/*
 * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
 * License v3.0 only", 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.cluster.routing.RoutingChangesObserver;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.UnassignedInfo;

public class ShardChangesObserver implements RoutingChangesObserver {

    private static final Logger logger = LogManager.getLogger(ShardChangesObserver.class);

    @Override
    public void shardInitialized(ShardRouting unassignedShard, ShardRouting initializedShard) {
        logger.trace(
            "{} initializing from {} on node [{}]",
            shardIdentifier(initializedShard),
            initializedShard.recoverySource().getType(),
            initializedShard.currentNodeId()
        );
    }

    @Override
    public void shardStarted(ShardRouting initializingShard, ShardRouting startedShard) {
        logger.debug(
            "{} started from {} on node [{}]",
            shardIdentifier(startedShard),
            initializingShard.recoverySource().getType(),
            startedShard.currentNodeId()
        );
    }

    @Override
    public void relocationStarted(ShardRouting startedShard, ShardRouting targetRelocatingShard, String reason) {
        logger.debug(
            "{} is relocating ({}) from [{}] to [{}]",
            shardIdentifier(startedShard),
            reason,
            startedShard.currentNodeId(),
            targetRelocatingShard.currentNodeId()
        );
    }

    @Override
    public void shardFailed(ShardRouting failedShard, UnassignedInfo unassignedInfo) {
        logger.debug("{} has failed on [{}]: {}", shardIdentifier(failedShard), failedShard.currentNodeId(), unassignedInfo.reason());
    }

    @Override
    public void replicaPromoted(ShardRouting replicaShard) {
        logger.debug("{} is promoted to primary on [{}]", shardIdentifier(replicaShard), replicaShard.currentNodeId());
    }

    private static String shardIdentifier(ShardRouting shardRouting) {
        return shardRouting.shardId().toString() + '[' + (shardRouting.primary() ? 'P' : 'R') + ']';
    }
}