/**
 * Generic object the SumlCanvas will be able to draw onto the screen. Defines 
 * the following abstract methods which must be overridden by children:
 *
 * <ul>
 *    <li>public void draw (Graphic g)</li>
 *    <li>public void move (Point delta)</li>
 *    <li>public void scale (double x, double y)</li>
 * </ul>
 *
 * @author Eric Liebowitz
 * @version 22jun11
 */
package simple_uml.view.canvas;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.awt.geom.Point2D;

import java.util.Stack;
import java.util.Vector;

public abstract class SumlShape 
{
   /* CONSTANTS ==>*/

   /** Base x-coord for BASE_ORIGIN */
   protected static final int X_BASE = 0;
   /** Base y-coord for BASE_ORIGIN */
   protected static final int Y_BASE = 0;

   /** Where all shapes are drawn relative to, by default */
   protected static final Point BASE_ORIGIN = new Point(X_BASE, Y_BASE);

   /*<==*/

   /* INSTANCE VARIABLES ==>*/

   /**
    * Stores Graphics2D AffineTransforms so that you can save transforms, alter
    * them, and restore them later. 
    *
    * @see #pushMatrix(Graphics2D)
    * @see #popMatrix(Graphics2D)
    */
   private Stack<AffineTransform> matrixStack = 
      new Stack<AffineTransform>();
   /**
    * The transform matrix applied to this shape before drawing
    */
   protected AffineTransform tMatrix = new AffineTransform();

   /**
    * The upper-left corner of this shape, where all components of said shape
    * are drawn relative to.
    */
   protected Point origin = new Point(BASE_ORIGIN);
   /**
    * Bounding box of the shape, letting you know the min height/width needed
    * to fully contain its members. Default is a rect with width/height = 0,
    * located at point (0, 0).
    */
   protected Rectangle bounds = new Rectangle(X_BASE, Y_BASE, 0, 0);
   /**
    * Color the shape should be. Default is Color.black
    */
   protected Color color = Color.black;
   /**
    * Whether this shape is selected. Default is false.
    */
   protected boolean selected = false;
   /**
    * List of any listeners who like to know when this shape changes
    */
   protected Vector<ShapeListener> listeners = new Vector<ShapeListener>();

   /*<==*/

   public SumlShape () { }
   
   /**
    * Creates a shape w/ the specified color
    */
   public SumlShape (Color c)
   {
      this.color = c;
   }

   public void addListener (ShapeListener sl)
   {
      this.listeners.add(sl);
   }

   /* GETTERS ==>*/

   /**
    * Returns the width of this shape, as defined by its bounding box
    *
    * @return the width of this shape (default 0)
    */
   public int getWidth () 
   {
      return (int)this.bounds.getWidth();
   }

   /**
    * Returns the height of this shape, as defined by its bounding box
    *
    * @return the height of this shape (default 0)
    */
   public int getHeight ()
   {
      return (int)this.bounds.getHeight();
   }

   /**
    * Returns this shape's origin.
    *
    * @return this shape's origin
    */
   public Point getOrigin ()
   {
      return this.origin;
   }

   /*<==*/

   /* SETTERS ==>*/

   /**
    * Sets this shape's origin
    *
    * @param x x-coord you want the origin to be at
    * @param y y-coord you want the origin to be at
    */
   public void setOrigin (int x, int y)
   {  
      this.origin = new Point(x, y);
   }

   /*<==*/

   /* DRAWING ==>*/

   public boolean intersects (Rectangle2D r)
   {
      return bounds.intersects(r);
   }

   /**
    * Moves this shape by a given amount. This will translate
    * the transform matrix by the same amount.
    * 
    * @param dx Amount in x-direction you wish to move
    * @param dy Amount in y-direction you wish to move
    */
   public void move (int dx, int dy)
   {
      this.tMatrix.translate(dx, dy);
      tMatrix.transform(BASE_ORIGIN, origin);

      for (ShapeListener sl: this.listeners)
      {
         sl.shapeMoved();
      }
   }

   /**
    * Scales this shape by the given percentages. This scales the transform
    * matrix in order to accomplish the task.
    *
    * @param x percentage in x-direction you wish to scale
    * @param y percentage in y-direction you wish to scale
    */
   public void scale (double x, double y)
   {
      this.tMatrix.scale(x, y);
   }

   /**
    * Pushes the Graphics2D transform onto this object's stack of saved 
    * transforms.
    *
    * @param g2d Graphics2D to get the current AffineTransform from
    */
   public void pushMatrix (Graphics2D g2d)
   {
      this.matrixStack.push(g2d.getTransform());
   }

   /**
    * Pops a transform off the stack and sets the Graphics2D to have the popped
    * transform. 
    *
    * @param g2d Graphics2D which is to have its transform set to the popped 
    *            value
    */
   public void popMatrix (Graphics2D g2d)
   {
      g2d.setTransform(this.matrixStack.pop());
   }

   /**
    * Paints the shape on the screen. Outsiders call this method to get things
    * drawn, as it automatically saved the current g2d transform and applies
    * this shape's transform matrix.
    *
    * @param g2d Graphics2D to do the drawing
    */
   public void paint (Graphics2D g2d)
   {
      pushMatrix(g2d);
      g2d.transform(this.tMatrix);
      draw(g2d);
      popMatrix(g2d);
   }
   
   /**
    * Does the work of actually drawing the shape.
    *
    * @param g2d Graphics2D to do the drawing.
    */
   protected abstract void draw (Graphics2D g2d);

   /*<==*/
}