import java.applet.*;
import java.awt.*;
import java.io.*;
import java.lang.*;
import java.net.*;

public class SpreadSheet extends Applet {
    String		title;
    Font		titleFont;
    Color		cellColor;
    Color		inputColor;
    int			cellWidth = 100;
    int			cellHeight = 15;
    int			titleHeight = 15;
    int			rowLabelWidth = 15;
    Font		inputFont;
    boolean		isStopped = false;
    boolean		fullUpdate = true;
    int			rows;
    int			columns;
    int			currentKey = -1;
    int			selectedRow = -1;
    int			selectedColumn = -1;
    SpreadSheetInput	inputArea;
    Cell		cells[][];
    Cell		current = null;
    Frame	        window = new Frame("Functions Window");
    Frame		winhelp = new Frame("Help Window");
    boolean		done = true;

    Node		tempNode;
    Cell		tempCell;

    Panel		top_button_bar;
    Button		cut = new Button("CUT");
    Button		paste = new Button("PASTE");
    Button		clearcell = new Button("CLEAR CELL");
    Button		clearall = new Button("CLEAR ALL");

    Panel		bottom_button_bar;
    Button		help = new Button("SHOW HELP");
    Button		nohelp = new Button("CLOSE HELP");
    Button		quit = new Button("QUIT WINDOW");
    TextArea		ta = new TextArea("INSTRUCTIONS:\n \nUse the mouse to select the cell in which you want to enter data.\nTHE MOUSE POINTER MUST BE IN THE SPREADSHEET DURING EDITING.\nThe default data type is a VALUE, denoted by a 'v' at the start of the cell.\nFor a FORMULA, use 'f'.\nFor a LABEL, use 'l'.\nAll cells must be in the form of [column][row], where the column is a\ncapital letter and the row is a number.\n \nOPERATORS\nThe operators used are as follows:\n'+'   Addition\n'-'   Subtraction\n'*'   Multiplication\n'/'   Division\n'$'   Summation (WIP)\n'^'   Average (WIP)\n \nFUNCTION BUTTONS\n'CUT'                   Cut the contents of the current cell.\n'PASTE'                Paste the buffer to the current cell.\n'CLEAR CELL'        Erase the current cell.\n'CLEAR ALL'          Reset the Spreadsheet.\n'SHOW HELP'        Show this window.\n'CLOSE HELP'       Close this window.\n'QUIT WINDOW'   Warning:  Closes the function window!\n");

   


public synchronized void init() {
	String rs;

	setLayout(new BorderLayout());
	
	
	cellColor = Color.white;
	inputColor = new Color(100, 100, 225);
	inputFont = new Font("Courier", Font.PLAIN, 10);
	titleFont = new Font("Courier", Font.BOLD, 12);
	title = getParameter("title");
	if (title == null) {
	    title = "Spreadsheet";
	}
	rs = getParameter("rows");
	if (rs == null) {
	    rows = 9;
	} else {
	    rows = Integer.parseInt(rs);
	}
	rs = getParameter("columns");
	if (rs == null) {
	    columns = 5;
	} else {
	    columns = Integer.parseInt(rs);
	}
	cells = new Cell[rows][columns];
	char l[] = new char[1];
	for (int i=0; i < rows; i++) {
	    for (int j=0; j < columns; j++) {

		cells[i][j] = new Cell(this,
				       Color.lightGray,
				       Color.black,
				       cellColor,
				       cellWidth - 2,
				       cellHeight - 2);
		l[0] = (char)((int)'a' + j);
		rs = getParameter("" + new String(l) + (i+1));
		if (rs != null) {
		    cells[i][j].setUnparsedValue(rs);
		}
	    }
	}

	Dimension d = size();
	inputArea = new SpreadSheetInput(null, this, d.width-2, cellHeight-1,
					 inputColor, Color.white); 
	resize(columns * cellWidth + rowLabelWidth,
	       ((rows + 1) * cellHeight) + cellHeight + titleHeight);

	    this.add(window);

