// Program to calculate values of resistors

import java.applet.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;

// Main class begins here
public class ResistorApplet extends JApplet implements ActionListener
{ JLabel picture; // Resistor Picture
  int numOfBands=0; // integer for number of bands (0=4-band, 1=5-band)
  int band1=0; // initialisation of band1 combo to 0
  int band2=0; // initialisation of band2 combo to 0
  int band3=0; // initialisation of band3 combo to 0
  int band4=0; // initialisation of band4 combo to 0
  int band5=0; // initialisation of band5 combo to 0
  static float value=0; // value float for ohms
  static float kvalue; // value float for k ohms
  static float mvalue; // value float for M ohms
  float multiplier=0; // multiplier float for multiplier band
  static int tol=1; // tol interger for tolerance band
  static JTextField myTextField;  // Text field for value
  static JTextField myTextField1; // Text field for kvalue
  static JTextField myTextField2; // Text field for mvalue
  static JTextField myTextField3; // Text field for tol
  JComboBox colourList1; // Combo box for colours
  JButton calcButton; // Button to calculate values
  // Image for four bands
  ImageIcon fourBandIcon = createAppletImageIcon("images/fourband.gif", "4-band");
  // Image for five bands
  ImageIcon fiveBandIcon = createAppletImageIcon("images/fiveband.gif", "5-band");
  aboutProgramWindow aboutWindow;

  public void init()
  { Container c = getContentPane();
    c.setLayout(new FlowLayout());
    c.setBackground(Color.white);
    // Combo box values for number of bands
    String[] bandNums = { "4-band", "5-band" };
    // Combo box values for normal set of colours list
    String[] colours = { "black", "brown", "red", "orange", "yellow", "green",
                         "blue", "purple", "white", "grey" };
    // Combo box values for normal set of colours list + silver and gold
    String[] colours2 = { "black", "brown", "red", "orange", "yellow", "green",
                         "blue", "gold", "silver" };
    // Combo box values for tolerance set of colours list
    String[] colours3 = { "brown", "red", "gold", "silver", "none" };

    // Program Title
    JTextField title = new JTextField("Resistor Calculator");
    title.setFont(new Font("Verdana", Font.BOLD, 32));
    title.setEditable(false);
    title.setBorder(BorderFactory.createEmptyBorder(0,0,0,0));
    title.setBackground(Color.white);
    c.add(title);

    // Create the band selector combo box, select the 4-band default
    JComboBox bandList = new JComboBox(bandNums);
    bandList.setSelectedIndex(0);
    bandList.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e) // When selected, do...
      { JComboBox cb = (JComboBox)e.getSource();
        String bandNum = (String)cb.getSelectedItem(); // Set the bandNum String
        if (bandNum == "4-band") // If 4-band, select 4-band picture
          picture.setIcon(fourBandIcon);
        else                     // Else must be 5-band, select 5-band picture
          picture.setIcon(fiveBandIcon);
        // Set numOfBands int for calculations below
        numOfBands = (int)cb.getSelectedIndex();
      }
    });

    c.add(bandList);

    // Add the picture, default is fourband
    picture = new JLabel(fourBandIcon);
    picture.setBorder(BorderFactory.createEmptyBorder(10,0,0,0));
    picture.setPreferredSize(new Dimension(320, 230+10));
    c.add(picture);

    // Create the 1st combo box, select the black
    JComboBox colourList1 = new JComboBox(colours);
    colourList1.setSelectedIndex(0);
    colourList1.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        band1 = (int)cb.getSelectedIndex();
      }
    });
    c.add(colourList1);

    // Create the 2nd combo box, select the black
    JComboBox colourList2 = new JComboBox(colours);
    colourList2.setSelectedIndex(0);
    colourList2.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        band2 = (int)cb.getSelectedIndex();
      }
    });
    c.add(colourList2);

    // Create the 3rd combo box, select the black
    JComboBox colourList3 = new JComboBox(colours);
    colourList3.setSelectedIndex(0);
    colourList3.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        band3 = (int)cb.getSelectedIndex();
      }
    });
    c.add(colourList3);

    // Create the 4th combo box, select the black
    JComboBox colourList4 = new JComboBox(colours2);
    colourList4.setSelectedIndex(0);
    colourList4.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        band4 = (int)cb.getSelectedIndex();
      }
    });
    c.add(colourList4);

    // Create the 5th combo box, select the brown
    JComboBox colourList5 = new JComboBox(colours3);
    colourList5.setSelectedIndex(0);
    colourList5.addActionListener(new ActionListener()
    { public void actionPerformed(ActionEvent e)
      { JComboBox cb = (JComboBox)e.getSource();
        band5 = (int)cb.getSelectedIndex();
      }
    });
    c.add(colourList5);

    // Create the 1st text field, for value in ohms
    myTextField = new JTextField("          0 Ohm");
    myTextField.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField.setEditable(false);
    myTextField.setBackground(Color.white);
    c.add(myTextField);

    // Create the 2nd text field, for value in kilo ohms
    myTextField1 = new JTextField("           0 k");
    myTextField1.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField1.setEditable(false);
    myTextField1.setBackground(Color.white);
    c.add(myTextField1);

    // Create the 3rd text field, for value in mega ohms
    myTextField2 = new JTextField("           0 M");
    myTextField2.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField2.setEditable(false);
    myTextField2.setBackground(Color.white);
    c.add(myTextField2);

    // Create the 4th text field, for tolerance value
    myTextField3 = new JTextField(" 0 %");
    myTextField3.setFont(new Font("Courier", Font.PLAIN, 12));
    myTextField3.setEditable(false);
    myTextField3.setBackground(Color.white);
    c.add(myTextField3);

