MultiStream

using System;
using System.IO;
using System.Collections;

namespace Streams
{
	public class MultiStream : Stream 
	{
		ArrayList streamList = new ArrayList();
		long position = 0;
		public override bool CanRead 
		{
			get { return true; }
		}

		public override bool CanSeek 
		{
			get { return true; }
		}

		public override bool CanWrite 
		{
			get { return false; }
		}

		public override long Length 
		{ 
			get 
			{
				long result = 0;
				foreach(Stream stream in streamList) 
				{
					result += stream.Length;
				}
				return result;
			}
		}

		public override long Position 
		{
			get { return position; }
			set { Seek(value, SeekOrigin.Begin); }
		}

		public override void Flush() {}

		public override long Seek(long offset, SeekOrigin origin) 
		{
			long len = Length;
			switch(origin) 
			{
				case SeekOrigin.Begin:
					position = offset;
					break;
				case SeekOrigin.Current:
					position += offset;
					break;
				case SeekOrigin.End:
					position = len - offset;
					break;
			}
			if(position > len) 
			{
				position = len;
			}
			else if(position < 0) 
			{
				position = 0;
			}
			return position;
		}

		public override void SetLength(long value) {}

		public void AddStream(Stream stream) 
		{
			streamList.Add(stream);
		}

		public override int Read(byte[] buffer, int offset, int count) 
		{
			long len = 0;
			int result = 0;
			int buf_pos = offset;
			int bytesRead;
			foreach(Stream stream in streamList) 
			{
				if(position < (len + stream.Length)) 
				{
					stream.Position = position - len;
					bytesRead = stream.Read(buffer, buf_pos, count);
					result += bytesRead;
					buf_pos += bytesRead;
					position += bytesRead;
					if(bytesRead < count) 
					{
						count -= bytesRead;
					}
					else 
					{
						break;
					}
				}
				len += stream.Length;
			}
			return result;
		}

		public override void Write(byte[] buffer, int offset, int count) 
		{
		}
	}
}