// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.gui;

import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

import javax.swing.AbstractAction;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

import org.openstreetmap.josm.data.coor.EastNorth;

/**
 * Enables moving of the map by holding down the right mouse button and drag
 * the mouse. Also, enables zooming by the mouse wheel.
 *
 * @author imi
 */
public class MapMover extends MouseAdapter implements MouseMotionListener, MouseWheelListener {

	private final class ZoomerAction extends AbstractAction {
		private final String action;
		public ZoomerAction(String action) {
			this.action = action;
        }
	    public void actionPerformed(ActionEvent e) {
	    	if (action.equals(".") || action.equals(",")) {
	    		Point mouse = nc.getMousePosition();
	    		if (mouse == null)
	    			mouse = new Point((int)nc.getBounds().getCenterX(), (int)nc.getBounds().getCenterY());
	    		MouseWheelEvent we = new MouseWheelEvent(nc, e.getID(), e.getWhen(), e.getModifiers(), mouse.x, mouse.y, 0, false, MouseWheelEvent.WHEEL_UNIT_SCROLL, 1, action.equals(",") ? -1 : 1);
	    		mouseWheelMoved(we);
	    	} else {
	    		EastNorth center = nc.getCenter();
	    		EastNorth newcenter = nc.getEastNorth(nc.getWidth()/2+nc.getWidth()/5, nc.getHeight()/2+nc.getHeight()/5);
	    		if (action.equals("left"))
	    			nc.zoomTo(new EastNorth(2*center.east()-newcenter.east(), center.north()), nc.getScale());
	    		else if (action.equals("right"))
	    			nc.zoomTo(new EastNorth(newcenter.east(), center.north()), nc.getScale());
	    		else if (action.equals("up"))
	    			nc.zoomTo(new EastNorth(center.east(), 2*center.north()-newcenter.north()), nc.getScale());
	    		else if (action.equals("down"))
	    			nc.zoomTo(new EastNorth(center.east(), newcenter.north()), nc.getScale());
	    	}
	    }
    }

	/**
	 * The point in the map that was the under the mouse point
	 * when moving around started.
	 */
	private EastNorth mousePosMove;
	/**
	 * The map to move around.
	 */
	private final NavigatableComponent nc;
	/**
	 * The old cursor when we changed it to movement cursor.
	 */
	private Cursor oldCursor;

	private boolean movementInPlace = false;

	/**
	 * Create a new MapMover
	 */
	public MapMover(NavigatableComponent navComp, JPanel contentPane) {
		this.nc = navComp;
		nc.addMouseListener(this);
		nc.addMouseMotionListener(this);
		nc.addMouseWheelListener(this);
		
		String[] n = {",",".","up","right","down","left"};
		int[] k = {KeyEvent.VK_COMMA, KeyEvent.VK_PERIOD, KeyEvent.VK_UP, KeyEvent.VK_RIGHT, KeyEvent.VK_DOWN, KeyEvent.VK_LEFT};

		if (contentPane != null) {
			for (int i = 0; i < n.length; ++i) {
				contentPane.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(k[i], KeyEvent.CTRL_DOWN_MASK), "MapMover.Zoomer."+n[i]);
				contentPane.getActionMap().put("MapMover.Zoomer."+n[i], new ZoomerAction(n[i]));
			}
		}
	}

	/**
	 * If the right (and only the right) mouse button is pressed, move the map
	 */
	public void mouseDragged(MouseEvent e) {
		int offMask = MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON2_DOWN_MASK;
		if ((e.getModifiersEx() & (MouseEvent.BUTTON3_DOWN_MASK | offMask)) == MouseEvent.BUTTON3_DOWN_MASK) {
			if (mousePosMove == null)
				startMovement(e);
			EastNorth center = nc.getCenter();
			EastNorth mouseCenter = nc.getEastNorth(e.getX(), e.getY());
			EastNorth p = new EastNorth(
					mousePosMove.east() + center.east() - mouseCenter.east(),
					mousePosMove.north() + center.north() - mouseCenter.north());
			nc.zoomTo(p, nc.getScale());
		} else
			endMovement();
	}

	/**
	 * Start the movement, if it was the 3rd button (right button).
	 */
	@Override public void mousePressed(MouseEvent e) {
		int offMask = MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON2_DOWN_MASK;
		if (e.getButton() == MouseEvent.BUTTON3 && (e.getModifiersEx() & offMask) == 0)
			startMovement(e);
	}

	/**
	 * Change the cursor back to it's pre-move cursor.
	 */
	@Override public void mouseReleased(MouseEvent e) {
		if (e.getButton() == MouseEvent.BUTTON3)
			endMovement();
	}

	/**
	 * Start movement by setting a new cursor and remember the current mouse
	 * position.
	 * @param e The mouse event that leat to the movement from.
	 */
	private void startMovement(MouseEvent e) {
		if (movementInPlace)
			return;
		movementInPlace = true;
		mousePosMove = nc.getEastNorth(e.getX(), e.getY());
		oldCursor = nc.getCursor();
		nc.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
	}

	/**
	 * End the movement. Setting back the cursor and clear the movement variables
	 */
	private void endMovement() {
		if (!movementInPlace)
			return;
		movementInPlace = false;
		if (oldCursor != null)
			nc.setCursor(oldCursor);
		else
			nc.setCursor(Cursor.getDefaultCursor());
		mousePosMove = null;
		oldCursor = null;
	}

	/**
	 * Zoom the map by 1/5th of current zoom per wheel-delta.
	 * @param e The wheel event.
	 */
	public void mouseWheelMoved(MouseWheelEvent e) {
		int w = nc.getWidth();
		int h = nc.getHeight();

		double zoom = Math.max(0.1, 1 + e.getWheelRotation()/5.0);
		double zoomfactor = (zoom-1)/2+1;

		double newHalfWidth = w*zoomfactor - w/2;
		double newHalfHeight = h*zoomfactor - h/2;
		double centerx = e.getX() - (e.getX()-w/2)*newHalfWidth*2/w;
		double centery = e.getY() - (e.getY()-h/2)*newHalfHeight*2/h;
		EastNorth newCenter = nc.getEastNorth((int)centerx, (int)centery); 

		nc.zoomTo(newCenter, nc.getScale()*zoom);
	}

	/**
	 * Does nothing. Only to satisfy MouseMotionListener
	 */
	public void mouseMoved(MouseEvent e) {}
}