            Panel bottom_button_bar = new Panel();
	    Panel top_button_bar = new Panel();

       	    top_button_bar.setLayout(new FlowLayout());
	    top_button_bar.add(cut);
	    top_button_bar.add(paste);
	    top_button_bar.add(clearcell);
	    top_button_bar.add(clearall);
	    window.add("North", top_button_bar);
	     
	    bottom_button_bar.setLayout(new FlowLayout());
	    bottom_button_bar.add(help);
	    bottom_button_bar.add(nohelp);
	    bottom_button_bar.add(quit);
	    window.add("South", bottom_button_bar);
  	    window.resize(400,150);
	    
	    window.show();
	    winhelp.resize(500,215);
	    winhelp.add("North",ta);
            ta.setEditable(false);


    }  //  end init



      public boolean action(Event evt, Object arg){
	if (evt.target instanceof Button)
	{
	    String label = (String)evt.arg;
	    if (label.equals("CLEAR CELL")){
		current.setValue(0);
	    }
 	    if (label.equals("CLEAR ALL")){
 		this.init();
                repaint();
	    }
 	    if (label.equals("QUIT WINDOW")){
		window.hide();
	    }
	    if (label.equals("SHOW HELP")){
		winhelp.show();
	    }
            if (label.equals("CLOSE HELP")){
	        winhelp.hide();
	    }
	    if (label.equals("CUT")){
		tempCell = current;
		current.setValue(0);
		repaint();
	    }
	    if (label.equals("PASTE")){
		current.setValue(tempCell.value);
		current.parseRoot = null;
		current.parseRoot = tempNode;
		repaint();
	    }
	}
        return true;
     }  //  end action
	  

    public void setCurrentValue(float val) {
	if (selectedRow == -1 || selectedColumn == -1) {
	    return;
	}
	cells[selectedRow][selectedColumn].setValue(val);
	repaint();
    }  //  end setCurrentValue


    public void stop() {
	isStopped = true;
        window.hide();
        winhelp.hide();
    }  //  end stop


    public void start() {
	isStopped = false;
    }  //  end start


    public void destroy() {
	for (int i=0; i < rows; i++) {
	    for (int j=0; j < columns; j++) {
		if (cells[i][j].type == Cell.URL) {
		    cells[i][j].updaterThread.stop();
		}
	    }
	}
    }  //end destroy


    public void setCurrentValue(int type, String val) {
	if (selectedRow == -1 || selectedColumn == -1) {
	    return;
	}
	cells[selectedRow][selectedColumn].setValue(type, val);
	repaint();
    }  //  end setCurrentValue


    public void update(Graphics g) {
	if (! fullUpdate) {
	    int cx, cy;

	    g.setFont(titleFont);
	    for (int i=0; i < rows; i++) {
		for (int j=0; j < columns; j++) {
		    if (cells[i][j].needRedisplay) {
			cx = (j * cellWidth) + 2 + rowLabelWidth;
			cy = ((i+1) * cellHeight) + 2 + titleHeight;
			cells[i][j].paint(g, cx, cy);
		    }
		}
	    }
	} else {
	    paint(g);
	    fullUpdate = false;
	}
    }  //  end update

    public void recalculate() {
	int	i,j;

	for (i=0; i < rows; i++) {
	    for (j=0; j < columns; j++) {
		if (cells[i][j] != null && cells[i][j].type == Cell.FORMULA) {
		    cells[i][j].setRawValue(evaluateFormula(cells[i][j].parseRoot));
		    cells[i][j].needRedisplay = true;
		}
	    }
	}
	repaint();
    }  //  recalculate

    public float evaluateFormula(Node n) {
	float	val = 0.0f;
	int i;
	Node endNode;
	float beg;
	float end;
	int begrow;
	int endrow;
	int temp;

