From e13d083a8c28436fd5efbafe026a7e762de77fd2 Mon Sep 17 00:00:00 2001
From: vfsfitvnm <vfsfitvnm@protonmail.com>
Date: Thu, 15 Sep 2022 18:56:34 +0200
Subject: [PATCH] Simplify queries to move song in playlist

---
 .../kotlin/it/vfsfitvnm/vimusic/Database.kt   | 18 +++++++-------
 .../ui/components/themed/MediaItemMenu.kt     | 13 ++--------
 .../vimusic/ui/screens/LocalPlaylistScreen.kt | 24 ++-----------------
 3 files changed, 14 insertions(+), 41 deletions(-)

diff --git a/app/src/main/kotlin/it/vfsfitvnm/vimusic/Database.kt b/app/src/main/kotlin/it/vfsfitvnm/vimusic/Database.kt
index 6db5aab..15add7d 100644
--- a/app/src/main/kotlin/it/vfsfitvnm/vimusic/Database.kt
+++ b/app/src/main/kotlin/it/vfsfitvnm/vimusic/Database.kt
@@ -197,14 +197,16 @@ interface Database {
     @RewriteQueriesToDropUnusedColumns
     fun songsWithContentLength(): Flow<List<DetailedSongWithContentLength>>
 
-    @Query("UPDATE SongPlaylistMap SET position = position - 1 WHERE playlistId = :playlistId AND position >= :fromPosition")
-    fun decrementSongPositions(playlistId: Long, fromPosition: Int)
-
-    @Query("UPDATE SongPlaylistMap SET position = position - 1 WHERE playlistId = :playlistId AND position >= :fromPosition AND position <= :toPosition")
-    fun decrementSongPositions(playlistId: Long, fromPosition: Int, toPosition: Int)
-
-    @Query("UPDATE SongPlaylistMap SET position = position + 1 WHERE playlistId = :playlistId AND position >= :fromPosition AND position <= :toPosition")
-    fun incrementSongPositions(playlistId: Long, fromPosition: Int, toPosition: Int)
+    @Query("""
+        UPDATE SongPlaylistMap SET position = 
+          CASE 
+            WHEN position < :fromPosition THEN position + 1
+            WHEN position > :fromPosition THEN position - 1
+            ELSE :toPosition
+          END 
+        WHERE playlistId = :playlistId AND position BETWEEN MIN(:fromPosition,:toPosition) and MAX(:fromPosition,:toPosition)
+    """)
+    fun move(playlistId: Long, fromPosition: Int, toPosition: Int)
 
     @Query("DELETE FROM SongPlaylistMap WHERE playlistId = :id")
     fun clearPlaylist(id: Long)
diff --git a/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/components/themed/MediaItemMenu.kt b/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/components/themed/MediaItemMenu.kt
index 541b253..b10c0ce 100644
--- a/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/components/themed/MediaItemMenu.kt
+++ b/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/components/themed/MediaItemMenu.kt
@@ -132,17 +132,8 @@ fun InPlaylistMediaItemMenu(
         onDismiss = onDismiss,
         onRemoveFromPlaylist = {
             transaction {
-                Database.delete(
-                    SongPlaylistMap(
-                        songId = song.id,
-                        playlistId = playlistId,
-                        position = positionInPlaylist
-                    )
-                )
-                Database.decrementSongPositions(
-                    playlistId = playlistId,
-                    fromPosition = positionInPlaylist + 1
-                )
+                Database.move(playlistId, positionInPlaylist, Int.MAX_VALUE)
+                Database.delete(SongPlaylistMap(song.id, playlistId, Int.MAX_VALUE))
             }
         },
         modifier = modifier
diff --git a/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/screens/LocalPlaylistScreen.kt b/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/screens/LocalPlaylistScreen.kt
index c26e9c3..66f4754 100644
--- a/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/screens/LocalPlaylistScreen.kt
+++ b/app/src/main/kotlin/it/vfsfitvnm/vimusic/ui/screens/LocalPlaylistScreen.kt
@@ -92,28 +92,8 @@ fun LocalPlaylistScreen(playlistId: Long) {
                 lazyListState = lazyListState,
                 key = playlistWithSongs.songs,
                 onDragEnd = { fromIndex, toIndex ->
-                    transaction {
-                        if (fromIndex > toIndex) {
-                            Database.incrementSongPositions(
-                                playlistId = playlistWithSongs.playlist.id,
-                                fromPosition = toIndex,
-                                toPosition = fromIndex - 1
-                            )
-                        } else if (fromIndex < toIndex) {
-                            Database.decrementSongPositions(
-                                playlistId = playlistWithSongs.playlist.id,
-                                fromPosition = fromIndex + 1,
-                                toPosition = toIndex
-                            )
-                        }
-
-                        Database.update(
-                            SongPlaylistMap(
-                                songId = playlistWithSongs.songs[fromIndex].id,
-                                playlistId = playlistWithSongs.playlist.id,
-                                position = toIndex
-                            )
-                        )
+                    query {
+                        Database.move(playlistWithSongs.playlist.id, fromIndex, toIndex)
                     }
                 },
                 extraItemCount = 1