From dbc8988119f400c0a99a715e92ced44d067165fc Mon Sep 17 00:00:00 2001
From: jz-k <jzkarap@gmail.com>
Date: Fri, 6 Sep 2024 08:29:56 -0400
Subject: [PATCH] Check hashed contents of memories and saves before saving
 archives (#324)

* update AssetsService to check content hash before saving compressed screenshots or save states

* prettier filenames for achives, includes date stamp again
---
 src/services/AssetsService.cs | 62 +++++++++++++++++++++++++++++++----
 1 file changed, 56 insertions(+), 6 deletions(-)

diff --git a/src/services/AssetsService.cs b/src/services/AssetsService.cs
index 3e010c19..7bf604e4 100644
--- a/src/services/AssetsService.cs
+++ b/src/services/AssetsService.cs
@@ -1,4 +1,6 @@
 using System.IO.Compression;
+using System.Security.Cryptography;
+using System.Text;
 using Newtonsoft.Json;
 using Pannella.Helpers;
 
@@ -6,7 +8,8 @@ namespace Pannella.Services;
 
 public class AssetsService
 {
-    private const string BLACKLIST = "https://raw.githubusercontent.com/mattpannella/pupdate/main/blacklist.json";
+    private const string BLACKLIST =
+        "https://raw.githubusercontent.com/mattpannella/pupdate/main/blacklist.json";
 
     private readonly bool useLocalBlacklist;
     private List<string> blacklist;
@@ -46,7 +49,11 @@ public static void BackupMemories(string directory, string backupLocation)
         BackupDirectory(directory, "Memories", backupLocation);
     }
 
-    private static void BackupDirectory(string rootDirectory, string folderName, string backupLocation)
+    public static void BackupDirectory(
+        string rootDirectory,
+        string folderName,
+        string backupLocation
+    )
     {
         if (string.IsNullOrEmpty(rootDirectory))
         {
@@ -60,22 +67,65 @@ private static void BackupDirectory(string rootDirectory, string folderName, str
 
         Console.WriteLine($"Compressing and backing up {folderName} directory...");
         string savesPath = Path.Combine(rootDirectory, folderName);
-        string fileName = $"{folderName}_Backup_{DateTime.Now:yyyy-MM-dd_HH.mm.ss}.zip";
-        string archiveName = Path.Combine(backupLocation, fileName);
 
         if (Directory.Exists(savesPath))
         {
+            string directoryHash = ComputeDirectoryHash(savesPath);
+            string truncatedHash = directoryHash.Substring(0, 8);
+            string dateStamp = DateTime.Now.ToString("yyyy-MM-dd_HH.mm.ss");
+            string fileName = $"{folderName}_Backup_{dateStamp}-version{truncatedHash}.zip";
+            string archiveName = Path.Combine(backupLocation, fileName);
+
             if (!Directory.Exists(backupLocation))
             {
                 Directory.CreateDirectory(backupLocation);
             }
 
-            ZipFile.CreateFromDirectory(savesPath, archiveName);
-            Console.WriteLine("Complete.");
+            bool isDuplicateBackup = Directory
+                .GetFiles(backupLocation, $"{folderName}_Backup_*-version{truncatedHash}.zip")
+                .Any();
+
+            if (!isDuplicateBackup)
+            {
+                ZipFile.CreateFromDirectory(savesPath, archiveName);
+                Console.WriteLine("Complete.");
+            }
+            else
+            {
+                Console.WriteLine($"Backup with the same contents already exists, skipping...");
+            }
         }
         else
         {
             Console.WriteLine($"No {folderName} directory found, skipping backup...");
         }
     }
+
+    private static string ComputeDirectoryHash(string directoryPath)
+    {
+        using (var sha256 = SHA256.Create())
+        {
+            var allFiles = Directory
+                .GetFiles(directoryPath, "*.*", SearchOption.AllDirectories)
+                .OrderBy(p => p)
+                .ToList();
+
+            var hashBuilder = new StringBuilder();
+
+            foreach (var filePath in allFiles)
+            {
+                byte[] fileBytes = File.ReadAllBytes(filePath);
+                byte[] hashBytes = sha256.ComputeHash(fileBytes);
+
+                hashBuilder.Append(
+                    BitConverter.ToString(hashBytes).Replace("-", "").ToLowerInvariant()
+                );
+            }
+
+            byte[] finalHashBytes = sha256.ComputeHash(
+                Encoding.UTF8.GetBytes(hashBuilder.ToString())
+            );
+            return BitConverter.ToString(finalHashBytes).Replace("-", "").ToLowerInvariant();
+        }
+    }
 }