package nl.bluering;
import java.awt.*;
import java.awt.event.*;

/**
* this class implements a calculator using Expressions. It is an applet,
* but can also run as application..
*/

public class Calc2 extends java.applet.Applet
implements ActionListener
{
 TextArea memview;				// Shows variables
 Label warnview;				// Shows warnings
 TextField infield;				// Input field
 TextArea output;				// Shows output
 Panel keypad;					// Shows the keypad
 Choice intest;
 ExpWriter memviewwriter;
 
 volatile boolean lock=false;
 public void setlock(boolean b)
 {lock=b;
 }

/**
* the object that does the calculations, and remembers the variables.
*/
 RootLib engine;

 public Calc2()
 {
 System.out.println("Welcome in WhiteSpace. Errors appear here:\n");
 }

/**
* sets up the graphical user interface and does all other initialisations.
*/
 public void init()
 {
  engine=new RootLib(this);
  memview = new TextArea("",10,40);
  memview.setEditable(false); 
  warnview = new Label(" ");
  warnview.setForeground(Color.red);
  infield =new TextField("");
  output = new TextArea("Welcome in WhiteSpace!\nVersion 1.1\n",10,40);
  output.setEditable(false);
  keypad = new Panel();
  createlayout();
  setLayout(new BorderLayout());
  add(keypad,"Center");
  memviewwriter=new ExpWriter(memview,ExpWriter.PROLOG);
  infield.requestFocus();
 }

/**
* this methods allows you to start the applet as an application. It 
* creates a window that shows the applet.
*/
 public static void main(String[] ps)
 {
  Frame f=new Frame("calculator");
  f.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent e){System.exit(0);}});
  Calc2 d=new Calc2();
  f.setSize(400,400);
  f.add(d);
  d.init();
  f.pack();
  f.show();
  d.infield.addActionListener(d);
  d.infield.requestFocus();
 }

/**
* this (deprecated) method is used by browsers with an old 
* java environment. It is needed to enable pressing enter in the 
* input textfield.
*/
 public boolean action(Event evt, Object o)
 {
  if(o instanceof String)
   actionPerformed(new ActionEvent(o,0,"OK"));
  return true;
 }
/**
* this method processes all events. If a key on the keypad is clicked, it
* appends the character to the input. If OK is clicked or enter is pressed
* it calculates the answer.
*/

 public void actionPerformed(ActionEvent e)
 { 
  warn(" ");  
  String command=e.getActionCommand();
  if(command.equals("OK")||e.getSource()==infield)
  {docalculate();
  }
  else if (command.equals("Backspace"))
  {String s = infield.getText();
   int l=s.length()-1;  
   infield.setText(s.substring(0,l>0?l:0));
  }
  else if (command.equals("Clear"))
  {infield.setText("");
  }
  else if (command.length()<2)
  {infield.setText(infield.getText()+command); 
  }
  infield.requestFocus();
  infield.setCaretPosition(infield.getText().length());
 }

/**
* do the calculation.
*/
 void docalculate()
 {
  if(lock)
  	return;
  Expression inexp=getinput();
  if (inexp==null)
  {
   warn("I do not understand input");
   lock=false;
   return;
  }
  Variable top;
  setlock(true);
  engine.toprun(inexp);
 }

 /**
 *The engine must call this function if it is finished,
 *
 */
 public void endquery()
 {
  memview.setText("");
  engine.uservar.dump(memviewwriter);
  engine.userdefdump(memviewwriter);
  setlock(false);
 }

/**
* Get the input from infield and parse it.
*/
 Expression getinput()
 {
  try
  {
  String inputstring=(String)infield.getText();
  CoolFileHandle incfh=new CoolFileHandle(inputstring);
  Expression input=new ExpParser(incfh).get();
  Expression gettherest=new Expression("allout",1).add("");
  String unparsedinput=incfh.get(gettherest);
  if(!unparsedinput.equals(""))
  	warn("warning, could not parse \""+unparsedinput+"\"");
  return input;
  }catch(Exception e)
  {e.printStackTrace();
  }
  return null;
 }

