[client] Working primary handoff

client/lib/ui/app/account_selector_web.dart

@@ -1,4 +1,6 @@
+import 'dart:async';
 import 'dart:js_interop';
+import 'dart:math';
 
 import 'package:flutter/material.dart';
 import 'package:offtheline/offtheline.dart';
@@ -6,6 +8,7 @@ import 'package:phylum/libphylum/phylum_account.dart';
 import 'package:phylum/ui/app/dialog_scaffold.dart';
 import 'package:phylum/ui/app/login_page.dart';
 import 'package:phylum/ui/layout/app_layout.dart';
+import 'package:phylum/util/logging.dart';
 import 'package:provider/provider.dart';
 import 'package:web/web.dart' as web;
 
@@ -23,12 +26,24 @@ class AccountSelector extends StatefulWidget {
 }
 
 class _AccountSelectorState extends State<AccountSelector> {
-  final channel = web.BroadcastChannel('takover');
+  final channel = web.BroadcastChannel('handoff');
+  late final AccountManager<PhylumAccount> accountManager;
+  String? requestId;
+  Timer? retryRequestTimer;
+  int retriesLeft = 0;
+  bool requestAccepted = false;
 
   @override
   void initState() {
     super.initState();
     channel.onmessage = processMessage.toJS;
+    accountManager = context.read();
+  }
+
+  @override
+  void dispose() {
+    channel.onmessage = null;
+    super.dispose();
   }
 
   @override
@@ -43,10 +58,8 @@ class _AccountSelectorState extends State<AccountSelector> {
             const Text('Phylum is already open in another tab or window'),
             const SizedBox(height: 12),
             ElevatedButton(
+              onPressed: requestId == null ? requestHandoff : null,
               child: const Text('Use Here'),
-              onPressed: () {
-                channel.postMessage('close'.toJS);
-              },
             ),
           ],
         ));
@@ -71,20 +84,74 @@ class _AccountSelectorState extends State<AccountSelector> {
     return AppLayout.create(account);
   }
 
+  void requestHandoff() {
+    if (requestId != null) return;
+    final r = Random();
+    const chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890';
+
+    setState(() {
+      requestId = String.fromCharCodes(Iterable.generate(12, (_) => chars.codeUnitAt(r.nextInt(chars.length))));
+    });
+
+    channel.postMessage('request|$requestId'.toJS);
+    retryRequestTimer = Timer.periodic(const Duration(milliseconds: 100), (t) {
+      if (retriesLeft-- > 0) {
+        if (!requestAccepted) {
+          channel.postMessage('request|$requestId'.toJS);
+        }
+      } else {
+        channel.postMessage('hijack|$requestId'.toJS);
+        retryRequestTimer?.cancel();
+        retryRequestTimer = null;
+        requestId = null;
+        setPrimary(true.toJS);
+        accountManager.initialize();
+      }
+    });
+    retriesLeft = 5;
+    requestAccepted = false;
+  }
+
   void processMessage(web.MessageEvent event) {
-    final msg = event.data.toString();
-    final accountManager = context.read<AccountManager<PhylumAccount>>();
-    if (msg == 'close') {
+    final data = event.data.toString();
+    final msg = data.split('|');
+    if (msg.length < 2) {
+      logger.w('Unrecognized message: $data');
+    }
+
+    if (msg[0] == 'request') {
+      final id = msg[1];
       if (accountManager.status == AccountManagerStatus.ready) {
-        channel.postMessage('closing'.toJS);
+        channel.postMessage('accept|$id'.toJS);
         accountManager.close().then((v) {
-          channel.postMessage('closed'.toJS);
+          channel.postMessage('success|$id'.toJS);
           setPrimary(false.toJS);
-          accountManager.close();
         });
+      } else {
+        channel.postMessage('reject|$id'.toJS);
       }
     }
-    if (msg == 'closed') {
+    if (msg[0] == 'hijack') {
+      setPrimary(false.toJS);
+    }
+
+    // Process responses, but make sure the id matches
+    if (msg[1] != requestId) return;
+
+    if (msg[0] == 'reject') {
+      retryRequestTimer?.cancel();
+      retryRequestTimer = null;
+      requestId = null;
+    }
+    if (msg[0] == 'accept') {
+      // Maybe display a message if this is taking time
+      requestAccepted = true;
+      retriesLeft += 10;
+    }
+    if (msg[0] == 'success') {
+      retryRequestTimer?.cancel();
+      retryRequestTimer = null;
+      requestId = null;
       setPrimary(true.toJS);
       accountManager.initialize();
     }