RequestPeriodicWork.kt

fun createConstraints() = Constraints.Builder()
                        .setRequiredNetworkType(NetworkType.UNMETERED)  // if connected to WIFI
                                                                          // other values(NOT_REQUIRED, CONNECTED, NOT_ROAMING, METERED)
                        .setRequiresBatteryNotLow(true)                 // if the battery is not low
                        .setRequiresStorageNotLow(true)                 // if the storage is not low
                        .build()

fun createWorkRequest(data: Data) = PeriodicWorkRequestBuilder<LocationWorker>(12, TimeUnit.HOURS)  // setting period to 12 hours
                // set input data for the work
                .setInputData(data)                                                     
                .setConstraints(createConstraints())
                // setting a backoff on case the work needs to retry
                .setBackoffCriteria(BackoffPolicy.LINEAR, PeriodicWorkRequest.MIN_BACKOFF_MILLIS, TimeUnit.MILLISECONDS)
                .build()

fun startWork() {
    // set the input data, it is like a Bundle
    val work = createWorkRequest(Data.EMPTY)
    /* enqueue a work, ExistingPeriodicWorkPolicy.KEEP means that if this work already existits, it will be kept
    if the value is ExistingPeriodicWorkPolicy.REPLACE, then the work will be replaced */
    WorkManager.getInstance().enqueueUniquePeriodicWork("Smart work", ExistingPeriodicWorkPolicy.KEEP, work)
    
    // Observe the result od the work
    WorkManager.getInstance().getWorkInfoByIdLiveData(work.id)
        .observe(lifecycleOwner, Observer { workInfo ->
            if (workInfo != null && workInfo.state == WorkInfo.State.SUCCEEDED) {
                // FINISHED SUCCESSFULLY!
            }
        })
}