using System;
using System.IO;

namespace Org.BouncyCastle.Crypto.IO
{
	public class MacStream
		: Stream
	{
		protected readonly Stream stream;
		protected readonly IMac inMac;
		protected readonly IMac outMac;

		public MacStream(
			Stream	stream,
			IMac	readMac,
			IMac	writeMac)
		{
			this.stream = stream;
			this.inMac = readMac;
			this.outMac = writeMac;
		}

		public virtual IMac ReadMac()
		{
			return inMac;
		}

		public virtual IMac WriteMac()
		{
			return outMac;
		}

		public override int Read(
			byte[]	buffer,
			int		offset,
			int		count)
		{
			int n = stream.Read(buffer, offset, count);
			if (inMac != null)
			{
				if (n > 0)
				{
					inMac.BlockUpdate(buffer, offset, n);
				}
			}
			return n;
		}

		public override int ReadByte()
		{
			int b = stream.ReadByte();
			if (inMac != null)
			{
				if (b >= 0)
				{
					inMac.Update((byte)b);
				}
			}
			return b;
		}

		public override void Write(
			byte[]	buffer,
			int		offset,
			int		count)
		{
			if (outMac != null)
			{
				if (count > 0)
				{
					outMac.BlockUpdate(buffer, offset, count);
				}
			}
			stream.Write(buffer, offset, count);
		}

		public override void WriteByte(byte b)
		{
			if (outMac != null)
			{
				outMac.Update(b);
			}
			stream.WriteByte(b);
		}

		public override bool CanRead
		{
			get { return stream.CanRead; }
		}

		public override bool CanWrite
		{
			get { return stream.CanWrite; }
		}

		public override bool CanSeek
		{
			get { return stream.CanSeek; }
		}

		public override long Length
		{
			get { return stream.Length; }
		}

		public override long Position
		{
			get { return stream.Position; }
			set { stream.Position = value; }
		}

		public override void Close()
		{
			stream.Close();
		}

		public override void Flush()
		{
			stream.Flush();
		}

		public override long Seek(
			long		offset,
			SeekOrigin	origin)
		{
			return stream.Seek(offset,origin);
		}

		public override void SetLength(
			long length)
		{
			stream.SetLength(length);
		}
	}
}

