malvinstn

// Dummy analytics event tracker that logs the events to Logcat
object EventTracker {
  private const val TAG = "EventTracker"
  fun logEvent(name: String, params: Bundle) {
    Log.d(TAG, "Logging event name: $name; params: $params")
  }
}

malvinstn

// Set Target as class since we want this annotation to be added to a class element
@Target(AnnotationTarget.CLASS)
// Set retention as Source since we only need this annotation 
// during annotation processing process and
// we don't need this class at runtime.
@Retention(AnnotationRetention.SOURCE)
annotation class AnalyticsEvent

malvinstn

apply plugin: 'kotlin'
apply plugin: 'kotlin-kapt'

dependencies {
  // Add dependency to your module that has the annotation class.
  compileOnly project(':annotation')
  implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"

  // To easily register your custom annotation processor to the annotation process flow.
  implementation "com.google.auto.service:auto-service:1.0-rc4"

malvinstn

@AnalyticsEvent
sealed class MyEvent {
  data class ShareImage(val imageName: String, val fullString: String) : MyEvent()
  object ButtonTapped : MyEvent()
}

malvinstn

@AutoService(Processor::class)
class AnalyticsEventProcessor : KotlinAbstractProcessor(), KotlinMetadataUtils {
  companion object {
    private val ANNOTATION = AnalyticsEvent::class.java
  }

  override fun getSupportedAnnotationTypes() = setOf(ANNOTATION.canonicalName)

  override fun getSupportedSourceVersion(): SourceVersion = SourceVersion.latestSupported()

malvinstn

@AutoService(Processor::class)
class AnalyticsEventProcessor : KotlinAbstractProcessor(), KotlinMetadataUtils {
  companion object {
    private val ANNOTATION = AnalyticsEvent::class.java
  }

  ...

  override fun process(
    annotations: Set<TypeElement>,

malvinstn

@AutoService(Processor::class)
class AnalyticsEventProcessor : KotlinAbstractProcessor(), KotlinMetadataUtils {
  companion object {
    private val ANNOTATION = AnalyticsEvent::class.java

    private const val EVENT_PARAMETER_NAME = "event"
    private const val EVENT_NAME_PARAMETER_NAME = "name"
    private const val EVENT_PARAM_PARAMETER_NAME = "params"

    private const val LOG_EVENT_FUNCTION_NAME = "logEvent"

malvinstn

...
apply plugin: 'kotlin-kapt'

android {
  ...
}

dependencies {
  implementation project(':tracker')

malvinstn

fun <T> Flow<T>.mergeWith(other: Flow<T>): Flow<T> = flow {
    coroutineScope {
        launch {
            collect { emit(it) }
        }
        launch {
            other.collect { emit(it) }
        }
    }
}

malvinstn

[
  {
    "eventType": "VIEW_CLICKED",
    "timestamp": 1561810695346,
    "replacementText": "",
    "actionCode": -1,
    "delayTime": 0,
    "canScrollTo": false,
    "elementDescriptors": [
      {