Refactor HostApplicationLifetime retrieval and registration

Simplified and improved the retrieval and registration of the
HostApplicationLifetime service in BotApp.cs and BotBuilder.cs.
In BotApp.cs, the code now retrieves IHostApplicationLifetime
and casts it to HostApplicationLifetime, throwing an
InvalidOperationException if the cast fails. In BotBuilder.cs,
the registration of HostApplicationLifetime has been simplified
by removing the factory method and directly registering the
service. These changes enhance the robustness and clarity of
the code.

Author: bvdcode

Sources/TelegramBot/BotApp.cs

@@ -122,7 +122,8 @@ public async Task StartAsync(CancellationToken cancellationToken = default)
                 await hostedService.StartAsync(mergedToken);
                 _logger.LogInformation("Started '{hostedService}'.", hostedService.GetType().Name);
             }
-            var hostApplicationLifetime = _serviceProvider.GetRequiredService<HostApplicationLifetime>();
+            var hostApplicationLifetime = _serviceProvider.GetRequiredService<IHostApplicationLifetime>()
+                as HostApplicationLifetime ?? throw new InvalidOperationException("Host application lifetime is not registered.");
             hostApplicationLifetime.NotifyStarted();
         }
 
@@ -141,7 +142,8 @@ public async Task StopAsync(CancellationToken cancellationToken = default)
         {
             CheckDisposed();
             _logger.LogInformation("Stopping hosted services...");
-            var hostApplicationLifetime = _serviceProvider.GetRequiredService<HostApplicationLifetime>();
+            var hostApplicationLifetime = _serviceProvider.GetRequiredService<IHostApplicationLifetime>()
+                as HostApplicationLifetime ?? throw new InvalidOperationException("Host application lifetime is not registered.");
             hostApplicationLifetime.NotifyStopping();
             var hostedServices = _serviceProvider.GetServices<IHostedService>();
             List<Task> tasks = new List<Task>();

Sources/TelegramBot/Builders/BotBuilder.cs

@@ -140,7 +140,7 @@ public IBot Build()
             {
                 Services.AddSingleton<IKeyValueProvider, InMemoryKeyValueProvider>();
             }
-            Services.AddSingleton<IHostApplicationLifetime, HostApplicationLifetime>(x => new HostApplicationLifetime());
+            Services.AddSingleton<IHostApplicationLifetime, HostApplicationLifetime>();
             return new BotApp(client, Services.BuildServiceProvider());
         }
     }