/*
 * 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.cluster.routing.allocation;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.Version;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ESAllocationTestCase;
import org.elasticsearch.cluster.TestShardRoutingRoleStrategies;
import org.elasticsearch.cluster.metadata.IndexMetadata;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.cluster.routing.IndexShardRoutingTable;
import org.elasticsearch.cluster.routing.RoutingNodes;
import org.elasticsearch.cluster.routing.RoutingTable;
import org.elasticsearch.common.settings.Settings;

import static org.elasticsearch.cluster.routing.ShardRoutingState.STARTED;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.not;

public class ElectReplicaAsPrimaryDuringRelocationTests extends ESAllocationTestCase {
    private final Logger logger = LogManager.getLogger(ElectReplicaAsPrimaryDuringRelocationTests.class);

    public void testElectReplicaAsPrimaryDuringRelocation() {
        AllocationService strategy = createAllocationService(
            Settings.builder().put("cluster.routing.allocation.node_concurrent_recoveries", 10).build()
        );

        logger.info("Building initial routing table");

        Metadata metadata = Metadata.builder()
            .put(IndexMetadata.builder("test").settings(settings(Version.CURRENT)).numberOfShards(2).numberOfReplicas(1))
            .build();

        RoutingTable initialRoutingTable = RoutingTable.builder(TestShardRoutingRoleStrategies.DEFAULT_ROLE_ONLY)
            .addAsNew(metadata.index("test"))
            .build();

        ClusterState clusterState = ClusterState.builder(ClusterName.DEFAULT).metadata(metadata).routingTable(initialRoutingTable).build();

        logger.info("Adding two nodes and performing rerouting");
        clusterState = ClusterState.builder(clusterState)
            .nodes(DiscoveryNodes.builder().add(newNode("node1")).add(newNode("node2")))
            .build();
        clusterState = strategy.reroute(clusterState, "reroute", ActionListener.noop());

        logger.info("Start the primary shards");
        clusterState = startInitializingShardsAndReroute(strategy, clusterState);

        logger.info("Start the replica shards");
        ClusterState resultingState = startInitializingShardsAndReroute(strategy, clusterState);
        assertThat(resultingState, not(equalTo(clusterState)));
        clusterState = resultingState;

        RoutingNodes routingNodes = clusterState.getRoutingNodes();
        assertThat(clusterState.routingTable().index("test").size(), equalTo(2));
        assertThat(routingNodes.node("node1").numberOfShardsWithState(STARTED), equalTo(2));
        assertThat(routingNodes.node("node2").numberOfShardsWithState(STARTED), equalTo(2));

        logger.info("Start another node and perform rerouting");
        clusterState = ClusterState.builder(clusterState).nodes(DiscoveryNodes.builder(clusterState.nodes()).add(newNode("node3"))).build();
        clusterState = strategy.reroute(clusterState, "reroute", ActionListener.noop());

        logger.info("find the replica shard that gets relocated");
        IndexShardRoutingTable indexShardRoutingTable = null;
        if (clusterState.routingTable().index("test").shard(0).replicaShards().get(0).relocating()) {
            indexShardRoutingTable = clusterState.routingTable().index("test").shard(0);
        } else if (clusterState.routingTable().index("test").shard(1).replicaShards().get(0).relocating()) {
            indexShardRoutingTable = clusterState.routingTable().index("test").shard(1);
        }

        // we might have primary relocating, and the test is only for replicas, so only test in the case of replica allocation
        if (indexShardRoutingTable != null) {
            logger.info(
                "kill the node [{}] of the primary shard for the relocating replica",
                indexShardRoutingTable.primaryShard().currentNodeId()
            );
            clusterState = ClusterState.builder(clusterState)
                .nodes(DiscoveryNodes.builder(clusterState.nodes()).remove(indexShardRoutingTable.primaryShard().currentNodeId()))
                .build();
            clusterState = strategy.disassociateDeadNodes(clusterState, true, "reroute");

            logger.info("make sure all the primary shards are active");
            assertThat(clusterState.routingTable().index("test").shard(0).primaryShard().active(), equalTo(true));
            assertThat(clusterState.routingTable().index("test").shard(1).primaryShard().active(), equalTo(true));
        }
    }
}
