/*
 * Copyright 2013 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.gc.agent.internal;

import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

import sun.jvmstat.monitor.MonitorException;
import sun.jvmstat.monitor.MonitoredHost;
import sun.jvmstat.monitor.MonitoredVm;
import sun.jvmstat.monitor.VmIdentifier;
import sun.jvmstat.monitor.event.HostEvent;
import sun.jvmstat.monitor.event.HostListener;
import sun.jvmstat.monitor.event.VmListener;
import sun.jvmstat.monitor.event.VmStatusChangeEvent;

import com.redhat.thermostat.common.utils.LoggingUtils;
import com.redhat.thermostat.vm.gc.common.VmGcStatDAO;

public class VmGcHostListener implements HostListener {

    private static final Logger logger = LoggingUtils.getLogger(VmGcHostListener.class);

    private boolean attachNew;

    private final VmGcStatDAO vmGcStatDAO;

    private Map<Integer, MonitoredVm> monitoredVms  = new HashMap<>();
    private Map<MonitoredVm, VmGcVmListener> registeredListeners  = new ConcurrentHashMap<>();
    
    VmGcHostListener(VmGcStatDAO vmGcStatDAO, boolean attachNew) {
        this.vmGcStatDAO = vmGcStatDAO;
        this.attachNew = attachNew;        
    }

    void removeAllListeners() {
        for (MonitoredVm vm : monitoredVms.values()) {
            VmListener listener = registeredListeners.get(vm);
            try {
                if (listener != null) {
                    vm.removeVmListener(listener);
                }
            } catch (MonitorException e) {
                logger.log(Level.WARNING, "can't remove vm listener", e);
            }
        }
    }
    
    @Override
    public void disconnected(HostEvent event) {
        logger.warning("Disconnected from host");
    }

    @SuppressWarnings("unchecked") // Unchecked casts to (Set<Integer>).
    @Override
    public void vmStatusChanged(VmStatusChangeEvent event) {
        MonitoredHost host = event.getMonitoredHost();

        for (Integer newVm : (Set<Integer>) event.getStarted()) {
            try {
                logger.fine("New vm: " + newVm);
                sendNewVM(newVm, host);
            } catch (MonitorException e) {
                logger.log(Level.WARNING, "error getting info for new vm" + newVm, e);
            } catch (URISyntaxException e) {
                logger.log(Level.WARNING, "error getting info for new vm" + newVm, e);
            }
        }

        for (Integer stoppedVm : (Set<Integer>) event.getTerminated()) {
            try {
                logger.fine("stopped vm: " + stoppedVm);
                sendStoppedVM(stoppedVm, host);
            } catch (URISyntaxException e) {
                logger.log(Level.WARNING, "error getting info for stopped vm" + stoppedVm, e);
            } catch (MonitorException e) {
                logger.log(Level.WARNING, "error getting info for stopped vm" + stoppedVm, e);
            }
        }
    }

    private void sendNewVM(Integer vmId, MonitoredHost host)
            throws MonitorException, URISyntaxException {
        MonitoredVm vm = host.getMonitoredVm(host.getHostIdentifier().resolve(
                new VmIdentifier(vmId.toString())));
        if (vm != null) {
            if (attachNew) {
                VmGcVmListener listener =  new VmGcVmListener(vmGcStatDAO, vmId);
                vm.addVmListener(listener);
                
                registeredListeners.put(vm, listener);
                logger.finer("Attached VmListener for VM: " + vmId);
            } else {
                logger.log(Level.FINE, "skipping new vm " + vmId);
            }

            monitoredVms.put(vmId, vm);
        }
    }

    private void sendStoppedVM(Integer vmId, MonitoredHost host) throws URISyntaxException, MonitorException {
        
        VmIdentifier resolvedVmID = host.getHostIdentifier().resolve(new VmIdentifier(vmId.toString()));
        if (resolvedVmID != null) {
            MonitoredVm vm = monitoredVms.remove(vmId);
            VmListener listener = registeredListeners.remove(vm);
            try {
                if (listener != null) {
                    vm.removeVmListener(listener);
                }
            } catch (MonitorException e) {
                logger.log(Level.WARNING, "can't remove vm listener", e);
            }
            vm.detach();
        }
    }
    
    /*
     * For testing purposes only.
     */
    Map<Integer, MonitoredVm> getMonitoredVms() {
        return monitoredVms;
    }
    
    /*
     * For testing purposes only.
     */
    Map<MonitoredVm, VmGcVmListener> getRegisteredListeners() {
        return registeredListeners;
    }

}