refactor: extract BLE logic from MainActivity to BleRelayManager

android/app/src/main/java/com/eddy/atomrelay/MainActivity.kt

@@ -1,193 +1,75 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 package com.eddy.atomrelay
 
-import android.Manifest
-import android.annotation.SuppressLint
-import android.app.Activity
-import android.bluetooth.BluetoothAdapter
-import android.bluetooth.BluetoothGatt
-import android.bluetooth.BluetoothGattCallback
-import android.bluetooth.BluetoothGattCharacteristic
-import android.bluetooth.BluetoothGattDescriptor
-import android.bluetooth.BluetoothProfile
-import android.bluetooth.le.ScanCallback
-import android.bluetooth.le.ScanFilter
-import android.bluetooth.le.ScanResult
-import android.bluetooth.le.ScanSettings
-import android.content.Context
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
-import android.os.ParcelUuid
-import android.util.Log
 import android.view.MotionEvent
 import android.widget.Button
 import android.widget.ImageButton
 import android.widget.TextView
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.app.ActivityCompat
-import java.nio.ByteBuffer
-import java.nio.ByteOrder
-import javax.crypto.Mac
-import javax.crypto.spec.SecretKeySpec
-import java.util.UUID
 
-class MainActivity : AppCompatActivity() {
+class MainActivity : AppCompatActivity(), BleCallbacks {
 
     companion object {
-        private const val TAG = "AtomRelay"
-        private val SERVICE_UUID: UUID = UUID.fromString("4fafc201-1fb5-459e-8fcc-c5c9c331914b")
-        private val CHARACTERISTIC_UUID: UUID = UUID.fromString("beb5483e-36e1-4688-b7f5-ea07361f26d8")
-        private val UUID_CHAR_UUID: UUID = UUID.fromString("beb5483e-36e1-4688-b7f5-ea07361f26d9")
-        private val CCCD_UUID: UUID = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb")
-        private const val DEVICE_NAME = "SylDa_Server"
-        private const val HMAC_PKT_SIZE = 37
-        private const val HMAC_LEN = 32
         private const val REQUEST_SETTINGS = 1
-        private const val SCAN_TIMEOUT_MS = 30000L
-        private const val RECONNECT_DELAY_MS = 2000L
         private const val POST_SETTINGS_RESCAN_MS = 500L
         private const val ON_RESUME_SCAN_DELAY_MS = 300L
-        private const val MAX_SCAN_RETRIES = 3
     }
 
-    private var bluetoothGatt: BluetoothGatt? = null
+    private lateinit var manager: BleRelayManager
-    private var relayCharacteristic: BluetoothGattCharacteristic? = null
-    private var isScanning = false
-    private var scanTimedOut = false
-    private var scanTimeoutRetries = 0
     private val handler = Handler(Looper.getMainLooper())
-    private val scanRunnable = Runnable { startScan() }
-    private var scanTimeoutRunnable: Runnable? = null
-
-    private var seq = 1
-    private var hmacKey: ByteArray? = null
-    private var deviceUuid: ByteArray? = null
-    private var triedAddresses = mutableSetOf<String>()
-    private var lastTheme: String? = null
 
     private lateinit var statusText: TextView
     private lateinit var relay1Button: Button
     private lateinit var relay2Button: Button
+    private var lastTheme: String? = null
 
