Android: Bluetooth Device App

MainActivity.kt

package com.example.cyborg2

import android.bluetooth.BluetoothA2dp
import android.bluetooth.BluetoothAdapter
import android.bluetooth.BluetoothHeadset
import android.bluetooth.BluetoothProfile
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.Bundle
import androidx.activity.ComponentActivity
import android.util.Log
import android.view.KeyEvent

class MainActivity : ComponentActivity() {
    private lateinit var bluetoothAdapter: BluetoothAdapter
    private var bluetoothHeadset: BluetoothHeadset? = null
    private lateinit var headsetFilter: IntentFilter

    private val profileListener = object: BluetoothProfile.ServiceListener {
        override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {
            if (profile == BluetoothProfile.HEADSET) {
                bluetoothHeadset = proxy as BluetoothHeadset
                Log.d("MainActivity", "BluetoothHeadset connected")
            }
        }

        override fun onServiceDisconnected(profile: Int) {
            if (profile == BluetoothProfile.HEADSET) {
                bluetoothHeadset = null
                Log.d("MainActivity", "BluetoothHeadset disconnected")
            }
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Initialize BluetoothAdapter
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter()

        // Initialize IntentFilter
        headsetFilter = IntentFilter().apply {
            addAction(BluetoothHeadset.ACTION_VENDOR_SPECIFIC_HEADSET_EVENT)
            addAction(BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED)
            addAction(BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED)
            addAction(BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED)
            addAction(BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED)
        }

        // Establish connection to the proxy.
        bluetoothAdapter.getProfileProxy(this, profileListener, BluetoothProfile.HEADSET)
    }

    override fun onStart() {
        super.onStart()

        // Register for BluetoothHeadset broadcasts
        registerReceiver(bluetoothHeadsetBroadcastReceiver, headsetFilter)
    }

    override fun onStop() {
        super.onStop()

        // Unregister BluetoothHeadset broadcasts
        unregisterReceiver(bluetoothHeadsetBroadcastReceiver)
    }

    private val bluetoothHeadsetBroadcastReceiver = object: BroadcastReceiver() {
        override fun onReceive(context: Context, intent: Intent) {
            when (intent.action) {
                BluetoothHeadset.ACTION_CONNECTION_STATE_CHANGED -> {
                    val state = intent.getIntExtra(BluetoothHeadset.EXTRA_STATE, -1)
                    Log.d("MainActivity", "BluetoothHeadset state: $state")
                }
                BluetoothHeadset.ACTION_AUDIO_STATE_CHANGED -> {
                    val state = intent.getIntExtra(BluetoothHeadset.EXTRA_STATE, -1)
                    Log.d("MainActivity", "BluetoothHeadset audio state: $state")
                }
                BluetoothHeadset.ACTION_VENDOR_SPECIFIC_HEADSET_EVENT -> {
                    val command = intent.getStringExtra(BluetoothHeadset.EXTRA_VENDOR_SPECIFIC_HEADSET_EVENT_CMD)
                    val args = intent.getIntArrayExtra(BluetoothHeadset.EXTRA_VENDOR_SPECIFIC_HEADSET_EVENT_ARGS)
                    Log.d("MainActivity", "BluetoothHeadset event: $command, args: ${args?.contentToString()}")
                }
                BluetoothA2dp.ACTION_CONNECTION_STATE_CHANGED -> {
                    val state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, -1)
                    Log.d("MainActivity", "BluetoothA2dp connection state: $state")
                }
                BluetoothA2dp.ACTION_PLAYING_STATE_CHANGED -> {
                    val state = intent.getIntExtra(BluetoothA2dp.EXTRA_STATE, -1)
                    Log.d("MainActivity", "BluetoothA2dp playing state: $state")
                }
                Intent.ACTION_MEDIA_BUTTON -> {
                    val keyEvent = intent.getParcelableExtra<KeyEvent>(Intent.EXTRA_KEY_EVENT)
                    Log.d("MainActivity", "Media button event: ${keyEvent?.keyCode}")
                }
            }
        }
    }
}