using RevokeMsgPatcher.Model;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace RevokeMsgPatcher.Utils
{
    public class FileUtil
    {
        /// <summary>
        /// 获取文件版本
        /// </summary>
        /// <param name="path"></param>
        /// <returns></returns>
        public static string GetFileVersion(string path)
        {
            if (File.Exists(path))
            {
                FileVersionInfo fileVersionInfo = FileVersionInfo.GetVersionInfo(path);
                return fileVersionInfo.FileVersion;
            }
            else
            {
                return null;
            }

        }

        /// <summary>
        /// 计算文件SHA1
        /// </summary>
        /// <param name="s">文件路径</param>
        /// <returns></returns>
        public static string ComputeFileSHA1(string s)
        {
            File.SetAttributes(s, FileAttributes.Normal);
            FileStream file = new FileStream(s, FileMode.Open);
            SHA1 sha1 = new SHA1CryptoServiceProvider();
            byte[] retval = sha1.ComputeHash(file);
            file.Close();

            StringBuilder sc = new StringBuilder();
            for (int i = 0; i < retval.Length; i++)
            {
                sc.Append(retval[i].ToString("x2"));
            }
            return sc.ToString();
        }

        /// <summary>
        /// 修改文件指定位置的字节
        /// </summary>
        /// <param name="path">文件对象的路径</param>
        /// <param name="position">偏移位置</param>
        /// <param name="after">修改后的值</param>
        /// <returns></returns>
        public static bool EditHex(string path, long position, byte after)
        {
            using (var stream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite))
            {
                stream.Position = position;
                stream.WriteByte(after);
            }
            return true;

        }

        /// <summary>
        /// 修改文件多个指定位置的多个字节
        /// </summary>
        /// <param name="path">文件对象的路径</param>
        /// <param name="changes">需要修改的位置和内容</param>
        public static void EditMultiHex(string path, List<Change> changes)
        {
            using (var stream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite))
            {
                foreach (Change change in changes)
                {
                    stream.Seek(change.Position, SeekOrigin.Begin);
                    foreach(byte b in change.Content)
                    {
                        // 跳过通配符
                        if(b == 0x3F)
                        {
                            stream.ReadByte();
                        }
                        else
                        {
                            stream.WriteByte(b);
                        }
                    }
                }
            }
        }
    }
}