	//n.print(3);
	if (n == null) {
	    return val;
	}
	switch (n.type) {
	  case Node.OP:
	    val = evaluateFormula(n.left);
	    switch (n.op) {
	      case '+':
		val += evaluateFormula(n.right);
		break;
	      case '*':
		val *= evaluateFormula(n.right);
		break;
	      case '-':
		val -= evaluateFormula(n.right);
		break;
	      case '/':
		val /= evaluateFormula(n.right);
		break;
	      //  case '$' WIP
	      case '$':
		beg = n.left.value;
		end = evaluateFormula(n.right);
		begrow = n.left.row;
		endrow = n.right.row;
		for (i=begrow; i<=endrow;)
		  val += n.value;
		break;
	      //  case '^' WIP
	      case '^':
		beg = n.left.value;
		end = evaluateFormula(n.right);
		begrow = n.left.row;
		endrow = n.right.row;
		for (i=begrow; i<=endrow;)
		  val += n.value;
		int count = endrow - begrow;
		val /= count;
	    }
	    break;
	  case Node.VALUE:
	    return n.value;
	  case Node.CELL:
	    if (n == null) {
	    } else {
		if (cells[n.row][n.column] == null) {
		} else {
		    return cells[n.row][n.column].value;
		}
	    }
	}

	return val;
    }  //  end evaluateFormula


    public synchronized void paint(Graphics g) {
	int i, j;
	int cx, cy;
	char l[] = new char[1];


	Dimension d = size();
	g.setFont(titleFont);
	i = g.getFontMetrics().stringWidth(title);
	g.drawString((title == null) ? "Spreadsheet" : title,
		     (d.width - i) / 2, 12);
	g.setColor(inputColor);
	g.fillRect(0, cellHeight, d.width, cellHeight);
	g.setFont(titleFont);
	for (i=0; i < rows+1; i++) {
	    cy = (i+2) * cellHeight;
	    g.setColor(getBackground());
	    g.draw3DRect(0, cy, d.width, 2, true);
	    if (i < rows) {
		g.setColor(Color.red);
		g.drawString("" + (i+1), 2, cy + 12);
	    }
	}
	g.setColor(Color.red);
	for (i=0; i < columns; i++) {
	    cx = i * cellWidth;
	    g.setColor(getBackground());
	    g.draw3DRect(cx + rowLabelWidth,
			  2 * cellHeight, 1, d.height, true);
	    if (i < columns) {
		g.setColor(Color.red);
		l[0] = (char)((int)'A' + i);
		g.drawString(new String(l),
			     cx + rowLabelWidth + (cellWidth / 2),
			     d.height - 3);
	    }
	}

	
	for (i=0; i < rows; i++) {
	    for (j=0; j < columns; j++) {
		cx = (j * cellWidth) + 2 + rowLabelWidth;
		cy = ((i+1) * cellHeight) + 2 + titleHeight;
		if (cells[i][j] != null) {
		    cells[i][j].paint(g, cx, cy);
		}
	    }
	}

	g.setColor(getBackground());
	g.draw3DRect(0, titleHeight,
		      d.width,
		      d.height - titleHeight,
		      false);
	inputArea.paint(g, 1, titleHeight + 1);
    }  //  end paint


    public boolean mouseDown(Event evt, int x, int y) {
	Cell cell;
	if (y < (titleHeight + cellHeight)) {
	    selectedRow = -1;
	    if (y <= titleHeight && current != null) {
		current.deselect();
		current = null;
	    }
	    return true;
	}
	if (x < rowLabelWidth) {
	    selectedRow = -1;
	    if (current != null) {
		current.deselect();
		current = null;
	    }
	    return true;
	}
	selectedRow = ((y - cellHeight - titleHeight) / cellHeight);
	selectedColumn = (x - rowLabelWidth) / cellWidth;
	if (selectedRow > rows ||
	    selectedColumn >= columns) {
	    selectedRow = -1;
	    if (current != null) {
		current.deselect();
		current = null;
	    }
	} else {
	    if (selectedRow >= rows) {
		selectedRow = -1;
		if (current != null) {
		    current.deselect();
		    current = null;
		}
		return true;
	    }
	    cell = cells[selectedRow][selectedColumn];
	    inputArea.setText(new String(cell.getPrintString()));
	    if (current != null) {
		current.deselect();
	    }
	    current = cell;
	    current.select();
	    requestFocus();
	    fullUpdate = true;
	    repaint();
	}
	return true;
    }  //  end mouseDown


    public boolean keyDown(Event evt, int key) {
	fullUpdate=true;
	inputArea.keyDown(key);
	return true;
    }  //  end keyDown


