//

// © Copyright Henrik Ravn 2004

//

// Use, modification and distribution are subject to the Boost Software License, Version 1.0. 

// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//

using System;

using System.Diagnostics;

using System.Runtime.InteropServices;

namespace DotZLib

{

    /// <summary>

    /// Implements a data decompressor, using the inflate algorithm in the ZLib dll

    /// </summary>

    public class Inflater : CodecBase

	{

        #region Dll imports

        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]

        private static extern int inflateInit_(ref ZStream sz, string vs, int size);

        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]

        private static extern int inflate(ref ZStream sz, int flush);

        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]

        private static extern int inflateReset(ref ZStream sz);

        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]

        private static extern int inflateEnd(ref ZStream sz);

        #endregion

        /// <summary>

        /// Constructs an new instance of the <c>Inflater</c>

        /// </summary>

        public Inflater() : base()

		{

            int retval = inflateInit_(ref _ztream, Info.Version, Marshal.SizeOf(_ztream));

            if (retval != 0)

                throw new ZLibException(retval, "Could not initialize inflater");

            resetOutput();

        }

        /// <summary>

        /// Adds more data to the codec to be processed.

        /// </summary>

        /// <param name="data">Byte array containing the data to be added to the codec</param>

        /// <param name="offset">The index of the first byte to add from <c>data</c></param>

        /// <param name="count">The number of bytes to add</param>

        /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>

        public override void Add(byte[] data, int offset, int count)

        {

            if (data == null) throw new ArgumentNullException();

            if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();

            if ((offset+count) > data.Length) throw new ArgumentException();

            int total = count;

            int inputIndex = offset;

            int err = 0;

            while (err >= 0 && inputIndex < total)

            {

                copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));

                err = inflate(ref _ztream, (int)FlushTypes.None);

                if (err == 0)

                    while (_ztream.avail_out == 0)

                    {

                        OnDataAvailable();

                        err = inflate(ref _ztream, (int)FlushTypes.None);

                    }

                inputIndex += (int)_ztream.total_in;

            }

            setChecksum( _ztream.adler );

        }

        /// <summary>

        /// Finishes up any pending data that needs to be processed and handled.

        /// </summary>

        public override void Finish()

        {

            int err;

            do 

            {

                err = inflate(ref _ztream, (int)FlushTypes.Finish);

                OnDataAvailable();

            }

            while (err == 0);

            setChecksum( _ztream.adler );

            inflateReset(ref _ztream);

            resetOutput();

        }

        /// <summary>

        /// Closes the internal zlib inflate stream

        /// </summary>

        protected override void CleanUp() { inflateEnd(ref _ztream); }

	}

}