Keep grid controls accessible if error occurs (#714)

## Description
If an error occurs while fetching data for the grid, leave the controls
accessible. This is useful in case a particular sort or filter causes an
error because the app remembers those values between page loads.

Essentially the error message is shown in place of the grid content
instead of the entire tab.

### Related issues
Fixes #712

app/src/main/java/com/github/damontecres/wholphin/ui/components/CollectionFolderGrid.kt

@@ -89,10 +89,10 @@ import com.github.damontecres.wholphin.ui.setValueOnMain
 import com.github.damontecres.wholphin.ui.toServerString
 import com.github.damontecres.wholphin.ui.tryRequestFocus
 import com.github.damontecres.wholphin.util.ApiRequestPager
+import com.github.damontecres.wholphin.util.DataLoadingState
 import com.github.damontecres.wholphin.util.ExceptionHandler
 import com.github.damontecres.wholphin.util.GetItemsRequestHandler
 import com.github.damontecres.wholphin.util.GetPersonsHandler
-import com.github.damontecres.wholphin.util.LoadingExceptionHandler
 import com.github.damontecres.wholphin.util.LoadingState
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
@@ -151,9 +151,8 @@ class CollectionFolderViewModel
             ): CollectionFolderViewModel
         }
 
-        val loading = MutableLiveData<LoadingState>(LoadingState.Loading)
+        val loading = MutableLiveData<DataLoadingState<List<BaseItem?>>>(DataLoadingState.Loading)
         val backgroundLoading = MutableLiveData<LoadingState>(LoadingState.Loading)
-        val pager = MutableLiveData<List<BaseItem?>>(listOf())
         val sortAndDirection = MutableLiveData<SortAndDirection>()
         val filter = MutableLiveData<GetItemsFilter>(GetItemsFilter())
         val viewOptions = MutableLiveData<ViewOptions>()
@@ -165,13 +164,9 @@ class CollectionFolderViewModel
             }
 
         init {
-            viewModelScope.launch(
+            viewModelScope.launchIO {
-                LoadingExceptionHandler(
-                    loading,
-                    context.getString(R.string.error_loading_collection, itemId),
-                ) + Dispatchers.IO,
-            ) {
                 super.itemId = itemId
+                try {
                     itemId.toUUIDOrNull()?.let {
                         fetchItem(it)
                     }
@@ -199,6 +194,10 @@ class CollectionFolderViewModel
                         }
 
                     loadResults(true, sortAndDirection, recursive, filterToUse, useSeriesForPrimary)
+                } catch (ex: Exception) {
+                    Timber.e(ex, "Error during init")
+                    loading.setValueOnMain(DataLoadingState.Error(ex))
+                }
             }
         }
 
@@ -269,8 +268,7 @@ class CollectionFolderViewModel
             viewModelScope.launch(Dispatchers.IO) {
                 withContext(Dispatchers.Main) {
                     if (resetState) {
-                        pager.value = listOf()
+                        loading.value = DataLoadingState.Loading
-                        loading.value = LoadingState.Loading
                     }
                     backgroundLoading.value = LoadingState.Loading
                     this@CollectionFolderViewModel.sortAndDirection.value = sortAndDirection
@@ -281,8 +279,7 @@ class CollectionFolderViewModel
                         createPager(sortAndDirection, recursive, filter, useSeriesForPrimary).init()
                     if (newPager.isNotEmpty()) newPager.getBlocking(0)
                     withContext(Dispatchers.Main) {
-                        pager.value = newPager
+                        loading.value = DataLoadingState.Success(newPager)
-                        loading.value = LoadingState.Success
                         backgroundLoading.value = LoadingState.Success
                     }
                 } catch (ex: Exception) {
@@ -293,8 +290,7 @@ class CollectionFolderViewModel
                         filter,
                     )
                     withContext(Dispatchers.Main) {
-                        loading.value = LoadingState.Error(ex)
+                        loading.value = DataLoadingState.Error(ex)
-                        pager.value = listOf()
                     }
                 }
             }
@@ -498,7 +494,9 @@ class CollectionFolderViewModel
             played: Boolean,
         ) = viewModelScope.launch(ExceptionHandler() + Dispatchers.IO) {
             favoriteWatchManager.setWatched(itemId, played)
-            (pager.value as? ApiRequestPager<*>)?.refreshItem(position, itemId)
+            (loading.value as? DataLoadingState.Success)?.let {
+                (it.data as? ApiRequestPager<*>)?.refreshItem(position, itemId)
+            }
         }
 
         fun setFavorite(
@@ -507,7 +505,9 @@ class CollectionFolderViewModel
             favorite: Boolean,
         ) = viewModelScope.launch(ExceptionHandler() + Dispatchers.IO) {
             favoriteWatchManager.setFavorite(itemId, favorite)
-            (pager.value as? ApiRequestPager<*>)?.refreshItem(position, itemId)
+            (loading.value as? DataLoadingState.Success)?.let {
+                (it.data as? ApiRequestPager<*>)?.refreshItem(position, itemId)
+            }
         }
 
