/*
 * Copyright 2012-2017 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.vm.classstat.agent.internal;

import java.util.logging.Level;
import java.util.logging.Logger;

import com.redhat.thermostat.common.utils.LoggingUtils;
import com.redhat.thermostat.jvm.overview.agent.VmUpdate;
import com.redhat.thermostat.jvm.overview.agent.VmUpdateException;
import com.redhat.thermostat.jvm.overview.agent.VmUpdateListener;
import com.redhat.thermostat.vm.classstat.model.VmClassStat;

class VmClassStatVmListener implements VmUpdateListener {
    
    private static final Logger logger = LoggingUtils.getLogger(VmClassStatVmListener.class);

    private final VmClassStatDAO dao;
    private final String vmId;
    private final String writerId;
    
    private boolean error;

    VmClassStatVmListener(String writerId, VmClassStatDAO dao, String vmId) {
        this.dao = dao;
        this.vmId = vmId;
        this.writerId = writerId;
    }

    @Override
    public void countersUpdated(VmUpdate update) {
        VmClassStatDataExtractor extractor = new VmClassStatDataExtractor(update);
        try {
            long loadedClasses = valueOrUnknown(extractor.getLoadedClasses(), "number of loaded classes", vmId);
            long loadedBytes = valueOrUnknown(extractor.getLoadedBytes(), "number of loaded bytes", vmId);
            long unloadedClasses = valueOrUnknown(extractor.getUnloadedClasses(), "number of unloaded", vmId);
            long unloadedBytes = valueOrUnknown(extractor.getUnloadedBytes(), "number of unloaded bytes", vmId);
            long classLoadTime = valueOrUnknown(extractor.getClassLoadTime(), "class load time", vmId);

            long timestamp = System.currentTimeMillis();
            VmClassStat stat = new VmClassStat(writerId, vmId, timestamp,
                    loadedClasses, loadedBytes,
                    unloadedClasses, unloadedBytes,
                    classLoadTime);

            dao.put(stat);

        } catch (VmUpdateException e) {
            logger.log(Level.WARNING, "Error gathering class info for VM " + vmId, e);
        }
    }

    private long valueOrUnknown(Long value, String valudDescription, String vmId) {
        if (value == null) {
            logWarningOnce("Unable to determine " + valudDescription + " for VM " + vmId);
        }
        return value == null ? VmClassStat.UNKNOWN : value;
    }

    private void logWarningOnce(String message) {
        if (!error) {
            logger.log(Level.WARNING, message);
            logger.log(Level.WARNING, "Further warnings will be ignored");
            error = true;
        }
    }

}