/*
 * Licensed 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 com.addthis.hydra.query.aggregate;

import javax.annotation.Nullable;

import java.util.Map;
import java.util.concurrent.Semaphore;

import com.addthis.hydra.data.query.QueryException;
import com.addthis.meshy.ChannelMaster;
import com.addthis.meshy.service.file.FileReference;
import com.addthis.meshy.service.stream.StreamSource;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class QueryTaskSourceOption {

    static final Logger log = LoggerFactory.getLogger(QueryTaskSourceOption.class);

    public final FileReference queryReference;
    public final Semaphore optionLeases;

    @Nullable StreamSource streamSource;

    public QueryTaskSourceOption(FileReference queryReference, Semaphore optionLeases) {
        this.queryReference = queryReference;
        this.optionLeases = optionLeases;
    }

    public boolean tryActivate(ChannelMaster meshy, Map<String, String> queryOptions) {
        if (optionLeases.tryAcquire()) {
            activate(meshy, queryOptions);
            log.debug("lease acquired for {}", queryReference.getHostUUID());
            return true;
        }
        return false;
    }

    private void activate(ChannelMaster meshy, Map<String, String> queryOptions) {
        try {
            streamSource = new StreamSource(meshy, queryReference.getHostUUID(),
                                            queryReference.getHostUUID(), queryReference.name, queryOptions, 0);
        } catch (Throwable e) {
            log.warn("Error getting query handle for fileReference: {}/{}",
                     queryReference.getHostUUID(), queryReference.name, e);
            optionLeases.release();
            throw new QueryException(e);
        }
    }

    public boolean isActive() {
        return streamSource != null;
    }

    public boolean isReady() {
        if (streamSource != null) {
            return streamSource.getMessageQueue().peek() != null;
        }
        return false;
    }

    /** The message is currently a no-op, but is left in to make it easier to support later and because
     *  it is handy for self-documenting-like calls. */
    public void cancel(String message) {
        try {
            if (streamSource != null) {
                optionLeases.release();
                log.debug("lease dropped for {} with reason {}", queryReference.getHostUUID(), message);
                streamSource.requestClose();
                streamSource = null;
            }
        } catch (Exception e) {
            log.warn("Exception canceling sourceInputStream for {}", queryReference, e);
        }
    }
}