//-----------------------------------------------------------------------
// <copyright file="TwitterConsumer.cs" company="Outercurve Foundation">
//     Copyright (c) Outercurve Foundation. All rights reserved.
// </copyright>
//-----------------------------------------------------------------------

namespace DotNetOpenAuth.ApplicationBlock {
	using System;
	using System.Collections.Generic;
	using System.Configuration;
	using System.Globalization;
	using System.IO;
	using System.Net;
	using System.Web;
	using System.Xml;
	using System.Xml.Linq;
	using System.Xml.XPath;
	using DotNetOpenAuth.Messaging;
	using DotNetOpenAuth.OAuth;
	using DotNetOpenAuth.OAuth.ChannelElements;

	/// <summary>
	/// A consumer capable of communicating with Twitter.
	/// </summary>
	public static class TwitterConsumer {
		/// <summary>
		/// The description of Twitter's OAuth protocol URIs for use with actually reading/writing
		/// a user's private Twitter data.
		/// </summary>
		public static readonly ServiceProviderDescription ServiceDescription = new ServiceProviderDescription {
			RequestTokenEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/request_token", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			UserAuthorizationEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/authorize", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			AccessTokenEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/access_token", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			TamperProtectionElements = new ITamperProtectionChannelBindingElement[] { new HmacSha1SigningBindingElement() },
		};

		/// <summary>
		/// The description of Twitter's OAuth protocol URIs for use with their "Sign in with Twitter" feature.
		/// </summary>
		public static readonly ServiceProviderDescription SignInWithTwitterServiceDescription = new ServiceProviderDescription {
			RequestTokenEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/request_token", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			UserAuthorizationEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/authenticate", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			AccessTokenEndpoint = new MessageReceivingEndpoint("http://twitter.com/oauth/access_token", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest),
			TamperProtectionElements = new ITamperProtectionChannelBindingElement[] { new HmacSha1SigningBindingElement() },
		};

		/// <summary>
		/// The URI to get a user's favorites.
		/// </summary>
		private static readonly MessageReceivingEndpoint GetFavoritesEndpoint = new MessageReceivingEndpoint("http://twitter.com/favorites.xml", HttpDeliveryMethods.GetRequest);

		/// <summary>
		/// The URI to get the data on the user's home page.
		/// </summary>
		private static readonly MessageReceivingEndpoint GetFriendTimelineStatusEndpoint = new MessageReceivingEndpoint("http://twitter.com/statuses/friends_timeline.xml", HttpDeliveryMethods.GetRequest);

		private static readonly MessageReceivingEndpoint UpdateProfileBackgroundImageEndpoint = new MessageReceivingEndpoint("http://twitter.com/account/update_profile_background_image.xml", HttpDeliveryMethods.PostRequest | HttpDeliveryMethods.AuthorizationHeaderRequest);

		private static readonly MessageReceivingEndpoint UpdateProfileImageEndpoint = new MessageReceivingEndpoint("http://twitter.com/account/update_profile_image.xml", HttpDeliveryMethods.PostRequest | HttpDeliveryMethods.AuthorizationHeaderRequest);

		private static readonly MessageReceivingEndpoint VerifyCredentialsEndpoint = new MessageReceivingEndpoint("http://api.twitter.com/1/account/verify_credentials.xml", HttpDeliveryMethods.GetRequest | HttpDeliveryMethods.AuthorizationHeaderRequest);

		/// <summary>
		/// The consumer used for the Sign in to Twitter feature.
		/// </summary>
		private static WebConsumer signInConsumer;

		/// <summary>
		/// The lock acquired to initialize the <see cref="signInConsumer"/> field.
		/// </summary>
		private static object signInConsumerInitLock = new object();

		/// <summary>
		/// Initializes static members of the <see cref="TwitterConsumer"/> class.
		/// </summary>
		static TwitterConsumer() {
			// Twitter can't handle the Expect 100 Continue HTTP header. 
			ServicePointManager.FindServicePoint(GetFavoritesEndpoint.Location).Expect100Continue = false;
		}

		/// <summary>
		/// Gets a value indicating whether the Twitter consumer key and secret are set in the web.config file.
		/// </summary>
		public static bool IsTwitterConsumerConfigured {
			get {
				return !string.IsNullOrEmpty(ConfigurationManager.AppSettings["twitterConsumerKey"]) &&
					!string.IsNullOrEmpty(ConfigurationManager.AppSettings["twitterConsumerSecret"]);
			}
		}

		/// <summary>
		/// Gets the consumer to use for the Sign in to Twitter feature.
		/// </summary>
		/// <value>The twitter sign in.</value>
		private static WebConsumer TwitterSignIn {
			get {
				if (signInConsumer == null) {
					lock (signInConsumerInitLock) {
						if (signInConsumer == null) {
							signInConsumer = new WebConsumer(SignInWithTwitterServiceDescription, ShortTermUserSessionTokenManager);
						}
					}
				}

				return signInConsumer;
			}
		}

		private static InMemoryTokenManager ShortTermUserSessionTokenManager {
			get {
				var store = HttpContext.Current.Session;
				var tokenManager = (InMemoryTokenManager)store["TwitterShortTermUserSessionTokenManager"];
				if (tokenManager == null) {
					string consumerKey = ConfigurationManager.AppSettings["twitterConsumerKey"];
					string consumerSecret = ConfigurationManager.AppSettings["twitterConsumerSecret"];
					if (IsTwitterConsumerConfigured) {
						tokenManager = new InMemoryTokenManager(consumerKey, consumerSecret);
						store["TwitterShortTermUserSessionTokenManager"] = tokenManager;
					} else {
						throw new InvalidOperationException("No Twitter OAuth consumer key and secret could be found in web.config AppSettings.");
					}
				}

