Added loading indicator to playlist view

app/src/main/java/org/schabi/newpipe/compose/playlist/Playlist.kt

@@ -18,12 +18,16 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.fragment.app.FragmentActivity
-import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
 import androidx.paging.compose.collectAsLazyPagingItems
+import kotlinx.coroutines.flow.Flow
 import my.nanihadesuka.compose.LazyColumnScrollbar
 import my.nanihadesuka.compose.LazyVerticalGridScrollbar
 import org.schabi.newpipe.DownloaderImpl
+import org.schabi.newpipe.compose.status.LoadingIndicator
 import org.schabi.newpipe.compose.stream.StreamCardItem
 import org.schabi.newpipe.compose.stream.StreamGridItem
 import org.schabi.newpipe.compose.stream.StreamListItem
@@ -31,24 +35,34 @@ import org.schabi.newpipe.compose.theme.AppTheme
 import org.schabi.newpipe.compose.util.determineItemViewMode
 import org.schabi.newpipe.extractor.NewPipe
 import org.schabi.newpipe.extractor.ServiceList
+import org.schabi.newpipe.extractor.playlist.PlaylistInfo
 import org.schabi.newpipe.extractor.stream.StreamInfoItem
 import org.schabi.newpipe.info_list.ItemViewMode
-import org.schabi.newpipe.util.KEY_SERVICE_ID
+import org.schabi.newpipe.paging.PlaylistItemsSource
-import org.schabi.newpipe.util.KEY_URL
 import org.schabi.newpipe.util.NavigationHelper
 import org.schabi.newpipe.viewmodels.PlaylistViewModel
 
 @Composable
 fun Playlist(playlistViewModel: PlaylistViewModel = viewModel()) {
+    Surface(color = MaterialTheme.colorScheme.background) {
         val playlistInfo by playlistViewModel.playlistInfo.collectAsState()
-    val streams = playlistViewModel.streamItems.collectAsLazyPagingItems()
+        playlistInfo?.let {
+            LoadedPlaylist(it, playlistViewModel.streamItems)
+        } ?: LoadingIndicator()
+    }
+}
+
+@Composable
+private fun LoadedPlaylist(playlistInfo: PlaylistInfo, flow: Flow<PagingData<StreamInfoItem>>) {
+    val streams = flow.collectAsLazyPagingItems()
+    val mode = determineItemViewMode()
+    val context = LocalContext.current
+
     val totalDuration by remember {
         derivedStateOf {
             streams.itemSnapshotList.sumOf { it!!.duration }
         }
     }
-
-    val context = LocalContext.current
     val onClick = { stream: StreamInfoItem ->
         NavigationHelper.openVideoDetailFragment(
             context, (context as FragmentActivity).supportFragmentManager,
@@ -56,17 +70,13 @@ fun Playlist(playlistViewModel: PlaylistViewModel = viewModel()) {
         )
     }
 
-    playlistInfo?.let {
-        Surface(color = MaterialTheme.colorScheme.background) {
-            val mode = determineItemViewMode()
-
     if (mode == ItemViewMode.GRID) {
         val gridState = rememberLazyGridState()
 
         LazyVerticalGridScrollbar(state = gridState) {
             LazyVerticalGrid(state = gridState, columns = GridCells.Adaptive(250.dp)) {
                 item(span = { GridItemSpan(maxLineSpan) }) {
-                            PlaylistHeader(playlistInfo = it, totalDuration = totalDuration)
+                    PlaylistHeader(playlistInfo, totalDuration)
                 }
 
                 items(streams.itemCount) {
@@ -81,7 +91,7 @@ fun Playlist(playlistViewModel: PlaylistViewModel = viewModel()) {
         LazyColumnScrollbar(state = listState) {
             LazyColumn(state = listState) {
                 item {
-                            PlaylistHeader(playlistInfo = it, totalDuration = totalDuration)
+                    PlaylistHeader(playlistInfo, totalDuration)
                 }
 
                 items(streams.itemCount) {
@@ -96,21 +106,24 @@ fun Playlist(playlistViewModel: PlaylistViewModel = viewModel()) {
         }
     }
 }
-    }
-}
 
 @Preview(name = "Light mode", uiMode = Configuration.UI_MODE_NIGHT_NO)
 @Preview(name = "Dark mode", uiMode = Configuration.UI_MODE_NIGHT_YES)
 @Composable
 private fun PlaylistPreview() {
     NewPipe.init(DownloaderImpl.init(null))
-    val params =
+
-        mapOf(
+    val playlistInfo = PlaylistInfo.getInfo(
-            KEY_SERVICE_ID to ServiceList.YouTube.serviceId,
+        ServiceList.YouTube,
-            KEY_URL to "https://www.youtube.com/playlist?list=PLAIcZs9N4171hRrG_4v32Ca2hLvSuQ6QI",
+        "https://www.youtube.com/playlist?list=PLAIcZs9N4171hRrG_4v32Ca2hLvSuQ6QI"
     )
+    val streams = Pager(PagingConfig(pageSize = 20, enablePlaceholders = false)) {
+        PlaylistItemsSource(playlistInfo)
+    }.flow
 
     AppTheme {
-        Playlist(PlaylistViewModel(SavedStateHandle(params)))
+        Surface(color = MaterialTheme.colorScheme.background) {
+            LoadedPlaylist(playlistInfo, streams)
+        }
     }
 }