Add UserAgent setting

src/Markdowser/Models/Settings.cs

@@ -1,6 +1,7 @@
 using Markdowser.Utilities;
 
 using System.IO;
+using System.Reflection;
 using System.Text.Json;
 
 namespace Markdowser.Models;
@@ -15,6 +16,8 @@ public class Settings
 
     public string? HomeUrl { get; set; }
 
+    public string UserAgent { get; set; } = $"{Assembly.GetExecutingAssembly().GetName().Name}/{Assembly.GetExecutingAssembly().GetName().Version?.ToString()}";
+
     public static void SaveSettings()
     {
         if (!Directory.Exists(Configuration.ApplicationDataPath))

src/Markdowser/ViewModels/MainWindowViewModel.cs

@@ -161,7 +161,6 @@ public partial class MainWindowViewModel : ViewModelBase
 
     public MainWindowViewModel()
     {
-        httpClient.DefaultRequestHeaders.UserAgent.ParseAdd($"{nameof(Markdowser)}/{Assembly.GetExecutingAssembly().GetName().Version?.ToString()}");
         httpClient.Timeout = TimeSpan.FromSeconds(10);
 
         content = DefaultContent;
@@ -232,6 +231,13 @@ public partial class MainWindowViewModel : ViewModelBase
             }
         }
 
+        httpClient.DefaultRequestHeaders.UserAgent.Clear();
+        if (!httpClient.DefaultRequestHeaders.UserAgent.TryParseAdd(Settings.Current.UserAgent))
+        {
+            WindowNotificationManager.Show(new Notification("Invalid User Agent", "Failed to set user agent.", NotificationType.Error));
+            return;
+        }
+
         IsBusy = true;
         Progress = 0;
 

src/Markdowser/ViewModels/SettingsViewModel.cs

@@ -16,6 +16,12 @@ public class SettingsViewModel : ViewModelBase
         set => Settings.Current.SearchEngineUrl = value;
     }
 
+    public string UserAgent
+    {
+        get => Settings.Current.UserAgent;
+        set => Settings.Current.UserAgent = value;
+    }
+
     public bool DarkMode
     {
         get => Settings.Current.DarkMode;

src/Markdowser/Views/SettingsView.axaml

@@ -28,5 +28,8 @@
 
         <TextBlock Text="Home URL" />
         <TextBox Text="{Binding HomeUrl}" Watermark="URL, or leave empty to use default" />
+
+        <TextBlock Text="User Agent" />
+        <TextBox Text="{Binding UserAgent}" Watermark="User agent string" />
     </StackPanel>
 </UserControl>