				return tokenManager;
			}
		}

		public static XDocument GetUpdates(ConsumerBase twitter, string accessToken) {
			IncomingWebResponse response = twitter.PrepareAuthorizedRequestAndSend(GetFriendTimelineStatusEndpoint, accessToken);
			return XDocument.Load(XmlReader.Create(response.GetResponseReader()));
		}

		public static XDocument GetFavorites(ConsumerBase twitter, string accessToken) {
			IncomingWebResponse response = twitter.PrepareAuthorizedRequestAndSend(GetFavoritesEndpoint, accessToken);
			return XDocument.Load(XmlReader.Create(response.GetResponseReader()));
		}

		public static XDocument UpdateProfileBackgroundImage(ConsumerBase twitter, string accessToken, string image, bool tile) {
			var parts = new[] {
				MultipartPostPart.CreateFormFilePart("image", image, "image/" + Path.GetExtension(image).Substring(1).ToLowerInvariant()),
				MultipartPostPart.CreateFormPart("tile", tile.ToString().ToLowerInvariant()),
			};
			HttpWebRequest request = twitter.PrepareAuthorizedRequest(UpdateProfileBackgroundImageEndpoint, accessToken, parts);
			request.ServicePoint.Expect100Continue = false;
			IncomingWebResponse response = twitter.Channel.WebRequestHandler.GetResponse(request);
			string responseString = response.GetResponseReader().ReadToEnd();
			return XDocument.Parse(responseString);
		}

		public static XDocument UpdateProfileImage(ConsumerBase twitter, string accessToken, string pathToImage) {
			string contentType = "image/" + Path.GetExtension(pathToImage).Substring(1).ToLowerInvariant();
			return UpdateProfileImage(twitter, accessToken, File.OpenRead(pathToImage), contentType);
		}

		public static XDocument UpdateProfileImage(ConsumerBase twitter, string accessToken, Stream image, string contentType) {
			var parts = new[] {
				MultipartPostPart.CreateFormFilePart("image", "twitterPhoto", contentType, image),
			};
			HttpWebRequest request = twitter.PrepareAuthorizedRequest(UpdateProfileImageEndpoint, accessToken, parts);
			IncomingWebResponse response = twitter.Channel.WebRequestHandler.GetResponse(request);
			string responseString = response.GetResponseReader().ReadToEnd();
			return XDocument.Parse(responseString);
		}

		public static XDocument VerifyCredentials(ConsumerBase twitter, string accessToken) {
			IncomingWebResponse response = twitter.PrepareAuthorizedRequestAndSend(VerifyCredentialsEndpoint, accessToken);
			return XDocument.Load(XmlReader.Create(response.GetResponseReader()));
		}

		public static string GetUsername(ConsumerBase twitter, string accessToken) {
			XDocument xml = VerifyCredentials(twitter, accessToken);
			XPathNavigator nav = xml.CreateNavigator();
			return nav.SelectSingleNode("/user/screen_name").Value;
		}

		/// <summary>
		/// Prepares a redirect that will send the user to Twitter to sign in.
		/// </summary>
		/// <param name="forceNewLogin">if set to <c>true</c> the user will be required to re-enter their Twitter credentials even if already logged in to Twitter.</param>
		/// <returns>The redirect message.</returns>
		/// <remarks>
		/// Call <see cref="OutgoingWebResponse.Send"/> or
		/// <c>return StartSignInWithTwitter().<see cref="MessagingUtilities.AsActionResult">AsActionResult()</see></c>
		/// to actually perform the redirect.
		/// </remarks>
		public static OutgoingWebResponse StartSignInWithTwitter(bool forceNewLogin) {
			var redirectParameters = new Dictionary<string, string>();
			if (forceNewLogin) {
				redirectParameters["force_login"] = "true";
			}
			Uri callback = MessagingUtilities.GetRequestUrlFromContext().StripQueryArgumentsWithPrefix("oauth_");
			var request = TwitterSignIn.PrepareRequestUserAuthorization(callback, null, redirectParameters);
			return TwitterSignIn.Channel.PrepareResponse(request);
		}

		/// <summary>
		/// Checks the incoming web request to see if it carries a Twitter authentication response,
		/// and provides the user's Twitter screen name and unique id if available.
		/// </summary>
		/// <param name="screenName">The user's Twitter screen name.</param>
		/// <param name="userId">The user's Twitter unique user ID.</param>
		/// <returns>
		/// A value indicating whether Twitter authentication was successful;
		/// otherwise <c>false</c> to indicate that no Twitter response was present.
		/// </returns>
		public static bool TryFinishSignInWithTwitter(out string screenName, out int userId) {
			screenName = null;
			userId = 0;
			var response = TwitterSignIn.ProcessUserAuthorization();
			if (response == null) {
				return false;
			}

			screenName = response.ExtraData["screen_name"];
			userId = int.Parse(response.ExtraData["user_id"]);

			// If we were going to make this LOOK like OpenID even though it isn't,
			// this seems like a reasonable, secure claimed id to allow the user to assume.
			OpenId.Identifier fake_claimed_id = string.Format(CultureInfo.InvariantCulture, "http://twitter.com/{0}#{1}", screenName, userId);

			return true;
		}
	}
}