/*
 * @(#)DragTracker.java
 *
 * Project:		JHotdraw - a GUI framework for technical drawings
 *				http://www.jhotdraw.org
 *				http://jhotdraw.sourceforge.net
 * Copyright:	© by the original author(s) and all contributors
 * License:		Lesser GNU Public License (LGPL)
 *				http://www.opensource.org/licenses/lgpl-license.html
 */

package CH.ifa.draw.standard;

import CH.ifa.draw.framework.*;
import CH.ifa.draw.util.UndoableAdapter;
import CH.ifa.draw.util.Undoable;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.util.*;

/**
 * DragTracker implements the dragging of the clicked
 * figure.
 *
 * @see SelectionTool
 *
 * @version <$CURRENT_VERSION$>
 */
public class DragTracker extends AbstractTool {

	private Figure  fAnchorFigure;
	private int     fLastX, fLastY;      // previous mouse position
	private boolean fMoved = false;

	public DragTracker(DrawingEditor newDrawingEditor, Figure anchor) {
		super(newDrawingEditor);
		fAnchorFigure = anchor;
	}

	public void mouseDown(MouseEvent e, int x, int y) {
		super.mouseDown(e, x, y);
		fLastX = x;
		fLastY = y;

		if (e.isShiftDown()) {
		   view().toggleSelection(fAnchorFigure);
		   fAnchorFigure = null;
		}
		else if (!view().isFigureSelected(fAnchorFigure)) {
			view().clearSelection();
			view().addToSelection(fAnchorFigure);
		}
	}

	public void mouseDrag(MouseEvent e, int x, int y) {
		super.mouseDrag(e, x, y);
		fMoved = (Math.abs(x - fAnchorX) > 4) || (Math.abs(y - fAnchorY) > 4);

		if (fMoved) {
			FigureEnumeration figures = getUndoActivity().getAffectedFigures();
			while (figures.hasMoreElements()) {
				figures.nextFigure().moveBy(x - fLastX, y - fLastY);
			}
		}
		fLastX = x;
		fLastY = y;
	}

	public void activate() {
		setUndoActivity(createUndoActivity());
		getUndoActivity().setAffectedFigures(view().selectionElements());
	}

	public void deactivate() {
		if (fMoved) {
			((DragTracker.UndoActivity)getUndoActivity()).setBackupPoint(new Point(fLastX, fLastY));
		}
		else {
			setUndoActivity(null);
		}
	}

	/**
	 * Factory method for undo activity
	 */
	protected Undoable createUndoActivity() {
		return new DragTracker.UndoActivity(view(), new Point(fLastX, fLastY));
	}

	public static class UndoActivity extends UndoableAdapter {
		private Point myOriginalPoint;
		private Point myBackupPoint;
		
		public UndoActivity(DrawingView newDrawingView, Point newOriginalPoint) {
			super(newDrawingView);
			setOriginalPoint(newOriginalPoint);
			setUndoable(true);
			setRedoable(true);
		}

		/*
		 * Undo the activity
		 * @return true if the activity could be undone, false otherwise
		 */
		public boolean undo() {
			if (!super.undo()) {
				return false;
			}
			moveAffectedFigures(getBackupPoint(), getOriginalPoint());
			return true;
		}

		/*
		 * Redo the activity
		 * @return true if the activity could be redone, false otherwise
		 */
		public boolean redo() {
			if (!super.redo()) {
				return false;
			}
			moveAffectedFigures(getOriginalPoint(), getBackupPoint());
			return true;
		}
		public void setBackupPoint(Point newBackupPoint) {
			myBackupPoint = newBackupPoint;
		}
		
		public Point getBackupPoint() {
			return myBackupPoint;
		}
		
		public void setOriginalPoint(Point newOriginalPoint) {
			myOriginalPoint = newOriginalPoint;
		}
		
		public Point getOriginalPoint() {
			return myOriginalPoint;
		}
		
		public void moveAffectedFigures(Point startPoint, Point endPoint) {
			FigureEnumeration figures = getAffectedFigures();
			while (figures.hasMoreElements()) {
				figures.nextFigure().moveBy(endPoint.x - startPoint.x,
					endPoint.y - startPoint.y);
			}
		}
	}
}