TwitterStream.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Dimebrain.TweetSharp.Extensions;
using Dimebrain.TweetSharp.Fluent;
using Dimebrain.TweetSharp.Model;

namespace Carrier.Extension.Twitter
{
	public interface ITwitterStream
	{
		ITwitterCredentials Credentials { get; set; }
		IEnumerable<TwitterDirectMessage> GetDirectMessages();
	}

	public class TwitterStream : ITwitterStream
	{
		private readonly ITwitterIdentifierRepository _identifierRepository;
		public ITwitterCredentials Credentials { get; set; }

		public TwitterStream(ITwitterIdentifierRepository identifierRepository, ITwitterCredentials credentials)
		{
			_identifierRepository = identifierRepository;
			Credentials = credentials;
		}
		
		public IEnumerable<TwitterDirectMessage> GetDirectMessages()
		{
			// Get the public timeline
			var twitter = AuthenticatedRequest().DirectMessages().Received();

			AddSinceClause(twitter);

			var response = twitter.Request();
			var directMessages = response.AsDirectMessages();

			RememberMostRecentDirectMessageIdentifier(directMessages);

			CheckResponseForError(response);

			return directMessages;
		}

		private void AddSinceClause(ITwitterDirectMessagesReceived twitter)
		{
			var mostRecentTweetId = _identifierRepository.Get();	
			if (mostRecentTweetId.HasValue)
				twitter.Since(mostRecentTweetId.Value);
		}

		private void RememberMostRecentDirectMessageIdentifier(IEnumerable<TwitterDirectMessage> directMessages)
		{
			if (directMessages != null && directMessages.Count() > 0)
				_identifierRepository.Save(directMessages.First().Id);
		}

		private static void CheckResponseForError(string response)
		{
			var error = response.AsError();
			if (error != null && !String.IsNullOrEmpty(error.ErrorMessage))
				throw new Exception(error.ErrorMessage);
		}

		private IFluentTwitter AuthenticatedRequest()
		{
			return FluentTwitter.CreateRequest().AuthenticateAs(Credentials.UserName, Credentials.Password);
		}
	}
}