tasks/app/src/main/java/org/tasks/location/GeocoderNominatim.kt

package org.tasks.location

import android.content.Context
import com.google.gson.JsonElement
import com.google.gson.JsonParser
import dagger.hilt.android.qualifiers.ApplicationContext
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import okhttp3.Request
import org.tasks.BuildConfig
import org.tasks.R
import org.tasks.data.Place
import org.tasks.data.Place.Companion.newPlace
import org.tasks.http.HttpClientFactory
import org.tasks.http.HttpException
import javax.inject.Inject

class GeocoderNominatim @Inject constructor(
        @ApplicationContext context: Context,
        private val httpClientFactory: HttpClientFactory,
) : Geocoder {
    private val url = context.getString(R.string.tasks_nominatim_url)

    override suspend fun reverseGeocode(mapPosition: MapPosition): Place? =
            withContext(Dispatchers.IO) {
                val client = httpClientFactory.newBuilder(foreground = true).build()
                val url = "$url/reverse?format=geocodejson&lat=${mapPosition.latitude}&lon=${mapPosition.longitude}"
                val response = client.newCall(
                        Request.Builder().get().url(url).addHeader(USER_AGENT, UA_VALUE).build()
                ).execute()
                if (response.isSuccessful) {
                    response.body?.string()?.let { jsonToPlace(it) }
                } else {
                    throw HttpException(response.code, response.message)
                }
            }

    companion object {
        private const val USER_AGENT = "User-Agent"
        private const val UA_VALUE = "${BuildConfig.APPLICATION_ID}/${BuildConfig.VERSION_NAME} (${BuildConfig.FLAVOR}-${BuildConfig.BUILD_TYPE})"

        internal fun jsonToPlace(json: String): Place? =
                JsonParser
                        .parseString(json).asJsonObject.getAsJsonArray("features")
                        .takeIf { it.size() > 0 }?.get(0)?.asJsonObject
                        ?.let { feature ->
                            val geocoding = feature
                                    .get("properties").asJsonObject
                                    .get("geocoding").asJsonObject
                            val geometry = feature.get("geometry").asJsonObject
                            newPlace().apply {
                                val type = geocoding.get("type").asString
                                name = if (type.equals("house")) {
                                    "${geocoding.get("housenumber").asString} ${geocoding.get("street").asString}"
                                } else {
                                    geocoding.get("name").asString
                                }
                                address = geocoding.get("label").asString
                                geometry.get("coordinates").asCoordinates.let {
                                    longitude = it.first
                                    latitude = it.second
                                }
                            }
                        }

        private val JsonElement.asCoordinates: Pair<Double, Double>
            get() = asJsonArray.let { Pair(it[0].asDouble, it[1].asDouble) }
    }
}