using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Common.IO.Compression
{
    public class GZipCompression
    {
        /// <summary>
        /// 压缩字节流
        /// </summary>
        /// <param name="baseStream">原字节流</param>
        /// <returns>返回压缩后的字节流</returns>
        public static byte[] Compress(byte[] baseStream)
        {
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            using (System.IO.Compression.GZipStream gs = new System.IO.Compression.GZipStream(ms, System.IO.Compression.CompressionMode.Compress))
            {
                gs.Write(baseStream, 0, baseStream.Length);
                gs.Flush();
            }
            byte[] rs = ms.ToArray();
            ms.Close();
            return rs;
        }

        /// <summary>
        /// 解压缩字节流
        /// </summary>
        /// <param name="compressedStream">经过压缩的字节流</param>
        /// <returns>返回解压缩之后的字节流</returns>
        public static byte[] Decompress(byte[] compressedStream)
        {
            byte[] buff = new byte[1024];
            using (System.IO.MemoryStream comp = new System.IO.MemoryStream(compressedStream))
            using (System.IO.Compression.GZipStream gs = new System.IO.Compression.GZipStream(comp, System.IO.Compression.CompressionMode.Decompress))
            using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
            {
                int rs = 0;
                rs = gs.Read(buff, 0, buff.Length);
                while (rs > 0)
                {
                    ms.Write(buff, 0, rs);
                    rs = gs.Read(buff, 0, buff.Length);
                }

                buff = ms.ToArray();
            }
            
            return buff;
        }

        /// <summary>
        /// 压缩字节流
        /// </summary>
        /// <param name="baseStream">原字节流</param>
        /// <returns>返回压缩后的字节流</returns>
        public static System.IO.MemoryStream Compress(System.IO.MemoryStream baseStream)
        {
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            using (System.IO.Compression.GZipStream gs = new System.IO.Compression.GZipStream(ms, System.IO.Compression.CompressionMode.Compress))
            {
                gs.Write(baseStream.ToArray(), 0, (int)baseStream.Length);
                gs.Flush();
            }
            return ms;
        }

        /// <summary>
        /// 解压缩字节流
        /// </summary>
        /// <param name="compressedStream">经过压缩的字节流</param>
        /// <returns>返回解压缩之后的字节流</returns>
        public static System.IO.MemoryStream Decompress(System.IO.MemoryStream compressedStream)
        {
            byte[] buff = new byte[1024];
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            using (System.IO.Compression.GZipStream gs = new System.IO.Compression.GZipStream(compressedStream, System.IO.Compression.CompressionMode.Decompress))
            {
                int rs = 0;
                rs = gs.Read(buff, 0, buff.Length);
                while (rs > 0)
                {
                    ms.Write(buff, 0, rs);
                    rs = gs.Read(buff, 0, buff.Length);
                }
            }
            return ms;
        }
    }
}