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

namespace HNWD.Pregrant.Common
{
    public class GZipCompress
    {
        /// <summary>
        /// 压缩字节数组
        /// </summary>
        /// <param name="str"></param>
        public static byte[] Compress(byte[] inputBytes)
        {
            using (MemoryStream outStream = new MemoryStream())
            {
                using (GZipStream zipStream = new GZipStream(outStream, CompressionMode.Compress, true))
                {
                    zipStream.Write(inputBytes, 0, inputBytes.Length);
                    zipStream.Close(); //很重要，必须关闭，否则无法正确解压
                    return outStream.ToArray();
                }
            }
        }

        /// <summary>
        /// 解压缩字节数组
        /// </summary>
        /// <param name="str"></param>
        public static byte[] Decompress(byte[] inputBytes)
        {
            using (MemoryStream inputStream = new MemoryStream(inputBytes))
            {
                using (MemoryStream outStream = new MemoryStream())
                {
                    using (GZipStream zipStream = new GZipStream(inputStream, CompressionMode.Decompress))
                    {
                        zipStream.CopyTo(outStream);
                        zipStream.Close();
                        return outStream.ToArray();
                    }
                }
            }
        }

        /// <summary>
        /// 压缩字符串
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public static string Compress(string input)
        {
            byte[] inputBytes = Encoding.Default.GetBytes(input);
            byte[] result = Compress(inputBytes);
            return Convert.ToBase64String(result);
        }

        /// <summary>
        /// 解压缩字符串
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public static string Decompress(string input)
        {
            byte[] inputBytes = Convert.FromBase64String(input);
            byte[] depressBytes = Decompress(inputBytes);
            return Encoding.Default.GetString(depressBytes);
        }

        /// <summary>
        /// 压缩目录
        /// </summary>
        /// <param name="dir"></param>
        public static void Compress(DirectoryInfo dir)
        {
            foreach (FileInfo fileToCompress in dir.GetFiles())
            {
                Compress(fileToCompress);
            }
        }

        /// <summary>
        /// 解压缩目录
        /// </summary>
        /// <param name="dir"></param>
        public static void Decompress(DirectoryInfo dir)
        {
            foreach (FileInfo fileToCompress in dir.GetFiles())
            {
                Decompress(fileToCompress);
            }
        }

        /// <summary>
        /// 压缩文件
        /// </summary>
        /// <param name="fileToCompress"></param>
        public static void Compress(FileInfo fileToCompress)
        {
            using (FileStream originalFileStream = fileToCompress.OpenRead())
            {
                if ((File.GetAttributes(fileToCompress.FullName) & FileAttributes.Hidden) != FileAttributes.Hidden & fileToCompress.Extension != ".gz")
                {
                    using (FileStream compressedFileStream = File.Create(fileToCompress.FullName + ".gz"))
                    {
                        using (GZipStream compressionStream = new GZipStream(compressedFileStream, CompressionMode.Compress))
                        {
                            originalFileStream.CopyTo(compressionStream);
                        }
                    }
                }
            }
        }

        /// <summary>
        /// 解压缩文件
        /// </summary>
        /// <param name="fileToDecompress"></param>
        public static void Decompress(FileInfo fileToDecompress)
        {
            using (FileStream originalFileStream = fileToDecompress.OpenRead())
            {
                string currentFileName = fileToDecompress.FullName;
                string newFileName = currentFileName.Remove(currentFileName.Length - fileToDecompress.Extension.Length);

                using (FileStream decompressedFileStream = File.Create(newFileName))
                {
                    using (GZipStream decompressionStream = new GZipStream(originalFileStream, CompressionMode.Decompress))
                    {
                        decompressionStream.CopyTo(decompressedFileStream);
                    }
                }
            }
        }
    }
}