using System;
using System.Net;
using System.IO;

namespace Janrain.OpenId.Consumer
{
    public abstract class Fetcher
    {
	public static uint MAX_BYTES = 1024 * 1024; // 1MB

	protected static int ReadData ( HttpWebResponse resp, 
					uint max_bytes, 
					out byte[] buffer )
	{
	    MemoryStream ms = null;
	    Stream stream = resp.GetResponseStream();
	    int length = (int)resp.ContentLength;
	    bool nolength = (length == -1);
	    int size = ((nolength) ? 8192 : length);
	    if (nolength)
		ms = new MemoryStream();

	    size = Math.Min(size, (int)max_bytes);

	    int nread = 0;
	    int offset = 0;
	    buffer = new byte[size];
	    while ((nread = stream.Read(buffer, offset, size)) != 0) 
	    {
		if (nolength)
		{
		    ms.Write(buffer, 0, nread);
		}
		else
		{
		    size -= nread;
		    offset += nread;
		}
	    }
	    if (nolength)
	    {
		buffer = ms.ToArray();
		offset = buffer.Length;
	    }

	    return offset;
	}

	protected static FetchResponse GetResponse ( HttpWebResponse resp,
						     uint maxRead )
	{
	    byte[] data;
	    int length = ReadData(resp, maxRead, out data);
	    return new FetchResponse(resp.StatusCode, resp.ResponseUri,
				     resp.CharacterSet, data, length);
	}

	public abstract FetchResponse Get ( Uri uri, 
					    uint maxRead );

	public virtual FetchResponse Get ( Uri uri )
	{
	    return Get(uri, MAX_BYTES);
	}

	public abstract FetchResponse Post ( Uri uri, 
					     byte[] body, 
					     uint maxRead );

	public virtual FetchResponse Post ( Uri uri, 
					    byte[] body )
	{
	    return Post(uri, body, MAX_BYTES);
	}
    }

}