Implemented export to CSV functionality.

PcgsInvUi/Views/MainWindow.axaml.cs

@@ -1,5 +1,8 @@
 using System;
+using System.IO;
+using System.Reactive;
 using System.Threading.Tasks;
+using Avalonia.Platform.Storage;
 using Avalonia.ReactiveUI;
 using PcgsInvUi.ViewModels;
 using ReactiveUI;
@@ -10,7 +13,8 @@ public partial class MainWindow : ReactiveWindow<MainWindowViewModel> {
     public MainWindow() {
         InitializeComponent();
         this.WhenActivated(d => d(ViewModel!.ShowDeleteWindow.RegisterHandler(ShowDeleteWindowAsync)));
-        this.WhenActivated(d => d(ViewModel!.ShowFindWindow.RegisterHandler(ShowFindWindowAsync)));
+        this.WhenActivated(d => d(ViewModel!.ShowExportWindow.RegisterHandler(ShowFilePickerAsync)));
+        // this.WhenActivated(d => d(ViewModel!.ShowFindWindow.RegisterHandler(ShowFindWindowAsync)));
     }
 
     public async Task ShowDeleteWindowAsync(InteractionContext<DeleteWindowViewModel, Boolean> interaction) {
@@ -28,4 +32,22 @@ public partial class MainWindow : ReactiveWindow<MainWindowViewModel> {
         var result = await window.ShowDialog<int>(this);
         interaction.SetOutput(result);
     }
+
+    public async Task ShowFilePickerAsync(InteractionContext<Unit, Stream> interationContext) {
+        var topLevel = GetTopLevel(this);
+        var file = await topLevel.StorageProvider.SaveFilePickerAsync(new FilePickerSaveOptions {
+            Title = "Save CSV...",
+            DefaultExtension = ".csv",
+            ShowOverwritePrompt = true,
+            SuggestedFileName = "coins.csv",
+            SuggestedStartLocation = await StorageProvider.TryGetWellKnownFolderAsync(WellKnownFolder.Documents)
+        });
+
+        Stream stream;
+        
+        if (file is not null) {
+            stream = await file.OpenWriteAsync();
+            interationContext.SetOutput(stream);
+        }
+    }
 }