[DynamicDatabaseLoader] redesign to fix orderless results

app/src/main/java/player/phonograph/repo/mediastore/loaders/DatabaseLoaders.kt

@@ -1,5 +1,5 @@
 /*
- *  Copyright (c) 2022~2023 chr_56
+ *  Copyright (c) 2022~2025 chr_56
  */
 package player.phonograph.repo.mediastore.loaders
 
@@ -11,15 +11,23 @@ import player.phonograph.repo.database.SongPlayCountStore
 import player.phonograph.repo.mediastore.internal.intoSongs
 import player.phonograph.repo.mediastore.internal.querySongs
 import android.content.Context
-import android.database.Cursor
 import android.provider.BaseColumns
 
 class TopTracksLoader(private val songPlayCountStore: SongPlayCountStore) :
-        DynamicDatabaseLoader(songPlayCountStore) {
+        DynamicDatabaseLoader(songPlayCountStore, NUMBER_OF_TOP_TRACKS) {
 
-    override fun queryCursorImpl(context: Context): Cursor? =
-        songPlayCountStore.getTopPlayedResults(NUMBER_OF_TOP_TRACKS)
-            .intoSongCursor(context, SongPlayCountStore.SongPlayCountColumns.ID)
+    override fun fetch(context: Context): LongArray? {
+        val cursor = songPlayCountStore.getTopPlayedResults(0)
+        val results = mutableListOf<Long>()
+        if (cursor.moveToFirst()) {
+            val idColumnIndex = cursor.getColumnIndex(SongPlayCountStore.SongPlayCountColumns.ID)
+            do {
+                val id = cursor.getLong(idColumnIndex)
+                results.add(id)
+            } while (cursor.moveToNext())
+        }
+        return results.toLongArray()
+    }
 
     companion object {
         private const val NUMBER_OF_TOP_TRACKS = 150
@@ -30,71 +38,46 @@ class TopTracksLoader(private val songPlayCountStore: SongPlayCountStore) :
 class RecentlyPlayedTracksLoader(private val historyStore: HistoryStore) :
         DynamicDatabaseLoader(historyStore) {
 
-    override fun queryCursorImpl(context: Context): Cursor? =
-        historyStore.queryRecentIds()
-            .intoSongCursor(context, HistoryStore.RecentStoreColumns.ID)
+    override fun fetch(context: Context): LongArray? {
+        val cursor = historyStore.queryRecentIds()
+        val results = mutableListOf<Long>()
+        if (cursor.moveToFirst()) {
+            val idColumnIndex = cursor.getColumnIndex(HistoryStore.RecentStoreColumns.ID)
+            do {
+                val id = cursor.getLong(idColumnIndex)
+                results.add(id)
+            } while (cursor.moveToNext())
+        }
+        return results.toLongArray()
+    }
 
     companion object {
         fun get() = GlobalContext.get().get<RecentlyPlayedTracksLoader>()
     }
 }
 
-abstract class DynamicDatabaseLoader(private val db: Any) {
-
-    fun tracks(context: Context): List<Song> = queryCursorAndClear(context).intoSongs()
-
-    protected abstract fun queryCursorImpl(context: Context): Cursor?
-
-    protected fun queryCursorAndClear(context: Context): Cursor? {
-
-        val songCursor = queryCursorImpl(context) ?: return null
-
+abstract class DynamicDatabaseLoader(private val db: Any, private val limit: Int = -1) {
+
+    protected abstract fun fetch(context: Context): LongArray?
+
+    fun tracks(context: Context): List<Song> {
+        val ids: LongArray = fetch(context) ?: return emptyList()
+        val songs = ids.map { id ->
+            val songs = querySongs(
+                context,
+                selection = "${BaseColumns._ID} = ?",
+                selectionValues = arrayOf(id.toString())
+            ).intoSongs()
+            if (songs.isNotEmpty()) {
+                songs.first()
+            } else {
+                null
+            }
+        }.filterNotNull()
         if (db is ShallowDatabase) {
-            // clean up the databases with any ids not found
-            val exists = songIds(songCursor)
-            db.gc(exists)
+            db.gc(songs.map { it.id })
         }
-
-        return songCursor
-    }
-
-    private fun songIds(songCursor: Cursor): List<Long> {
-        val exists = mutableListOf<Long>()
-        if (songCursor.moveToFirst()) {
-            val index = songCursor.getColumnIndex(BaseColumns._ID)
-            do {
-                val id = songCursor.getLong(index)
-                if (id > 0) exists.add(id)
-            } while (songCursor.moveToNext())
-        }
-        return exists
-    }
-
-    protected fun Cursor.intoSongCursor(context: Context, idColumnName: String): Cursor? =
-        use { cursor -> generateSongCursor(context, cursor, idColumnName) }
-
-    protected fun generateSongCursor(context: Context, cursor: Cursor, idColumnName: String): Cursor? {
-        val count = cursor.count
-        val idColumnIndex = cursor.getColumnIndex(idColumnName)
-
-        if (count < 0 || idColumnIndex < 0) return null
-
-        cursor.moveToFirst()
-        val selectionPlaceHolder = when {
-            count > 1  -> "?" + ",?".repeat(count - 1)
-            count == 1 -> "?"
-            else       -> return null // empty cursor
-        }
-
-        val ids = Array(count) {
-            cursor.getLong(idColumnIndex).toString().also { cursor.moveToNext() }
-        }
-
-        return querySongs(
-            context,
-            selection = "${BaseColumns._ID}  IN ( $selectionPlaceHolder )",
-            selectionValues = ids
-        )
+        return if (limit > 0) songs.take(limit) else songs
     }
 
 }