var filePath = FileUtil.getSongFile(e).absolutePath
+
+                if (!File(filePath).exists()) {
+                    val ext = FileUtil.getExtension(filePath)
+                    val base = FileUtil.getBaseName(filePath)
+                    filePath = "$base.complete.$ext"
+                }
+                fw.write(filePath + "\n")
+            }
+        } catch (e: IOException) {
+            Timber.w("Failed to save playlist: %s", name)
+            throw e
+        } finally {
+            bw.close()
+            fw.close()
+        }
+    }
+}

ultrasonic/src/test/kotlin/org/moire/ultrasonic/domain/APIIndexConverterTest.kt

@@ -11,7 +11,7 @@ import org.moire.ultrasonic.api.subsonic.models.Indexes
 /**
  * Unit tests for extension functions in [APIIndexesConverter.kt].
  */
-class APIIndexesConverterTest {
+class APIIndexConverterTest {
     @Test
     fun `Should convert Indexes entity`() {
         val artistsA = listOf(
@@ -31,15 +31,12 @@ class APIIndexesConverterTest {
             shortcutList = artistsA
         )
 
-        val convertedEntity = entity.toDomainEntity()
+        val convertedEntity = entity.toIndexList(null)
 
         val expectedArtists = (artistsA + artistsT).map { it.toDomainEntity() }.toMutableList()
         with(convertedEntity) {
-            lastModified `should be equal to` entity.lastModified
-            ignoredArticles `should be equal to` entity.ignoredArticles
-            artists.size `should be equal to` expectedArtists.size
-            artists `should be equal to` expectedArtists
-            shortcuts `should be equal to` artistsA.map { it.toDomainEntity() }.toMutableList()
+            size `should be equal to` expectedArtists.size
+            this `should be equal to` expectedArtists
         }
     }
 }