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

namespace POSV.Utils
{
    public class RequestUtils
    {
        public static string Post(string url, SortedList<string, string> parameters)
        {
            var sb = new StringBuilder();
            foreach (var item in parameters)
            {
                if (sb.ToString().Length != 0)
                {
                    sb.Append("&");
                }
                var key = Uri.EscapeDataString(item.Key).Replace("%20", "+");
                var value = Uri.EscapeDataString(item.Value).Replace("%20", "+");
                sb.Append(key + "=" + value);
            }
            MemoryStream request = RequestUtils.Post(url, sb.ToString());

            return System.Text.Encoding.UTF8.GetString(request.ToArray());
        }

        public static MemoryStream Post(string url, string data)
        {
            return Post(url, data, Encoding.UTF8);
        }

        public static MemoryStream Post(string url, string data, Encoding encoding)
        {
            return Post(url, data, 10000, Encoding.UTF8);
        }

        public static MemoryStream Post(string url, string data, int timeout, Encoding encoding)
        {
            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);
            webRequest.ContentType = "application/json";
            webRequest.Method = "POST";
            webRequest.Timeout = timeout;
            WriteRequestStream(ref webRequest, data, encoding);
            return GetResponseStream(ref webRequest);
        }

        private static void WriteRequestStream(ref HttpWebRequest webRequest, string data, Encoding encoding)
        {
            using (Stream requestStream = webRequest.GetRequestStream())
            {
                byte[] bArray = encoding.GetBytes(data);
                requestStream.Write(bArray, 0, bArray.Length);
                requestStream.Close();
            }
        }

        private static MemoryStream GetResponseStream(ref HttpWebRequest webRequest)
        {
            using (WebResponse webResponse = webRequest.GetResponse())
            {
                Stream stream = webResponse.GetResponseStream();
                MemoryStream memoryStream = new MemoryStream();
                byte[] bs = new byte[256];
                for (int j = stream.Read(bs, 0, (int)bs.Length); j > 0; j = stream.Read(bs, 0, (int)bs.Length))
                {
                    memoryStream.Write(bs, 0, j);
                }
                stream.Close();
                memoryStream.Position = (long)0;
                return memoryStream;
            }
        }
    }
}