// Copyright (c) Microsoft. All rights reserved.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
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;
using SDKTemplate.Common;

namespace SDKTemplate
{
    /// <summary>
    /// Provides application-specific behavior to supplement the default Application class.
    /// </summary>
    sealed partial class App : Application
    {
#if WINDOWS_PHONE_APP
        ContinuationManager continuationManager;
#endif
        /// <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;
        }

        private Frame CreateRootFrame()
        {
            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();

                // Set the default language
                rootFrame.Language = Windows.Globalization.ApplicationLanguages.Languages[0];
                rootFrame.NavigationFailed += OnNavigationFailed;

                // Place the frame in the current Window
                Window.Current.Content = rootFrame;
            }

            return rootFrame;
        }

        private async Task RestoreStatusAsync(ApplicationExecutionState previousExecutionState)
        {
            // Do not repeat app initialization when the Window already has content,
            // just ensure that the window is active
            if (previousExecutionState == ApplicationExecutionState.Terminated)
            {
                // Restore the saved session state only when appropriate
                try
                {
                    await SuspensionManager.RestoreAsync();
                }
                catch (SuspensionManagerException)
                {
                    //Something went wrong restoring state.
                    //Assume there is no state and continue
                }
            }
        }

#if WINDOWS_PHONE_APP
        /// <summary>
        /// Handle OnActivated event to deal with File Open/Save continuation activation kinds
        /// </summary>
        /// <param name="e">Application activated event arguments, it can be casted to proper sub-type based on ActivationKind</param>
        protected async override void OnActivated(IActivatedEventArgs e)
        {
            base.OnActivated(e);

            continuationManager = new ContinuationManager();

            Frame rootFrame = CreateRootFrame();
            await RestoreStatusAsync(e.PreviousExecutionState);

            if(rootFrame.Content == null)
            {
                rootFrame.Navigate(typeof(MainPage));
            }

            var continuationEventArgs = e as IContinuationActivatedEventArgs;
            if (continuationEventArgs != null)
            {
                Frame scenarioFrame = MainPage.Current.FindName("ScenarioFrame") as Frame;
                if (scenarioFrame != null)
				{
                    // Call ContinuationManager to handle continuation activation
                    continuationManager.Continue(continuationEventArgs, scenarioFrame);
                }
            }

            Window.Current.Activate();
        }
#endif

        /// <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 async override void OnLaunched(LaunchActivatedEventArgs e)
        {
            Frame rootFrame = CreateRootFrame();
            await RestoreStatusAsync(e.PreviousExecutionState);

            //MainPage is always in rootFrame so we don't have to worry about restoring the navigation state on resume
            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 async void OnSuspending(object sender, SuspendingEventArgs e)
        {
            var deferral = e.SuspendingOperation.GetDeferral();
            await SuspensionManager.SaveAsync();
            deferral.Complete();
        }
    }
}