-    private val scanCallback = object : ScanCallback() {
+    override fun onStatusChanged(status: BleStatus) {
-        override fun onScanResult(callbackType: Int, result: ScanResult) {
+        when (status) {
-            val device = result.device
+            BleStatus.Connected -> {
-            val address = device?.address ?: return
+                statusText.text = getString(R.string.status_connected)
-            val name = device?.name ?: ""
+                setupRelayButton()
-            Log.d(TAG, "Found device: $name ($address)")
+                setupRelay2Button()
-            if (triedAddresses.contains(address)) {
+                relay1Button.isEnabled = true
-                Log.d(TAG, "Skipping already-tried device $address")
+                relay2Button.isEnabled = true
-                return
             }
-            stopScan()
+            BleStatus.Disconnected -> {
-            connectToDevice(device)
+                statusText.text = getString(R.string.status_connecting)
-        }
+                relay1Button.isEnabled = false
-    }
+                relay2Button.isEnabled = false
-
-    private val gattCallback = object : BluetoothGattCallback() {
-        @SuppressLint("MissingPermission")
-        override fun onConnectionStateChange(gatt: BluetoothGatt, status: Int, newState: Int) {
-            if (status != BluetoothGatt.GATT_SUCCESS) {
-                Log.w(TAG, "GATT connection state change error: status=$status newState=$newState")
             }
-            if (newState == BluetoothProfile.STATE_CONNECTED) {
+            BleStatus.Scanning -> statusText.text = getString(R.string.status_scanning)
-                if (hmacKey == null) {
+            BleStatus.Connecting -> statusText.text = getString(R.string.status_connecting)
-                    Log.w(TAG, "GATT connected but no key — disconnecting")
+            BleStatus.NoKey -> statusText.text = getString(R.string.status_no_key)
-                    runOnUiThread { statusText.text = getString(R.string.status_no_key) }
+            BleStatus.WrongDevice -> statusText.text = getString(R.string.status_wrong_device)
-                    gatt.disconnect()
+            BleStatus.ServiceNotFound -> statusText.text = getString(R.string.status_service_not_found)
-                    return
+            BleStatus.ServiceError -> statusText.text = getString(R.string.status_service_error)
+            BleStatus.CommError -> statusText.text = getString(R.string.status_comm_error)
+            BleStatus.BluetoothDisabled -> statusText.text = getString(R.string.status_bluetooth_disabled)
+            BleStatus.PermissionsDenied -> {
+                statusText.text = getString(R.string.status_permissions_denied)
+                relay1Button.isEnabled = false
+                relay2Button.isEnabled = false
+            }
+            BleStatus.DeviceNotFound -> {
+                relay1Button.setOnTouchListener(null)
+                relay2Button.setOnTouchListener(null)
+                relay1Button.setOnClickListener(null)
+                relay2Button.setOnClickListener(null)
+                relay1Button.text = getString(R.string.button_retry_scan)
+                relay2Button.text = getString(R.string.button_hold)
+                relay2Button.isEnabled = false
+                relay1Button.isEnabled = true
+                relay1Button.setOnClickListener {
+                    setupRelayButton()
+                    setupRelay2Button()
+                    manager.startScan()
                 }
-                Log.d(TAG, "GATT connected")
-                bluetoothGatt = gatt
-                runOnUiThread { statusText.text = getString(R.string.status_discovering_services) }
-                gatt.discoverServices()
-            } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
-                Log.d(TAG, "GATT disconnected")
-                runOnUiThread {
-                    statusText.text = getString(R.string.status_connecting)
-                    relay1Button.isEnabled = false
-                    relay2Button.isEnabled = false
-                }
-                gatt.close()
-                bluetoothGatt = null
-                relayCharacteristic = null
-                seq = 1
-                handler.postDelayed(scanRunnable, RECONNECT_DELAY_MS)
-            }
-        }
-
-        @SuppressLint("MissingPermission")
-        override fun onServicesDiscovered(gatt: BluetoothGatt, status: Int) {
-            if (status != BluetoothGatt.GATT_SUCCESS) {
-                Log.w(TAG, "Service discovery failed (status=$status)")
