remember selected collection (#36)

ErsatzTV/Shared/AddToCollectionDialog.razor

@@ -1,6 +1,8 @@
-@using ErsatzTV.Application.MediaCollections
+@using Microsoft.Extensions.Caching.Memory
+@using ErsatzTV.Application.MediaCollections
 @using ErsatzTV.Application.MediaCollections.Queries
 @inject IMediator Mediator
+@inject IMemoryCache MemoryCache
 
 <MudDialog>
     <DialogContent>
@@ -46,12 +48,22 @@
 
     private MediaCollectionViewModel _selectedCollection;
 
-    protected override async Task OnParametersSetAsync() =>
+    protected override async Task OnParametersSetAsync()
+    {
         _collections = await Mediator.Send(new GetAllCollections());
+        if (MemoryCache.TryGetValue("AddToCollectionDialog.SelectedCollectionId", out int id))
+        {
+            _selectedCollection = _collections.SingleOrDefault(c => c.Id == id);
+        }
+    }
 
     private string FormatText() => $"Select the collection to add the {EntityType} {EntityName}";
 
-    private void Submit() => MudDialog.Close(DialogResult.Ok(_selectedCollection));
+    private void Submit()
+    {
+        MemoryCache.Set("AddToCollectionDialog.SelectedCollectionId", _selectedCollection.Id);
+        MudDialog.Close(DialogResult.Ok(_selectedCollection));
+    }
 
     private void Cancel() => MudDialog.Cancel();