//
// $Id: AIGameTicker.java,v 1.2 2002/04/19 21:33:21 ray Exp $

package com.threerings.parlor.game;

import java.util.Iterator;
import java.util.HashSet;

import com.samskivert.util.Interval;
import com.samskivert.util.IntervalManager;

import com.threerings.crowd.server.CrowdServer;

/**
 * Handles ticking all the GameManagers that are hosting games with AIs.
 */
public class AIGameTicker implements Interval, Runnable
{
    /**
     * Register the specified GameManager to receive AI ticks.
     */
    public static synchronized void registerAIGame (GameManager mgr)
    {
        if (_ticker == null) {
            _ticker = new AIGameTicker();
        }
        _ticker.addAIGame(mgr);
    }

    /**
     * Take the specified GameManager off the AI tick list.
     */
    public static synchronized void unregisterAIGame (GameManager mgr)
    {
        if (_ticker != null) {
            _ticker.removeAIGame(mgr);
        }
    }

    /**
     * Construct an AIGameTicker and start it ticking.
     */
    private AIGameTicker ()
    {
        _games = new HashSet();

        _id = IntervalManager.register(this, TICK_FREQUENCY, null, true);
    }

    /**
     * Add the specified manager to the list of those receiving AI ticks.
     */
    protected void addAIGame (GameManager mgr)
    {
        _games.add(mgr);
    }

    /**
     * Remove the specified manager from receiving AI ticks.
     *
     * @return true if there are no more games.
     */
    protected void removeAIGame (GameManager mgr)
    {
        _games.remove(mgr);

        // if there aren't any AIs, let's stop running
        if (_games.isEmpty()) {
            _ticker = null;
            IntervalManager.remove(_id);
        }
    }

    // documentation inherited from interface
    public void intervalExpired (int id, Object arg)
    {
        CrowdServer.omgr.postUnit(this);
    }

    /**
     * Tick all the game AIs while on the dobj thread.
     */
    public void run ()
    {
        Iterator iter = _games.iterator();
        while (iter.hasNext()) {
            ((GameManager) iter.next()).tickAIs();
        }
    }

    /** Our set of ai games. */
    protected HashSet _games;

    /** Our interval id. */
    protected int _id;

    /** Our single ticker for all AI games. */
    protected static AIGameTicker _ticker;

    /** The frequency with which we dispatch AI game ticks. */
    protected static final long TICK_FREQUENCY = 3333L; // every 3 1/3 seconds
}