using System;
using System.IO;
using System.IO.Compression;
using System.Text;

namespace iWareCommon.Utils
{
    public class ZipHelper
    {
        /// <summary>
        /// 将传入字符串以GZip算法压缩后，返回Base64编码字符
        /// </summary>
        /// <param name="rawString">需要压缩的字符串</param>
        /// <returns>压缩后的Base64编码的字符串</returns>
        public static string GZipCompressString(string rawString)
        {
            var bs = Encoding.UTF8.GetBytes(rawString);
            
            for (var i = 1; i < bs.Length; i += 2) { bs[i] = Convert.ToByte(bs[i] ^ 0x30); }
            return StringHelper.Compress(MyBase64Helper.ToBase64String(bs));
        }

        /// <summary>
        /// 将传入的二进制字符串资料以GZip算法解压缩
        /// </summary>
        /// <param name="zippedString">经GZip压缩后的二进制字符串</param>
        /// <returns>原始未压缩字符串</returns>
        public static string GZipDecompressString(string zippedString)
        {
            var bs = MyBase64Helper.ToBytes(StringHelper.DeCompress(zippedString));

            for (var i = 1; i < bs.Length; i += 2) { bs[i] = Convert.ToByte(bs[i] ^ 0x30); }
            return Encoding.UTF8.GetString(bs);
        }




        
        

        
        /// <summary>
        /// GZip压缩
        /// </summary>
        /// <param name="rawData"></param>
        /// <returns></returns>
        public static byte[] Compress(byte[] rawData)
        {
            MemoryStream ms = new MemoryStream();
            GZipStream compressedzipStream = new GZipStream(ms, CompressionMode.Compress, true);
            compressedzipStream.Write(rawData, 0, rawData.Length);
            compressedzipStream.Close();
            return ms.ToArray();
        }


        

        /// <summary>
        /// ZIP解压
        /// </summary>
        /// <param name="zippedData"></param>
        /// <returns></returns>
        public static byte[] Decompress(byte[] zippedData)
        {
            MemoryStream ms = new MemoryStream(zippedData);
            GZipStream compressedzipStream = new GZipStream(ms, CompressionMode.Decompress);
            MemoryStream outBuffer = new MemoryStream();
            byte[] block = new byte[1024];
            while (true)
            {
                int bytesRead = compressedzipStream.Read(block, 0, block.Length);
                if (bytesRead <= 0)
                    break;
                else
                    outBuffer.Write(block, 0, bytesRead);
            }
            compressedzipStream.Close();
            return outBuffer.ToArray();
        }
    }
}