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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.gds.modularity;

import org.neo4j.gds.api.Graph;
import org.neo4j.gds.collections.haa.HugeAtomicDoubleArray;
import org.neo4j.gds.core.utils.partition.Partition;

import java.util.concurrent.atomic.DoubleAdder;
import java.util.function.LongUnaryOperator;

class RelationshipCountCollector implements Runnable {
    private final Partition partition;
    private final Graph localGraph;
    private final HugeAtomicDoubleArray insideRelationships;
    private final HugeAtomicDoubleArray totalCommunityRelationships;
    private final LongUnaryOperator communityIdProvider;

    private final DoubleAdder totalRelationshipWeight;

    RelationshipCountCollector(
        Partition partition,
        Graph graph,
        HugeAtomicDoubleArray insideRelationships,
        HugeAtomicDoubleArray totalCommunityRelationships,
        LongUnaryOperator communityIdProvider,
        DoubleAdder totalRelationshipWeight
    ) {
        this.totalRelationshipWeight = totalRelationshipWeight;
        assert insideRelationships.size() == totalCommunityRelationships.size();
        this.partition = partition;
        this.localGraph = graph.concurrentCopy();
        this.insideRelationships = insideRelationships;
        this.totalCommunityRelationships = totalCommunityRelationships;
        this.communityIdProvider = communityIdProvider;
    }

    @Override
    public void run() {
        long startNode = partition.startNode();
        long endNode = startNode + partition.nodeCount();
        for (long nodeId = startNode; nodeId < endNode; ++nodeId) {
            long communityId = communityIdProvider.applyAsLong(nodeId);
            localGraph.forEachRelationship(nodeId, 1.0, (s, t, w) -> {
                long tCommunityId = communityIdProvider.applyAsLong(t);
                if (tCommunityId == communityId) {
                    insideRelationships.getAndAdd(communityId, w);
                }
                totalCommunityRelationships.getAndAdd(communityId, w);
                totalRelationshipWeight.add(w);
                return true;
            });
        }
    }

}