/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2004 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.openide;

import org.openide.util.Lookup;

/** Manages major aspects of the NetBeans lifecycle - currently saving all objects and exiting.
 * @author Jesse Glick
 * @since 3.14
 */
public abstract class LifecycleManager {

    /**
     * Get the default lifecycle manager.
     * Normally this is found in {@link Lookup#getDefault} but if no instance is
     * found there, a fallback instance is returned which behaves as follows:
     * 

     * 
{@link #saveAll} does nothing
     * 
{@link #exit} calls {@link System#exit} with an exit code of 0
     * 
     * This is useful for unit tests and perhaps standalone library usage.
     * @return the default instance (never null)
     */
    public static LifecycleManager getDefault() {
        LifecycleManager lm = (LifecycleManager) Lookup.getDefault().lookup(LifecycleManager.class);
        if (lm == null) {
            lm = new Trivial();
        }
        return lm;
    }

    /** Subclass constructor. */
    protected LifecycleManager() {}

    /** Save all opened objects.
     */
    public abstract void saveAll();

    /** Exit NetBeans.
     * This method will return only if {@link java.lang.System#exit} fails, or if at least one component of the
     * system refuses to exit (because it cannot be properly shut down).
     */
    public abstract void exit();
    
    /** Fallback instance. */
    private static final class Trivial extends LifecycleManager {
        
        public Trivial() {}

        public void exit() {
            System.exit(0);
        }

        public void saveAll() {}
        
    }

}