From d373d8f2630daea37cbd1cb837cc1750606f334f Mon Sep 17 00:00:00 2001
From: miku-666 <74728189+NessieHax@users.noreply.github.com>
Date: Thu, 20 Nov 2025 02:46:43 +0100
Subject: [PATCH] Core - Add FileObserver.cs

---
 PckStudio.Core/IO/FileObserver.cs    | 71 ++++++++++++++++++++++++++++
 PckStudio.Core/PckStudio.Core.csproj |  1 +
 2 files changed, 72 insertions(+)
 create mode 100644 PckStudio.Core/IO/FileObserver.cs

diff --git a/PckStudio.Core/IO/FileObserver.cs b/PckStudio.Core/IO/FileObserver.cs
new file mode 100644
index 00000000..7bd207fe
--- /dev/null
+++ b/PckStudio.Core/IO/FileObserver.cs
@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+
+namespace PckStudio.Core.IO
+{
+    public sealed class FileObserver : IDisposable
+    {
+
+        private readonly IDictionary<string, FileSystemWatcher> _watchers = new Dictionary<string, FileSystemWatcher>();
+
+        public bool AddFileWatcher<T>(string filepath, Action<T, FileInfo> onChange, T value)
+            => AddFileWatcher(new FileInfo(filepath), onChange, value);
+
+        public bool AddFileWatcher<T>(FileInfo fileInfo, Action<T, FileInfo> onChange, T value)
+        {
+            var watcher = new FileSystemWatcher(fileInfo.DirectoryName);
+
+            watcher.NotifyFilter = NotifyFilters.Size | NotifyFilters.CreationTime | NotifyFilters.FileName;
+
+            watcher.Filter = fileInfo.Name;
+            watcher.EnableRaisingEvents = true;
+
+            watcher.Error += (e, a) => InternalRemoveFileWatcher(Path.Combine(watcher.Path, watcher.Filter), $"ERROR:({a.GetException().Message})");
+            watcher.Deleted += (e, a) => InternalRemoveFileWatcher(Path.Combine(watcher.Path, watcher.Filter), "path deleted");
+            watcher.Changed += (e, a) =>
+            {
+                switch (a.ChangeType)
+                {
+                    case WatcherChangeTypes.Renamed:
+                    case WatcherChangeTypes.Deleted:
+                        InternalRemoveFileWatcher(Path.Combine(watcher.Path, watcher.Filter), $"File {a.ChangeType}");
+                        return;
+                    case WatcherChangeTypes.Changed:
+                        onChange(value, new FileInfo(a.FullPath));
+                        break;
+                }
+            };
+            if (_watchers.ContainsKey(fileInfo.FullName))
+            {
+                Debug.WriteLine($"File watcher for: {fileInfo.FullName} already listening.");
+                return false;
+            }
+            _watchers.Add(fileInfo.FullName, watcher);
+            Debug.WriteLine($"Added file watcher for: {fileInfo.FullName}.");
+            return true;
+        }
+
+        public bool RemoveFileWatcher(FileInfo fileInfo) => RemoveFileWatcher(fileInfo.FullName);
+
+        public bool RemoveFileWatcher(string filepath) => InternalRemoveFileWatcher(filepath, "User");
+
+        public void Dispose()
+        {
+            foreach (KeyValuePair<string, FileSystemWatcher> fsw in _watchers)
+            {
+                Debug.WriteLine($"Releasing: {fsw.Key}");
+                fsw.Value.Dispose();
+            }
+            _watchers.Clear();
+        }
+
+        private bool InternalRemoveFileWatcher(string fullpath, string reason = "None")
+        {
+            Debug.WriteLine($"Releasing: {fullpath}. Reason: {reason}.");
+            _watchers[fullpath]?.Dispose();
+            return _watchers.Remove(fullpath);
+        }
+    }
+}
diff --git a/PckStudio.Core/PckStudio.Core.csproj b/PckStudio.Core/PckStudio.Core.csproj
index c05415ef..5f7291f3 100644
--- a/PckStudio.Core/PckStudio.Core.csproj
+++ b/PckStudio.Core/PckStudio.Core.csproj
@@ -128,6 +128,7 @@
     <Compile Include="IO\3DST\3DSTextureReader.cs" />
     <Compile Include="IO\3DST\3DSTextureWriter.cs" />
     <Compile Include="IO\3DST\TextureCodec.cs" />
+    <Compile Include="IO\FileObserver.cs" />
     <Compile Include="IO\PckAudio\PckAudioFileReader.cs" />
     <Compile Include="IO\PckAudio\PckAudioFileWriter.cs" />
     <Compile Include="IO\TGA\TGADataTypeCode.cs" />