/**
* print the string in the output window.
*/
 public void println(String s)
 {output.append(s+"\n");
  output.setCaretPosition(output.getText().length()-1);
 }

/**
* print the string in the warning field.
*/
 void warn(String s)
 {warnview.setText(s);
 }

/**
*create the very complicated gridbag layout. 
*/  
 void createlayout()
 {GridBagLayout gridbag = new GridBagLayout();
  GridBagConstraints c = new GridBagConstraints();
  keypad.setFont(new Font("Helvetica", Font.PLAIN, 14));
  keypad.setLayout(gridbag);
  c.fill = GridBagConstraints.BOTH;

  c.weightx=1.0; c.weighty=0.0;
  c.gridwidth = GridBagConstraints.REMAINDER;
  gridbag.setConstraints(memview, c);
  keypad.add(memview);
  
  c.gridx=0;c.gridy=1;
  gridbag.setConstraints(output, c);
  keypad.add(output);
  
  c.gridx=0;c.gridy=2;
  gridbag.setConstraints(warnview, c);
  keypad.add(warnview);
  
  c.gridx=0;c.gridy=3;
  gridbag.setConstraints(infield, c);
  keypad.add(infield);

  //Row 1
  c.gridheight = 1; c.gridwidth=1;
  c.gridy = 4;
  c.gridx=0;makebutton("7", gridbag, c);
  c.gridx=1;makebutton("8", gridbag, c);
  c.gridx=2;makebutton("9", gridbag, c);
  c.gridx=3;makebutton("+", gridbag, c);
  c.gridx=4;makebutton("(", gridbag, c);
  c.gridx=5;makebutton(")", gridbag, c);
  c.gridx=6;c.gridwidth=2;
  makebutton("Backspace", gridbag, c);

  //Row 2
  c.gridheight = 1; c.gridwidth=1;
  c.gridy = 5;
  c.gridx=0;makebutton("4", gridbag, c);
  c.gridx=1;makebutton("5", gridbag, c);
  c.gridx=2;makebutton("6", gridbag, c);
  c.gridx=3;makebutton("-", gridbag, c);
  c.gridx=4;makebutton("^", gridbag, c);
  c.gridx=5;makebutton("%", gridbag, c);
  c.gridx=6;makebutton(";", gridbag, c);
  c.gridx=7;makebutton("Clear", gridbag, c);  
  
  //Row 3
  c.gridwidth = 1; c.gridheight = 1;
  c.gridy=6;
  c.gridx=0;makebutton("1", gridbag, c);
  c.gridx=1;makebutton("2", gridbag, c);
  c.gridx=2;makebutton("3", gridbag, c);
  c.gridx=3;makebutton("*", gridbag, c);
  c.gridx=4;makebutton("&", gridbag, c);
  c.gridx=5;makebutton("|", gridbag, c);
  c.gridx=6;makebutton("!", gridbag, c);  
  c.gridheight = 2;c.gridx=7;
  makebutton("OK", gridbag, c);
  
  //Row 4
  c.gridwidth = 1; c.gridheight = 1;
  c.gridy=7;c.gridwidth=2;
  c.gridx=0;makebutton("0", gridbag, c);
  c.gridwidth=1;
  c.gridx=2;makebutton(".", gridbag, c);
  c.gridx=3;makebutton("/", gridbag, c);
  c.gridx=4;makebutton("<", gridbag, c);
  c.gridx=5;makebutton(">", gridbag, c);
  c.gridx=6;makebutton("=", gridbag, c);
 }


/**
* add a new button. This method is used for making the keypad.
*/
 void makebutton(String name, GridBagLayout gridbag,GridBagConstraints c)
 {Button button = new Button(name);
  gridbag.setConstraints(button, c);
  keypad.add(button);
  button.addActionListener(this);
 }

}