/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.
 */

package org.apache.falcon.workflow.engine;

import org.apache.falcon.FalconException;
import org.apache.falcon.entity.ClusterHelper;
import org.apache.falcon.entity.store.ConfigurationStore;
import org.apache.falcon.entity.v0.EntityType;
import org.apache.falcon.entity.v0.cluster.Cluster;
import org.apache.falcon.workflow.util.OozieConstants;
import org.apache.oozie.client.LocalProxyOozieClient;
import org.apache.oozie.client.OozieClient;
import org.apache.oozie.client.ProxyOozieClient;
import org.apache.oozie.local.LocalOozie;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Factory for providing appropriate oozie client.
 */
public final class OozieClientFactory {

    private static final Logger LOG = LoggerFactory.getLogger(OozieClientFactory.class);

    private static volatile boolean localInitialized = false;

    private OozieClientFactory() {}

    public static synchronized OozieClient get(Cluster cluster)
        throws FalconException {

        assert cluster != null : "Cluster cant be null";
        String oozieUrl = ClusterHelper.getOozieUrl(cluster);
        LOG.trace("Creating Oozie client object for {}", oozieUrl);
        return getClientRef(oozieUrl);
    }

    public static OozieClient get(String clusterName) throws FalconException {
        return get((Cluster) ConfigurationStore.get().get(EntityType.CLUSTER, clusterName));
    }

    public static OozieClient getClientRef(String oozieUrl)
        throws FalconException {

        if (OozieConstants.LOCAL_OOZIE.equals(oozieUrl)) {
            return getLocalOozieClient();
        } else {
            return new ProxyOozieClient(oozieUrl);
        }
    }

    private static OozieClient getLocalOozieClient() throws FalconException {
        try {
            if (!localInitialized) {
                LocalOozie.start();
                localInitialized = true;
            }
            return new LocalProxyOozieClient();
        } catch (Exception e) {
            throw new FalconException(e);
        }
    }
}