WebAuthenticationBroker_Facebook_Utility.cs

using System; 
using System.Threading.Tasks;
using Windows.Data.Json;
using Windows.Security.Authentication.Web;
using Windows.Web.Http;

namespace WabCS
{
class WebAuthenticationBroker_Facebook_Utility
{
public class FaceBook
{
    public string access_token { get; set; }
    public string expires_in { get; set; }
    public string Person_Name { get; set; }
}

static public async Task<FaceBook> Authentication()
{
    String FacebookClientIDText = "";
    String FacebookCallbackUrlText = "";

    String FacebookURL = "";
    FacebookURL += "https://www.facebook.com/dialog/oauth?client_id=";
    FacebookURL += Uri.EscapeDataString(FacebookClientIDText);
    FacebookURL += "&redirect_uri=";
    FacebookURL += Uri.EscapeDataString(FacebookCallbackUrlText);
    FacebookURL += "&scope=read_stream&display=popup&response_type=token";


    System.Uri StartUri = new Uri(FacebookURL);
    System.Uri EndUri = new Uri(FacebookCallbackUrlText);

    FaceBook fb = await AuthenticateAsync(StartUri, EndUri);
    return fb;
}

static private async Task<FaceBook> AuthenticateAsync(System.Uri StartUri,
                                                        System.Uri EndUri)
{
    try
    {
        string rowData = await GetHttpResponseAsync(StartUri, EndUri);
        FaceBook fb = Deserialize(rowData);
        fb.Person_Name = await GetPersonNameAsync(fb);
        return fb;
    }
    catch (Exception exp)
    {
        // exp.Message 
        return new FaceBook();
    }

}

static private async Task<string> GetHttpResponseAsync(System.Uri StartUri,
                                                         System.Uri EndUri)
{
    WebAuthenticationResult WebAuthenticationResult =
                          await WebAuthenticationBroker.
                          AuthenticateAsync(WebAuthenticationOptions.None,
                          StartUri,
                          EndUri);
    if (WebAuthenticationResult.ResponseStatus ==
                          WebAuthenticationStatus.Success)
    {

        return WebAuthenticationResult.ResponseData.ToString();

    }
    else if (WebAuthenticationResult.ResponseStatus ==
                          WebAuthenticationStatus.ErrorHttp)
    {
        // WebAuthenticationResult.ResponseErrorDetail.ToString()
        return String.Empty;
    }
    else
    {
        //WebAuthenticationResult.ResponseStatus.ToString()
        return String.Empty;
    }
}

static private FaceBook Deserialize(string webAuthResultResponseData)
{
    //Get Access Token first
    string responseData = webAuthResultResponseData.Substring(
                        webAuthResultResponseData.IndexOf("access_token"));
    String[] keyValPairs = responseData.Split('&');
    string access_token = null;
    string expires_in = null;
    for (int i = 0; i < keyValPairs.Length; i++)
    {
        String[] splits = keyValPairs[i].Split('=');
        switch (splits[0])
        {
            case "access_token":
                access_token = splits[1]; 
                break;
            case "expires_in":
                expires_in = splits[1];
                break;
        }
    }

    return new FaceBook() { access_token = access_token,
                             expires_in = expires_in };

}

static private async Task<string> GetPersonNameAsync(FaceBook fb)
{
    HttpClient httpClient = new HttpClient();
    string response = await httpClient.GetStringAsync(
            new Uri("https://graph.facebook.com/me?access_token=" 
                                             + fb.access_token));
    JsonObject value = JsonValue.Parse(response).GetObject();
    string facebookUserName = value.GetNamedString("name");
    return facebookUserName;
}


}

}