LocationLiveData.kt

import android.Manifest
import android.content.Context
import android.content.pm.PackageManager
import android.location.Location
import android.os.Looper
import androidx.core.app.ActivityCompat
import androidx.lifecycle.LiveData
import com.google.android.gms.common.api.ApiException
import com.google.android.gms.location.*
import com.google.android.gms.maps.model.LatLng
import timber.log.Timber

class LocationLiveData(var context: Context): LiveData<LocationState>() {
    private val fusedLocationClient = LocationServices.getFusedLocationProviderClient(context)
    private val settingsClient = LocationServices.getSettingsClient(context)

    override fun onActive() {
        super.onActive()
        if (ActivityCompat.checkSelfPermission(
                context,
                Manifest.permission.ACCESS_COARSE_LOCATION
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            return
        }
        fusedLocationClient.lastLocation.addOnSuccessListener { location ->
            location.also {
                setLocationData(it)
            }
        }

        requestLocationUpdates()
    }

    override fun onInactive() {
        super.onInactive()
        fusedLocationClient.removeLocationUpdates(locationCallback)
    }

    internal fun requestLocationUpdates() {
        settingsClient.checkLocationSettings(locationSettingsRequest)
            .addOnSuccessListener {
                Timber.i("All location settings are satisfied. The client can initialize location requests here.")
                startLocationUpdates()
            }
            .addOnFailureListener {
                Timber.e("FAILURE!! - Location settings are NOT satisfied.")
                value = LocationState(LatLng(0.0, 0.0), it as ApiException)
            }
    }

    private fun setLocationData(location: Location?) {
        location?.let {
            value = LocationState(LatLng(it.latitude, it.longitude), null)
        }
    }

    private fun startLocationUpdates() {
        if (ActivityCompat.checkSelfPermission(
                context,
                Manifest.permission.ACCESS_COARSE_LOCATION
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            return
        }
        fusedLocationClient.requestLocationUpdates(locationRequest, locationCallback, Looper.getMainLooper())
    }

    private val locationCallback = object : LocationCallback() {
        override fun onLocationResult(locationResult: LocationResult) {
            super.onLocationResult(locationResult)
            locationResult.locations.forEach {
                setLocationData(it)
            }
        }
    }

    companion object {
        private const val TWO_MINUTES = 2 * 60 * 1000
        private const val THREE_MINUTES = 3 * 60 * 1000
        private const val TEN_MINUTES = 10 * 60 * 1000

        val locationRequest =
            LocationRequest.Builder(
                Priority.PRIORITY_BALANCED_POWER_ACCURACY,
                THREE_MINUTES.toLong()
            ).setWaitForAccurateLocation(false)
            .setMinUpdateIntervalMillis(TWO_MINUTES.toLong())
            .setMaxUpdateDelayMillis(TEN_MINUTES.toLong())
            .build()

        val locationSettingsRequest = LocationSettingsRequest.Builder()
            .addLocationRequest(locationRequest)
            .build()

    }
}

data class LocationState(
    val coordinates: LatLng,
    val exception: ApiException?
)