/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-07 The eXist Project
 *  http://exist-db.org
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * $Id: Database.java 6177 2007-07-08 14:42:37Z wolfgang_m $
 */
package org.exist.management.impl;

import java.io.StringWriter;
import java.util.Map;
import java.util.Optional;
import javax.management.openmbean.*;
import org.exist.storage.BrokerPool;
import org.exist.storage.DBBroker;

public class Database implements DatabaseMXBean {

    private static final String[] itemNames = {
        "owner", "referenceCount", "stack", "stackAcquired"};
    
    private static final String[] itemDescriptions = {
        "Name of the thread owning the broker",
        "Number of references held by the thread",
        "Stack trace",
        "Broker acquired"
    };
    
    private static final String[] indexNames = {"owner"};

    private final BrokerPool pool;

    public Database(BrokerPool pool) {
        this.pool = pool;
    }

    @Override
    public String getInstanceId() {
        return pool.getId();
    }

    @Override
    public int getMaxBrokers() {
        return pool.getMax();
    }

    @Override
    public int getAvailableBrokers() {
        return pool.available();
    }

    @Override
    public int getActiveBrokers() {
        return pool.countActiveBrokers();
    }

    @Override
    public int getTotalBrokers() {
    	return pool.total();
    }
    
    @Override
    public TabularData getActiveBrokersMap() {
        final OpenType<?>[] itemTypes = { SimpleType.STRING, SimpleType.INTEGER, SimpleType.STRING, SimpleType.STRING };
        try {
            final CompositeType infoType = new CompositeType("brokerInfo", "Provides information on a broker instance.",
                    itemNames, itemDescriptions, itemTypes);
            final TabularType tabularType = new TabularType("activeBrokers", "Lists all threads currently using a broker instance", infoType, indexNames);
            final TabularDataSupport data = new TabularDataSupport(tabularType);
            for (final Map.Entry<Thread, DBBroker> entry : pool.getActiveBrokers().entrySet()) {
                final Thread thread = entry.getKey();
                final DBBroker broker = entry.getValue();
                final String trace = printStackTrace(thread);
                final String watchdogTrace = pool.getWatchdog().map(wd -> wd.get(broker)).orElse(null);
                final Object[] itemValues = { thread.getName(), broker.getReferenceCount(), trace, watchdogTrace };
                data.put(new CompositeDataSupport(infoType, itemNames, itemValues));
            }
            return data;
        } catch (final OpenDataException e) {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    public long getReservedMem() {
        return pool.getReservedMem();
    }

    @Override
    public long getCacheMem() {
        return pool.getCacheManager().getTotalMem();
    }

    @Override
    public long getCollectionCacheMem() {
        return pool.getCollectionCacheMgr().getMaxTotal();
    }

    @Override
    public long getUptime() {
        return System.currentTimeMillis() - pool.getStartupTime().getTimeInMillis();
    }

    @Override
    public String getExistHome() {
        return pool.getConfiguration().getExistHome().map(p -> p.toAbsolutePath().toString()).orElse(null);
    }
    
    public String printStackTrace(Thread thread) {
        final StackTraceElement[] stackElements = thread.getStackTrace();
    	final StringWriter writer = new StringWriter();
        final int showItems = stackElements.length > 20 ? 20 : stackElements.length;
		for (int i = 0; i < showItems; i++) {
            writer.append(stackElements[i].toString()).append('\n');
		}
		return writer.toString();
    }
}