﻿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 SkiaSharpFormsDemos. 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();
        }
    }
}