-                runOnUiThread { statusText.text = getString(R.string.status_service_error) }
-                return
-            }
-            Log.d(TAG, "Services discovered, requesting MTU...")
-            gatt.requestMtu(256)
-        }
-
-        @SuppressLint("MissingPermission")
-        override fun onMtuChanged(gatt: BluetoothGatt, mtu: Int, status: Int) {
-            if (status != BluetoothGatt.GATT_SUCCESS) {
-                Log.w(TAG, "MTU negotiation failed (status=$status)")
-            }
-            Log.d(TAG, "MTU changed to $mtu")
-            val service = gatt.getService(SERVICE_UUID)
-            if (service != null) {
-                relayCharacteristic = service.getCharacteristic(CHARACTERISTIC_UUID)
-                val uuidChar = service.getCharacteristic(UUID_CHAR_UUID)
-                if (relayCharacteristic != null && uuidChar != null) {
-                    Log.d(TAG, "Reading device UUID characteristic...")
-                    gatt.readCharacteristic(uuidChar)
-                } else {
-                    Log.e(TAG, "Service or characteristics not found")
-                    runOnUiThread { statusText.text = getString(R.string.status_service_not_found) }
-                }
-            } else {
-                Log.e(TAG, "Service not found")
-                runOnUiThread { statusText.text = getString(R.string.status_service_not_found) }
-            }
-        }
-
-        @SuppressLint("MissingPermission")
-        override fun onCharacteristicRead(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic, value: ByteArray, status: Int) {
-            if (characteristic.uuid == UUID_CHAR_UUID && status == BluetoothGatt.GATT_SUCCESS) {
-                val storedUuid = deviceUuid
-                if (storedUuid != null && value.contentEquals(storedUuid)) {
-                    Log.d(TAG, "UUID verified, setting up relay")
-                    relayCharacteristic?.let { rc ->
-                        gatt.setCharacteristicNotification(rc, true)
-                        val descriptor = rc.getDescriptor(CCCD_UUID)
-                        descriptor.value = BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE
-                        gatt.writeDescriptor(descriptor)
-                    }
-                    runOnUiThread {
-                        setupRelayButton()
-                        setupRelay2Button()
-                        statusText.text = getString(R.string.status_connected)
-                        relay1Button.isEnabled = true
-                        relay2Button.isEnabled = true
-                    }
-                } else {
-                    Log.w(TAG, "UUID mismatch — disconnecting")
-                    triedAddresses.add(gatt.device.address)
-                    runOnUiThread { statusText.text = getString(R.string.status_wrong_device) }
-                    gatt.disconnect()
-                }
-            }
-        }
-
-        @SuppressLint("MissingPermission")
-        override fun onCharacteristicWrite(gatt: BluetoothGatt, characteristic: BluetoothGattCharacteristic, status: Int) {
-            if (status == BluetoothGatt.GATT_SUCCESS) {
-                Log.d(TAG, "Write confirmed by local BLE stack (status=$status)")
-            } else {
-                Log.w(TAG, "Write failed (status=$status)")
-                runOnUiThread { statusText.text = getString(R.string.status_comm_error) }
             }
         }
     }
@@ -198,6 +80,8 @@ class MainActivity : AppCompatActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
+        manager = BleRelayManager(this, this)
+
         statusText = findViewById(R.id.statusText)
         relay1Button = findViewById(R.id.relay1Button)
         relay2Button = findViewById(R.id.relay2Button)
@@ -214,14 +98,10 @@ class MainActivity : AppCompatActivity() {
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         super.onActivityResult(requestCode, resultCode, data)
         if (requestCode == REQUEST_SETTINGS && resultCode == SettingsActivity.RESULT_SCAN) {
-            stopScan()
+            manager.disconnect()
-            bluetoothGatt?.close()
+            manager.resetTriedAddresses()
-            bluetoothGatt = null
+            manager.updateKeys()
-            relayCharacteristic = null
+            handler.postDelayed({ manager.startScan() }, POST_SETTINGS_RESCAN_MS)
-            seq = 1
-            triedAddresses.clear()
-            loadState()
-            handler.postDelayed(scanRunnable, POST_SETTINGS_RESCAN_MS)
         }
     }
 
