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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package apoc.algo;

import apoc.path.RelationshipTypeAndDirections;
import org.apache.commons.lang3.tuple.Pair;
import org.neo4j.graphalgo.EstimateEvaluator;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.PathExpander;
import org.neo4j.graphdb.PathExpanderBuilder;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.values.storable.PointValue;

public class PathFindingUtils {
    public static class GeoEstimateEvaluatorPointCustom implements EstimateEvaluator {
        // -- from org.neo4j.graphalgo.impl.util.GeoEstimateEvaluator
        private static final double EARTH_RADIUS = 6371 * 1000; // Meters
        private Node cachedGoal;
        private final String pointPropertyKey;
        private double[] cachedGoalCoordinates;

        public GeoEstimateEvaluatorPointCustom(String pointPropertyKey) {
            this.pointPropertyKey = pointPropertyKey;
        }

        @Override
        public Double getCost(Node node, Node goal) {
            double[] nodeCoordinates = getCoordinates(node);
            if (cachedGoal == null || !cachedGoal.equals(goal)) {
                cachedGoalCoordinates = getCoordinates(goal);
                cachedGoal = goal;
            }
            return distance(nodeCoordinates[0], nodeCoordinates[1], cachedGoalCoordinates[0], cachedGoalCoordinates[1]);
        }

        private static double distance(double latitude1, double longitude1, double latitude2, double longitude2) {
            latitude1 = Math.toRadians(latitude1);
            longitude1 = Math.toRadians(longitude1);
            latitude2 = Math.toRadians(latitude2);
            longitude2 = Math.toRadians(longitude2);
            double cLa1 = Math.cos(latitude1);
            double xA = EARTH_RADIUS * cLa1 * Math.cos(longitude1);
            double yA = EARTH_RADIUS * cLa1 * Math.sin(longitude1);
            double zA = EARTH_RADIUS * Math.sin(latitude1);
            double cLa2 = Math.cos(latitude2);
            double xB = EARTH_RADIUS * cLa2 * Math.cos(longitude2);
            double yB = EARTH_RADIUS * cLa2 * Math.sin(longitude2);
            double zB = EARTH_RADIUS * Math.sin(latitude2);
            return Math.sqrt((xA - xB) * (xA - xB) + (yA - yB) * (yA - yB) + (zA - zB) * (zA - zB));
        }
        // -- end from org.neo4j.graphalgo.impl.util.GeoEstimateEvaluator

        private double[] getCoordinates(Node node) {
            return ((PointValue) node.getProperty(pointPropertyKey)).coordinate();
        }
    }

    public static PathExpander buildPathExpander(String relationshipsAndDirections) {
        PathExpanderBuilder builder = PathExpanderBuilder.empty();
        for (Pair pair : RelationshipTypeAndDirections.parse(relationshipsAndDirections)) {
            if (pair.getLeft() == null) {
                if (pair.getRight() == null) {
                    builder = PathExpanderBuilder.allTypesAndDirections();
                } else {
                    builder = PathExpanderBuilder.allTypes(pair.getRight());
                }
            } else {
                if (pair.getRight() == null) {
                    builder = builder.add(pair.getLeft());
                } else {
                    builder = builder.add(pair.getLeft(), pair.getRight());
                }
            }
        }
        return builder.build();
    }
}