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

namespace GeoSigmaDrawLib
{
    
    /// <summary>
    /// 文件操作功能类
    /// </summary>
    public class FileUtility
    {
        public const string TempPath = @".\temp\";
        /// <summary>
        /// 文件编码
        /// </summary>
        /// <param name="inputPath">输入文件</param>
        /// <param name="outputPath">输出文件</param>
        /// <returns>是否成功</returns>
        public static bool EncodeFile(string inputPath, string outputPath)
        {
            bool ret = false;
            ret = File.Exists(inputPath);
            //文本不存在
            if (!ret)
            {
                return false;
            }
            //输入与输出文件相同
            if (inputPath == outputPath)
            {
                return false;
            }
            //文本不是文本文件
            ret = IsTextFile(inputPath);
            string dstPath = Path.GetDirectoryName(outputPath);
            if (!Directory.Exists(dstPath))
            {
                Directory.CreateDirectory(dstPath);
            }
            if (!ret)
            {
                File.Copy(inputPath, outputPath);
                return true;
            }

            ret = GeoSigmaLib.EncodeFile(inputPath, outputPath);
            return ret;
        }

        /// <summary>
        /// 解码文件,返回解码临时文件
        /// </summary>
        /// <param name="inputPath">输入文件</param>
        /// <param name="outputPath">输出文件</param>
        /// <returns>是否成功</returns>
        public static bool DecodeFile(string inputPath, out string outputPath)
        {
            bool ret = false;
            ret = File.Exists(inputPath);
            if (!ret)
            {
                outputPath = @"";
                return false;
            }

            string extention = Path.GetExtension(inputPath);
            if (!Directory.Exists(TempPath))
            {
                Directory.CreateDirectory(TempPath);
            }
            Guid guid = Guid.NewGuid();
            outputPath = Path.Combine(TempPath + guid.ToString() + extention);
            //输入与输出文件相同
            if (inputPath == outputPath)
            {
                return false;
            }
            //文本是文本文件
            ret = IsTextFile(inputPath);
            if (ret)
            {
                File.Copy(inputPath, outputPath);
                return true;
            }
            else
            {
                ret = GeoSigmaLib.DecodeFile(inputPath, outputPath);
            }
            return ret;
        }

        /// <summary>
        /// Determines whether [is text file] [the specified file path].
        /// </summary>
        /// <param name="filePath">The file path.</param>
        /// <returns>
        ///   <c>true</c> if [is text file] [the specified file path]; otherwise, <c>false</c>.
        /// </returns>
        public static bool IsTextFile(string filePath)
        {
            if (!File.Exists(filePath))
            {
                return false;
            }
            bool isBinary = false;
            try
            {
                using (BinaryReader br = new BinaryReader(
                    File.Open(filePath, FileMode.Open, FileAccess.ReadWrite)
                    , Encoding.Default))
                {
                    byte[] buffer = br.ReadBytes(512);
                    int nLength = buffer.Length;
                    if (nLength > 0)
                    {
                        for(int i = 0; i < nLength; i++)
                        {
                            if (buffer[i] <= 8 || buffer[i] == 11 || buffer[i] == 12 || buffer[i] == 14 || buffer[i] == 15)
                            {
                                isBinary = true;
                                break;
                            }
                        }
                    }
                }
                //byte[] buffer = new byte[4096]; // 定义一个缓冲区来读取文件内容

                //using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                //{
                //    int bytesRead = fileStream.Read(buffer, 0, buffer.Length); // 读取一部分文件内容到缓冲区

                //    // 检查文件内容是否是二进制数据
                //    for (int i = 0; i < bytesRead; i++)
                //    {
                //        if (buffer[i] == 0)
                //        {
                //            return false; // 文件含有空字符，认为是二进制文件
                //        }
                //        else if (buffer[i] < 8 || (buffer[i] > 13 && buffer[i] < 32))
                //        {
                //            return false; // 文件包含非打印字符，认为是二进制文件
                //        }
                //    }

                //    // 如果读取的文件内容为空，则认为是二进制文件
                //    if (bytesRead == 0)
                //    {
                //        return false;
                //    }
                //}

                //isBinary = true;
            }
            catch (IOException)
            {
                return true; // 文件访问异常，认为是二进制文件
            }
            return !isBinary;
        }
    }
}