@@ -233,54 +113,17 @@ class MainActivity : AppCompatActivity() {
             recreate()
             return
         }
-        loadState()
+        if (!manager.hasPermissions()) {
-        if (hmacKey == null || deviceUuid == null) {
+            requestPermissions()
-            statusText.text = getString(R.string.status_no_key)
+            return
-        } else if (!isScanning && bluetoothGatt == null) {
-            triedAddresses.clear()
-            handler.postDelayed(scanRunnable, ON_RESUME_SCAN_DELAY_MS)
         }
+        manager.resetTriedAddresses()
+        handler.postDelayed({ manager.startScan() }, ON_RESUME_SCAN_DELAY_MS)
     }
 
     override fun onPause() {
         super.onPause()
-        handler.removeCallbacks(scanRunnable)
+        manager.stopScan()
-        stopScan()
-    }
-
-    private fun loadState() {
-        val prefs = PrefsHelper.getPrefs(this)
-        val hexKey = prefs.getString(PrefsHelper.PREF_KEY, null)
-        hmacKey = hexKey?.let { hexStringToBytes(it) }
-        val hexUuid = prefs.getString(PrefsHelper.PREF_UUID, null)
-        deviceUuid = hexUuid?.let { hexStringToBytes(it) }
-        seq = prefs.getInt(PrefsHelper.PREF_SEQ, 1).coerceAtMost(PrefsHelper.SEQ_MAX)
-        Log.d(TAG, "HMAC key loaded: ${if (hmacKey != null) "${hmacKey!!.size} bytes" else "none"}, UUID: ${if (deviceUuid != null) "${deviceUuid!!.size} bytes" else "none"}, seq=$seq")
-    }
-
-    private fun hexStringToBytes(hex: String): ByteArray? {
-        val cleaned = hex.uppercase().filter { it in "0123456789ABCDEF" }
-        if (cleaned.isEmpty() || cleaned.length % 2 != 0) return null
-        return cleaned.chunked(2).map { it.toInt(16).toByte() }.toByteArray()
-    }
-
-    private fun hmacSha256(data: ByteArray, key: ByteArray): ByteArray {
-        val mac = Mac.getInstance("HmacSHA256")
-        mac.init(SecretKeySpec(key, "HmacSHA256"))
-        return mac.doFinal(data)
-    }
-
-    private fun buildPacket(cmd: Byte, key: ByteArray): ByteArray {
-        val seqBytes = ByteBuffer.allocate(4).order(ByteOrder.BIG_ENDIAN).putInt(seq).array()
-        val hmacData = ByteArray(5)
-        hmacData[0] = cmd
-        System.arraycopy(seqBytes, 0, hmacData, 1, 4)
-        val hmac = hmacSha256(hmacData, key)
-        val packet = ByteArray(HMAC_PKT_SIZE)
-        packet[0] = cmd
-        System.arraycopy(seqBytes, 0, packet, 1, 4)
-        System.arraycopy(hmac, 0, packet, 5, HMAC_LEN)
-        return packet
     }
 
