Twitter View Component

Default.cshtml

@model List<TwitterViewComponent.Tweet>

<h3>Recent Tweets</h3>
<ul>
  @foreach (var tweet in Model)
  {
    <li>
        @tweet.Message<br/>
        <a href="http://twitter.com/@tweet.Username/statuses/@tweet.Id">@(tweet.Timestamp)</a>
    </li>
</ul>

ITwitterService.cs

public interface ITwitterService
{
  string ObtainBearerToken(string consumerKey, string consumerSecret);
  Task<List<Tweet>> RetrieveTweetsAsync(TwitterOptions options);
}

RetrieveTweetsViewComponent.cs

public class RetrieveTweetsViewComponent : ViewComponent
{
  protected TwitterOptions TwitterOptions { get; private set; }

  public RetrieveTweetsViewComponent(IOptions<TwitterOptions> options = null)
  {
    if (options != null)
      TwitterOptions = options.Value;
    else
      TwitterOptions = new TwitterOptions();
  }

  public async Task<IViewComponentResult> InvokeAsync()
  {
    var service = new TwitterService();
    var tweets = await service.RetrieveTweetsAsync(TwitterOptions);
    return View("Default", tweets);
  }
}

ServiceCollectionExtensions.cs

public static class ServiceCollectionExtensions
{
  public static IServiceCollection AddTwitter(this IServiceCollection services, IConfiguration configuration = null)
  {
    if (configuration != null)
      services.Configure<TwitterOptions>(configuration);
    else
      services.TryAddSingleton<TwitterOptions, TwitterOptions>();

    services.TryAddScoped<ITwitterService, TwitterService>();

    return services;
  }
}

Token.cs

public class Token
{
  public string access_token { get; set; }
}

Tweet.cs

public class Tweet
{
  public string Username { get; set; }
  public string Message { get; set; }
  public string Avatar { get; set; }
  public string Timestamp { get; set; }
  public string Id { get; set; }
}

TweetRaw.cs

public class TweetRaw
{
  public string id_str { get; set; }
  public string text { get; set; }
  public string created_at { get; set; }
  public string in_reply_to_screen_name { get; set; }
  public UserRaw user { get; set; }
}

public class UserRaw
{
  public string id_str { get; set; }
  public string profile_image_url { get; set; }
  public string screen_name { get; set; }
}

TwitterOptions.cs

public class TwitterOptions
{
  [Required]
  public string ConsumerKey { get; set; } = "";
  [Required]
  public string ConsumerSecret { get; set; } = "";
  public string Username { get; set; }
}

TwitterService.cs

public class TwitterService : ITwitterService
{
  public string ObtainBearerToken(string consumerKey, string consumerSecret)
  {
    var applicationAuthorization = Convert.ToBase64String(Encoding.UTF8.GetBytes(string.Format("{0}:{1}", Uri.EscapeDataString(consumerKey), Uri.EscapeDataString(consumerSecret))));

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://api.twitter.com/oauth2/token");
    request.Headers.Add("Authorization", "Basic " + applicationAuthorization);
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded;charset=UTF-8";
    request.AutomaticDecompression = DecompressionMethods.GZip;
    using (StreamWriter writer = new StreamWriter(request.GetRequestStream()))
    {
      writer.Write("grant_type=client_credentials");
    }

    WebResponse response = request.GetResponse();
    var token = "";
    using (var reader = new StreamReader(response.GetResponseStream()))
    {
      token = reader.ReadToEnd();
    }

    return JsonConvert.DeserializeObject<Token>(token).access_token;
  }

  public async Task<List<Tweet>> RetrieveTweetsAsync(TwitterOptions options)
  {
    var tweets = new List<Tweet>();

    if (!string.IsNullOrEmpty(options.Username) && !string.IsNullOrEmpty(options.ConsumerKey) && !string.IsNullOrEmpty(options.ConsumerSecret))
    {
      var bearerToken = ObtainBearerToken(options.ConsumerKey, options.ConsumerSecret);

      var timelineUrl = 
        string.Format("https://api.twitter.com/1.1/statuses/user_timeline.json?exclude_replies={0}&screen_name={1}", 
          "false", 
          Uri.EscapeDataString(options.Username));
      HttpWebRequest request = (HttpWebRequest)WebRequest.Create(timelineUrl);
      request.Headers.Add("Authorization", "Bearer " + bearerToken);
      request.Method = "GET";
      request.ContentType = "application/x-www-form-urlencoded;charset=UTF-8";
      request.AutomaticDecompression = DecompressionMethods.GZip;

      WebResponse response = await request.GetResponseAsync();
      string responseData = await new StreamReader(response.GetResponseStream()).ReadToEndAsync();
      var jsonResponse = JsonConvert.DeserializeObject<IEnumerable<TweetRaw>>(responseData);

      tweets = jsonResponse.Select(t => 
        new Tweet() { Message = t.text,
          Username = t.user.screen_name,
          Avatar = t.user.profile_image_url,
          Timestamp = DateTime.ParseExact(t.created_at, "ddd MMM dd HH:mm:ss %zzzz yyyy", 
            CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal).ToFriendlyDate(),
          Id = t.id_str
      }).ToList();
    }

    return tweets;
  }
}