/*
 * Licensed to CRATE Technology GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.operation.reference.sys.cluster;

import io.crate.ClusterIdService;
import io.crate.metadata.ReferenceImplementation;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.common.inject.Inject;

import java.util.concurrent.ExecutionException;

public class ClusterIdExpression implements ReferenceImplementation<BytesRef> {

    public static final String NAME = "id";
    private final ClusterIdService clusterIdService;
    private BytesRef value = null;

    @Inject
    public ClusterIdExpression(ClusterIdService clusterIdService) {
        this.clusterIdService = clusterIdService;
    }

    @Override
    public BytesRef value() {
        // value could not be ready on node start-up, but is static once set
        try {
            if (value == null && clusterIdService.clusterId().get() != null) {
                value = new BytesRef(clusterIdService.clusterId().get().value().toString());
            }
        } catch (InterruptedException | ExecutionException e) {
            return null;
        }
        return value;
    }

}