     @Deprecated("Deprecated in Java")
@@ -288,11 +131,9 @@ class MainActivity : AppCompatActivity() {
         super.onRequestPermissionsResult(requestCode, permissions, grantResults)
         if (requestCode == 1) {
             if (grantResults.all { it == PackageManager.PERMISSION_GRANTED }) {
-                startScan()
+                manager.startScan()
             } else {
-                statusText.text = getString(R.string.status_permissions_denied)
+                onStatusChanged(BleStatus.PermissionsDenied)
-                relay1Button.isEnabled = false
-                relay2Button.isEnabled = false
             }
         }
     }
@@ -303,12 +144,12 @@ class MainActivity : AppCompatActivity() {
         relay1Button.setOnTouchListener { _, event ->
             when (event.action) {
                 MotionEvent.ACTION_DOWN -> {
-                    sendRelayCommand(0x01.toByte())
+                    manager.sendRelayCommand(0x01.toByte())
                     relay1Button.text = getString(R.string.button_on)
                     true
                 }
                 MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
-                    sendRelayCommand(0x00.toByte())
+                    manager.sendRelayCommand(0x00.toByte())
                     relay1Button.text = getString(R.string.button_hold)
                     true
                 }
@@ -323,12 +164,12 @@ class MainActivity : AppCompatActivity() {
         relay2Button.setOnTouchListener { _, event ->
             when (event.action) {
                 MotionEvent.ACTION_DOWN -> {
-                    sendRelayCommand(0x02.toByte())
+                    manager.sendRelayCommand(0x02.toByte())
                     relay2Button.text = getString(R.string.button_on)
                     true
                 }
                 MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
-                    sendRelayCommand(0x03.toByte())
+                    manager.sendRelayCommand(0x03.toByte())
                     relay2Button.text = getString(R.string.button_hold)
                     true
                 }
@@ -337,132 +178,14 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
-    @SuppressLint("MissingPermission")
-    private fun startScan() {
-        if (isScanning) return
-        if (!hasPermissions()) {
-            requestPermissions()
-            return
-        }
-
-        val adapter = BluetoothAdapter.getDefaultAdapter()
-        if (adapter == null || !adapter.isEnabled) {
-            statusText.text = getString(R.string.status_bluetooth_disabled)
-            return
-        }
-
-        if (hmacKey == null || deviceUuid == null) {
-            statusText.text = getString(R.string.status_no_key)
-            return
-        }
-
-        isScanning = true
-        scanTimedOut = false
-        statusText.text = getString(R.string.status_scanning)
-        Log.d(TAG, "Starting BLE scan with service UUID filter")
-
-        val filter = ScanFilter.Builder().setServiceUuid(ParcelUuid(SERVICE_UUID)).build()
-        val settings = ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY).build()
-        adapter.bluetoothLeScanner.startScan(listOf(filter), settings, scanCallback)
-
-        scanTimeoutRunnable?.let { handler.removeCallbacks(it) }
-        scanTimeoutRunnable = Runnable {
-            if (isScanning) {
-                scanTimedOut = true
-                stopScan()
-            }
-        }
-        handler.postDelayed(scanTimeoutRunnable!!, SCAN_TIMEOUT_MS)
-    }
-
-    @SuppressLint("MissingPermission")
-    private fun stopScan() {
-        if (!isScanning) return
-        isScanning = false
-        scanTimeoutRunnable?.let { handler.removeCallbacks(it) }
-        val adapter = BluetoothAdapter.getDefaultAdapter()
-        adapter?.bluetoothLeScanner?.stopScan(scanCallback)
-        if (scanTimedOut) {
-            if (scanTimeoutRetries < MAX_SCAN_RETRIES) {
-                scanTimeoutRetries++
-                Log.d(TAG, "Scan timeout, retry $scanTimeoutRetries/$MAX_SCAN_RETRIES")
-                statusText.text = getString(R.string.status_scanning)
-                handler.postDelayed(scanRunnable, 2000L)
-                return
-            }
-            statusText.text = getString(R.string.status_device_not_found)
-            relay1Button.setOnTouchListener(null)
-            relay2Button.setOnTouchListener(null)
-            relay1Button.setOnClickListener(null)
-            relay2Button.setOnClickListener(null)
-            relay1Button.text = getString(R.string.button_retry_scan)
-            relay2Button.text = getString(R.string.button_hold)
-            relay2Button.isEnabled = false
-            relay1Button.isEnabled = true
-            relay1Button.setOnClickListener {
-                setupRelayButton()
-                setupRelay2Button()
-                startScan()
-            }
-        }
-    }
-
-    @SuppressLint("MissingPermission")
-    private fun connectToDevice(device: android.bluetooth.BluetoothDevice) {
-        runOnUiThread { statusText.text = getString(R.string.status_connecting) }
-        Log.d(TAG, "Connecting to ${device.address}")
-        bluetoothGatt = device.connectGatt(this, false, gattCallback)
-    }
-
-    @SuppressLint("MissingPermission")
-    private fun sendRelayCommand(cmd: Byte) {
-        val char = relayCharacteristic ?: return
-        val gatt = bluetoothGatt ?: return
-        val key = hmacKey ?: return
-
-        val packet = buildPacket(cmd, key)
-        char.value = packet
-        // WRITE_TYPE_NO_RESPONSE is intentional. Previously, WRITE_TYPE_DEFAULT (with ACK) was
-        // used, but the BLE write acknowledgement took long enough that the user could release
-        // the button before the ACK arrived. When ACTION_UP fired during a pending write, the
-        // release was silently ignored and the relay (and app) got stuck in the ON state.
-        // WRITE_TYPE_NO_RESPONSE removes that latency and allows immediate ON→OFF sequences.
-        // This means the UI reflects the user's intent ("pressed" / "released") rather than
-        // confirmed relay state — an acceptable trade-off for a hold-to-activate interaction.
-        char.writeType = BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE
-        gatt.writeCharacteristic(char)
-        seq++
-        if (seq > PrefsHelper.SEQ_MAX) seq = 1
-        PrefsHelper.getPrefs(this).edit().putInt(PrefsHelper.PREF_SEQ, seq).apply()
-        Log.d(TAG, "Sent relay cmd 0x${cmd.toString(16)} (seq=${seq - 1})")
-    }
-
-    private fun getRequiredPermissions(): Array<String> {
-        return if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.S) {
-            arrayOf(
-                Manifest.permission.BLUETOOTH_SCAN,
-                Manifest.permission.BLUETOOTH_CONNECT,
-                Manifest.permission.ACCESS_FINE_LOCATION
-            )
-        } else {
-            arrayOf(Manifest.permission.ACCESS_FINE_LOCATION)
-        }
-    }
-
-    private fun hasPermissions(): Boolean {
-        return getRequiredPermissions().all {
-            ActivityCompat.checkSelfPermission(this, it) == PackageManager.PERMISSION_GRANTED
-        }
-    }
-
     private fun requestPermissions() {
-        ActivityCompat.requestPermissions(this, getRequiredPermissions(), 1)
+        val perms = manager.getRequiredPermissions()
+        ActivityCompat.requestPermissions(this, perms, 1)
     }
 
     override fun onDestroy() {
         super.onDestroy()
         handler.removeCallbacksAndMessages(null)
-        stopScan()
+        manager.destroy()
-        bluetoothGatt?.close()
     }
 }