// Copyright (c) CypherCore <http://github.com/CypherCore> All rights reserved.
// Licensed under the GNU GENERAL PUBLIC LICENSE. See LICENSE file in the project root for full license information.

using System;
using System.IO;
using System.IO.Compression;
using System.Linq;

namespace Framework.IO
{
    public static partial class ZLib
    {
        public static byte[] Compress(byte[] data)
        {
            ByteBuffer buffer = new();
            buffer.WriteUInt8(0x78);
            buffer.WriteUInt8(0x9c);

            uint adler32 = ZLib.adler32(1, data, (uint)data.Length);// Adler32(1, data, (uint)data.Length);
            var ms = new MemoryStream();
            using (var deflateStream = new DeflateStream(ms, CompressionMode.Compress))
            {
                deflateStream.Write(data, 0, data.Length);
                deflateStream.Flush();
            }
            buffer.WriteBytes(ms.ToArray());
            var adlerBytes = BitConverter.GetBytes(adler32);
            adlerBytes.Reverse();
            buffer.WriteBytes(adlerBytes);

            return buffer.GetData();
        }

        public static byte[] Decompress(byte[] data, uint unpackedSize)
        {
            byte[] decompressData = new byte[unpackedSize];
            using (var deflateStream = new DeflateStream(new MemoryStream(data, 2, data.Length - 6), CompressionMode.Decompress))
            {
                var decompressed = new MemoryStream();
                deflateStream.CopyTo(decompressed);

                decompressed.Seek(0, SeekOrigin.Begin);
                for (int i = 0; i < unpackedSize; i++)
                    decompressData[i] = (byte)decompressed.ReadByte();
            }

            return decompressData;
        }
    }
}