Add auto-connect support (#206)

* Add autoConnect support

* Enhance autoConnect functionality for Bluetooth devices

- Added support for managing a set of auto-connect devices in both Android and iOS implementations.
- Updated connection and disconnection logic to handle auto-reconnect scenarios appropriately.
- Improved cleanup processes to prevent unwanted reconnections when devices are manually disconnected.

* Refactor connection button and add auto-reconnect toggle

- Updated the connection button layout for better UI consistency.
- Introduced an auto-reconnect toggle to manage automatic reconnections when devices become available.
- Enhanced connection and disconnection logic to respect the auto-connect setting.

* Update version to 1.2.0 and add CHANGELOG for new features

- Bumped version to 1.2.0.
- Added CHANGELOG.md detailing new features including support for `autoConnect` and UI updates for automatic reconnection.

* Improve readme

* Refactor variable naming for clarity in Bluetooth connection logic

- Changed variable name from `isAutoConnect` to `shouldAutoConnect` for better readability and understanding of its purpose in the connection state handling.

* Refactor connection handling in UniversalBlePlugin

- Simplified connection logic by always cleaning up internal state before sending connection change callbacks.
- Ensured GATT resources are only closed when autoConnect is disabled, allowing for better management of Bluetooth connections.

* Refactor disconnection handling in UniversalBlePlugin

- Introduced a new method `handlePeripheralDisconnection` to encapsulate disconnection logic, improving code readability and maintainability.
- Updated the `centralManager` methods to utilize the new disconnection handler, ensuring consistent behavior across connection state changes.

* Update darwin/Classes/UniversalBlePlugin.swift

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Foti Dim <fotios.dimanidis@a2zebra.de>
Co-authored-by: Navideck Labs <130186950+navidecklabs@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

android/src/main/kotlin/com/navideck/universal_ble/UniversalBle.g.kt

@@ -517,7 +517,7 @@ interface UniversalBlePlatformChannel {
   fun startScan(filter: UniversalScanFilter?)
   fun stopScan()
   fun isScanning(): Boolean
-  fun connect(deviceId: String)
+  fun connect(deviceId: String, autoConnect: Boolean?)
   fun disconnect(deviceId: String)
   fun setNotifiable(deviceId: String, service: String, characteristic: String, bleInputProperty: Long, callback: (Result<Unit>) -> Unit)
   fun discoverServices(deviceId: String, withDescriptors: Boolean, callback: (Result<List<UniversalBleService>>) -> Unit)
@@ -686,8 +686,9 @@ interface UniversalBlePlatformChannel {
           channel.setMessageHandler { message, reply ->
             val args = message as List<Any?>
             val deviceIdArg = args[0] as String
+            val autoConnectArg = args[1] as Boolean?
             val wrapped: List<Any?> = try {
-              api.connect(deviceIdArg)
+              api.connect(deviceIdArg, autoConnectArg)
               listOf(null)
             } catch (exception: Throwable) {
               UniversalBlePigeonUtils.wrapError(exception)

android/src/main/kotlin/com/navideck/universal_ble/UniversalBlePlugin.kt

@@ -61,6 +61,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
     private val subscriptionResultFutureList = mutableListOf<SubscriptionResultFuture>()
     private val pairResultFutures = mutableMapOf<String, (Result<Boolean>) -> Unit>()
     private val rssiResultFutureList = mutableListOf<RssiResultFuture>()
+    private val autoConnectDevices = mutableSetOf<String>()
 
     override fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
         UniversalBlePlatformChannel.setUp(flutterPluginBinding.binaryMessenger, this)
@@ -213,7 +214,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
         return safeScanner.isScanning()
     }
 
-    override fun connect(deviceId: String) {
+    override fun connect(deviceId: String, autoConnect: Boolean?) {
         // If already connected, send connected message,
         // if connecting, do nothing
         deviceId.findGatt()?.let {
@@ -232,24 +233,31 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
 
-
+        val shouldAutoConnect = autoConnect ?: false
+        if (shouldAutoConnect) {
+            autoConnectDevices.add(deviceId)
+        } else {
+            autoConnectDevices.remove(deviceId)
+        }
         val remoteDevice = bluetoothManager.adapter.getRemoteDevice(deviceId)
         val gatt = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             remoteDevice.connectGatt(
                 context,
-                false,
+                shouldAutoConnect,
                 this,
                 BluetoothDevice.TRANSPORT_LE
             )
         } else {
-            remoteDevice.connectGatt(context, false, this)
+            remoteDevice.connectGatt(context, shouldAutoConnect, this)
         }
         gatt.saveCacheIfNeeded()
     }
 
     override fun disconnect(deviceId: String) {
+        autoConnectDevices.remove(deviceId)
         val gatt = deviceId.findGatt()
         if (gatt == null) {
+            cleanUpConnection(deviceId)
             mainThreadHandler?.post {
                 callbackChannel?.onConnectionChanged(deviceId, false, null) {}
             }
@@ -955,15 +963,13 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
         }
     }
 
-    private fun cleanConnection(gatt: BluetoothGatt) {
-        gatt.removeCache()
-        gatt.disconnect()
+    private fun cleanUpConnection(deviceId: String) {
         val deviceDisconnectedError: FlutterError = createFlutterError(
             UniversalBleErrorCode.DEVICE_DISCONNECTED,
             "Device Disconnected",
         )
         readResultFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -971,7 +977,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
         writeResultFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -979,7 +985,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
         subscriptionResultFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -987,7 +993,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
         mtuResultFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -995,7 +1001,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
         discoverServicesFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -1003,7 +1009,7 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
             }
         }
         rssiResultFutureList.removeAll {
-            if (it.deviceId == gatt.device.address) {
+            if (it.deviceId == deviceId) {
                 it.result(Result.failure(deviceDisconnectedError))
                 true
             } else {
@@ -1012,6 +1018,12 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
         }
     }
 
+    private fun cleanConnection(gatt: BluetoothGatt) {
+        gatt.removeCache()
+        gatt.disconnect()
+        cleanUpConnection(gatt.device.address)
+    }
+
     private fun onBondStateUpdate(deviceId: String, bonded: Boolean, error: String? = null) {
         val future = pairResultFutures.remove(deviceId)
         future?.let { it(Result.success(bonded)) }
@@ -1134,14 +1146,27 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
                 ) {}
             }
         } else if (newState == BluetoothGatt.STATE_DISCONNECTED) {
-            cleanConnection(gatt)
+            val deviceId = gatt.device.address
+            val shouldAutoConnect = autoConnectDevices.contains(deviceId)
+            
+            // Always clean up internal state (futures, etc.)
+            cleanUpConnection(deviceId)
+            
+            // Send connection changed callback
             mainThreadHandler?.post {
                 callbackChannel?.onConnectionChanged(
-                    gatt.device.address, false, status.parseHciErrorCode()
+                    deviceId, false, status.parseHciErrorCode()
                 ) {}
             }
-            UniversalBleLogger.logDebug("Closing gatt for ${gatt.device.name}")
-            gatt.close()
+            
+            if (!shouldAutoConnect) {
+                // Only close GATT resources when autoConnect is disabled
+                gatt.removeCache()
+                gatt.disconnect()
+                UniversalBleLogger.logDebug("Closing gatt for ${gatt.device.name}")
+                gatt.close()
+            }
+            // When autoConnect is enabled, keep GATT open for Android to reconnect
         }
     }