/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.discovery;

import org.elasticsearch.cluster.coordination.PeersResponse;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodeUtils;
import org.elasticsearch.test.ESTestCase;
import org.elasticsearch.test.EqualsHashCodeTestUtils;
import org.elasticsearch.test.EqualsHashCodeTestUtils.CopyFunction;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Optional;

import static java.util.Collections.emptyList;
import static java.util.Collections.singletonList;

public class PeerFinderMessagesTests extends ESTestCase {
    private DiscoveryNode createNode(String id) {
        return DiscoveryNodeUtils.create(id);
    }

    public void testPeersRequestEqualsHashCodeSerialization() {
        final PeersRequest initialPeersRequest = new PeersRequest(
            createNode(randomAlphaOfLength(10)),
            Arrays.stream(generateRandomStringArray(10, 10, false)).map(this::createNode).toList()
        );

        // Note: the explicit cast of the CopyFunction is needed for some IDE (specifically Eclipse 4.8.0) to infer the right type
        EqualsHashCodeTestUtils.checkEqualsAndHashCode(
            initialPeersRequest,
            (CopyFunction<PeersRequest>) publishRequest -> copyWriteable(publishRequest, writableRegistry(), PeersRequest::new),
            in -> {
                final List<DiscoveryNode> discoveryNodes = new ArrayList<>(in.getKnownPeers());
                if (randomBoolean()) {
                    return new PeersRequest(createNode(randomAlphaOfLength(10)), discoveryNodes);
                } else {
                    return new PeersRequest(in.getSourceNode(), modifyDiscoveryNodesList(in.getKnownPeers(), true));
                }
            }
        );
    }

    public void testPeersResponseEqualsHashCodeSerialization() {
        final long initialTerm = randomNonNegativeLong();
        final PeersResponse initialPeersResponse;

        if (randomBoolean()) {
            initialPeersResponse = new PeersResponse(Optional.of(createNode(randomAlphaOfLength(10))), emptyList(), initialTerm);
        } else {
            initialPeersResponse = new PeersResponse(
                Optional.empty(),
                Arrays.stream(generateRandomStringArray(10, 10, false, false)).map(this::createNode).toList(),
                initialTerm
            );
        }

        // Note: the explicit cast of the CopyFunction is needed for some IDE (specifically Eclipse 4.8.0) to infer the right type
        EqualsHashCodeTestUtils.checkEqualsAndHashCode(
            initialPeersResponse,
            (CopyFunction<PeersResponse>) publishResponse -> copyWriteable(publishResponse, writableRegistry(), PeersResponse::new),
            in -> {
                final long term = in.getTerm();
                if (randomBoolean()) {
                    return new PeersResponse(
                        in.getMasterNode(),
                        in.getKnownPeers(),
                        randomValueOtherThan(term, ESTestCase::randomNonNegativeLong)
                    );
                } else {
                    if (in.getMasterNode().isPresent()) {
                        if (randomBoolean()) {
                            return new PeersResponse(Optional.of(createNode(randomAlphaOfLength(10))), in.getKnownPeers(), term);
                        } else {
                            return new PeersResponse(Optional.empty(), singletonList(createNode(randomAlphaOfLength(10))), term);
                        }
                    } else {
                        if (randomBoolean()) {
                            return new PeersResponse(Optional.of(createNode(randomAlphaOfLength(10))), emptyList(), term);
                        } else {
                            return new PeersResponse(in.getMasterNode(), modifyDiscoveryNodesList(in.getKnownPeers(), false), term);
                        }
                    }
                }
            }
        );
    }

    private List<DiscoveryNode> modifyDiscoveryNodesList(Collection<DiscoveryNode> originalNodes, boolean allowEmpty) {
        final List<DiscoveryNode> discoveryNodes = new ArrayList<>(originalNodes);
        if (discoveryNodes.isEmpty() == false && randomBoolean() && (allowEmpty || discoveryNodes.size() > 1)) {
            discoveryNodes.remove(randomIntBetween(0, discoveryNodes.size() - 1));
        } else if (discoveryNodes.isEmpty() == false && randomBoolean()) {
            discoveryNodes.set(randomIntBetween(0, discoveryNodes.size() - 1), createNode(randomAlphaOfLength(10)));
        } else {
            discoveryNodes.add(createNode(randomAlphaOfLength(10)));
        }
        return discoveryNodes;
    }
}
