Catel - Part 5 of n: Building a WPF example application with Catel in 1 hour

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Net;
using SocialMediaStream.UI.Windows;
using TweetSharp;

namespace SocialMediaStream.Providers.Twitter
{
    /// <summary>
    /// Social media provider for Twitter.
    /// </summary>
    public class TwitterProvider : SocialMediaProviderBase
    {
        #region Constants
        private const string ConsumerKey = "nsQMpd8qSUodHVox4NtEA";

        private const string ConsumerSecret = "iFVUiIQQMt89Dywi2VeIrWgJWBuB44Dv9qnPeQvw";

        private const string RequestTokenUrl = "https://twitter.com/oauth/request_token";

        private const string AccessTokenUrl = "https://twitter.com/oauth/access_token";

        private const string AuthorizeUrl = "https://twitter.com/oauth/authorize";
        #endregion

        #region Fields
        private readonly TwitterService _twitterService = new TwitterService(ConsumerKey, ConsumerSecret);
        private OAuthRequestToken _requestToken;
        private OAuthAccessToken _accessToken;
        #endregion

        #region Constructor & destructor
        /// <summary>
        /// Initializes a new instance of the <see cref="TwitterProvider"/> class.
        /// </summary>
        public TwitterProvider()
            : base("Twitter")
        {
        }
        #endregion

        #region Properties
        /// <summary>
        /// Gets or sets a value indicating whether this instance has an access token.
        /// </summary>
        /// <value>
        /// 	<c>true</c> if this instance has an access token; otherwise, <c>false</c>.
        /// </value>
        private bool HasAccessToken { get { return _accessToken != null; } }
        #endregion

        #region Methods
        /// <summary>
        /// Gets the last 10 updates.
        /// </summary>
        /// <returns>
        /// 	<see cref="IEnumerable{ISocialMediaEntry}"/> containing all the updates.
        /// </returns>
        public override IEnumerable<ISocialMediaEntry> GetLast10Updates()
        {
            List<ISocialMediaEntry> updates = new List<ISocialMediaEntry>();

            if (Connect())
            {
                try
                {
                    //IEnumerable<TwitterStatus> tweets = _twitterService.ListTweetsOnHomeTimeline(10);
                    IEnumerable<TwitterStatus> tweets = _twitterService.ListTweetsOnFriendsTimeline(10);
                    foreach (var tweet in tweets)
                    {
                        var entry = ConvertTwitterStatusToSocialMediaEntry(tweet);
                        if (entry != null)
                        {
                            updates.Add(entry);
                        }
                    }
                }
                catch (Exception ex)
                {
                    Log.Error(ex);
                }
            }

            return updates;
        }

        /// <summary>
        /// Converts the twitter status object to social media entry.
        /// </summary>
        /// <param name="entryAsTwitterStatus">The entry as twitter status.</param>
        /// <returns>
        /// New <see cref="ISocialMediaEntry"/> or <c>null</c> if the item could not be constructed.
        /// </returns>
        private ISocialMediaEntry ConvertTwitterStatusToSocialMediaEntry(TwitterStatus entryAsTwitterStatus)
        {
            Bitmap photo = GetBitmapFromUrl(entryAsTwitterStatus.Author.ProfileImageUrl);
            string author = entryAsTwitterStatus.Author.ScreenName;
            string message = entryAsTwitterStatus.Text;
            DateTime timestamp = entryAsTwitterStatus.CreatedDate;
            string url = string.Format("http://www.twitter.com/{0}", entryAsTwitterStatus.User.ScreenName);

            return new SocialMediaEntry(photo, author, message, timestamp, url, Name);
        }

        /// <summary>
        /// Connects this instance to twitter.
        /// </summary>
        /// <returns><c>true</c> if successful; otherwise <c>false</c>.</returns>
        private bool Connect()
        {
            if (!HasAccessToken)
            {
                try
                {
                    _requestToken = _twitterService.GetRequestToken();
                    Uri logInUrl = _twitterService.GetAuthenticationUrl(_requestToken);
                    AuthenticationWindow authWindow = new AuthenticationWindow(logInUrl.ToString(), ValidateLogin);
                    return authWindow.ShowDialog() ?? false;
                }
                catch (Exception ex)
                {
                    Log.Error(ex);
                    return false;
                }
            }

            return true;
        }

        /// <summary>
        /// Validates the login.
        /// </summary>
        /// <param name="url">The URL.</param>
        /// <param name="source">The source.</param>
        /// <returns>
        /// 	<c>true</c> if successful; otherwise <c>false</c>.
        /// </returns>
        private bool ValidateLogin(string url, string source)
        {
            if (url.ToLower().StartsWith("https://api.twitter.com/oauth/"))
            {
                // Pin is stored like this:
                //<div id="oauth_pin">
                //  1234567
                //</div>
                const string PinIdentifier = "<div id=oauth_pin>";

                try
                {
                    source = source.ToLower();
                    if (source.Contains(PinIdentifier))
                    {
                        // Extract the pin
                        int pinStart = source.IndexOf(PinIdentifier) + PinIdentifier.Length;
                        int pinEnd = source.IndexOf("</div>", pinStart);
                        string pin = source.Substring(pinStart, pinEnd - pinStart).Trim();

                        _accessToken = _twitterService.GetAccessToken(_requestToken, pin);
                        _twitterService.AuthenticateWith(_accessToken.Token, _accessToken.TokenSecret);
                        return true;
                    }
                }
                catch (Exception ex)
                {
                    Log.Error(ex);
                    return false;
                }
            }

            return false;
        }
        #endregion
    }
}