Convert nearby data sources and contract to Kotlin

Author: Saifuddin53

app/src/main/java/fr/free/nrw/commons/nearby/MarkerPlaceGroup.java

@@ -0,0 +1,9 @@
+package fr.free.nrw.commons.nearby
+
+/**
+ * Groups a map marker with its corresponding [Place] and bookmark state.
+ */
+data class MarkerPlaceGroup(
+    var isBookmarked: Boolean,
+    var place: Place
+)

app/src/main/java/fr/free/nrw/commons/nearby/MarkerPlaceGroup.kt

@@ -0,0 +1,40 @@
+package fr.free.nrw.commons.nearby
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import io.reactivex.Completable
+
+/**
+ * DAO for storing and retrieving [Place] objects, used for Nearby map caching.
+ */
+@Dao
+abstract class PlaceDao {
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    abstract fun saveSynchronous(place: Place)
+
+    @Query("SELECT * from place WHERE entityID=:entity")
+    abstract fun getPlace(entity: String): Place
+
+    @Query(
+        "SELECT * from place WHERE name!='' AND latitude>=:latBegin AND longitude>=:lngBegin " +
+            "AND latitude<:latEnd AND longitude<:lngEnd"
+    )
+    abstract fun fetchPlaces(
+        latBegin: Double,
+        lngBegin: Double,
+        latEnd: Double,
+        lngEnd: Double
+    ): List<Place>
+
+    fun save(place: Place): Completable =
+        Completable.fromAction { saveSynchronous(place) }
+
+    @Query("DELETE FROM place")
+    abstract fun deleteAllSynchronous()
+
+    fun deleteAll(): Completable =
+        Completable.fromAction { deleteAllSynchronous() }
+}

app/src/main/java/fr/free/nrw/commons/nearby/PlaceDao.java

@@ -0,0 +1,49 @@
+package fr.free.nrw.commons.nearby
+
+import fr.free.nrw.commons.location.LatLng
+import io.reactivex.Completable
+import javax.inject.Inject
+
+/**
+ * Local data source handling cached [Place] objects.
+ */
+class PlacesLocalDataSource @Inject constructor(
+    private val placeDao: PlaceDao
+) {
+
+    fun fetchPlace(entityID: String): Place = placeDao.getPlace(entityID)
+
+    fun fetchPlaces(mapBottomLeft: LatLng, mapTopRight: LatLng): List<Place> {
+        data class Constraint(val latBegin: Double, val lngBegin: Double, val latEnd: Double, val lngEnd: Double)
+        val constraints = mutableListOf<Constraint>()
+
+        if (mapTopRight.latitude < mapBottomLeft.latitude) {
+            if (mapTopRight.longitude < mapBottomLeft.longitude) {
+                constraints += Constraint(mapBottomLeft.latitude, mapBottomLeft.longitude, 90.0, 180.0)
+                constraints += Constraint(mapBottomLeft.latitude, -180.0, 90.0, mapTopRight.longitude)
+                constraints += Constraint(-90.0, mapBottomLeft.longitude, mapTopRight.latitude, 180.0)
+                constraints += Constraint(-90.0, -180.0, mapTopRight.latitude, mapTopRight.longitude)
+            } else {
+                constraints += Constraint(mapBottomLeft.latitude, mapBottomLeft.longitude, 90.0, mapTopRight.longitude)
+                constraints += Constraint(-90.0, mapBottomLeft.longitude, mapTopRight.latitude, mapTopRight.longitude)
+            }
+        } else {
+            if (mapTopRight.longitude < mapBottomLeft.longitude) {
+                constraints += Constraint(mapBottomLeft.latitude, mapBottomLeft.longitude, mapTopRight.latitude, 180.0)
+                constraints += Constraint(mapBottomLeft.latitude, -180.0, mapTopRight.latitude, mapTopRight.longitude)
+            } else {
+                constraints += Constraint(mapBottomLeft.latitude, mapBottomLeft.longitude, mapTopRight.latitude, mapTopRight.longitude)
+            }
+        }
+
+        val cachedPlaces = mutableListOf<Place>()
+        for (c in constraints) {
+            cachedPlaces += placeDao.fetchPlaces(c.latBegin, c.lngBegin, c.latEnd, c.lngEnd)
+        }
+        return cachedPlaces
+    }
+
+    fun savePlace(place: Place): Completable = placeDao.save(place)
+
+    fun clearCache(): Completable = placeDao.deleteAll()
+}