WIP: clustering in DB

app/src/main/java/net/vonforst/evmap/model/ChargersModel.kt

@@ -3,6 +3,7 @@ package net.vonforst.evmap.model
 import android.content.Context
 import android.os.Parcelable
 import androidx.core.text.HtmlCompat
+import androidx.room.ColumnInfo
 import androidx.room.Embedded
 import androidx.room.Entity
 import androidx.room.PrimaryKey
@@ -356,8 +357,8 @@ abstract class ChargerPhoto(open val id: String) : Parcelable {
 }
 
 data class ChargeLocationCluster(
-    val clusterCount: Int,
-    val coordinates: Coordinate,
+    @ColumnInfo("clusterCount") val clusterCount: Int,
+    @ColumnInfo("coordinates") val coordinates: Coordinate,
     val items: List<ChargeLocation>? = null
 ) : ChargepointListItem()
 

app/src/main/java/net/vonforst/evmap/storage/ChargeLocationsDao.kt

@@ -100,6 +100,18 @@ abstract class ChargeLocationsDao {
     @RawQuery(observedEntities = [ChargeLocation::class])
     abstract fun getChargeLocationsCustom(query: SupportSQLiteQuery): LiveData<List<ChargeLocation>>
 
+    @SkipQueryVerification
+    @Query("SELECT SUM(1) AS clusterCount, MakePoint(AVG(X(coordinates)), AVG(Y(coordinates)), 4326) as center, SnapToGrid(coordinates, :precision) AS snapped FROM chargelocation WHERE dataSource == :dataSource AND Within(coordinates, BuildMbr(:lng1, :lat1, :lng2, :lat2)) AND timeRetrieved > :after GROUP BY snapped")
+    abstract fun getChargeLocationClusters(
+        lat1: Double,
+        lat2: Double,
+        lng1: Double,
+        lng2: Double,
+        dataSource: String,
+        after: Long,
+        precision: Double
+    ): LiveData<List<ChargeLocationClusterSimple>>
+
     @Query("SELECT COUNT(*) FROM chargelocation")
     abstract fun getCount(): LiveData<Long>
 
@@ -111,6 +123,12 @@ abstract class ChargeLocationsDao {
     abstract suspend fun getSize(): Long
 }
 
+data class ChargeLocationClusterSimple(
+    @ColumnInfo("clusterCount") val clusterCount: Int,
+    @ColumnInfo("center") val center: Coordinate,
+    @ColumnInfo("snapped") val snapped: Coordinate,
+)
+
 /**
  * The ChargeLocationsRepository wraps the ChargepointApi and the DB to provide caching
  * and clustering functionality.