MultiformRequest

namespace Zelka.Apis
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Net;
    using System.Text;

    public class MultiformRequest
    {
        private const string DefaultUserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.154 Safari/537.36 OPR/20.0.1387.82";

        private readonly string Boundary;

        public MultiformRequest(string url)
        {
            this.Url = url;
            this.Boundary = GetNewBoundary();
            this.Stream = new MemoryStream();
            this.RequestParameters = new List<IRequestParameter>();
            this.Encoding = Encoding.UTF8;
            this.UserAgent = DefaultUserAgent;
            this.CookieContainer = new CookieContainer();
        }

        public string Url { get; set; }

        public Encoding Encoding { get; set; }

        private Stream Stream { get; set; }

        public string UserAgent { get; set; }

        public CookieContainer CookieContainer { get; set; }

        public List<IRequestParameter> RequestParameters { get; set; }

        public HttpWebResponse GetResponse()
        {
            this.AddRequestParameters();
            this.AddRequestFooter();

            byte[] requestData = this.GetDataFromStream();

            HttpWebRequest request = this.BuildRequest(requestData);

            return request.GetResponse() as HttpWebResponse;
        }

        private HttpWebRequest BuildRequest(byte[] requestData)
        {
            HttpWebRequest request = WebRequest.Create(this.Url) as HttpWebRequest;

            request.Method = "POST";
            request.ContentType = "multipart/form-data; boundary=" + this.Boundary;
            request.UserAgent = this.UserAgent;
            request.CookieContainer = this.CookieContainer;
            request.ContentLength = requestData.Length;

            WriteDataToStream(requestData, request.GetRequestStream());

            return request;
        }

        private static void WriteDataToStream(byte[] requestData, Stream stream)
        {
            stream.Write(requestData, 0, requestData.Length);
            stream.Close();
        }

        private byte[] GetDataFromStream()
        {
            this.Stream.Position = 0;
            byte[] formData = new byte[this.Stream.Length];
            this.Stream.Read(formData, 0, formData.Length);
            this.Stream.Close();
            return formData;
        }

        private void AddRequestParameters()
        {
            bool needsNewLine = false;

            foreach (IRequestParameter parameter in this.RequestParameters)
            {
                if (needsNewLine)
                {
                    this.Stream.Write(this.Encoding.GetBytes("\r\n"), 0, this.Encoding.GetByteCount("\r\n"));
                }

                needsNewLine = true;

                parameter.WriteToStream(this.Stream, this.Boundary, this.Encoding);
            }
        }

        private void AddRequestFooter()
        {
            string footer = "\r\n--" + this.Boundary + "--\r\n";
            this.Stream.Write(this.Encoding.GetBytes(footer), 0, this.Encoding.GetByteCount(footer));
        }

        private static string GetNewBoundary()
        {
            return string.Format("----------{0:N}", Guid.NewGuid());
        }
    }
}