/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.cluster.shards;

import org.opensearch.test.OpenSearchTestCase;
import org.junit.Assert;

import static org.hamcrest.Matchers.lessThanOrEqualTo;

public class ShardCounts {
    private final int shardsPerNode;

    private final int firstIndexShards;
    private final int firstIndexReplicas;

    private final int failingIndexShards;
    private final int failingIndexReplicas;

    private ShardCounts(int shardsPerNode, int firstIndexShards, int firstIndexReplicas, int failingIndexShards, int failingIndexReplicas) {
        this.shardsPerNode = shardsPerNode;
        this.firstIndexShards = firstIndexShards;
        this.firstIndexReplicas = firstIndexReplicas;
        this.failingIndexShards = failingIndexShards;
        this.failingIndexReplicas = failingIndexReplicas;
    }

    public static ShardCounts forDataNodeCount(int dataNodes) {
        Assert.assertThat(
            "this method will not work reliably with this many data nodes due to the limit of shards in a single index,"
                + "use fewer data nodes or multiple indices",
            dataNodes,
            lessThanOrEqualTo(90)
        );
        int mainIndexReplicas = OpenSearchTestCase.between(0, dataNodes - 1);
        int mainIndexShards = OpenSearchTestCase.between(1, 10);
        int totalShardsInIndex = (mainIndexReplicas + 1) * mainIndexShards;
        // Sometimes add some headroom to the limit to check that it works even if you're not already right up against the limit
        int shardsPerNode = (int) Math.ceil((double) totalShardsInIndex / dataNodes) + OpenSearchTestCase.between(0, 10);
        int totalCap = shardsPerNode * dataNodes;

        int failingIndexShards;
        int failingIndexReplicas;
        if (dataNodes > 1 && OpenSearchTestCase.frequently()) {
            failingIndexShards = Math.max(1, totalCap - totalShardsInIndex);
            failingIndexReplicas = OpenSearchTestCase.between(1, dataNodes - 1);
        } else {
            failingIndexShards = totalCap - totalShardsInIndex + OpenSearchTestCase.between(1, 10);
            failingIndexReplicas = 0;
        }

        return new ShardCounts(shardsPerNode, mainIndexShards, mainIndexReplicas, failingIndexShards, failingIndexReplicas);
    }

    public int getShardsPerNode() {
        return shardsPerNode;
    }

    public int getFirstIndexShards() {
        return firstIndexShards;
    }

    public int getFirstIndexReplicas() {
        return firstIndexReplicas;
    }

    public int getFailingIndexShards() {
        return failingIndexShards;
    }

    public int getFailingIndexReplicas() {
        return failingIndexReplicas;
    }
}