import java.awt.*;

// A square of the game Checkers
public class CheckersSquare extends Canvas {
static public final int EMPTY= 0; 	// Constants used to indicate
static public final int RED= 1; 	// what is on a square.
static public final int BLACK= 2; 	// Meaning: obvious
static public final int REDKING= 3;
static public final int BLACKKING= 4;

// Colors used for the background of red and black squares.
// Red (black) are not used because they are used for the pieces.
static public Color REDSQUARE= Color.pink;
static public Color BLACKSQUARE= Color.gray;

private Rectangle b; 		// Containing rectangle of this square
public int col;			// column number of this square on board
public int row;			// row number of this square on board

// EMPTY: square is empty;
// RED (or REDKING) means red piece (red king) is on square;
// BLACK (or BLACKKING) means black piece (black king) is on square.
private int fill= EMPTY;

// = "This square contains the piece to be moved"
private boolean toBeMoved= false;
				
// Constructor: An initially empty square that belongs in
// column c, row r of the board
public CheckersSquare(int c, int r) {
	super();
	col= c;
	row= r;
	if ((c+r)%2 == 1)
	    setBackground(BLACKSQUARE);
	else
	    setBackground(REDSQUARE);
	resize(42,42);
	b= bounds();
	repaint();
	}

// Paint the square (with its piece, if any), using Graphics g
public void paint (Graphics g) {
	// A checker is drawn as two circles. The first one is offset and
	// smaller, so that when the second is drawn, it covers most of the
	// first except for what appears as a side of the piece.
	// A King has a yellow "K" on it.
	// If toBeMoved is true, highlight this piece by making it
	// a radius of ew=eh=5 bigger than the others
	// 
	int ew= 0;
	int eh= 0;
	if (toBeMoved) {
		ew= 5;
		eh= 5;
		}
	
	if (fill == EMPTY)
		{return;}
	
	Color save= g.getColor(); // Save the color, to be reset at end
	
	// Draw an oval that will provide the "side" of a piece
		if (containsRed()) 	g.setColor(Color.magenta.darker());
		else 				g.setColor(Color.darkGray.brighter());
		g.fillOval(b.x+b.width/4-ew, b.y+b.width/4-ew,
		           b.width/2+ew+ew, b.height/2+ew+ew);
	
	// Draw an oval that provides the "top" of the piece
		if (containsRed()) 	g.setColor(Color.red);
		else 				g.setColor(Color.black);
		g.fillOval(b.x+b.width/5-ew, b.y+b.width/5-ew,
		           b.width/2+ew+ew, b.height/2+ew+ew);
	
	// If the piece is a king, put a yellow K on it
		if (fill==REDKING || fill==BLACKKING) {
			g.setColor(Color.yellow);
			g.drawLine(b.x+3*b.width/8, b.y+b.height/3,
					   b.x+3*b.width/8, b.y+b.height/2);
					   
			g.drawLine(b.x+3*b.width/8 + b.width/10, b.y+b.height/3,
					   b.x+3*b.width/8, b.y+5*b.height/12);
					   
			g.drawLine(b.x+3*b.width/8, b.y+5*b.height/12,
					   b.x+3*b.width/8+b.width/10, b.y+b.height/2);
			}
	g.setColor(save);
	}
	
// Set field toBeMoved to b
public void setToBeMoved(boolean b) {
	toBeMoved= b;
	repaint();
	}
	
// Yield the contents of the square --EMPTY, RED, REDKING,
// BLACK, or BLACKKING
public int contents() {
	return fill;
	}
	
// Return "The square contains a king"
public boolean isKing() {
	return fill==REDKING || fill==BLACKKING;
	}

// Place piece p (RED, REDKING, BLACK, or BLACKKING) in
// this square (no action if square already filled)
public void placePiece(int p) {
	if (fill != EMPTY) return;
	fill= p;
	repaint();
	return;
	}
	
// return "This square is red"
public boolean isRed() {
	return (col+row) % 2 == 0;
	}
	    
// Pick up the piece (no action if square is empty)
public void pickUpPiece() {
	if (fill == EMPTY) return;
	fill= EMPTY;
	repaint();
	return;
	}
	
// return "piece on square is red"
public boolean containsRed() {
	return (fill==RED) || (fill==REDKING);
	}
	
// return "piece on square is black"
public boolean containsBlack() {
	return fill==BLACK || fill == BLACKKING;
	}
	
// return "square contains piece that is same color as x
// (which is one of RED, REDKING, BLACK, BLACKKING)"
public boolean isSameColor(int x) {
	if (fill == EMPTY) return false;
	if ((x == RED || x == REDKING) && containsRed()) return true;
	return ((x == BLACK || x == BLACKKING) && containsBlack());
	}
	
// return description of the square
public String toString() {
	String s= "Square(" + col + "," + row + "):";
	if (fill== EMPTY) s= s + "empty";
	if (fill== RED) s= s + "red";
	if (fill== BLACK) s= s + "black";
	if (fill== REDKING) s= s + "red king";
	if (fill== BLACKKING) s= s + "black king";
	return s;
	}
}