    // Button to perform calculations
    JButton myButton = new JButton("Calculate");
    myButton.addActionListener(new calculateButtonHandler());
    c.add(myButton);

    // About Button
    JButton aboutButton = new JButton("About");
    aboutButton.addActionListener(this);
	c.add(aboutButton);

	aboutWindow = new aboutProgramWindow(getAppletContext());
    aboutWindow.pack();

  }

  public void destroy()
  { aboutWindow.setVisible(false);
    aboutWindow = null;
  }

  public void actionPerformed(ActionEvent event)
  { aboutWindow.setVisible(true);
  }

  // Performed when calculate button is pressed
  class calculateButtonHandler implements ActionListener
  { public void actionPerformed(ActionEvent e)
    { if (numOfBands == 0) // if 4-bands
      { value = 0; // make sure values are reset
        multiplier = 0; // make sure multiplier is reset
        switch (band3) // Switch to do the multiplications from band 3
        { case 0:
            multiplier = 1;       break;
          case 1:
            multiplier = 10;      break;
          case 2:
            multiplier = 100;     break;
          case 3:
            multiplier = 1000;    break;
          case 4:
            multiplier = 10000;   break;
          case 5:
            multiplier = 100000;  break;
          case 6:
            multiplier = 1000000; break;
          default:
            multiplier = 1;
        }
        // Do the maths
        value = (band1 * 10) + band2;
        value = (value * multiplier);
        kvalue = (value / 1000f);
        mvalue = (value / 1000000f);
      }
      else // Else 5-band resistor calculations
      { value = 0; // make sure values are reset
        multiplier = 0; // make sure multiplier is reset
        switch (band4) // Switch to do the multiplications from band 4
        { case 0:
            multiplier = 1;       break;
          case 1:
            multiplier = 10;      break;
          case 2:
            multiplier = 100;     break;
          case 3:
            multiplier = 1000;    break;
          case 4:
            multiplier = 10000;   break;
          case 5:
            multiplier = 100000;  break;
          case 6:
            multiplier = 1000000; break;
          case 7:
            multiplier = 0.1f;     break;
          case 8:
            multiplier = 0.01f;    break;
          default:
            multiplier = 1;
        }
        // Do the maths
        value = (band1*100)+(band2*10)+(band3);
        value = ((float)value * (float)multiplier);
        kvalue = (value / 1000f);
        mvalue = (value / 1000000f);
      }
      switch (band5) // Switch to work out the tolerances from band 5
      { case 0:
          tol = 1;  break;
        case 1:
          tol = 2;  break;
        case 2:
          tol = 5;  break;
        case 3:
          tol = 10; break;
        case 4:
          tol = 20; break;
        default:
          tol = 20;
      }
      // Write the value to textfield
      StringBuffer sb = new StringBuffer("               ");
      sb.insert(15, (ResistorApplet.value+" Ohm"));
      ResistorApplet.myTextField.setText(sb.toString());

      // Write the kvalue to textfield1
      StringBuffer sb1 = new StringBuffer("               ");
      sb1.insert(15, (ResistorApplet.kvalue+" k"));
      ResistorApplet.myTextField1.setText(sb1.toString());

      // Write the mvalue to textfield2
      StringBuffer sb2 = new StringBuffer("               ");
      sb2.insert(15, (ResistorApplet.mvalue+" M"));
      ResistorApplet.myTextField2.setText(sb2.toString());

      // Write the tolerance to textfield3
      StringBuffer sb3 = new StringBuffer("   ");
      sb3.insert(3, (ResistorApplet.tol+" %"));
      ResistorApplet.myTextField3.setText(sb3.toString());
    }
  }

  // PRE-WRITTEN - Handles the images...
  // http://java.sun.com/docs/books/tutorial/uiswing/misc/icon.html
  protected static ImageIcon createAppletImageIcon(String path, String description)
  { int MAX_IMAGE_SIZE = 4000;
    int count = 0;
    BufferedInputStream imgStream = new BufferedInputStream(
           ResistorApplet.class.getResourceAsStream(path));
    if (imgStream != null)
    { byte buf[] = new byte[MAX_IMAGE_SIZE];
      try
      { count = imgStream.read(buf);
      }
      catch (IOException ieo)
      { System.err.println("Couldn't read stream from file: " + path);
      }
      try
      { imgStream.close();
      }
      catch (IOException ieo)
      { System.err.println("Can't close file " + path);
      }

      if (count <= 0)
      { System.err.println("Empty file: " + path);
        return null;
      }
      return new ImageIcon(Toolkit.getDefaultToolkit().createImage(buf), description);
    }
    else
    { System.err.println("Couldn't find file: " + path);
      return null;
    }
  }
}

class aboutProgramWindow extends JFrame //implements ActionListener
{ TextField aboutField;
  AppletContext appletContext;
  public aboutProgramWindow(AppletContext appletContext)
  { super("About this Applet!");

    this.appletContext = appletContext;

    Container contentPane = getContentPane();
    contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));

    contentPane.setBackground(Color.white);


    JLabel label1 = new JLabel("  Resistor Calculator Applet Produced by Electro-Dan  ");
    label1.setFont(new Font("Verdana", Font.ITALIC, 16));
    label1.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label1);
    JLabel label2 = new JLabel("Free to use and distribute but do not modify without consent");
    label2.setFont(new Font("Verdana", Font.BOLD, 12));
    label2.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label2);
    JLabel label3 = new JLabel("http://jump.to/electro-dan");
    label3.setFont(new Font("Verdana", Font.BOLD, 12));
    label3.setAlignmentX(Component.CENTER_ALIGNMENT);
    contentPane.add(label3);

    addWindowListener(new WindowAdapter()
    { public void windowClosing(WindowEvent event)
      { setVisible(false);
      }
	});
  }
}