using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Security.Cryptography;

namespace SeniorIT.ServerAdmin.ServiceAgents
{
    public class QuickBloxAgent
    {
        public static string GetToken()
        {
            HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create("https://api.quickblox.com/session.xml");

            string application_id = "xxxx";
            string auth_key = "xxxxxxxxx";
            string auth_secret = "xxxxxxx";

            ASCIIEncoding encoding = new ASCIIEncoding();
            string postData = "application_id=" + application_id;
            postData += "&auth_key=" + auth_key;
            postData += "&nonce=" + GetNonce();
            postData += "&timestamp=" + GetTimestamp();

            string signature = GetHashString(auth_secret, postData);
            postData += "&signature=" + signature;
            byte[] data = encoding.GetBytes(postData);

            httpWReq.Method = "POST";
            httpWReq.ContentType = "application/x-www-form-urlencoded";
            httpWReq.ContentLength = data.Length;
            httpWReq.Headers["QuickBlox-REST-API-Version"] = "0.1.0";

            using (Stream stream = httpWReq.GetRequestStream())
            {
                stream.Write(data, 0, data.Length);
            }

            try
            {
                HttpWebResponse response = (HttpWebResponse)httpWReq.GetResponse();

                string responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();

                return responseString;
            }
            catch (Exception ex)
            {
                string err = ex.Message;

                return null;
            }
        }

        private static int GetNonce()
        {
            return new Random().Next(1000, 9999);
        }

        private static string GetTimestamp()
        {
            long ticks = DateTime.UtcNow.Ticks - DateTime.Parse("01/01/1970 00:00:00").Ticks;
            ticks /= 10000000;

            return ticks.ToString();
        }

        private static byte[] GetHash(string inputString)
        {
            HashAlgorithm algorithm = HMACSHA1.Create();

            return algorithm.ComputeHash(Encoding.UTF8.GetBytes(inputString));
        }

        private static string GetHashString(string secret, string postdata)
        {
            StringBuilder sb = new StringBuilder();

            foreach (byte b in GetHash(string.Format("{0}{1}", secret, postdata)))
            {
                sb.Append(b.ToString("X2"));
            }

            return sb.ToString();
        }
    }
}