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

namespace TestUpload
{
    public delegate void UploadCallback(ImageShackUploadDetails details, Exception e);

    public class ImageShackUploader
    {
        class UploadState
        {
            public HttpWebRequest Request { get; set; }
            public UploadCallback Callback { get; set; }
        }

        public static void UploadImage(string filename, UploadCallback callback)
        {
            if (callback == null)
                throw new ArgumentNullException("callback", "upload is asynchronous and must provide a callback");

            try
            {
                HttpWebRequest request = GetImageShackRequest(
                    filename,
                    "http://iload2.imageshack.us/upload_api.php?swfupload=1&cookie=&optsize=resample&ulevel=&nocache=29632");

                request.BeginGetResponse(
                    new AsyncCallback(GetImageShackResponse),
                    new UploadState()
                    {
                        Request = request,
                        Callback = callback
                    });
            }
            catch (Exception e) { callback(null, e); }
        }


        private static HttpWebRequest GetImageShackRequest(string fileName, string webPostAddress)
        {
            // the request header
            HttpWebRequest imageShackWebRequest = WebRequest.Create(webPostAddress) as HttpWebRequest;
            imageShackWebRequest.Method = "POST";

            string boundary = "----------" + DateTime.Now.Ticks.ToString("x");
            imageShackWebRequest.ContentType = @"multipart/form-data; boundary=" + boundary;

            FileInfo fileToUploadInfo = new FileInfo(fileName);

            if (!fileToUploadInfo.Exists)
            {
                throw new FileNotFoundException("The specified file doesn't seem to exist.", fileName);
            }

            string contentType;
            switch (fileToUploadInfo.Extension.ToLower())
            {
                case ".jpg":
                    contentType = "image/jpg";
                    break;
                case ".jpeg":
                    contentType = "image/jpeg";
                    break;
                case ".gif":
                    contentType = "image/gif";
                    break;
                case ".png":
                    contentType = "image/png";
                    break;
                case ".bmp":
                    contentType = "image/bmp";
                    break;
                case ".tif":
                    contentType = "image/tiff";
                    break;
                case ".tiff":
                    contentType = "image/tiff";
                    break;
                default:
                    contentType = "image/unknown";
                    break;

            }

            // build up the post message header.
            StringBuilder sb = new StringBuilder();
            sb.Append("--");
            sb.Append(boundary);
            sb.Append("\r\n");
            sb.Append("Content-Disposition: form-data; name=\"");
            sb.Append("fileupload");
            sb.Append("\"; filename=\"");
            sb.Append(fileToUploadInfo.Name);
            sb.Append("\"");
            sb.Append("\r\n");
            sb.Append("Content-Type: ");
            sb.Append(contentType);
            sb.Append("\r\n");
            sb.Append("\r\n");

            string imagePostHeader = sb.ToString();
            byte[] imagePostHeaderBytes = Encoding.UTF8.GetBytes(imagePostHeader);

            // trailing boundary string as a byte array
            byte[] trailingBoundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

            FileStream imageFileStream = new FileStream(fileToUploadInfo.FullName, FileMode.Open, FileAccess.Read);
            imageShackWebRequest.ContentLength = imagePostHeaderBytes.Length + imageFileStream.Length + trailingBoundaryBytes.Length;

            Stream httpRequestStream = imageShackWebRequest.GetRequestStream();
            httpRequestStream.Write(imagePostHeaderBytes, 0, imagePostHeaderBytes.Length);

            int bytesRead = 0;
            byte[] imageFileBuffer = new Byte[checked((uint)Math.Min(4096, (int)imageFileStream.Length))];

            while ((bytesRead = imageFileStream.Read(imageFileBuffer, 0, imageFileBuffer.Length)) != 0)
                httpRequestStream.Write(imageFileBuffer, 0, bytesRead);

            httpRequestStream.Write(trailingBoundaryBytes, 0, trailingBoundaryBytes.Length);

            imageFileStream.Dispose();
            return imageShackWebRequest;
        }

        private static void GetImageShackResponse(IAsyncResult ar)
        {
            Stream rstream = null;
            UploadState state = (UploadState)ar.AsyncState;

            try
            {
                HttpWebResponse response = (HttpWebResponse)state.Request.EndGetResponse(ar);

                rstream = response.GetResponseStream();

                ImageShackUploadDetails details = ExtractImageDetails(rstream);
                state.Callback(details, null);

                rstream.Dispose();
            }
            catch (Exception e) { state.Callback(null, e); }
            
            finally { if (rstream != null) rstream.Dispose(); }
        }


        public static ImageShackUploadDetails ExtractImageDetails(Stream stream)
        {
            XmlSerializer serializer = new XmlSerializer(typeof(ImageShackUploadDetails));
            ImageShackUploadDetails details = null;

            try
            {
                details = (ImageShackUploadDetails)serializer.Deserialize(stream);
            }
            catch (Exception e) { Console.WriteLine(e.Message); }

            return details;
        }
    }
}