feat(fl_query_connectivity_plus_adapter): lookup based offline detection

packages/fl_query/example/pubspec.lock

@@ -111,21 +111,21 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "1.0.0-alpha.4"
+    version: "1.0.0-alpha.5"
   fl_query_connectivity_plus_adapter:
     dependency: "direct main"
     description:
       path: "../../fl_query_connectivity_plus_adapter"
       relative: true
     source: path
-    version: "0.1.0-alpha.3"
+    version: "0.1.0-alpha.4"
   fl_query_devtools:
     dependency: "direct main"
     description:
       path: "../../fl_query_devtools"
       relative: true
     source: path
-    version: "0.1.0-alpha.2"
+    version: "0.1.0-alpha.3"
   flutter:
     dependency: "direct main"
     description: flutter

packages/fl_query_connectivity_plus_adapter/lib/connection_checker.dart

@@ -0,0 +1,74 @@
+import 'dart:async';
+
+import 'package:connectivity_plus/connectivity_plus.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:fl_query_connectivity_plus_adapter/lookups/connection_lookup_io.dart'
+    if (dart.library.html) 'package:fl_query_connectivity_plus_adapter/lookups/connection_lookup_web.dart';
+
+abstract class ConnectionLookup {
+  Future<bool> doesConnectTo(String address);
+  Future<bool> isVpnActive();
+}
+
+class InternetConnectivityChecker
+    with WidgetsBindingObserver, ConnectionLookupMixin {
+  final StreamController<bool> controller;
+
+  bool _wasConnected = true;
+
+  bool get isAppPaused =>
+      WidgetsBinding.instance.lifecycleState == AppLifecycleState.paused;
+
+  InternetConnectivityChecker(Duration duration)
+      : controller = StreamController<bool>.broadcast() {
+    Timer.periodic(duration, (timer) async {
+      if (isAppPaused) {
+        return;
+      }
+      await hasConnection();
+    });
+    Connectivity().onConnectivityChanged.listen((event) async {
+      if (isAppPaused) {
+        return;
+      }
+      await hasConnection();
+    });
+  }
+
+  @override
+  didChangeAppLifecycleState(AppLifecycleState state) async {
+    if (state == AppLifecycleState.resumed) {
+      await hasConnection();
+    }
+  }
+
+  Future<bool> hasConnection() async {
+    final connectivityResult = await (Connectivity().checkConnectivity());
+    final hasNetwork = [
+      ConnectivityResult.mobile,
+      ConnectivityResult.wifi,
+      ConnectivityResult.ethernet,
+    ].contains(connectivityResult);
+
+    final isVpn =
+        connectivityResult == ConnectivityResult.vpn || await isVpnActive();
+
+    final connected = hasNetwork
+        ? kIsWeb
+            ? await doesConnectTo('/favicon.ico') ||
+                await doesConnectTo('/favicon.png') ||
+                await doesConnectTo('/favicon.gif')
+            : await doesConnectTo('google.com') ||
+                await doesConnectTo('www.baidu.com')
+        : isVpn;
+
+    if (connected != _wasConnected) {
+      _wasConnected = connected;
+      controller.add(connected);
+    }
+    return connected;
+  }
+
+  Stream<bool> get onConnectionChanged => controller.stream;
+}

packages/fl_query_connectivity_plus_adapter/lib/fl_query_connectivity_plus_adapter.dart

@@ -1,32 +1,20 @@
 library fl_query_connectivity_plus_adapter;
 
 import 'package:fl_query/fl_query.dart';
-import 'package:connectivity_plus/connectivity_plus.dart';
+import 'package:fl_query_connectivity_plus_adapter/connection_checker.dart';
 
 /// A [ConnectivityAdapter] that uses the `connectivity_plus` package.
 class FlQueryConnectivityPlusAdapter extends ConnectivityAdapter {
+  final InternetConnectivityChecker _adapter;
+  FlQueryConnectivityPlusAdapter({
+    Duration pollingDuration = const Duration(minutes: 5),
+  }) : _adapter = InternetConnectivityChecker(pollingDuration);
+
   @override
   Future<bool> get isConnected async {
-    final connection = await Connectivity().checkConnectivity();
-
-    switch (connection) {
-      case ConnectivityResult.bluetooth:
-      case ConnectivityResult.none:
-        return false;
-      default:
-        return true;
-    }
+    return await _adapter.hasConnection();
   }
 
   @override
-  Stream<bool> get onConnectivityChanged =>
-      Connectivity().onConnectivityChanged.map((event) {
-        switch (event) {
-          case ConnectivityResult.bluetooth:
-          case ConnectivityResult.none:
-            return false;
-          default:
-            return true;
-        }
-      });
+  Stream<bool> get onConnectivityChanged => _adapter.onConnectionChanged;
 }

packages/fl_query_connectivity_plus_adapter/lib/lookups/connection_lookup_io.dart

@@ -0,0 +1,55 @@
+import 'dart:io';
+
+import 'package:fl_query_connectivity_plus_adapter/connection_checker.dart';
+
+mixin ConnectionLookupMixin implements ConnectionLookup {
+  @override
+  Future<bool> doesConnectTo(String address) async {
+    try {
+      final result = await InternetAddress.lookup(address);
+      return result.isNotEmpty && result[0].rawAddress.isNotEmpty;
+    } catch (_) {
+      return false;
+    }
+  }
+
+  static const _vpnNames = [
+    'tun',
+    'tap',
+    'ppp',
+    'pptp',
+    'l2tp',
+    'ipsec',
+    'vpn',
+    'wireguard',
+    'openvpn',
+    'softether',
+    'proton',
+    'strongswan',
+    'cisco',
+    'forticlient',
+    'fortinet',
+    'hideme',
+    'hidemy',
+    'hideman',
+    'hidester',
+    'lightway',
+  ];
+
+  @override
+  Future<bool> isVpnActive() async {
+    final interfaces = await NetworkInterface.list(
+      includeLoopback: false,
+      type: InternetAddressType.any,
+    );
+
+    if (interfaces.isEmpty) {
+      return false;
+    }
+
+    return interfaces.any(
+      (interface) =>
+          _vpnNames.any((name) => interface.name.toLowerCase().contains(name)),
+    );
+  }
+}

packages/fl_query_connectivity_plus_adapter/lib/lookups/connection_lookup_web.dart

@@ -0,0 +1,29 @@
+import 'dart:html';
+import 'package:fl_query_connectivity_plus_adapter/connection_checker.dart';
+
+mixin ConnectionLookupMixin implements ConnectionLookup {
+  @override
+  Future<bool> doesConnectTo(String address) async {
+    try {
+      final url = address.startsWith("http") || address.startsWith("/")
+          ? address
+          : "https://$address";
+      final request = await HttpRequest.request(
+        url,
+        requestHeaders: {
+          'Cache-Control': 'no-cache',
+          'Pragma': 'no-cache',
+        },
+      );
+
+      return (request.status ?? 0) < 400;
+    } catch (_) {
+      return false;
+    }
+  }
+
+  @override
+  Future<bool> isVpnActive() {
+    return Future.value(false);
+  }
+}