Implement queue (#11)

* Implement queue

* Enable queue by default, remove queue from web and update readme

* Rename useQueue to queuesRequests

* Rename queuesRequests and improve readme

* Rename _executeMethod and improve readme

* Rename to _isQueueEnabled

---------

Co-authored-by: Foti Dim <fdimanidis@gmail.com>

example/lib/data/mock_universal_ble.dart

@@ -0,0 +1,108 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:universal_ble/universal_ble.dart';
+
+/// Mock implementation of [UniversalBlePlatform] for testing
+class MockUniversalBle extends UniversalBlePlatform {
+  final _mockBleScanResult = BleScanResult(
+    name: 'MockDevice',
+    deviceId: 'MockDeviceId',
+    rssi: 50,
+    manufacturerData: Uint8List(0),
+  );
+
+  Uint8List _serviceValue = utf8.encode('Result');
+
+  final BleService _mockService = BleService('180', [
+    BleCharacteristic('180A', [
+      CharacteristicProperty.read,
+      CharacteristicProperty.write,
+      CharacteristicProperty.notify,
+    ]),
+  ]);
+
+  @override
+  Future<void> startScan({WebRequestOptionsBuilder? webRequestOptions}) async {
+    onScanResult?.call(_mockBleScanResult);
+  }
+
+  @override
+  Future<void> stopScan() async {}
+
+  @override
+  Future<void> connect(String deviceId, {Duration? connectionTimeout}) async {
+    onConnectionChanged?.call(deviceId, BleConnectionState.connected);
+  }
+
+  @override
+  Future<void> disconnect(String deviceId) async {
+    onConnectionChanged?.call(deviceId, BleConnectionState.disconnected);
+  }
+
+  @override
+  Future<List<BleService>> discoverServices(String deviceId) async {
+    return [_mockService];
+  }
+
+  @override
+  Future<bool> enableBluetooth() async {
+    await Future.delayed(const Duration(milliseconds: 500));
+    return true;
+  }
+
+  @override
+  Future<AvailabilityState> getBluetoothAvailabilityState() async {
+    return AvailabilityState.poweredOn;
+  }
+
+  @override
+  Future<List<BleScanResult>> getConnectedDevices(
+      List<String>? withServices) async {
+    return [];
+  }
+
+  @override
+  Future<Uint8List> readValue(
+      String deviceId, String service, String characteristic) async {
+    await Future.delayed(const Duration(milliseconds: 500));
+    return _serviceValue;
+  }
+
+  @override
+  Future<void> writeValue(
+      String deviceId,
+      String service,
+      String characteristic,
+      Uint8List value,
+      BleOutputProperty bleOutputProperty) async {
+    await Future.delayed(const Duration(milliseconds: 500));
+    _serviceValue = value;
+  }
+
+  @override
+  Future<int> requestMtu(String deviceId, int expectedMtu) async {
+    await Future.delayed(const Duration(seconds: 1));
+    return 512;
+  }
+
+  @override
+  Future<void> setNotifiable(String deviceId, String service,
+      String characteristic, BleInputProperty bleInputProperty) async {}
+
+  @override
+  Future<bool> isPaired(String deviceId) async {
+    await Future.delayed(const Duration(milliseconds: 500));
+    return true;
+  }
+
+  @override
+  Future<void> pair(String deviceId) async {
+    onPairingStateChange?.call(deviceId, true, null);
+  }
+
+  @override
+  Future<void> unPair(String deviceId) async {
+    onPairingStateChange?.call(deviceId, false, null);
+  }
+}

example/lib/home/home.dart

@@ -4,6 +4,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:universal_ble/universal_ble.dart';
 import 'package:universal_ble_example/data/capabilities.dart';
+import 'package:universal_ble_example/data/mock_universal_ble.dart';
 import 'package:universal_ble_example/home/widgets/scanned_devices_placeholder_widget.dart';
 import 'package:universal_ble_example/home/widgets/scanned_item_widget.dart';
 import 'package:universal_ble_example/data/permission_handler.dart';
@@ -21,6 +22,8 @@ class MyApp extends StatefulWidget {
 class _MyAppState extends State<MyApp> {
   final _scanResults = <BleScanResult>[];
   bool _isScanning = false;
+  bool _isQueueEnabled = true;
+
   AvailabilityState? bleAvailabilityState;
   late WebRequestOptionsBuilder _requestOptions;
   final List<String> _services = [
@@ -36,6 +39,15 @@ class _MyAppState extends State<MyApp> {
   void initState() {
     super.initState();
 
+    /// Set mock instance for testing
+    if (const bool.fromEnvironment('MOCK')) {
+      UniversalBle.setInstance(MockUniversalBle());
+    }
+
+    /// Setup queue and timeout
+    UniversalBle.queuesCommands = _isQueueEnabled;
+    UniversalBle.timeout = const Duration(seconds: 10);
+
     /// Add common services for web
     if (kIsWeb) {
       _services.addAll(WebRequestOptionsBuilder.defaultServices);
@@ -162,6 +174,15 @@ class _MyAppState extends State<MyApp> {
                       });
                     },
                   ),
+                PlatformButton(
+                  text: _isQueueEnabled ? 'Disable Queue' : 'Enable Queue',
+                  onPressed: () {
+                    setState(() {
+                      _isQueueEnabled = !_isQueueEnabled;
+                      UniversalBle.queuesCommands = _isQueueEnabled;
+                    });
+                  },
+                ),
                 if (_scanResults.isNotEmpty)
                   PlatformButton(
                     text: 'Clear List',