ContinuationManager.cs

//----------------------------------------------------------------------------------------------
//    Copyright 2014 Microsoft Corporation
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//----------------------------------------------------------------------------------------------

namespace OneNoteServiceSamplesWinUniversal
{
	using System;
	using System.Collections.Generic;
	using System.Linq;
	using System.Reflection;
	using System.Text;
	using System.Threading.Tasks;
	using Windows.ApplicationModel.Activation;
	using Windows.UI.Xaml;
	using Windows.UI.Xaml.Controls;

	/// <summary>
	/// ContinuationManager is used to detect if the most recent activation was due
	/// to a continuation such as the FileOpenPicker or WebAuthenticationBroker
	/// </summary>
	public class ContinuationManager
	{
		private IContinuationActivatedEventArgs args = null;
		private bool handled = false;
		private Guid id = Guid.Empty;

		/// <summary>
		/// Sets the ContinuationArgs for this instance. Using default Frame of current Window
		/// Should be called by the main activation handling code in App.xaml.cs
		/// </summary>
		/// <param name="args">The activation args</param>
		internal void Continue(IContinuationActivatedEventArgs args)
		{
			Continue(args, Window.Current.Content as Frame);
		}

		public bool HandleActivation(IContinuationActivatedEventArgs args, Frame rootFrame)
		{
			if (args.Kind == ActivationKind.WebAuthenticationBrokerContinuation)
			{
				var wabPage = rootFrame.Content as IWebAuthenticationContinuable;
				if (wabPage != null)
				{
					wabPage.ContinueWebAuthentication(args as WebAuthenticationBrokerContinuationEventArgs);
				}
				return true;
			}
			else
			{
				return false;
			}

		}

		/// <summary>
		/// Sets the ContinuationArgs for this instance. Should be called by the main activation
		/// handling code in App.xaml.cs
		/// </summary>
		/// <param name="args">The activation args</param>
		/// <param name="rootFrame">The frame control that contains the current page</param>
		internal void Continue(IContinuationActivatedEventArgs args, Frame rootFrame)
		{
			if (args == null)
				throw new ArgumentNullException("args");

			if (this.args != null && !handled)
				throw new InvalidOperationException("Can't set args more than once");

			this.args = args;
			this.handled = false;
			this.id = Guid.NewGuid();

			if (rootFrame == null)
				return;

			switch (args.Kind)
			{
				case ActivationKind.PickFileContinuation:
					break;

				case ActivationKind.PickSaveFileContinuation:
					break;

				case ActivationKind.PickFolderContinuation:
					break;

				case ActivationKind.WebAuthenticationBrokerContinuation:
					var wabPage = rootFrame.Content as IWebAuthenticationContinuable;

					if (wabPage != null)
					{
						wabPage.ContinueWebAuthentication(args as WebAuthenticationBrokerContinuationEventArgs);
					}
					break;
			}
		}

		/// <summary>
		/// Marks the contination data as 'stale', meaning that it is probably no longer of
		/// any use. Called when the app is suspended (to ensure future activations don't appear
		/// to be for the same continuation) and whenever the continuation data is retrieved 
		/// (so that it isn't retrieved on subsequent navigations)
		/// </summary>
		internal void MarkAsStale()
		{
			this.handled = true;
		}

		/// <summary>
		/// Retrieves the continuation args, if they have not already been retrieved, and 
		/// prevents further retrieval via this property (to avoid accidentla double-usage)
		/// </summary>
		public IContinuationActivatedEventArgs ContinuationArgs
		{
			get
			{
				if (handled)
					return null;
				MarkAsStale();
				return args;
			}
		}

		/// <summary>
		/// Unique identifier for this particular continuation. Most useful for components that 
		/// retrieve the continuation data via <see cref="GetContinuationArgs"/> and need
		/// to perform their own replay check
		/// </summary>
		public Guid Id
		{
			get { return id; }
		}

		/// <summary>
		/// Retrieves the continuation args, optionally retrieving them even if they have already
		/// been retrieved
		/// </summary>
		/// <param name="includeStaleArgs">Set to true to return args even if they have previously been returned</param>
		/// <returns>The continuation args, or null if there aren't any</returns>
		public IContinuationActivatedEventArgs GetContinuationArgs(bool includeStaleArgs)
		{
			if (!includeStaleArgs && handled)
				return null;
			MarkAsStale();
			return args;
		}
	}

	/// <summary>
	/// Implement this interface if your page invokes the web authentication
	/// broker
	/// </summary>
	internal interface IWebAuthenticationContinuable
	{
		/// <summary>
		/// This method is invoked when the web authentication broker returns
		/// with the authentication result
		/// </summary>
		/// <param name="args">Activated event args object that contains returned authentication token</param>
		void ContinueWebAuthentication(WebAuthenticationBrokerContinuationEventArgs args);
	}
}