fix: do not forward invalid payloads

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

@@ -129,13 +129,25 @@ class KirbyDevice(
 
     private fun addMeasurement(characteristic: BluetoothGattCharacteristic) {
         val hexPayload = characteristic.value.toHexString().substring(2)
-        val payload = Payload(hexPayload)
+        val measurement = DecoderIaq.parseMeasurement(hexPayload)
-        val base64Payload = Base64.getEncoder().encodeToString(characteristic.value)
+        var payload : Payload
+        if (measurement == null) {
+            payload = Payload(hexPayload)
+        } else {
+            payload = Payload(measurement.toString())
             Log.i("BleListener", "Char received: $payload")
-        measurements.add(payload)
+            val base64Payload = Base64.getEncoder().encodeToString(characteristic.value)
             publishMeasurement(base64Payload)
         }
 
+        measurements.add(payload)
+
+        if (measurements.size > maxMeasurements) {
+            measurements.removeFirst()
+        }
+
+    }
+
     private fun publishMeasurement(payload: String) {
         val accessKey = BuildConfig.API_KEY
         val url = BuildConfig.API_BASE_URL
@@ -163,6 +175,7 @@ class KirbyDevice(
     }
 
     private val measurements = ArrayList<Payload>()
+    private val maxMeasurements = 20
 
     private val statuses = EnumSet.noneOf(DeviceStatus::class.java)
 
@@ -362,12 +375,8 @@ private fun payloadToMeasurements(payload: Payload): List<Measurement> {
         }
 
         override fun getFormattedValue(): String {
-            val measurement = DecoderIaq.parseMeasurement(payload.payload)
-            if(measurement == null) {
             return payload.payload
         }
-            return measurement.toString()
-        }
 
         override fun getIcon(): Int? {
             return R.drawable.baseline_numbers_24