import java.awt.*;
import javax.swing.*;

/** TemperaturesWriter2 creates a graphics window for displaying temperatures */
public class TemperaturesWriter2 extends JFrame
{ // these fields define the sizes and positions of the two thermometers:
  private int CELSIUS_POS = 20;    // x-position of the Celsius thermometer
  private int FAHRENHEIT_POS = 170; // x-position of the Fahrenheit thermometer
  private int TOP = 60;            // the y-position of the thermometers' tops
  private int LENGTH = 50;         // the length of the thermometer
  private int WIDTH = 100;         // the width of the thermometer
  private int MIN_TEMP =   0;      // the min. temp.
  private int MAX_TEMP = 100;      // the max. temp.
  private int TEXT_OFFSET = 15;    // where to position the text labels 

  // these fields remember the two temperatures that are displayed:
  private int celsius_degrees;            // the degrees celsius
  private boolean celsius_degrees_contains_data = false;

  private int fahrenheit_degrees;         // the degrees fahrenheit
  private boolean fahrenheit_degrees_contains_data = false;
    
  /** Constructor TemperaturesWriter2 creates the window and makes it visible */
  public TemperaturesWriter2()
  { setTitle("Celsius into Fahrenheit");
    setSize(300,200);
    setBackground(Color.white);
    setVisible(true);
  }

  /** displayCelsius draws the Celsius thermometer
    * @param degrees - temperature to display */
  public void displayCelsius(int degrees)
  {
      celsius_degrees = degrees;
      celsius_degrees_contains_data = true;
      repaint();  // repaint the window with the new celsius_degrees
  }

  /** displayFahrenheit draws the Fahrenheit thermometer
    * @param degrees - temperature to display */
  public void displayFahrenheit(int degrees)
  {
      fahrenheit_degrees = degrees;
      fahrenheit_degrees_contains_data = true;
      repaint();  // repaint the window with the new fahrenheit_degrees
  }

  /** paint fills the window with two thermometers
    * @param g - the ``graphics pen'' that draws the items onto the window */
  public void paint(Graphics g)
  {
      g.clearRect(0, 0, getWidth(), getHeight());

      g.setColor(Color.black);
      g.drawString("Celsius", CELSIUS_POS + TEXT_OFFSET, TOP - TEXT_OFFSET);
      g.drawString("is", (CELSIUS_POS + WIDTH + FAHRENHEIT_POS)/2, TOP + TEXT_OFFSET);
      g.drawString("Fahrenheit", FAHRENHEIT_POS + TEXT_OFFSET, TOP - TEXT_OFFSET);
      drawThermometer(CELSIUS_POS, celsius_degrees,
                      celsius_degrees_contains_data, g);

      drawThermometer(FAHRENHEIT_POS, fahrenheit_degrees,
                      fahrenheit_degrees_contains_data, g);
  }

  /** drawThermometer paints a thermometer
    * @param where - the horizontal position of the thermometer 
    * @param degrees - how high to fill the thermometer 
    * @param data_available - contains degrees a reasonable value?
    * @param g - the graphics pen  */
  private void drawThermometer(int where, int degrees,
                               boolean data_available, Graphics g)
  {
      if (data_available)
          {
              if (MIN_TEMP <= degrees && degrees <= MAX_TEMP)
                  {
                      g.setColor(Color.red);
                      g.drawArc(where, TOP, WIDTH, WIDTH, 0, 180);
                      g.drawLine(where, TOP+LENGTH, where+WIDTH, TOP+LENGTH);
                      
                      paintTemp(where, degrees, g);  // show temperature
                  }
              else
                  {
                      g.setColor(Color.red);
                      g.drawString("Out of range", where, TOP+LENGTH);
                      
                  }
              g.drawString(degrees + "", where + TEXT_OFFSET, TOP+LENGTH+20);
          }
      else
          {
              g.drawString("No data", where, TOP+LENGTH);
              System.out.println("No data" );
          }
  }


  /** paintTemp  fills a thermometer with the appropriate temperature
    * @param where - the location of the thermometer
    * @param degrees - how high to fill it 
    * @param g - the graphics pen  */
  private void paintTemp(int where, int degrees, Graphics g)
  { 
      int x_center = where + WIDTH/2,   // Mittelpunkt des Kreisbogens
          y_center = TOP + LENGTH;
      
      int radius = WIDTH/2 - 5;         // Radius des Kreisbogens
      

      int x_tip = x_center              // Spitze des Zeigers
                  - (int) (radius * Math.cos(degrees * Math.PI/MAX_TEMP)),
          y_tip = y_center
                  - (int) (radius * Math.sin(degrees * Math.PI/MAX_TEMP));

      g.drawLine(x_center, y_center, x_tip, y_tip);
  }
}