import ifi.plot.DoubleBufferedCanvas;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Canvas;
import java.awt.Polygon;

import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;


/**
 * The RoundClock implements a simple round clock, which consits of
 * three hands and markings for every hour.
 * The clock does not update itself (see ClockAdmin).
 */

public class RoundClock extends DoubleBufferedCanvas{
  
  // ---------------
  // Local variables
  // ---------------

  // Used to store the current time. Updated by updateClock.
  Date current_time = new Date();

  // Default calandar uses Central European Time time.
  Calendar local_calendar = Calendar.getInstance();

  /*
   * Draw the clock face and the three hands.
   */
  public void drawClock(Graphics g){
    // Variables that control the size and position of the clock.

    double radius;
    int center_x;
    int center_y;

    Dimension d = getSize();

    if(d.width < d.height)
      radius = d.width/2-5;
    else
      radius = d.height/2-5;

    center_x = d.width/2;
    center_y = d.height/2;

    // Get size of the canvas, and compute the largest circle
    // that fits the canvas. Reduce the radius so that you get
    // a border which is 5 pixels large. Also find the center
    // of the cock. Put the results in radius, center_x and center_y


    // Erase old clock.
    g.clearRect(0, 0, d.width, d.height);

    // Draw clock face (circle and 12 hour marks).
    g.drawOval(5, 5, (int) d.width - 10, d.height - 10);

    for(double a = 0; a < 2 * Math.PI; a += Math.PI / 6)
      g.drawLine((int) (Math.cos(a) * (radius - 10) + center_x),
		 (int) (Math.sin(a) * (radius - 10) + center_y), 
		 (int) (Math.cos(a) * (radius - 15) + center_x), 
		 (int) (Math.sin(a) * (radius - 15) + center_y));  


    // Get current time.
    local_calendar.setTime(current_time);

    int hour   = local_calendar.get(Calendar.HOUR);
    int minute = local_calendar.get(Calendar.MINUTE);
    int second = local_calendar.get(Calendar.SECOND);


    // Draw hour hand
    double angle;

    Polygon p = new Polygon();

    angle = ((double) hour + (double) minute / 60) * Math.PI / 6 - Math.PI / 2;
    p.addPoint((int)(Math.cos(angle) * (6 * radius / 10) + center_x), (int) (Math.sin(angle) * (6 * radius / 10) + center_y));
    angle = ((double) hour + (double) minute / 60) * Math.PI / 6;
    p.addPoint((int)(Math.cos(angle) * (3.5 * radius / 100) + center_x), (int) (Math.sin(angle) * (3.5 * radius / 100) + center_y));
    angle = ((double) hour + (double) minute / 60) * Math.PI / 6 - Math.PI;
    p.addPoint((int)(Math.cos(angle) * (3.5 * radius / 100) + center_x), (int) (Math.sin(angle) * (3.5 * radius / 100) + center_y));

    g.fillPolygon(p);


    // Draw minute hand
    p = new Polygon();

    angle = ((double) minute + (double) second / 60) * (Math.PI / 30) -  Math.PI / 2;
    p.addPoint((int)(Math.cos(angle) * (8 * radius / 10) + center_x), (int) (Math.sin(angle) * (8 * radius / 10) + center_y));
    angle = ((double) minute + (double) second / 60) * (Math.PI / 30);
    p.addPoint((int)(Math.cos(angle) * (3 * radius / 100) + center_x), (int) (Math.sin(angle) * (3 * radius / 100) + center_y));
    angle = ((double) minute + (double) second / 60) * (Math.PI / 30) +  Math.PI;
    p.addPoint((int)(Math.cos(angle) * (3 * radius / 100) + center_x), (int) (Math.sin(angle) * (3 * radius / 100) + center_y));
    
    g.fillPolygon(p);


    // Draw second hand
    angle = second * Math.PI / 30 - Math.PI / 2;
    g.drawLine(center_x,
	       center_y,
	       (int) (Math.cos(angle) * (radius - 20) + center_x),
	       (int) (Math.sin(angle) * (radius - 20) + center_y));
  }

  /*
   * This method should update the current time, and
   * redraw the clock.
   */

  public void updateClock(){
    current_time = new Date();
    updateCanvas();
  }

  /*
   * Build a calendar object which represent the given time zone.
   */

  public void setTimeZone(String zone){
    local_calendar = Calendar.getInstance(TimeZone.getTimeZone(zone));
    updateClock();
  }

  /**
   * This method is required by Canvas. It is called when the
   * canvas receives a paint/update request from AWT.
   */

  public synchronized void updateCanvas(Graphics g)
  {
    drawClock(g);
  }

}