bluetoothServiceListener.kt

private inner class BluetoothServiceListener : BluetoothProfile.ServiceListener {
    // Called to notify the client when the proxy object has been connected to the service.    
    // Once we have the profile proxy object, we can use it to monitor the state of the    
    // connection and perform other operations that are relevant to the headset profile.    
    override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {    
        if (profile != BluetoothProfile.HEADSET || bluetoothState == State.UNINITIALIZED) {    
            return    
        }    
        // Android only supports one connected Bluetooth Headset at a time.    
        bluetoothHeadset = proxy as BluetoothHeadset    
        updateAudioDeviceState()    
    }    
    /**
    Notifies the client when the proxy object has been disconnected from the service.    
    */    
    override fun onServiceDisconnected(profile: Int) {    
        if (profile != BluetoothProfile.HEADSET || bluetoothState == State.UNINITIALIZED) {    
            return    
        }    
        stopScoAudio()    
        bluetoothHeadset = null    
        bluetoothDevice = null    
        bluetoothState = State.HEADSET_UNAVAILABLE    
        updateAudioDeviceState()    
    }    
}    
// Intent broadcast receiver which handles changes in Bluetooth device availability.    
// Detects headset changes and Bluetooth SCO state changes.    
private inner class BluetoothHeadsetBroadcastReceiver : BroadcastReceiver() {    
    override fun onReceive(context: Context, intent: Intent) {    
        if (bluetoothState == State.UNINITIALIZED) {    
            return    
        }    
        val action = intent.action    
        // Change in connection state of the Headset profile. Note that the    
        // change does not tell us anything about whether we're streaming    
        // audio to BT over SCO. Typically received when user turns on a BT    
        // headset while audio is active using another audio device.    
        if (action == BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED) {    
            val state = intent.getIntExtra(    
                BluetoothHeadset.EXTRA_STATE,    
                BluetoothHeadset.STATE_DISCONNECTED    
            )    
            when (state) {    
                BluetoothHeadset.STATE_CONNECTED -> {    
                    scoConnectionAttempts = 0    
                    updateAudioDeviceState()    
                }    
                BluetoothHeadset.STATE_CONNECTING -> {    
                    // No action needed.    
                }    
                BluetoothHeadset.STATE_DISCONNECTING -> {    
                    // No action needed.    
                }    
                BluetoothHeadset.STATE_DISCONNECTED -> {    
                    // Bluetooth is probably powered off during the call.    
                    stopScoAudio()    
                    updateAudioDeviceState()    
                }    
            }    
        } else if (action == BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED) {    
            // Change in the audio (SCO) connection state of the Headset profile.    
            // Typically received after call to startScoAudio() has finalized.    
            val state = intent.getIntExtra(    
                BluetoothHeadset.EXTRA_STATE,    
                BluetoothHeadset.STATE_AUDIO_DISCONNECTED    
            )    
            if (state == BluetoothHeadset.STATE_AUDIO_CONNECTED) {    
                cancelTimer()    
                if (bluetoothState == State.SCO_CONNECTING) {    
                    bluetoothState = State.SCO_CONNECTED    
                    scoConnectionAttempts = 0    
                    updateAudioDeviceState()    
                }    
            } else if (state == BluetoothHeadset.STATE_AUDIO_DISCONNECTED) {    
                if (isInitialStickyBroadcast) {    
                    return    
                }    
                updateAudioDeviceState()    
            }    
        }    
    }    
}