}  //  end class SpreadSheet




class CellUpdater extends Thread {
    Cell 	target;
    InputStream dataStream = null;
    StreamTokenizer tokenStream;

    public CellUpdater(Cell c) {
	super("cell updater");
	target = c;
    }  //  end CellUpdater


    public void run() {
	try {
	    dataStream = new URL(target.app.getDocumentBase(),
				 target.getValueString()).openStream();
	    tokenStream = new StreamTokenizer(dataStream);
	    tokenStream.eolIsSignificant(false);

	    while (true) {
		switch (tokenStream.nextToken()) {
		case tokenStream.TT_EOF:
		    dataStream.close();
		    return;
		default:
		    break;
		case tokenStream.TT_NUMBER:
		    target.setTransientValue((float)tokenStream.nval);
		    if (! target.app.isStopped && ! target.paused) {
			target.app.repaint();
		    }
		    break;
		}
		try {
		    Thread.sleep(2000);
		} catch (InterruptedException e) {
		    break;
		}
	    }
	} catch (IOException e) {
	    return;
	}
    }
}  //  end class CellUpdater




class Cell {
    public static final int VALUE = 0;
    public static final int LABEL = 1;
    public static final int URL   = 2;
    public static final int FORMULA = 3;
    
    Node	parseRoot;
    boolean	needRedisplay;
    boolean selected = false;
    boolean transientValue = false;
    public int	type = Cell.VALUE;
    String	valueString = "";
    String	printString = "v";
    float	value;
    Color	bgColor;
    Color	fgColor;
    Color	highlightColor;
    int		width;
    int		height;
    SpreadSheet app;
    CellUpdater	updaterThread;
    boolean	paused = false;

    public Cell(SpreadSheet app,
		Color bgColor,
		Color fgColor,
		Color highlightColor,
		int width,
		int height) {
	this.app = app;
	this.bgColor = bgColor;
	this.fgColor = fgColor;
	this.highlightColor = highlightColor;
	this.width = width;
	this.height = height;
	needRedisplay = true;
    }  //  end Cell

		
    public void setRawValue(float f) {
	valueString = Float.toString(f);
	value = f;
    }  //  end setRawValue


    public void setValue(float f) {
	setRawValue(f);
	printString = "v" + valueString;
	type = Cell.VALUE;
	paused = false;
	app.recalculate();
	needRedisplay = true;
    }  //  end set Value


    public void setTransientValue(float f) {
	transientValue = true;
	value = f;
	needRedisplay = true;
	app.recalculate();
    }  //  end setTransientValue


    public void setUnparsedValue(String s) {
	switch (s.charAt(0)) {
	  case 'v':
	    setValue(Cell.VALUE, s.substring(1));
	    break;
	  case 'f':
	    setValue(Cell.FORMULA, s.substring(1));
	    break;
	  case 'l':
	    setValue(Cell.LABEL, s.substring(1));
	    break;
	  case 'u':
	    setValue(Cell.URL, s.substring(1));
	    break;
	}
    }  //  end setUnparsedValue



    /**
     * Parse a spreadsheet formula. The syntax is defined as:
     *
     * formula -> value
     * formula -> value op value
     * value -> '(' formula ')'
     * value -> cell
     * value -> <number>
     * op -> '+' | '*' | '/' | '-'
     * cell -> <letter><number>
     */
    public String parseFormula(String formula, Node node) {
	String subformula;
	String restFormula;
	float value;
	int length = formula.length();
	Node left;
	Node right;
	char op;

	if (formula == null) {
	    return null;
	}
	subformula = parseValue(formula, node);
	if (subformula == null || subformula.length() == 0) {
	    return null;
	}
	if (subformula == formula) {
	    return formula;
	}

	// parse an operator and then another value
	switch (op = subformula.charAt(0)) {
	  case 0:
	    return null;
	  case ')':
	    return subformula;
	  case '+':
	  case '*':
	  case '-':
	  case '/':
	    restFormula = subformula.substring(1);
	    subformula = parseValue(restFormula, right=new Node());
	    if (subformula != restFormula) {
		left = new Node(node);
		node.left = left;
		node.right = right;
		node.op = op;
		node.type = Node.OP;
		return subformula;
	    } else {
		return formula;
	    }
	  default:
	    return formula;
	}
    }  //  end parseFormula


