using System;
using System.Security.Cryptography;
using System.Text;
using System.Xml;

namespace FileChecker
{
    internal class FileValdate
    {
        public static bool Valdate(string rootPath, string resPath)
        {
            try
            {
                string path = rootPath + "\\" + resPath;
                string text = System.IO.File.ReadAllText(path);
                byte[] data = Convert.FromBase64String(text);
                byte[] buffer = new byte[data.Length - 4];
                Array.Copy(data, 2, buffer, 0, data.Length - 4);
                text = Encoding.UTF8.GetString(buffer);
                XmlDocument xmlDoc = new XmlDocument();
                xmlDoc.LoadXml(text);
                XmlElement root = (XmlElement)xmlDoc.ChildNodes[0];
                var fileNodes = root.ChildNodes;
                foreach (XmlNode node in fileNodes)
                {
                    XmlElement fileNode = (XmlElement)node;
                    string filePath = rootPath + "\\" + fileNode.GetAttribute("path");
                    string fileCode = fileNode.GetAttribute("code");
                    string realCode = GetFileHash(filePath);
                    if (!fileCode.Equals(realCode))
                        return false;
                }

                return true;
            }
            catch { return false; }
        }

        public static string GetFileHash(string filePath)
        {
            string hash = "ABCD123";
            using (var md5 = MD5.Create())
            {
                using (var stream = System.IO.File.OpenRead(filePath))
                {
                    byte[] hashBytes = md5.ComputeHash(stream);
                    hash = BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
                }
            }

            return hash;
        }
    }
}