package edu.jsu.leathrum.mathlets.shared;
import javax.swing.*;
import java.awt.geom.*;
import java.awt.Graphics2D;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Dimension;

public abstract class ASimpleGraphCanvas extends JComponent {
  Dimension size;
  protected int wd, ht, sc; 
  GeneralPath axpath = new GeneralPath();
  public AffineTransform tr = new AffineTransform();
  public AffineTransform trinv = new AffineTransform();

  public ASimpleGraphCanvas(int initialWidth, int initialHeight, int scale) {
    wd = initialWidth;
    ht = initialHeight;
    sc = scale;
    size = new Dimension(initialWidth, initialHeight);
    setBackground(Color.white);
    tr.setToIdentity();
    tr.scale(sc,-sc);
    tr.translate(wd/(2*sc),-ht/(2*sc));
    try {trinv = tr.createInverse();}
    catch (NoninvertibleTransformException e) {trinv.setToIdentity();}
    buildAxesPath();
  }

  public Dimension getPreferredSize() {
    return getMinimumSize();
  }

  public Dimension getMinimumSize() {
    return size;
  }

  private void buildAxesPath() {
    double value = 0.0;
    double temp = 0.0;
    Point2D p2;
    double xmax = wd/(2*sc), xmin = -xmax, delx = 1.0;
    double ymax = ht/(2*sc), ymin = -ymax, dely = 1.0;

    axpath = new GeneralPath();
    p2 = tr.transform(new Point2D.Double(0.0,0.0),null);
    axpath.append(tr.createTransformedShape(
        new Line2D.Double(xmin,0.0,xmax,0.0)),false);
    axpath.append(tr.createTransformedShape(
        new Line2D.Double(0.0,ymin,0.0,ymax)),false);

    for (value = delx; value < xmax ; value+=delx) {
	temp = tr.transform(new Point2D.Double(value,0.0),null).getX();
	axpath.append(new Line2D.Double(temp, p2.getY()-3, temp, p2.getY()+3),false);
    }
    for (value = -delx; value > xmin ; value-=delx) {
	temp = tr.transform(new Point2D.Double(value,0.0),null).getX();
	axpath.append(new Line2D.Double(temp, p2.getY()-3, temp, p2.getY()+3),false);
    }
    for (value = dely; value < ymax ; value+=dely) {
	temp = tr.transform(new Point2D.Double(0.0,value),null).getY();
	axpath.append(new Line2D.Double(p2.getX()-3, temp, p2.getX()+3, temp),false);
    }
    for (value = -dely; value > ymin ; value-=dely) {
	temp = tr.transform(new Point2D.Double(0.0,value),null).getY();
	axpath.append(new Line2D.Double(p2.getX()-3, temp, p2.getX()+3, temp),false);
    }
  }

  public void drawAxes(Graphics2D g) {
    g.setPaint(Color.black);
    g.draw(axpath);
  }

  protected abstract void drawFigure(Graphics2D g);

  public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    drawAxes(g2);
    drawFigure(g2);
  }
}