    public String parseValue(String formula, Node node) {
	char	c = formula.charAt(0);
	String	subformula;
	String	restFormula;
	float	value;
	int	row;
	int	column;

	restFormula = formula;
	if (c == '(') {
	    restFormula = formula.substring(1);
	    subformula = parseFormula(restFormula, node);
	    if (subformula == null ||
		subformula.length() == restFormula.length()) {
		return formula;
	    } else if (! (subformula.charAt(0) == ')')) {
		return formula;
	    }
	    restFormula = subformula;
	} else if (c >= '0' && c <= '9') {
	    int i;

	    try {
		value = Float.valueOf(formula).floatValue();
	    } catch (NumberFormatException e) {
		return formula;
	    }
	    for (i=0; i < formula.length(); i++) {
		c = formula.charAt(i);
		if ((c < '0' || c > '9') && c != '.') {
		    break;
		}
	    }
	    node.type = Node.VALUE;
	    node.value = value;
	    restFormula = formula.substring(i);
	    return restFormula;
	} else if (c >= 'A' && c <= 'Z') {
	    int i;

	    column = c - 'A';
	    restFormula = formula.substring(1);
	    row = Float.valueOf(restFormula).intValue();
	    for (i=0; i < restFormula.length(); i++) {
		c = restFormula.charAt(i);
		if (c < '0' || c > '9') {
		    break;
		}
	    }
	    node.row = row - 1;
	    node.column = column;
	    node.type = Node.CELL;
	    if (i == restFormula.length()) {
		restFormula = null;
	    } else {
		restFormula = restFormula.substring(i);
		if (restFormula.charAt(0) == 0) {
		    return null;
		}
	    }	    
	}

	return restFormula;
    }  //  end parseValue


    public void setValue(int type, String s) {
	paused = false;
	if (this.type == Cell.URL) {
	    updaterThread.stop();
	    updaterThread = null;
	}

	valueString = new String(s);
	this.type = type;
	needRedisplay = true;
	switch (type) {
	  case Cell.VALUE:
	    setValue(Float.valueOf(s).floatValue());
	    break;
	  case Cell.LABEL:
	    printString = "l" + valueString;
	    break;
	  case Cell.URL:
	    printString = "u" + valueString;
	    updaterThread = new CellUpdater(this);
	    updaterThread.start();
	    break;
	  case Cell.FORMULA:
	    parseFormula(valueString, parseRoot = new Node());
	    printString = "f" + valueString;
	    break;
	}
	app.recalculate();
    }  //  end setValue


    public String getValueString() {
	return valueString;
    }  //  end getValueString


    public String getPrintString() {
	return printString;
    }  //  end getPrintString


    public void select() {
	selected = true;
	paused = true;
    }  //  end select


    public void deselect() {
	selected = false;
	paused = false;
	needRedisplay = true;
	app.repaint();
    }  //  end deselect


    public void paint(Graphics g, int x, int y) {
	if (selected) {
	    g.setColor(highlightColor);
	} else {
	    g.setColor(bgColor);
	}
	g.fillRect(x, y, width - 1, height);
	if (valueString != null) {
	    switch (type) {
	      case Cell.VALUE:
	      case Cell.LABEL:
		g.setColor(fgColor);
		break;
	      case Cell.FORMULA:
		g.setColor(Color.red);
		break;
	      case Cell.URL:
		g.setColor(Color.blue);
		break;
	    }
	    if (transientValue){
		g.drawString("" + value, x, y + (height / 2) + 5);
	    } else {
		if (valueString.length() > 14) {
		    g.drawString(valueString.substring(0, 14),
				 x, y + (height / 2) + 5);
		} else {
		    g.drawString(valueString, x, y + (height / 2) + 5);
		}
	    }
	}
	needRedisplay = false;
    }  //  end paint
}  //  end class Cell




class Node {
    public static final int OP = 0;
    public static final	int VALUE = 1;
    public static final int CELL = 2;

    int		type;
    Node 	left;
    Node 	right;
    int  	row;
    int  	column;
    float	value;
    char	op;

    public Node() {
	left = null;
	right = null;
	value = 0;
	row = -1;
	column = -1;
	op = 0;
	type = Node.VALUE;
    }  //  Node


