import java.awt.Color;
import java.awt.Canvas;
import java.awt.Button;
import java.awt.Image;
import java.awt.Graphics;
import java.awt.Frame;
import java.awt.event.*;
import java.util.*;

/**
 * Class ShapeCanvas:  holds shapes in a custom drawn area
 * @author Barb Ericson
 */
public class ShapeCanvas extends Canvas implements ShapeInterface
{
  
  
  ///////////////// Private Attributes /////////////////////////////
  
  private List<Shape> shapes = new ArrayList<Shape>(); // a list of shapes
  private Shape currentShape = null; // current shape being dragged
  private String currShapeType = Shape.RECTANGLE; // default shape type
  private int width = 100;  // canvas width
  private int height = 100;  // canvas height
  private Color backgroundColor = Color.yellow;
  private Image backgroundImage = null;        // background image for double buffering
  private Graphics backgroundG = null;    // graphics context of background image
  
  /////////////////// Constructors //////////////////////////////////
  
  /** A constructor that uses the default size */
  public ShapeCanvas ()
  {
    init();
  }
  
  /**
   * A constructor that takes the width and height
   * @param width   the width of the canvas
   * @param height  the height of the canvas
   */
  public ShapeCanvas(int width, int height)
  {
    // set the local variables
    this.width = width;
    this.height = height;
    
    init();
  }
  
  ////////////////////// Private Methods ////////////////////////////////
  
  /* Method to initialize the shape canvas size and set the mouse listeners*/
  private void init()
  {
    // set the size of the canvas to the current width and height
    setSize(width,height);
    
    // add the mouse listener and mouse motion listener
    addMouseListener(new MyMouseAdapter());
    addMouseMotionListener(new MyMouseMotionAdapter());
    
    // add a component listener
    addComponentListener(new ComponentAdapter() {
      public void componentResized(ComponentEvent e)
      {
        backgroundImage = null;
      }
    });
    
    // set the background color
    setBackground(backgroundColor);
  }
  
  ///////////////////////// Public Methods ///////////////////////////////
  
  /**
   * Method to add a shape to the shape vector
   * @param shape   the shape to add
   */
  public void add(Shape shape)
  {
    // add the shape to the vector of shapes
    shapes.add(shape);
    
    // force a repaint to show the new shape
    repaint();
  }
  
  /**
   * Method to remove a shape from the shape vector
   * @param shape   the shape to remove
   */
  public void remove(Shape shape)
  {
    // remove the shape from the vector of shapes
    shapes.remove(shape); // removes first one
    
    // force a repaint to show that it is gone
    repaint();
  }
  
  /**
   * Method to remove a shape given the index
   * @param index   the index of the shape in the shape vector that you
   *                wish to remove
   */
  public void remove(int index)
  {
    // remove the shape at the given index
    shapes.remove(index);
    
    // force a repaint to show it is gone
    repaint();
  }
  
  /**
   * Update normally clears the background and calls paint
   * override it here to just call paint
   * @param g   the graphics context on which to draw
   */
  public void update(Graphics g)
  {
    paint(g);
  }
  
  /**
   * Method to paint the shape canvas and all objects in it
   * @param g   the graphic context on which to paint
   */
  public void paint (Graphics g)
  {
    Shape currShape;
    int height = getSize().height;
    int width = getSize().width;
    
    // if background image not created then create it
    if (backgroundImage == null)
    {
      // create the background image for double buffering
      backgroundImage = createImage(width,height);
      
      // get the graphics context of the background image
      backgroundG = backgroundImage.getGraphics();
    }
    
    // clear the drawing area in the background image
    backgroundG.setColor(getBackground());
    backgroundG.clearRect(0, 0, width, height);
    
    // loop through the shape objects and draw each one
    for (int i=0; i<shapes.size(); i++)
    {
      currShape = shapes.get(i);
      currShape.draw(backgroundG);
    }
    
    // when drawing to background is done display background
    // image
    g.drawImage(backgroundImage,0,0,this);
  }
  
  /**
   * Set the type of the shape that will be created when the user
   * clicks in the shape canvas.
   * @param shapeType the name of the shape
   */
  public void setShape(String shapeType)
  {
    currShapeType = shapeType;
  }
  
  /**
   * Clear all shapes out of the shape vector
   */
  public void clearShapes()
  {
    // remove all shapes from the shape vector
    shapes.clear();
    
    // repaint to show that they are gone
    repaint();
  }
  
  /////////////////// Main Method for Testing ///////////////////////////
  public static void main (String argv[])
  {
    // create a frame
    Frame frame = new Frame();
    
    // create a ShapeCanvas
    ShapeCanvas shapeCanvas = new ShapeCanvas(500,500);
    
    // create a rectangle shape
    Shape shape = new Rectangle(50,50,60,60);
    
    // add the shape to the shape canvas
    shapeCanvas.add(shape);
    
    // create an oval
    shape = new Oval(10,10,30,30);
    shapeCanvas.add(shape);
    
    // add the shape canvas to the frame
    frame.add(shapeCanvas);
    frame.pack(); // shrink to fit preferred size
    frame.setVisible(true); // show the frame
  }
  
  /** An inner class for handling the mouse listener interface */
  class MyMouseAdapter extends MouseAdapter
  {
    /** Method to handle when the user presses down the button */
    public void mousePressed(MouseEvent e)
    {
      int currX = e.getX();
      int currY = e.getY();
      
      // create an object of the current shape type
      try {
        Class shapeClass = Class.forName(currShapeType);
        currentShape = (Shape) shapeClass.newInstance();
      } catch (Exception ex)
      {
        System.err.println("Problem in creating a shape");
        ex.printStackTrace();
        System.exit(1);
        
      }
      
      // fill in point1 and point2 in the new shape
      currentShape.setPoint1Values(currX,currY);
      currentShape.setPoint2Values(currX + 1, currY + 1);
      
      // add the shape to the vector of shapes
      add(currentShape);
      
      // repaint all
      repaint();
      
    }
    
    /** Method to handle when the user releases the mouse */
    public void mouseReleased(MouseEvent e)
    {
      int currX = e.getX();
      int currY = e.getY();
      
      // update the the point 2 values
      currentShape.setPoint2Values(currX,currY);
      
      // no current shape being dragged
      currentShape = null;
      
      // repaint
      repaint();
      
    }
  }
  
  /** Inner class for handling the mouse motion listener */
  class MyMouseMotionAdapter extends MouseMotionAdapter
  {
    /** Method to handle the drag of a mouse */
    public void mouseDragged(MouseEvent e)
    {
      int currX = e.getX();
      int currY = e.getY();
      
      // set the point 2 values
      currentShape.setPoint2Values(currX, currY);
      
      // repaint
      repaint();
    }
  }
  
}