feat: store scanning results

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

@@ -27,6 +27,8 @@ import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.navigateUp
 import androidx.navigation.ui.setupActionBarWithNavController
 import com.example.sensortestingapp.databinding.ActivityMainBinding
+import java.util.stream.Collectors
+import java.util.stream.Collectors.toList
 
 private const val ENABLE_BLUETOOTH_REQUEST_CODE = 1
 
@@ -46,6 +48,7 @@ fun Context.hasRequiredRuntimePermissions(): Boolean {
     }
 }
 
+@SuppressLint("MissingPermission")
 class MainActivity : AppCompatActivity() {
 
     private lateinit var appBarConfiguration: AppBarConfiguration
@@ -72,6 +75,8 @@ class MainActivity : AppCompatActivity() {
             }
         }
 
+    private var scanResults: MutableMap<String, ScanResult> = HashMap();
+
     override fun onCreate(savedInstanceState: Bundle?) {
         WindowCompat.setDecorFitsSystemWindows(window, false)
         super.onCreate(savedInstanceState)
@@ -186,26 +191,45 @@ class MainActivity : AppCompatActivity() {
     @SuppressLint("MissingPermission")
     val scanCallback = object : ScanCallback() {
         override fun onScanResult(callbackType: Int, result: ScanResult) {
-            with(result.device) {
+
+            scanResults.merge(result.device.address, result, fun(o, n): ScanResult {
+                return if (n.rssi >= o.rssi) n else o;
+            })
+            val displayScanResults = getDisplayScanResults();
             Log.i(
                 "ScanCallback",
-                    "Found BLE device! Name: ${name ?: "Unnamed"}, address: $address"
+                "Found BLE device ${result.device.name ?: result.device.address} (rssi: ${result.rssi}). Current scan results (${displayScanResults.size}): ${
+                    toDebugScanResults(displayScanResults)
+                }"
             )
-            }
+
         }
     }
 
-    @SuppressLint("MissingPermission")
+    private fun getDisplayScanResults(): List<ScanResult> {
+        return scanResults.values.stream()
+            .filter { r -> r.rssi > -80 }
+            .sorted { r1, r2 -> Integer.compare(r2.rssi, r1.rssi) }
+            .collect(toList())
+    }
+
+    private fun toDebugScanResults(scanResults: List<ScanResult>): String {
+        return scanResults.stream()
+            .map { r -> "${r.device.name ?: r.device.address} (${r.rssi})" }
+            .collect(Collectors.joining(", "))
+    }
+
+
     private fun startBleScan() {
         if (!hasRequiredRuntimePermissions()) {
             requestRelevantRuntimePermissions()
         } else {
+            scanResults.clear()
             bleScanner.startScan(null, scanSettings, scanCallback)
             isScanning = true
         }
     }
 
-    @SuppressLint("MissingPermission")
     private fun stopBleScan() {
         bleScanner.stopScan(scanCallback)
         isScanning = false