/*
 * 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.decider;

import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;

/**
 * Only allow rebalancing when all shards are active within the shard replication group.
 */
public class RebalanceOnlyWhenActiveAllocationDecider extends AllocationDecider {

    public static final String NAME = "rebalance_only_when_active";

    static final Decision YES_ALL_REPLICAS_ACTIVE = Decision.single(
        Decision.Type.YES,
        NAME,
        "rebalancing is allowed as all copies of this shard are active"
    );
    static final Decision NO_SOME_REPLICAS_INACTIVE = Decision.single(
        Decision.Type.NO,
        NAME,
        "rebalancing is not allowed until all copies of this shard are active"
    );

    @Override
    public Decision canRebalance(ShardRouting shardRouting, RoutingAllocation allocation) {
        return allocation.routingNodes().allShardsActive(shardRouting.shardId(), allocation.metadata().projectFor(shardRouting.index()))
            ? YES_ALL_REPLICAS_ACTIVE
            : NO_SOME_REPLICAS_INACTIVE;
    }
}