fix: request for Bluetooth permissions on startup to fetch bonded devices

app/src/main/java/com/example/sensortestingapp/MainActivity.kt

@@ -64,6 +64,8 @@ class MainActivity : AppCompatActivity() {
         DeviceListAdapter(kirbyDevices)
     }
 
+    private var onPermissionsGrantedCallback: Runnable? = null
+
     override fun onCreate(savedInstanceState: Bundle?) {
         WindowCompat.setDecorFitsSystemWindows(window, false)
         super.onCreate(savedInstanceState)
@@ -77,12 +79,14 @@ class MainActivity : AppCompatActivity() {
 
         binding.fab.setOnClickListener { view ->
             if (!hasRequiredRuntimePermissions()) {
-                requestRelevantRuntimePermissions()
+                onPermissionsGrantedCallback = object : Runnable {
+                    override fun run() {
+                        toggleScanning()
                     }
-            if (connectionManager.isScanning) {
-                connectionManager.stopScan()
+                }
+                requestRelevantRuntimePermissions()
             } else {
-                startBleScan()
+                toggleScanning()
             }
         }
 
@@ -90,6 +94,14 @@ class MainActivity : AppCompatActivity() {
 
     }
 
+    private fun toggleScanning(): Unit {
+        if (connectionManager.isScanning) {
+            connectionManager.stopScan()
+        } else {
+            connectionManager.startScan()
+        }
+    }
+
     private fun isKirbyDevice(device: BluetoothDevice): Boolean {
         return (device.name ?: "").lowercase().contains("kirby")
     }
@@ -104,11 +116,25 @@ class MainActivity : AppCompatActivity() {
             animator.supportsChangeAnimations = false
         }
 
+        if (hasRequiredRuntimePermissions()) {
+            addBondedDevices()
+        } else {
+            onPermissionsGrantedCallback = object : Runnable {
+                override fun run() {
+                    addBondedDevices()
+                }
+            }
+            requestRelevantRuntimePermissions()
+        }
+
+
+        //addDummyDevices()
+    }
+
+    private fun addBondedDevices(): Unit {
         bluetoothAdapter.bondedDevices.filter { isKirbyDevice(it) }.forEach {
             newKirbyDevice(it)
         }
-
-        //addDummyDevices()
     }
 
     @SuppressLint("NotifyDataSetChanged")
@@ -163,14 +189,6 @@ class MainActivity : AppCompatActivity() {
         return device
     }
 
-    private fun startBleScan() {
-        if (!hasRequiredRuntimePermissions()) {
-            requestRelevantRuntimePermissions()
-        } else {
-            connectionManager.startScan()
-        }
-    }
-
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         // Inflate the menu; this adds items to the action bar if it is present.
         menuInflater.inflate(R.menu.menu_main, menu)
@@ -231,7 +249,7 @@ class MainActivity : AppCompatActivity() {
                     }
 
                     allGranted && hasRequiredRuntimePermissions() -> {
-                        startBleScan()
+                        onPermissionsGrantedCallback?.run()
                     }
 
                     else -> {