app: local: Sort songs and folders

* We sort in UI instead of view model as the directory trees have their own nuances and I do not feel like
   torturing myself with database gymnastics today
* Song folders are only sortable by name

app/src/main/java/com/dd3boh/outertune/ui/screens/library/LibrarySongsFolderScreen.kt

@@ -57,6 +57,7 @@ import com.dd3boh.outertune.utils.rememberEnumPreference
 import com.dd3boh.outertune.utils.rememberPreference
 import com.dd3boh.outertune.viewmodels.LibrarySongsViewModel
 import com.dd3boh.outertune.ui.utils.ItemWrapper
+import java.time.ZoneOffset
 import java.util.Stack
 
 @SuppressLint("StateFlowValueCalledInComposition")
@@ -108,6 +109,27 @@ fun LibrarySongsFolderScreen(
     }
 
     val wrappedSongs = currDir.files.map { item -> ItemWrapper(item) }.toMutableList()
+
+    // sort songs
+    wrappedSongs.sortBy {
+        when (sortType) {
+            SongSortType.CREATE_DATE -> it.item.song.inLibrary?.toEpochSecond(ZoneOffset.UTC).toString()
+            SongSortType.NAME -> it.item.song.title
+            SongSortType.ARTIST -> it.item.artists.firstOrNull()?.name
+            SongSortType.PLAY_TIME -> it.item.song.totalPlayTime.toString()
+        }
+    }
+    if (sortDescending) {
+        wrappedSongs.reverse()
+    }
+
+    // sort folders
+    currDir.subdirs.sortBy { it.currentDir } // only sort by name
+
+    if (sortDescending) {
+        currDir.subdirs.reverse()
+    }
+
     var selection by remember {
         mutableStateOf(false)
     }