Implement IPC to show up existing instance when re-running

lib/main.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:journaler/db.dart';
@@ -8,6 +9,8 @@ import 'package:window_manager/window_manager.dart';
 import 'package:audioplayers/audioplayers.dart';
 import 'package:flutter/gestures.dart';
 import 'dart:math';
+import 'package:path/path.dart' as path;
+import 'package:ps_list/ps_list.dart';
 
 // TODO: Sound does not play when ran from a different workdir? Weird
 // TODO: Fix saving the same scratch over and over again
@@ -16,9 +19,55 @@ import 'dart:math';
 const Duration _defaultPopupInterval = Duration(minutes: 20);
 const String _defaultNotificationSound = 'MeetTheSniper.mp3';
 
+// Flag to indicate if there's a pending show request from a secondary instance
+bool _pendingShowRequest = false;
+
+// Global navigator key to access the navigator state from anywhere
+final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
+
+/// Paths for IPC file in system temp directory
+class AppFiles {
+  static String get ipcFilePath =>
+      path.join(Directory.systemTemp.path, 'journaler_ipc.txt');
+}
+
 void main() async {
-  await DB.init();
   WidgetsFlutterBinding.ensureInitialized();
+
+  final ipcFile = File(AppFiles.ipcFilePath);
+
+  if (await alreadyRunning()) {
+    await signalPrimaryInstanceAndExit(ipcFile);
+  } else {
+    await runPrimaryInstance(ipcFile);
+  }
+}
+
+Future<bool> alreadyRunning() async {
+  final processes = await PSList.getRunningProcesses();
+  final executable = Platform.resolvedExecutable;
+  final executableName = path.basename(executable);
+  final journalers =
+      processes
+          .where((process) => process == executableName)
+          .toList();
+  debugPrint("Journalers: $journalers");
+  return journalers.length > 1;
+}
+
+/// Run the primary instance of the application
+Future<void> runPrimaryInstance(File ipcFile) async {
+  debugPrint("Starting as primary instance");
+
+  // Create or clear the IPC file
+  if (!await ipcFile.exists()) {
+    await ipcFile.create();
+  }
+  // Start a watcher for the IPC file to detect signals from other instances
+  startIpcWatcher(ipcFile);
+
+  // Initialize the app
+  await DB.init();
   await windowManager.ensureInitialized();
 
   WindowOptions windowOptions = const WindowOptions(
@@ -34,6 +83,114 @@ void main() async {
   });
 
   runApp(const JournalerApp());
+
+  // Set up termination handlers to clean up resources
+  setupTerminationHandlers(ipcFile);
+}
+
+/// Handle termination signals by cleaning up IPC file
+void setupTerminationHandlers(File ipcFile) {
+  // Handle normal termination
+  ProcessSignal.sigterm.watch().listen((_) async {
+    await cleanupFiles(ipcFile);
+    exit(0);
+  });
+
+  // Handle Windows and Linux CTRL+C termination
+  if (Platform.isWindows || Platform.isLinux) {
+    ProcessSignal.sigint.watch().listen((_) async {
+      await cleanupFiles(ipcFile);
+      exit(0);
+    });
+  }
+}
+
+/// Clean up IPC file
+Future<void> cleanupFiles(File ipcFile) async {
+  try {
+    if (await ipcFile.exists()) {
+      await ipcFile.delete();
+    }
+    debugPrint("Removed IPC file on app termination");
+  } catch (e) {
+    debugPrint("Error cleaning up files: $e");
+  }
+}
+
+/// Signal the primary instance to show itself, then exit
+Future<void> signalPrimaryInstanceAndExit(File ipcFile) async {
+  debugPrint(
+    "Another instance is already running. Signaling it to show window.",
+  );
+
+  try {
+    // Create the IPC file if it doesn't exist
+    if (!await ipcFile.exists()) {
+      await ipcFile.create();
+    }
+
+    // Write a 'show' command with a timestamp
+    final timestamp = DateTime.now().millisecondsSinceEpoch;
+    await ipcFile.writeAsString('show:$timestamp');
+    debugPrint("Signal sent to primary instance via IPC file");
+
+    // Give the primary instance a moment to process the signal
+    await Future.delayed(const Duration(seconds: 2));
+  } catch (e) {
+    debugPrint("Error signaling primary instance: $e");
+  }
+
+  // Exit this instance
+  debugPrint("Exiting secondary instance");
+  exit(0);
+}
+
+/// Start watching the IPC file for signals from other instances
+void startIpcWatcher(File ipcFile) {
+  // Initial check of the file content
+  checkIpcFileContent(ipcFile);
+
+  // Set up a file watcher
+  final watcher = ipcFile.watch();
+  watcher.listen((event) {
+    if (event.type == FileSystemEvent.modify) {
+      checkIpcFileContent(ipcFile);
+    }
+  });
+
+  // Also set up a periodic check as a fallback
+  Timer.periodic(const Duration(milliseconds: 200), (_) {
+    checkIpcFileContent(ipcFile);
+  });
+
+  debugPrint("IPC file watcher started");
+}
+
+/// Check the IPC file content for commands
+Future<void> checkIpcFileContent(File ipcFile) async {
+  try {
+    if (await ipcFile.exists()) {
+      final content = await ipcFile.readAsString();
+
+      if (content.isNotEmpty && content.startsWith('show:')) {
+        // Clear the file immediately to avoid processing the same command multiple times
+        await ipcFile.writeAsString('');
+
+        // Process the show command
+        if (MainPageState.instance != null) {
+          debugPrint("Received show command - making window visible");
+          MainPageState.instance!.showWindow();
+        } else {
+          debugPrint(
+            "MainPageState not initialized yet - setting pending flag",
+          );
+          _pendingShowRequest = true;
+        }
+      }
+    }
+  } catch (e) {
+    debugPrint("Error processing IPC file: $e");
+  }
 }
 
