// Copyright 2003 Nokia Corporation.
//
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER,
// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE
// OR TRADE PRACTICE, RELATING TO THE SOURCE CODE OR ANY WARRANTY OTHERWISE
// ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE AND WITH NO
// OBLIGATION OF NOKIA TO PROVIDE THE LICENSEE WITH ANY MAINTENANCE OR
// SUPPORT. FURTHERMORE, NOKIA MAKES NO WARRANTY THAT EXERCISE OF THE
// RIGHTS GRANTED HEREUNDER DOES NOT INFRINGE OR MAY NOT CAUSE INFRINGEMENT
// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED
// BY THIRD PARTIES
//
// Furthermore, information provided in this source code is preliminary,
// and may be changed substantially prior to final release. Nokia Corporation
// retains the right to make changes to this source code at
// any time, without notice. This source code is provided for informational
// purposes only.
//
// Nokia and Nokia Connecting People are registered trademarks of Nokia
// Corporation.
// Java and all Java-based marks are trademarks or registered trademarks of
// Sun Microsystems, Inc.
// Other product and company names mentioned herein may be trademarks or
// trade names of their respective owners.
//
// A non-exclusive, non-transferable, worldwide, limited license is hereby
// granted to the Licensee to download, print, reproduce and modify the
// source code. The licensee has the right to market, sell, distribute and
// make available the source code in original or modified form only when
// incorporated into the programs developed by the Licensee. No other
// license, express or implied, by estoppel or otherwise, to any other
// intellectual property rights is granted herein.
package whiteboard;

import java.util.*;

// Singleton Whiteboard
class Whiteboard
{
    // Holds a single instance of this whiteboard
    private static Whiteboard instance;
    // It holds the messages sorted by order of arrival
    private final List messages = new ArrayList();

    private final static int DEFAULTCOUNT = 10;


    private Whiteboard()
    {
    }


    static synchronized Whiteboard getInstance()
    {
        if (instance == null)
        {
            instance = new Whiteboard();
        }
        return instance;
    }


    // Returns a clone of the messages
    synchronized Collection getMessages()
    {
        return getMessages(DEFAULTCOUNT);
    }


    // Returns a clone of the last count messages
    synchronized Collection getMessages(int count)
    {
        return new ArrayList(messages.subList(0, Math.min(count, messages.size())));
    }


    // Adds a new message
    synchronized void addMessage(Message msg)
    {
        // Inserts it in the first place
        messages.add(0, msg);
    }

}