// InflaterInputStream.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.Security.Cryptography;
using System.IO;

using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.Checksums;

namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams 
{

   /// <summary>
   /// An input buffer customised for use by <see cref="InflaterInputStream"/>
   /// </summary>
   /// <remarks>
   /// The buffer supports decryption of incoming data.
   /// </remarks>
	public class InflaterInputBuffer
	{
		/// <summary>
		/// Initialise a new instance of <see cref="InflaterInputBuffer"/>
		/// </summary>
		/// <param name="stream">The stream to buffer.</param>
		public InflaterInputBuffer(Stream stream)
		{
			inputStream = stream;
			rawData = new byte[4096];
			clearText = rawData;
		}
		
		/// <summary>
		/// Get the length of bytes bytes in the <see cref="RawData"/>
		/// </summary>
		public int RawLength
		{
			get { 
				return rawLength; 
			}
		}
		
		/// <summary>
		/// Get the contents of the raw data buffer.
		/// </summary>
		/// <remarks>This may contain encrypted data.</remarks>
		public byte[] RawData
		{
			get {
				return rawData;
			}
		}
		
		/// <summary>
		/// Get the number of useable bytes in <see cref="ClearText"/>
		/// </summary>
		public int ClearTextLength
		{
			get {
				return clearTextLength;
			}
		}
		
		/// <summary>
		/// Get the contents of the clear text buffer.
		/// </summary>
		public byte[] ClearText
		{
			get {
				return clearText;
			}
		}
		
		/// <summary>
		/// Get/set the number of bytes available
		/// </summary>
		public int Available
		{
			get { return available; }
			set { available = value; }
		}

		/// <summary>
		/// Call <see cref="Inflater.SetInput"/> passing the current clear text buffer contents.
		/// </summary>
		/// <param name="inflater">The inflater to set input for.</param>
		public void SetInflaterInput(Inflater inflater)
		{
			if ( available > 0 ) {
				inflater.SetInput(clearText, clearTextLength - available, available);
				available = 0;
			}
		}

		/// <summary>
		/// Fill the buffer from the underlying input stream.
		/// </summary>
		public void Fill()
		{
			rawLength = 0;
			int toRead = rawData.Length;
			
			while (toRead > 0) {
				int count = inputStream.Read(rawData, rawLength, toRead);
				if ( count <= 0 ) {
					if (rawLength == 0) {
						throw new SharpZipBaseException("Unexpected EOF"); 
					}
					break;
				}
				rawLength += count;
				toRead -= count;
			}

			if ( cryptoTransform != null ) {
				clearTextLength = cryptoTransform.TransformBlock(rawData, 0, rawLength, clearText, 0);
			}
			else {
				clearTextLength = rawLength;
			}

			available = clearTextLength;
		}
		
		/// <summary>
		/// Read a buffer directly from the input stream
		/// </summary>
		/// <param name="buffer">The buffer to fill</param>
		/// <returns>Returns the number of bytes read.</returns>
		public int ReadRawBuffer(byte[] buffer)
		{
			return ReadRawBuffer(buffer, 0, buffer.Length);
		}

		/// <summary>
		/// Read a buffer directly from the input stream
		/// </summary>
		/// <param name="outBuffer">The buffer to read into</param>
		/// <param name="offset">The offset to start reading data into.</param>
		/// <param name="length">The number of bytes to read.</param>
		/// <returns>Returns the number of bytes read.</returns>
		public int ReadRawBuffer(byte[] outBuffer, int offset, int length)
		{
			if ( length <= 0 ) {
				throw new ArgumentOutOfRangeException("length");
			}
			
			int currentOffset = offset;
			int currentLength = length;
			
			while ( currentLength > 0 ) {
				if ( available <= 0 ) {
					Fill();
					if (available <= 0) {
						return 0;
					}
				}
				int toCopy = Math.Min(currentLength, available);
				System.Array.Copy(rawData, rawLength - (int)available, outBuffer, currentOffset, toCopy);
            currentOffset += toCopy;
				currentLength -= toCopy;
				available -= toCopy;
			}
			return length;
		}
		
		/// <summary>
		/// Read clear text data from the input stream.
		/// </summary>
		/// <param name="outBuffer">The buffer to add data to.</param>
		/// <param name="offset">The offset to start adding data at.</param>
		/// <param name="length">The number of bytes to read.</param>
		/// <returns>Returns the number of bytes actually read.</returns>
		public int ReadClearTextBuffer(byte[] outBuffer, int offset, int length)
		{
			if ( length <= 0 ) {
				throw new ArgumentOutOfRangeException("length");
			}
			
			int currentOffset = offset;
			int currentLength = length;
			
			while ( currentLength > 0 ) {
				if ( available <= 0 ) {
					Fill();
					if (available <= 0) {
						return 0;
					}
				}
				
				int toCopy = Math.Min(currentLength, available);
				System.Array.Copy(clearText, clearTextLength - (int)available, outBuffer, currentOffset, toCopy);
				currentOffset += toCopy;
				currentLength -= toCopy;
				available -= toCopy;
			}
			return length;
		}
		
		/// <summary>
		/// Read a byte from the input stream.
		/// </summary>
		/// <returns>Returns the byte read.</returns>
		public int ReadLeByte()
		{
			if (available <= 0) {
				Fill();
				if (available <= 0) {
					throw new ZipException("EOF in header");
				}
			}
			byte result = (byte)(rawData[rawLength - available] & 0xff);
			available -= 1;
			return result;
		}
		
		/// <summary>
		/// Read an unsigned short in little endian byte order.
		/// </summary>
		public int ReadLeShort()
		{
			return ReadLeByte() | (ReadLeByte() << 8);
		}
		
		/// <summary>
		/// Read an int in little endian byte order.
		/// </summary>
		public int ReadLeInt()
		{
			return ReadLeShort() | (ReadLeShort() << 16);
		}
		
		/// <summary>
		/// Read an int baseInputStream little endian byte order.
		/// </summary>
		public long ReadLeLong()
		{
			return ReadLeInt() | (ReadLeInt() << 32);
		}

		/// <summary>
		/// Get/set the <see cref="ICryptoTransform"/> to apply to any data.
		/// </summary>
		/// <remarks>Set this value to null to have no transform applied.</remarks>
		public ICryptoTransform CryptoTransform
		{
			set { 
				cryptoTransform = value;
				if ( cryptoTransform != null ) {
					if ( rawData == clearText ) {
						if ( internalClearText == null ) {
							internalClearText = new byte[4096];
						}
						clearText = internalClearText;
					}
					clearTextLength = rawLength;
					if ( available > 0 ) {
						cryptoTransform.TransformBlock(rawData, rawLength - available, available, clearText, rawLength - available);
					}
				} else {
					clearText = rawData;
					clearTextLength = rawLength;
				}
			}
		}

		#region Instance Fields
		int rawLength;
		byte[] rawData;
		
		int clearTextLength;
		byte[] clearText;
		
		byte[] internalClearText;
		
		int available;
		
		ICryptoTransform cryptoTransform;
		Stream inputStream;
		#endregion
	}
	
	/// <summary>
	/// This filter stream is used to decompress data compressed using the "deflate"
	/// format. The "deflate" format is described in RFC 1951.
	///
	/// This stream may form the basis for other decompression filters, such
	/// as the <see cref="ICSharpCode.SharpZipLib.GZip.GZipInputStream">GZipInputStream</see>.
	///
	/// Author of the original java version : John Leuner.
	/// </summary>
	public class InflaterInputStream : Stream
	{