using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Web;
using System.Runtime.Serialization.Json;

namespace Translator
{
    class AdmAuthentication
    {
        public static readonly string DatamarketAccessUri = "https://datamarket.accesscontrol.windows.net/v2/OAuth2-13";
        private string clientId;
        private string cientSecret;
        private string request;

        public AdmAuthentication(string clientId, string clientSecret)
        {
            this.clientId = clientId;
            this.cientSecret = clientSecret;
            //If clientid or client secret has special characters, encode before sending request
            this.request = string.Format("grant_type=client_credentials&client_id={0}&client_secret={1}&scope=http://api.microsofttranslator.com",
                HttpUtility.UrlEncode(clientId), HttpUtility.UrlEncode(clientSecret));
        }

        public AdmAccessToken GetAccessToken()
        {
            return HttpPost(DatamarketAccessUri, this.request);
        }

        private AdmAccessToken HttpPost(string DatamarketAccessUri, string requestDetails)
        {
            //Prepare OAuth request 
            WebRequest webRequest = WebRequest.Create(DatamarketAccessUri);
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.Method = "POST";
            byte[] bytes = Encoding.ASCII.GetBytes(requestDetails);
            webRequest.ContentLength = bytes.Length;
            using (Stream outputStream = webRequest.GetRequestStream())
            {
                outputStream.Write(bytes, 0, bytes.Length);
            }
            using (WebResponse webResponse = webRequest.GetResponse())
            {
                DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(AdmAccessToken));
                //Get deserialized object from JSON stream
                AdmAccessToken token = (AdmAccessToken)serializer.ReadObject(webResponse.GetResponseStream());
                return token;
            }
        }
    }
}