         fun updateBackdrop(item: BaseItem) {
@@ -598,7 +598,6 @@ fun CollectionFolderGrid(
     val loading by viewModel.loading.observeAsState(LoadingState.Loading)
     val backgroundLoading by viewModel.backgroundLoading.observeAsState(LoadingState.Loading)
     val item by viewModel.item.observeAsState()
-    val pager by viewModel.pager.observeAsState()
     val viewOptions by viewModel.viewOptions.observeAsState(defaultViewOptions)
 
     var moreDialog by remember { mutableStateOf<Optional<PositionItem>>(Optional.absent()) }
@@ -606,18 +605,15 @@ fun CollectionFolderGrid(
     val playlistState by playlistViewModel.playlistState.observeAsState(PlaylistLoadingState.Pending)
 
     when (val state = loading) {
-        is LoadingState.Error -> {
+        DataLoadingState.Loading,
-            ErrorMessage(state)
+        DataLoadingState.Pending,
-        }
-
-        LoadingState.Loading,
-        LoadingState.Pending,
         -> {
             LoadingPage()
         }
 
-        LoadingState.Success -> {
+        is DataLoadingState.Error,
-            pager?.let { pager ->
+        is DataLoadingState.Success<*>,
+        -> {
             val title =
                 initialFilter.nameOverride
                     ?: item?.name
@@ -629,7 +625,7 @@ fun CollectionFolderGrid(
                     initialPosition = viewModel.position,
                     item = item,
                     title = title,
-                        pager = pager,
+                    loadingState = state as DataLoadingState<List<BaseItem?>>,
                     sortAndDirection = sortAndDirection!!,
                     modifier = Modifier.fillMaxSize(),
                     focusRequesterOnEmpty = focusRequesterOnEmpty,
@@ -698,7 +694,6 @@ fun CollectionFolderGrid(
             }
         }
     }
-    }
     moreDialog.compose { (position, item) ->
         DialogPopup(
             showDialog = true,
@@ -755,7 +750,7 @@ fun CollectionFolderGridContent(
     preferences: UserPreferences,
     item: BaseItem?,
     title: String,
-    pager: List<BaseItem?>,
+    loadingState: DataLoadingState<List<BaseItem?>>,
     sortAndDirection: SortAndDirection,
     onClickItem: (Int, BaseItem) -> Unit,
     onLongClickItem: (Int, BaseItem) -> Unit,
@@ -781,13 +776,14 @@ fun CollectionFolderGridContent(
 ) {
     val context = LocalContext.current
 
+    val pager = (loadingState as? DataLoadingState.Success)?.data
     var showHeader by rememberSaveable { mutableStateOf(true) }
     var showViewOptions by rememberSaveable { mutableStateOf(false) }
     var viewOptions by remember { mutableStateOf(viewOptions) }
     val headerRowFocusRequester = remember { FocusRequester() }
 
     val gridFocusRequester = remember { FocusRequester() }
-    if (pager.isNotEmpty()) {
+    if (pager?.isNotEmpty() == true) {
         RequestOrRestoreFocus(gridFocusRequester)
     } else {
         LaunchedEffect(Unit) {
@@ -797,7 +793,7 @@ fun CollectionFolderGridContent(
     var backdropImageUrl by remember { mutableStateOf<String?>(null) }
 
     var position by rememberInt(initialPosition)
-    val focusedItem = pager.getOrNull(position)
+    val focusedItem = pager?.getOrNull(position)
     if (viewOptions.showDetails) {
         LaunchedEffect(focusedItem) {
             focusedItem?.let(onChangeBackdrop)
@@ -810,7 +806,7 @@ fun CollectionFolderGridContent(
             modifier = Modifier.fillMaxSize(),
         ) {
             AnimatedVisibility(
-                showHeader,
+                showHeader || loadingState !is DataLoadingState.Success,
                 enter = slideInVertically() + fadeIn(),
                 exit = slideOutVertically() + fadeOut(),
             ) {
@@ -871,7 +867,7 @@ fun CollectionFolderGridContent(
                                 )
                             }
                         }
-                        if (playEnabled) {
+                        if (playEnabled && pager?.isNotEmpty() == true) {
                             Row(
                                 horizontalArrangement = Arrangement.spacedBy(8.dp),
                                 verticalAlignment = Alignment.CenterVertically,
@@ -903,8 +899,21 @@ fun CollectionFolderGridContent(
                             .padding(16.dp),
                 )
             }
+            when (val state = loadingState) {
+                DataLoadingState.Pending,
+                DataLoadingState.Loading,
+                -> {
+                    // This shouldn't happen, so just show placeholder
+                    Text("Loading")
+                }
+
+                is DataLoadingState.Error -> {
+                    ErrorMessage(state.message, state.exception)
+                }
+
+                is DataLoadingState.Success<List<BaseItem?>> -> {
                     CardGrid(
-                pager = pager,
+                        pager = state.data,
                         onClickItem = onClickItem,
                         onLongClickItem = onLongClickItem,
                         onClickPlay = onClickPlay,
@@ -948,6 +957,8 @@ fun CollectionFolderGridContent(
                 }
             }
         }
+    }
+}
 
 data class PositionItem(
     val position: Int,