/*
 * Copyright 2007 Mat Gessel <mat.gessel@gmail.com>
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package org.litesoft.GWT.client.widgets.nonpublic.external;

import com.google.gwt.core.client.*;
import com.google.gwt.user.client.*;
import org.litesoft.GWT.client.*;
import org.litesoft.core.*;

public class MousePerformanceFilter extends MouseHandlerWrapper
{
    private static final MoveStrategy s_defaultImpl = (MoveStrategy) GWT.create( MoveStrategy.class );

    private MoveStrategy m_MoveStrategy = s_defaultImpl;

    public MousePerformanceFilter( MouseHandler delegate )
    {
        super( delegate );
    }

    public MoveStrategy getMoveStrategy()
    {
        return m_MoveStrategy;
    }

    public void setMoveStrategy( MoveStrategy impl )
    {
        m_MoveStrategy = impl;
    }

    public void onMouseMove( MouseEvent e )
    {
        getMoveStrategy().step( getDelegate(), e );
    }

    public void onMouseUp( MouseEvent e )
    {
        getMoveStrategy().finish();
        super.onMouseUp( e );
    }

    public static abstract class MoveStrategy
    {
        protected abstract void step( MouseHandler handler, MouseEvent e );

        protected abstract void finish();
    }

    public static class MoveStrategyImmediate extends MoveStrategy
    {
        protected void step( MouseHandler handler, MouseEvent e )
        {
            handler.onMouseMove( e );
        }

        protected void finish()
        {
        }
    }

    public static class MoveStrategyDeferred extends MoveStrategy
    {
        /**
         * Note: the timer is active if this field is not null
         */
        private StepTimer m_timer = null;

        protected void step( MouseHandler handler, MouseEvent moveEvent )
        {
            if ( m_timer != null )
            {
                m_timer.update( moveEvent );
            }
            else
            {
                m_timer = new StepTimer( handler, moveEvent );
                m_timer.schedule( 1 );
            }
        }

        protected void finish()
        {
            if ( m_timer != null )
            {
                m_timer.cancel();
                m_timer.run();
            }
        }

        private class StepTimer extends Timer
        {
            private final MouseHandler m_handler;

            private MouseEvent m_moveEvent;

            public StepTimer( MouseHandler gesture, MouseEvent moveEvent )
            {
                m_handler = gesture;
                update( moveEvent );
            }

            public void update( MouseEvent e )
            {
                m_moveEvent = e;
            }

            public void run()
            {
                m_timer = null;
                m_handler.onMouseMove( m_moveEvent );
            }
        }
    }

    public static class MoveStrategyMozilla extends MoveStrategy
    {
        private final MoveStrategy m_strategy;

        public MoveStrategyMozilla()
        {
            if ( Platform.Other.equals( UserAgent.getInstance().getPlatform() ) )
            {
                m_strategy = new MoveStrategyDeferred();
            }
            else
            {
                m_strategy = new MoveStrategyImmediate();
            }
        }

        protected void step( MouseHandler handler, MouseEvent moveEvent )
        {
            m_strategy.step( handler, moveEvent );
        }

        protected void finish()
        {
            m_strategy.finish();
        }
    }
}