/*
 * @(#)DragTracker.java  2.0.1  2007-11-05
 *
 * Copyright (c) 1996-2007 by the original authors of JHotDraw
 * and all its contributors.
 * All rights reserved.
 *
 * The copyright of this software is owned by the authors and  
 * contributors of the JHotDraw project ("the copyright holders").  
 * You may not use, copy or modify this software, except in  
 * accordance with the license agreement you entered into with  
 * the copyright holders. For details see accompanying license terms. 
 */

package org.jhotdraw.draw;

import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import java.util.*;

/**
 * <code>DragTracker</code> implements interactions with the content area of a
 * <code>Figure</code>.
 * <p>
 * The <code>DragTracker</code> handles one of the three states of the
 * <code>SelectionTool</code>. It comes into action, when the user presses
 * the mouse button over the content area of a <code>Figure</code>.
 *
 * @see SelectionTool
 *
 * @author Werner Randelshofer
 * @version 2.0.1 2007-11-05 Fixed a null pointer exception in method
 * mousePressed which occured, when the user deselected the selected
 * figure using shift-click.
 * <br>2.0 2006-01-14 Changed to support double precision coordinates.
 * <br>1.0 2003-12-01 Derived from JHotDraw 5.4b1.
 */
public class DragTracker extends AbstractTool {
    protected Figure anchorFigure;
    
    /**
     * The drag rectangle encompasses the bounds of all dragged figures.
     */
    protected Rectangle2D.Double dragRect;
    /**
     * The previousOrigin holds the origin of all dragged figures of the
     * previous mouseDragged event. This coordinate is constrained using
     * the Constrainer of the DrawingView.
     */
    protected Point2D.Double previousOrigin;
    /**
     * The anchorOrigin holds the origin of all dragged figures of the
     * mousePressed event.
     */
    protected Point2D.Double anchorOrigin;
    /**
     * The previousPoint holds the location of the mouse of the previous
     * mouseDragged event. This coordinate is not constrained using
     * the Constrainer of the DrawingView.
     */
    protected Point2D.Double previousPoint;
    /**
     * The anchorPoint holds the location of the mouse of the
     * mousePressed event. This coordinate is not constrained using
     * the Constrainer of the DrawingView.
     */
    protected Point2D.Double anchorPoint;
    
    private boolean isDragging;
    
    /** Creates a new instance. */
    public DragTracker(Figure figure) {
        anchorFigure = figure;
    }
    
    public void mouseMoved(MouseEvent evt) {
        updateCursor(editor.findView((Container) evt.getSource()), new Point(evt.getX(), evt.getY()));
    }
    
    public void mousePressed(MouseEvent evt) {
        super.mousePressed(evt);
        DrawingView view = getView();
        
        if (evt.isShiftDown()) {
            view.setHandleDetailLevel(0);
            view.toggleSelection(anchorFigure);
            if (! view.isFigureSelected(anchorFigure)) {
                anchorFigure = null;
            }
        } else if (! view.isFigureSelected(anchorFigure)) {
            view.setHandleDetailLevel(0);
            view.clearSelection();
            view.addToSelection(anchorFigure);
        }
        
        if (! view.getSelectedFigures().isEmpty()) {
            
            dragRect = null;
            for (Figure f : view.getSelectedFigures()) {
                if (dragRect == null) {
                    dragRect = f.getBounds();
                } else {
                    dragRect.add(f.getBounds());
                }
            }
            
            
            anchorPoint = previousPoint = view.viewToDrawing(anchor);
            anchorOrigin = previousOrigin = new Point2D.Double(dragRect.x, dragRect.y);
        }
    }
    
    public void mouseDragged(MouseEvent evt) {
        DrawingView view = getView();
        if (! view.getSelectedFigures().isEmpty()) {
            if (isDragging == false) {
                isDragging = true;
                updateCursor(editor.findView((Container) evt.getSource()),new Point(evt.getX(), evt.getY()));
            }
            
            Point2D.Double currentPoint = view.viewToDrawing(new Point(evt.getX(), evt.getY()));
            
            dragRect.x += currentPoint.x - previousPoint.x;
            dragRect.y += currentPoint.y - previousPoint.y;
            Rectangle2D.Double constrainedRect = (Rectangle2D.Double) dragRect.clone();
            if (view.getConstrainer() != null) {
                view.getConstrainer().constrainRectangle(
                        constrainedRect
                        );
            }
            
            AffineTransform tx = new AffineTransform();
            tx.translate(
                    constrainedRect.x - previousOrigin.x,
                    constrainedRect.y - previousOrigin.y
                    );
            Constrainer c = view.getConstrainer();
            for (Figure f : view.getSelectedFigures()) {
                f.willChange();
                f.transform(tx);
                f.changed();
            }
            
            previousPoint = currentPoint;
            previousOrigin = new Point2D.Double(constrainedRect.x, constrainedRect.y);
        }
    }
    
    
    public void mouseReleased(MouseEvent evt) {
        super.mouseReleased(evt);
        DrawingView view = getView();
        if (! view.getSelectedFigures().isEmpty()) {
            isDragging = false;
            int x = evt.getX();
            int y = evt.getY();
            updateCursor(editor.findView((Container) evt.getSource()),new Point(x, y));
            Point2D.Double newPoint = view.viewToDrawing(new Point(x,y));
            
            Collection<Figure> draggedFigures = new LinkedList(view.getSelectedFigures());
            Figure dropTarget = getDrawing().findFigureExcept(newPoint, draggedFigures);
            if (dropTarget != null) {
                boolean snapBack = dropTarget.handleDrop(newPoint, draggedFigures, view);
                if (snapBack) {
                    AffineTransform tx = new AffineTransform();
                    tx.translate(
                            anchorOrigin.x - previousOrigin.x,
                            anchorOrigin.y - previousOrigin.y
                            );
                    Constrainer c = view.getConstrainer();
                    for (Figure f : draggedFigures) {
                        f.willChange();
                        f.transform(tx);
                        f.changed();
                    }
                    fireToolDone();
                    return;
                }
            }
            
            AffineTransform tx = new AffineTransform();
            tx.translate(
                    -anchorOrigin.x + previousOrigin.x,
                    -anchorOrigin.y + previousOrigin.y
                    );
            if (! tx.isIdentity()) {
                getDrawing().fireUndoableEditHappened(new TransformEdit(
                        draggedFigures, tx
                        ));
            }
        }
        fireToolDone();
    }
    
    /*
    public void draw(Graphics2D g) {
        if (dragRect != null) {
            g.setColor(Color.GREEN);
           g.draw(getView().drawingToView(dragRect));
        }
    }*/
}