 class JournalerApp extends StatelessWidget {
@@ -114,6 +271,7 @@ class JournalerApp extends StatelessWidget {
       themeMode: ThemeMode.system,
       home: const MainPage(),
       debugShowCheckedModeBanner: false,
+      navigatorKey: navigatorKey,
     );
   }
 }
@@ -126,6 +284,9 @@ class MainPage extends StatefulWidget {
 }
 
 class MainPageState extends State<MainPage> with WindowListener {
+  // Static reference to the current instance
+  static MainPageState? instance;
+
   final SystemTray _systemTray = SystemTray();
   final Menu _menu = Menu();
   final AudioPlayer _audioPlayer = AudioPlayer();
@@ -157,16 +318,31 @@ class MainPageState extends State<MainPage> with WindowListener {
   @override
   void initState() {
     super.initState();
+    // Store reference to this instance
+    instance = this;
     windowManager.addListener(this);
     _initSystemTray();
     _loadData();
     _loadVolume();
     windowManager.setPreventClose(true);
     _setWindowConfig();
+
+    // Check if there's a pending show request from another instance
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (_pendingShowRequest) {
+        debugPrint("Processing pending show request during initialization");
+        _pendingShowRequest = false;
+        showWindow();
+      }
+    });
   }
 
   @override
   void dispose() {
+    // Clear reference to this instance
+    if (instance == this) {
+      instance = null;
+    }
     windowManager.removeListener(this);
     _popupTimer?.cancel();
     _debounceTimer?.cancel();
@@ -210,7 +386,7 @@ class MainPageState extends State<MainPage> with WindowListener {
     _systemTray.registerSystemTrayEventHandler((eventName) {
       debugPrint("System Tray Event: $eventName");
       if (eventName == kSystemTrayEventClick) {
-        _showWindow();
+        showWindow();
       } else if (eventName == kSystemTrayEventRightClick) {
         _systemTray.popUpContextMenu();
       }
@@ -220,26 +396,56 @@ class MainPageState extends State<MainPage> with WindowListener {
   void _startPopupTimer() {
     _popupTimer?.cancel();
     _popupTimer = Timer.periodic(_currentPopupInterval, (timer) {
-      _showWindow();
+      showWindow();
     });
     debugPrint(
       "Popup timer started with interval: ${_currentPopupInterval.inMinutes} minutes",
     );
   }
 
-  Future<void> _showWindow() async {
+  Future<void> showWindow() async {
     _loadData();
+    try {
       bool wasVisible = await windowManager.isVisible();
+      debugPrint("Current window visibility: $wasVisible");
+
       if (!wasVisible) {
+        // First make sure the window has the right size and position
         await windowManager.setSize(const Size(1600, 900));
         await windowManager.center();
+
+        // Now show and focus
+        await windowManager.show();
+        await Future.delayed(const Duration(milliseconds: 100)); // Short delay
+        await windowManager.focus();
+
+        // Set input focus
+        _currentEntryFocusNode.requestFocus();
+
+        // Play notification sound
+        await _playSound();
+
+        debugPrint("Window made visible and focused");
+      } else {
+        // Already visible, just focus
+        await windowManager.focus();
+        _currentEntryFocusNode.requestFocus();
+        debugPrint("Window already visible, just focused");
+      }
+
+      // Verify the window is now visible
+      bool isNowVisible = await windowManager.isVisible();
+      debugPrint("Window visibility after show attempt: $isNowVisible");
+
+      if (!isNowVisible) {
+        debugPrint(
+          "WARNING: Window still not visible after show attempt, trying again",
+        );
         await windowManager.show();
         await windowManager.focus();
-      _currentEntryFocusNode.requestFocus();
+      }
-      await _playSound();
+    } catch (e) {
-    } else {
+      debugPrint("Error showing window: $e");
-      await windowManager.focus();
-      _currentEntryFocusNode.requestFocus();
     }
   }
 

pubspec.lock

@@ -289,7 +289,7 @@ packages:
     source: hosted
     version: "1.16.0"
   path:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: path
       sha256: "75cca69d1490965be98c73ceaea117e8a04dd21217b37b292c9ddbec0d955bc5"
@@ -376,6 +376,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.2"
+  ps_list:
+    dependency: "direct main"
+    description:
+      name: ps_list
+      sha256: "19d32f6c643313cf4f5101bb144b8978b9ba3dc42c9a01b247e8ed90581bc0ab"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.0.5"
   screen_retriever:
     dependency: transitive
     description:

pubspec.yaml

@@ -38,6 +38,8 @@ dependencies:
   window_manager: ^0.4.3
   audioplayers: ^6.4.0
   sqflite_common_ffi: ^2.3.5
+  path: ^1.8.0
+  ps_list: ^0.0.5
 
 dev_dependencies:
   flutter_test: