use xdg_desktop_portal over flutter_local_notifications on linux

lib/controllers/notification.dart

@@ -1,10 +1,13 @@
 import "dart:io";
 
+import "package:flutter/foundation.dart";
 import "package:material_ui/material_ui.dart";
+import "package:nexus/controllers/portal.dart";
 import "package:nexus/main.dart";
 import "package:flutter_local_notifications/flutter_local_notifications.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:nexus/pages/notifications.dart";
+import "package:xdg_desktop_portal/xdg_desktop_portal.dart";
 
 class NotificationController
     extends AsyncNotifier<FlutterLocalNotificationsPlugin> {
@@ -12,40 +15,77 @@ class NotificationController
   Future<FlutterLocalNotificationsPlugin> build() async {
     final notifications = FlutterLocalNotificationsPlugin();
 
-    final darwin = DarwinInitializationSettings();
+    if (!Platform.isLinux) {
+      final darwin = DarwinInitializationSettings();
 
-    await notifications.initialize(
-      settings: .new(
-        windows: .new(
-          appName: "Nexus",
-          appUserModelId: "nexus.federated.nexus",
-          guid: "dde78daf-130f-4e46-a80a-e31deeab45d7",
+      await notifications.initialize(
+        settings: .new(
+          windows: .new(
+            appName: "Nexus",
+            appUserModelId: "nexus.federated.nexus",
+            guid: "dde78daf-130f-4e46-a80a-e31deeab45d7",
+          ),
+          android: .new("ic_launcher_foreground"),
+          iOS: darwin,
+          macOS: darwin,
         ),
-        android: .new("ic_launcher_foreground"),
-        iOS: darwin,
-        macOS: darwin,
-        linux: .new(defaultActionName: "Open"),
-      ),
-      onDidReceiveNotificationResponse: (details) {
-        if (details.payload case final eventId?) {
-          if (navigatorKey.currentContext case final context?) {
+        onDidReceiveNotificationResponse: (details) {
+          if (details.payload case final eventId?) {
+            if (navigatorKey.currentContext case final context?) {
+              Navigator.of(context).push(
+                MaterialPageRoute(
+                  builder: (_) => NotificationsPage(
+                    highlightedEventId: eventId,
+                    defaultToAllNotifications: true,
+                  ),
+                ),
+              );
+            }
+          }
+        },
+      );
+    }
+
+    if (Platform.isLinux) {
+      final portal = await ref.watch(PortalController.provider.future);
+
+      portal.notification.actionInvoked.listen((event) {
+        if (event.action != "app.event") {
+          return;
+        }
+
+        if (navigatorKey.currentContext case final context?) {
+          if (context.mounted) {
             Navigator.of(context).push(
               MaterialPageRoute(
                 builder: (_) => NotificationsPage(
-                  highlightedEventId: eventId,
+                  highlightedEventId: event.id,
                   defaultToAllNotifications: true,
                 ),
               ),
             );
           }
         }
-      },
-    );
+      });
+    }
+
+    ref.onDispose(() {
+      // The portal client owns its D-Bus connection.
+      if (Platform.isLinux) {
+        ref.read(PortalController.provider.future).then((portal) {
+          portal.close();
+        });
+      }
+    });
 
     return notifications;
   }
 
   Future<bool> requestPermissions() async {
+    if (Platform.isLinux) {
+      return true;
+    }
+
     final controller = await future;
 
     if (Platform.isIOS) {
@@ -82,31 +122,41 @@ class NotificationController
     String? payload,
   }) async {
     debugPrint("Sending notification for $id");
-    final notificationDetails = NotificationDetails(
-      android: .new(
-        "messages",
-        "Messages",
-        largeIcon: icon == null ? null : FilePathAndroidBitmap(icon.path),
-      ),
-      linux: .new(
-        category: LinuxNotificationCategory.imReceived,
-        defaultActionName: "app.event",
-        icon: icon == null ? null : FilePathLinuxIcon(icon.path),
-      ),
-      // TODO: See if icons can be added to iOS, macOS, and Windows notifications (#68)
-      iOS: .new(),
-      macOS: .new(),
-      windows: .new(),
-    );
 
-    final controller = await future;
-    await controller.show(
-      id: id,
-      title: title,
-      body: body,
-      notificationDetails: notificationDetails,
-      payload: payload,
-    );
+    if (Platform.isLinux) {
+      final portal = await ref.read(PortalController.provider.future);
+
+      await portal.notification.addNotification(
+        id.toString(),
+        title: title,
+        body: body,
+        icon: icon == null ? null : XdgNotificationIconFile(icon.path),
+        defaultAction: "app.event",
+      );
+    } else {
+      final notificationDetails = NotificationDetails(
+        android: .new(
+          "messages",
+          "Messages",
+          largeIcon: icon == null ? null : FilePathAndroidBitmap(icon.path),
+        ),
+        // TODO: See if icons can be added to iOS, macOS, and Windows
+        // notifications (#68)
+        iOS: .new(),
+        macOS: .new(),
+        windows: .new(),
+      );
+
+      final controller = await future;
+
+      await controller.show(
+        id: id,
+        title: title,
+        body: body,
+        notificationDetails: notificationDetails,
+        payload: payload,
+      );
+    }
   }
 
   static final provider =

lib/controllers/portal.dart

@@ -0,0 +1,17 @@
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:xdg_desktop_portal/xdg_desktop_portal.dart";
+
+class PortalController extends AsyncNotifier<XdgDesktopPortalClient> {
+  @override
+  Future<XdgDesktopPortalClient> build() async {
+    final portal = XdgDesktopPortalClient();
+    await portal.registerApplication("nexus.federated.nexus");
+
+    return portal;
+  }
+
+  static final provider =
+      AsyncNotifierProvider<PortalController, XdgDesktopPortalClient>(
+        PortalController.new,
+      );
+}