text: ﻿using System;
  using System.Collections.Generic;
  using System.IO;
  using System.Linq;
  using System.Runtime.InteropServices.WindowsRuntime;
  using Windows.ApplicationModel;
  using Windows.ApplicationModel.Activation;
  using Windows.Foundation;
  using Windows.Foundation.Collections;
  using Windows.UI.Xaml;
  using Windows.UI.Xaml.Controls;
  using Windows.UI.Xaml.Controls.Primitives;
  using Windows.UI.Xaml.Data;
  using Windows.UI.Xaml.Input;
  using Windows.UI.Xaml.Media;
  using Windows.UI.Xaml.Navigation;
  
  namespace TodoList.UWP
  {
      /// <summary>
      /// Provides application-specific behavior to supplement the default Application class.
      /// </summary>
      sealed partial class App : Application
      {
          /// <summary>
          /// Initializes the singleton application object.  This is the first line of authored code
          /// executed, and as such is the logical equivalent of main() or WinMain().
          /// </summary>
          public App()
          {
              this.InitializeComponent();
              this.Suspending += OnSuspending;
          }
  
          /// <summary>
          /// Invoked when the application is launched normally by the end user.  Other entry points
          /// will be used such as when the application is launched to open a specific file.
          /// </summary>
          /// <param name="e">Details about the launch request and process.</param>
          protected override void OnLaunched(LaunchActivatedEventArgs e)
          {
  
  #if DEBUG
              if (System.Diagnostics.Debugger.IsAttached)
              {
                  this.DebugSettings.EnableFrameRateCounter = true;
              }
  #endif
  
              Frame rootFrame = Window.Current.Content as Frame;
  
              // Do not repeat app initialization when the Window already has content,
              // just ensure that the window is active
              if (rootFrame == null)
              {
                  // Create a Frame to act as the navigation context and navigate to the first page
                  rootFrame = new Frame();
  
                  rootFrame.NavigationFailed += OnNavigationFailed;
  
                  Xamarin.Forms.Forms.Init(e);
  
                  if (e.PreviousExecutionState == ApplicationExecutionState.Terminated)
                  {
                      //TODO: Load state from previously suspended application
                  }
  
                  // Place the frame in the current Window
                  Window.Current.Content = rootFrame;
              }
  
              if (rootFrame.Content == null)
              {
                  // When the navigation stack isn't restored navigate to the first page,
                  // configuring the new page by passing required information as a navigation
                  // parameter
                  rootFrame.Navigate(typeof(MainPage), e.Arguments);
              }
              // Ensure the current window is active
              Window.Current.Activate();
          }
  
          /// <summary>
          /// Invoked when Navigation to a certain page fails
          /// </summary>
          /// <param name="sender">The Frame which failed navigation</param>
          /// <param name="e">Details about the navigation failure</param>
          void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
          {
              throw new Exception("Failed to load Page " + e.SourcePageType.FullName);
          }
  
          /// <summary>
          /// Invoked when application execution is being suspended.  Application state is saved
          /// without knowing whether the application will be terminated or resumed with the contents
          /// of memory still intact.
          /// </summary>
          /// <param name="sender">The source of the suspend request.</param>
          /// <param name="e">Details about the suspend request.</param>
          private void OnSuspending(object sender, SuspendingEventArgs e)
          {
              var deferral = e.SuspendingOperation.GetDeferral();
              //TODO: Save application state and stop any background activity
              deferral.Complete();
          }
      }
  }
  