/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.gui.flow;

import java.awt.AWTEvent;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.AWTEventListener;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;

import javax.swing.JComponent;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

/**
 * This manages the panning of the process flow design window.
 * 
 * @author Simon Fischer
 */
public class PanningManager implements AWTEventListener  {

    private static final int PAN_DELAY = 50;
    private static final int PAN_STEP_SIZE = 20;

    private JComponent target;

    private Point mouseOnScreenPoint;

    private Timer timer = new Timer(PAN_DELAY, new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            scrollNow();
        }
    });

    public PanningManager(JComponent target) {
        super();
        this.target = target;
        timer.setRepeats(true);
        timer.start();
        Toolkit.getDefaultToolkit().addAWTEventListener(this, AWTEvent.MOUSE_MOTION_EVENT_MASK | AWTEvent.MOUSE_EVENT_MASK);
    }

    @Override
    public void eventDispatched(AWTEvent e) {
        if (e instanceof MouseEvent) {
            MouseEvent me = (MouseEvent) e;
            if (!SwingUtilities.isDescendingFrom(me.getComponent(), target)) {
                return;
            }
            if (me.getID() == MouseEvent.MOUSE_RELEASED) {
                // stop when mouse released
                mouseOnScreenPoint = null;
                if (timer.isRunning()) {
                    timer.stop();
                }
            } else if (me.getID() == MouseEvent.MOUSE_DRAGGED && me.getComponent() == target) {
                mouseOnScreenPoint = me.getLocationOnScreen();
            } else if (me.getID() == MouseEvent.MOUSE_PRESSED && me.getComponent() == target) {
                mouseOnScreenPoint = me.getLocationOnScreen();
                timer.start();
            }
        }
    }

    private void scrollNow() {
        if (mouseOnScreenPoint != null && target.isShowing()) {
            Point origin = target.getLocationOnScreen();
            Point relative = new Point(mouseOnScreenPoint.x - origin.x, mouseOnScreenPoint.y - origin.y);

            Rectangle visibleRect = target.getVisibleRect();

            if (!visibleRect.contains(relative)) {
                int destX = relative.x;
                if (relative.getX() < visibleRect.getMinX()) {
                    destX = (int)visibleRect.getMinX() - PAN_STEP_SIZE;
                }
                if (relative.getX() > visibleRect.getMaxX()) {
                    destX = (int)visibleRect.getMaxX() + PAN_STEP_SIZE;
                }

                int destY = relative.y;
                if (relative.getY() < visibleRect.getMinY()) {
                    destY = (int)visibleRect.getMinY() - PAN_STEP_SIZE;
                }
                if (relative.getY() > visibleRect.getMaxY()) {
                    destY = (int)visibleRect.getMaxY() + PAN_STEP_SIZE;
                }

                target.scrollRectToVisible(new Rectangle(new Point(destX, destY)));
            }
        }
    }
}