    public Node(Node n) {
	left = n.left;
	right = n.right;
	value = n.value;
	row = n.row;
	column = n.column;
	op = n.op;
	type = n.type;
    }  //  end Node


    public void indent(int ind) {
	for (int i = 0; i < ind; i++) {
	    System.out.print(" ");
	}
    }  //  end indent


    public void print(int indentLevel) {
	char l[] = new char[1];
	indent(indentLevel);
	System.out.println("NODE type=" + type);
	indent(indentLevel);
	switch (type) {
	  case Node.VALUE:
	    System.out.println(" value=" + value);
	    break;
	  case Node.CELL:
	    l[0] = (char)((int)'A' + column);
	    System.out.println(" cell=" + new String(l) + (row+1));
	    break;
	  case Node.OP:
	    System.out.println(" op=" + op);
	    left.print(indentLevel + 3);
	    right.print(indentLevel + 3);
	    break;
	}
    }  //  end print


}  //  end class Node




class InputField {
    int		maxchars = 50;
    int		cursorPos = 0;
    Applet	app;
    String	sval;
    char	buffer[];
    int		nChars;
    int		width;
    int		height;
    Color	bgColor;
    Color	fgColor;

    public InputField(String initValue, Applet app, int width, int height,
		      Color bgColor, Color fgColor) {
	this.width = width;
	this.height = height;
	this.bgColor = bgColor;
	this.fgColor = fgColor;
	this.app = app;
	buffer = new char[maxchars];
	nChars = 0;
	if (initValue != null) {
	    initValue.getChars(0, initValue.length(), this.buffer, 0);
	    nChars = initValue.length();
	}
	sval = initValue;
    }  //  end InputField

    public void setText(String val) {
	int i;

	for (i=0; i < maxchars; i++) {
	    buffer[i] = 0;
	}
	sval = new String(val);
	if (val == null) {
	    sval = "";
	    nChars = 0;
	    buffer[0] = 0;
	} else {
	    sval.getChars(0, sval.length(), buffer, 0);
	    nChars = val.length();
	    sval = new String(buffer);
	}
    }  //  end setText


    public String getValue() {
	return sval;
    }  //  end getValue


    public void paint(Graphics g, int x, int y) {
	g.setColor(bgColor);
	g.fillRect(x, y, width, height);
	if (sval != null) {
	    g.setColor(fgColor);
	    g.drawString(sval, x, y + (height / 2) + 3);
	}
    }  //  end paint


    public void mouseUp(int x, int y) {
	// set the edit position
    }  //  end mouseUp


    public void keyDown(int key) {
	if (nChars < maxchars) {
	    switch (key) {
	      case 8: // delete
		--nChars;
		if (nChars < 0) {
		    nChars = 0;
		}
		buffer[nChars] = 0;
		sval = new String(new String(buffer));
		break;
	      case 10: // return
		selected();
		break;
	      default:
		buffer[nChars++] = (char)key;
		sval = new String(new String(buffer));
		break;
	    }
	}
	app.repaint();
    }  //  end  keyDown

 
    public void selected() {
    }  //  end selected
}  //  end class InputField



class SpreadSheetInput extends InputField {
    public SpreadSheetInput(String initValue,
			    SpreadSheet app,
			    int width,
			    int height,
			    Color bgColor,
			    Color fgColor) {
	super(initValue, app, width, height, bgColor, fgColor);
    }  //  end SpreadSheetInput


    public void selected() {
	float f;

	switch (sval.charAt(0)) {
	  case 'v':
	    try {
		f = Float.valueOf(sval.substring(1)).floatValue();
		((SpreadSheet)app).setCurrentValue(f);
	    } catch (NumberFormatException e) {
		System.out.println("Not a float...");
	    }
	    break;
	  case 'l':
	    ((SpreadSheet)app).setCurrentValue(Cell.LABEL, sval.substring(1));
	    break;
	  case 'u':
	    ((SpreadSheet)app).setCurrentValue(Cell.URL, sval.substring(1));
	    break;
	  case 'f':
	    ((SpreadSheet)app).setCurrentValue(Cell.FORMULA, sval.substring(1));
	    break;
	}
    }  //  end selected
}  //  end class SpreadSheetInput