com.unity.services.samples.game-lobby/Packages/ParrelSync/Editor/ValidateCopiedFoldersIntegrity.cs

namespace ParrelSync.NonCore
{
    using UnityEditor;
    using UnityEngine;
    using System;
    using System.Text;
    using System.Security.Cryptography;
    using System.IO;
    using System.Linq;

    [InitializeOnLoad]
    public class ValidateCopiedFoldersIntegrity
    {
        const string SessionStateKey = "ValidateCopiedFoldersIntegrity_Init";
        /// <summary>
        /// Called once on editor startup.
        /// Validate copied folders integrity in clone project
        /// </summary>
        static ValidateCopiedFoldersIntegrity()
        {
            if (!SessionState.GetBool(SessionStateKey, false))
            {
                SessionState.SetBool(SessionStateKey, true);
                if (!ClonesManager.IsClone()) { return; }

                ValidateFolder("Packages");
            }
        }

        static void ValidateFolder(string folderName)
        {
            var currentProjectPath = Path.Combine(ClonesManager.GetCurrentProjectPath(), folderName);
            var currentFolderHash = CreateMd5ForFolder(currentProjectPath);

            var originalProjectPath = Path.Combine(ClonesManager.GetOriginalProjectPath(), folderName);
            var originalFolderHash = CreateMd5ForFolder(originalProjectPath);

            if (currentFolderHash != originalFolderHash)
            {
                Debug.Log("ParrelSync: Detected '" + folderName + "' folder changes in the original project. Updating...");
                FileUtil.ReplaceDirectory(originalProjectPath, currentProjectPath);
            }
        }

        static string CreateMd5ForFolder(string path)
        {
            // assuming you want to include nested folders
            var files = Directory.GetFiles(path, "*.*", SearchOption.AllDirectories)
                                 .OrderBy(p => p).ToList();

            MD5 md5 = MD5.Create();

            for (int i = 0; i < files.Count; i++)
            {
                string file = files[i];

                // hash path
                string relativePath = file.Substring(path.Length + 1);
                byte[] pathBytes = Encoding.UTF8.GetBytes(relativePath.ToLower());
                md5.TransformBlock(pathBytes, 0, pathBytes.Length, pathBytes, 0);

                // hash contents
                byte[] contentBytes = File.ReadAllBytes(file);
                if (i == files.Count - 1)
                    md5.TransformFinalBlock(contentBytes, 0, contentBytes.Length);
                else
                    md5.TransformBlock(contentBytes, 0, contentBytes.Length, contentBytes, 0);
            }

            return BitConverter.ToString(md5.Hash).Replace("-", "").ToLower();
        }
    }
}