Add default timeout in Connect, Pair and IsPaired apis

lib/src/universal_ble.dart

@@ -76,12 +76,14 @@ class UniversalBle {
   /// Connect to a device.
   /// It is advised to stop scanning before connecting.
   /// It might throw errors if device is not connectable.
-  /// `connectionTimeout` is supported on Web only.
+  /// Default connection timeout is 60 sec
   static Future<bool> connect(
     String deviceId, {
     Duration? connectionTimeout,
   }) async {
+    connectionTimeout ??= const Duration(seconds: 60);
     StreamSubscription? connectionSubscription;
+
     try {
       Completer<bool> completer = Completer();
 
@@ -104,10 +106,7 @@ class UniversalBle {
         },
       );
 
-      if (connectionTimeout != null) {
-        return await completer.future.timeout(connectionTimeout);
-      }
-      return await completer.future;
+      return await completer.future.timeout(connectionTimeout);
     } finally {
       connectionSubscription?.cancel();
     }
@@ -211,6 +210,7 @@ class UniversalBle {
   static Future<bool?> isPaired(
     String deviceId, {
     BleCommand? pairingCommand,
+    Duration? connectionTimeout,
   }) async {
     if (BleCapabilities.hasSystemPairingApi) {
       return _bleCommandQueue.queueCommand(
@@ -218,8 +218,12 @@ class UniversalBle {
         deviceId: deviceId,
       );
     } else if (pairingCommand != null) {
-      return _connectAndExecuteBleCommand(deviceId, pairingCommand,
-          updateCallbackValue: false);
+      return _connectAndExecuteBleCommand(
+        deviceId,
+        pairingCommand,
+        connectionTimeout: connectionTimeout,
+        updateCallbackValue: false,
+      );
     }
     return null;
   }
@@ -236,11 +240,16 @@ class UniversalBle {
   static Future<bool?> pair(
     String deviceId, {
     BleCommand? pairingCommand,
+    Duration? connectionTimeout,
   }) async {
     if (BleCapabilities.hasSystemPairingApi) {
       return _platform.pair(deviceId);
     }
-    return _connectAndExecuteBleCommand(deviceId, pairingCommand);
+    return _connectAndExecuteBleCommand(
+      deviceId,
+      pairingCommand,
+      connectionTimeout: connectionTimeout,
+    );
   }
 
   /// Unpair a device.
@@ -306,12 +315,20 @@ class UniversalBle {
   static Future<bool?> _connectAndExecuteBleCommand(
     String deviceId,
     BleCommand? bleCommand, {
+    Duration? connectionTimeout,
     bool updateCallbackValue = false,
   }) async {
     try {
-      if (await getConnectionState(deviceId) != BleConnectionState.connected) {
-        await connect(deviceId);
+      bool isConnected =
+          await getConnectionState(deviceId) != BleConnectionState.connected;
+
+      if (!isConnected) {
+        isConnected = await connect(
+          deviceId,
+          connectionTimeout: connectionTimeout,
+        );
       }
+      if (!isConnected) return null;
 
       List<BleService> services = await discoverServices(deviceId);