source: branches/HeuristicLab.Problems.GrammaticalOptimization/SharpVectorCore/Utils/Net/DataWebResponse.cs @ 13067

using System;
using System.Net;
using System.IO;
using System.Web;
using System.Text;
using System.Text.RegularExpressions;

namespace SharpVectors.Net
{
  /// <summary>
  /// Summary description for DataWebResponse.
  /// </summary>
  /// <remarks>According to http://www.ietf.org/rfc/rfc2397.txt</remarks>
  public class DataWebResponse : WebResponse
  {
    private byte[] decodedData;

    private static Regex re = new Regex(@"^data:(?<mediatype>.*?),(?<data>.*)$", RegexOptions.Singleline);
    private static Regex wsRemover = new Regex(@"\s", RegexOptions.Singleline);
    private static Regex charsetFinder = new Regex(@"charset=(?<charset>[^;]+)", RegexOptions.Singleline);

    internal DataWebResponse(Uri uri)
    {
      this.responseUri = uri;
      
      string fullUri = HttpUtility.UrlDecode(uri.AbsoluteUri);
      fullUri = fullUri.Replace(' ', '+');

      // remove all whitespace
      fullUri = contentType = wsRemover.Replace(fullUri, "");
      
      Match match = re.Match(fullUri);

      if(match.Success)
      {
        contentType = match.Groups["mediatype"].Value;

        string data = match.Groups["data"].Value;
      

        if(contentType.Length == 0)
        {
          contentType = "text/plain;charset=US-ASCII";
        }
        else if (contentType.StartsWith(";"))
        {
          if (contentType.IndexOf(";charset=") > 0)
          {
            contentType = "text/plain" + contentType;
          }
          else
          {
            throw new Exception("Malformed data URI");
          }
        }

        if(contentType.EndsWith(";base64"))
        {
          contentType = contentType.Remove(contentType.Length - 7, 7);
          decodedData = Convert.FromBase64String(data);
        }
        else
        {
          Match charsetMatch = charsetFinder.Match(contentType);
          if(charsetMatch.Success && charsetMatch.Groups["charset"].Success)
          {
            try
            {
              contentEncoding = Encoding.GetEncoding(charsetMatch.Groups["charset"].Value);
            }
            catch(NotSupportedException)
            {
              contentEncoding = Encoding.ASCII;
            }
          }
          
          decodedData = HttpUtility.UrlDecodeToBytes(data);
        }
      }
      else
      {
        throw new Exception("Malformed data URI");
      }
    }

    public override long ContentLength
    {
      get
      {
        return decodedData.Length;
      }
    }

    private Encoding contentEncoding = Encoding.ASCII;
    public Encoding ContentEncoding
    {
      get
      {
        return contentEncoding;
      }
    }

    private string contentType;
    public override string ContentType
    {
      get
      {
        return contentType;
      }
    }

    private Uri responseUri;
    public override Uri ResponseUri
    {
      get
      {
        return responseUri;
      }
    }

    public override Stream GetResponseStream()
    {
      MemoryStream ms; 
      ms = new MemoryStream(decodedData, false);
      ms.Position = 0;
      return ms;
    }
  }
}