/*************************************************************************
 * 
 * ADOBE CONFIDENTIAL __________________
 * 
 * Copyright 2002 - 2007 Adobe Systems Incorporated All Rights Reserved.
 * 
 * NOTICE: All information contained herein is, and remains the property of Adobe Systems Incorporated and its suppliers, if any. The intellectual and technical concepts contained herein are
 * proprietary to Adobe Systems Incorporated and its suppliers and may be covered by U.S. and Foreign Patents, patents in process, and are protected by trade secret or copyright law. Dissemination of
 * this information or reproduction of this material is strictly forbidden unless prior written permission is obtained from Adobe Systems Incorporated.
 **************************************************************************/
package flex.management;

import flex.messaging.log.Log;
import flex.messaging.log.LogCategories;
import flex.messaging.util.ClassUtil;

/**
 * Factory to get a <code>MBeanServerLocator</code>.
 * 
 * @author shodgson
 */
public class MBeanServerLocatorFactory
{
    // --------------------------------------------------------------------------
    //
    // Private Static Variables
    //
    // --------------------------------------------------------------------------

    /**
     * The MBeanServerLocator impl to use; lazily init'ed on first access.
     */
    private static MBeanServerLocator locator;

    // --------------------------------------------------------------------------
    //
    // Public Static Methods
    //
    // --------------------------------------------------------------------------

    /**
     * Returns a <code>MBeanServerLocator</code> that exposes the <code>MBeanServer</code> to register MBeans with.
     * 
     * @return The <code>MBeanServerLocator</code> that exposes the <code>MBeanServer</code> to register MBeans with.
     */
    public static synchronized MBeanServerLocator getMBeanServerLocator()
    {
        if (locator == null)
        {
            // Try app-server specific locators.
            // WebSphere provides access to its MBeanServer via a custom admin API.
            instantiateLocator("flex.management.WebSphereMBeanServerLocator", new String[] { "com.ibm.websphere.management.AdminServiceFactory" });

            // Try Sun JRE 1.5 based implementation
            if (locator == null)
                instantiateLocator("flex.management.PlatformMBeanServerLocator", new String[] { "java.lang.management.ManagementFactory" });

            // Try Sun JRE 1.4 based default implementation
            if (locator == null)
                instantiateLocator("flex.management.DefaultMBeanServerLocator", null);

            if (Log.isDebug())
                Log.getLogger(LogCategories.MANAGEMENT_GENERAL).debug("Using MBeanServerLocator: " + locator.getClass().getName());
        }
        return locator;
    }

    // TODO UCdetector: Remove unused code:
    // /**
    // * Release static MBeanServerLocator
    // * Called on MessageBroker shutdown.
    // */
    // public static void clear()
    // {
    // locator = null;
    // }

    // --------------------------------------------------------------------------
    //
    // Private Static Methods
    //
    // --------------------------------------------------------------------------

    /**
     * Helper method that attempts to load a specific MBeanServerLocator.
     * 
     * @param locatorClassName
     *            The classname of the desired MBeanServerLocator.
     * @param dependencyClassNames
     *            Any additional dependent classnames that the desired locator depends upon that should also be tested for availability.
     */
    private static void instantiateLocator(String locatorClassName, String[] dependencyClassNames)
    {
        try
        {
            if (dependencyClassNames != null)
            {
                for (int i = 0; i < dependencyClassNames.length; i++)
                    ClassUtil.createClass(dependencyClassNames[i]);
            }

            Class locatorClass = ClassUtil.createClass(locatorClassName);
            locator = (MBeanServerLocator) locatorClass.newInstance();
        }
        catch (Throwable t)
        {
            if (Log.isDebug())
                Log.getLogger(LogCategories.MANAGEMENT_MBEANSERVER).debug("Not using MBeanServerLocator: " + locatorClassName + ". Reason: " + t.getMessage());
        }
    }

    // --------------------------------------------------------------------------
    //
    // Constructor
    //
    // --------------------------------------------------------------------------

    /**
     * Direct instantiation is not allowed. Use <code>getMBeanServerLocator()</code> to obtain a <code>MBeanServerLocator</code> instance to lookup the proper MBean server to use.
     */
    private MBeanServerLocatorFactory()
    {
    }

}