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/*
 * Licensed to ElasticSearch and Shay Banon 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.
 */

package org.elasticsearch.rest.action.main;

import org.apache.lucene.util.Constants;
import org.elasticsearch.ExceptionsHelper;
import org.elasticsearch.Version;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.admin.cluster.state.ClusterStateRequest;
import org.elasticsearch.action.admin.cluster.state.ClusterStateResponse;
import org.elasticsearch.client.Client;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.rest.*;
import org.elasticsearch.rest.action.support.RestXContentBuilder;

import static org.elasticsearch.rest.RestRequest.Method.GET;
import static org.elasticsearch.rest.RestRequest.Method.HEAD;

/**
 *
 */
public class RestMainAction extends BaseRestHandler {

    @Inject
    public RestMainAction(Settings settings, Client client, RestController controller) {
        super(settings, client);

        controller.registerHandler(GET, "/", this);
        controller.registerHandler(HEAD, "/", this);
    }

    @Override
    public void handleRequest(final RestRequest request, final RestChannel channel) {
        ClusterStateRequest clusterStateRequest = new ClusterStateRequest();
        clusterStateRequest.listenerThreaded(false);
        clusterStateRequest.masterNodeTimeout(TimeValue.timeValueMillis(0));
        clusterStateRequest.local(true);
        clusterStateRequest.filterAll().filterBlocks(false);
        client.admin().cluster().state(clusterStateRequest, new ActionListener() {
            @Override
            public void onResponse(ClusterStateResponse response) {
                RestStatus status = RestStatus.OK;
                if (response.getState().blocks().hasGlobalBlock(RestStatus.SERVICE_UNAVAILABLE)) {
                    status = RestStatus.SERVICE_UNAVAILABLE;
                }
                if (request.method() == RestRequest.Method.HEAD) {
                    channel.sendResponse(new StringRestResponse(status));
                    return;
                }

                try {
                    XContentBuilder builder = RestXContentBuilder.restContentBuilder(request).prettyPrint();
                    builder.startObject();
                    builder.field("ok", true);
                    builder.field("status", status.getStatus());
                    if (settings.get("name") != null) {
                        builder.field("name", settings.get("name"));
                    }
                    builder.startObject("version")
                        .field("number", Version.CURRENT.number())
                        .field("snapshot_build", Version.CURRENT.snapshot)
                        // We use the lucene version from lucene constants since
                        // this includes bugfix release version as well and is already in
                        // the right format. We can also be sure that the format is maitained
                        // since this is also recorded in lucene segments and has BW compat
                        .field("lucene_version", Constants.LUCENE_MAIN_VERSION)
                    .endObject();
                    builder.field("tagline", "You Know, for Search");
                    builder.endObject();
                    channel.sendResponse(new XContentRestResponse(request, status, builder));
                } catch (Throwable e) {
                    onFailure(e);
                }
            }

            @Override
            public void onFailure(Throwable e) {
                try {
                    if (request.method() == HEAD) {
                        channel.sendResponse(new StringRestResponse(ExceptionsHelper.status(e)));
                    } else {
                        channel.sendResponse(new XContentThrowableRestResponse(request, e));
                    }
                } catch (Exception e1) {
                    logger.warn("Failed to send response", e);
                }
            }
        });
    }
}