using System;
using System.IO;
using ICSharpCode.SharpZipLib.Checksum;
using ICSharpCode.SharpZipLib.Zip;

namespace CommonTool
{
	public class ZipHelper
	{
		public static ZipHelper Instance { get; } = new ZipHelper();

		/// <summary>
		/// 压缩文件
		/// </summary>
		/// <param name="sourceFilePath"></param>
		/// <param name="destinationZipFilePath"></param>
		public bool CreateZip(string sourceFilePath, string destinationZipFilePath)
		{
			if (string.IsNullOrEmpty(sourceFilePath))
				return false;
			if (sourceFilePath[sourceFilePath.Length - 1] != Path.DirectorySeparatorChar)
				sourceFilePath += Path.DirectorySeparatorChar;
			if (File.Exists(destinationZipFilePath))
			{
				try
				{
					File.Delete(destinationZipFilePath);
				}
				catch
				{
					return false;
				}
			}
			if (!File.Exists(sourceFilePath) && !Directory.Exists(sourceFilePath))
				return false;
			ZipOutputStream zipStream = new ZipOutputStream(File.Create(destinationZipFilePath));
			zipStream.SetLevel(6);  // 压缩级别 0-9
			CreateZipFiles(sourceFilePath, zipStream, sourceFilePath);
			zipStream.Finish();
			zipStream.Close();
			return true;
		}

		/// <summary>
		/// 递归压缩文件
		/// </summary>
		/// <param name="sourceFilePath">待压缩的文件或文件夹路径</param>
		/// <param name="zipStream">打包结果的zip文件路径（类似 D:\WorkSpace\a.zip）,全路径包括文件名和.zip扩展名</param>
		/// <param name="staticFile"></param>
		private void CreateZipFiles(string sourceFilePath, ZipOutputStream zipStream, string staticFile)
		{
			Crc32 crc = new Crc32();
			string[] filesArray = Directory.GetFileSystemEntries(sourceFilePath);
			foreach (string file in filesArray)
			{
				if (Directory.Exists(file))                     //如果当前是文件夹，递归
				{
					CreateZipFiles(file, zipStream, staticFile);
				}
				else                                            //如果是文件，开始压缩
				{
					FileStream fileStream = File.OpenRead(file);

					byte[] buffer = new byte[fileStream.Length];
					fileStream.Read(buffer, 0, buffer.Length);
					string tempFile = file.Substring(staticFile.LastIndexOf("\\", StringComparison.Ordinal) + 1);
					ZipEntry entry = new ZipEntry(tempFile)
					{
						DateTime = DateTime.Now,
						Size = fileStream.Length
					};

					fileStream.Close();
					crc.Reset();
					crc.Update(buffer);
					entry.Crc = crc.Value;
					zipStream.PutNextEntry(entry);

					zipStream.Write(buffer, 0, buffer.Length);
				}
			}
		}
	}
}