import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.net.*;
import java.applet.*;
import java.lang.Math;

public class chess extends Applet implements MouseListener
{
    Image   imagePieces[];
    
    static final int Black = 0;
    static final int White = 1;

    static final int Empty = -1;
    static final int PawnB = 0;
    static final int RookeB = 1;
    static final int KnightB = 2;
    static final int BishopB = 3;
    static final int QueenB = 4;
    static final int KingB = 5;
    static final int PawnW = 6;
    static final int RookeW = 7;
    static final int KnightW = 8;
    static final int BishopW = 9;
    static final int QueenW = 10;
    static final int KingW = 11;

    int anBoard[][];

    int nActivePiece[] = { -1, -1 };

    int nPlayer = White;

    public void init()
    {
	imagePieces = new Image[12];
	imagePieces[ PawnB ] = getImage( getCodeBase(), "images/pawnb.gif" );
	imagePieces[ RookeB ] = getImage( getCodeBase(), "images/rookeb.gif" );
	imagePieces[ KnightB ] = getImage( getCodeBase(), "images/knightb.gif" );
	imagePieces[ BishopB ] = getImage( getCodeBase(), "images/bishopb.gif" );
	imagePieces[ QueenB ] = getImage( getCodeBase(), "images/queenb.gif" );
	imagePieces[ KingB ] = getImage( getCodeBase(), "images/kingb.gif" );
	imagePieces[ PawnW ] = getImage( getCodeBase(), "images/pawnw.gif" );
	imagePieces[ RookeW ] = getImage( getCodeBase(), "images/rookew.gif" );
	imagePieces[ KnightW ] = getImage( getCodeBase(), "images/knightw.gif" );
	imagePieces[ BishopW ] = getImage( getCodeBase(), "images/bishopw.gif" );
	imagePieces[ QueenW ] = getImage( getCodeBase(), "images/queenw.gif" );
	imagePieces[ KingW ] = getImage( getCodeBase(), "images/kingw.gif" );

	// Clear the board
	anBoard = new int[8][8];

	for ( int i = 0; i < 8; ++i )
	    for ( int j = 0; j < 8; ++j )
		anBoard[i][j] = Empty;

	anBoard[0][0] = RookeB;
	anBoard[0][1] = KnightB;
	anBoard[0][2] = BishopB;
	anBoard[0][3] = QueenB;
	anBoard[0][4] = KingB;
	anBoard[0][5] = BishopB;
	anBoard[0][6] = KnightB;
	anBoard[0][7] = RookeB;
	anBoard[1][0] = PawnB;
	anBoard[1][1] = PawnB;
	anBoard[1][2] = PawnB;
	anBoard[1][3] = PawnB;
	anBoard[1][4] = PawnB;
	anBoard[1][5] = PawnB;
	anBoard[1][6] = PawnB;
	anBoard[1][7] = PawnB;

	anBoard[7][0] = RookeW;
	anBoard[7][1] = KnightW;
	anBoard[7][2] = BishopW;
	anBoard[7][3] = QueenW;
	anBoard[7][4] = KingW;
	anBoard[7][5] = BishopW;
	anBoard[7][6] = KnightW;
	anBoard[7][7] = RookeW;
	anBoard[6][0] = PawnW;
	anBoard[6][1] = PawnW;
	anBoard[6][2] = PawnW;
	anBoard[6][3] = PawnW;
	anBoard[6][4] = PawnW;
	anBoard[6][5] = PawnW;
	anBoard[6][6] = PawnW;
	anBoard[6][7] = PawnW;

	addMouseListener( this );
    }

    public void destroy()
    {
	removeMouseListener( this );
    }

    public void paint( Graphics g )
    {
	Dimension d = getSize();

	Image offScrImage = createImage( d.width, d.height );
	Graphics og = offScrImage.getGraphics();

	int xoff = d.width / 8;
	int yoff = d.height / 8;
	
	/* Draw grid of black/white squares, oriented according
	   to whether this player is white or black. */
	
	for ( int c = 0; c < 8; ++c ) {
	    for ( int r = 0; r < 8; ++r ) {
		if ( (c + r) % 2 == 0 ) {
		    og.setColor( Color.black );
		} else {
		    og.setColor( Color.white );
		}
		og.fillRect( xoff * c, yoff * r, xoff, yoff );

		/* Draw each image according to map */
	
		int nPiece = anBoard[ r ][ c ];
		if ( nPiece >= 0 ) {
		    og.drawImage( imagePieces[ nPiece ],
				 c * xoff,
				 r * yoff,
				 this );
		}
	    }
	}

	/* Draw rect around active piece */
	if ( nActivePiece[0] >= 0 ) {
	    if ( nPlayer == White )
		og.setColor( Color.red );
	    else
		og.setColor( Color.blue );

	    og.drawRect( xoff * nActivePiece[0],
			yoff * nActivePiece[1],
			xoff, yoff );
	    og.drawRect( xoff * nActivePiece[0] - 1,
			yoff * nActivePiece[1] - 1,
			xoff + 2, yoff + 2 );
	}

	g.drawImage( offScrImage, 0, 0, this );
    }

    boolean checkMoveLat( int c1, int r1, int c2, int r2 ) {
	boolean bOK = false;
	int nPiece = anBoard[ r1 ][ c1 ];
	int nPType = nPiece % 6;
	int nDestPiece = anBoard[ r2 ][ c2 ];
	int nDestPType = nDestPiece % 6;

	if ( c1 == c2 && r1 != r2 ) {
	    int rd;
	    if ( r1 < r2 )
		rd = 1;
	    else
		rd = -1;
		
	    bOK = true;
	    for ( int r = r1 + rd; r != r2; r += rd ) {
		if ( anBoard[ r ][ c1 ] != -1 ) {
		    bOK = false;
		    break;
		}
	    }
	}
	else if ( r1 == r2 && c1 != c2 ) {
	    int cd;
	    if ( c1 < c2 )
		cd = 1;
	    else
		cd = -1;
		
	    bOK = true;
	    for ( int c = c1 + cd; c != c2; c += cd ) {
		if ( anBoard[ r1 ][ c ] != -1 ) {
		    bOK = false;
		    break;
		}
	    }
	}

	return bOK;
    }

    boolean checkMoveDiag( int c1, int r1, int c2, int r2 ) {
	boolean bOK = false;
	int nPiece = anBoard[ r1 ][ c1 ];
	int nPType = nPiece % 6;
	int nDestPiece = anBoard[ r2 ][ c2 ];
	int nDestPType = nDestPiece % 6;

	if ( (c1 + r1) % 2 == 0 && (c2 + r2) % 2 == 0 ) {
	    if ( c1 + r1 == c2 + r2 ) {
		bOK = true;
	    }
	    else if ( c1 - r1 == c2 - r2 ) {
		bOK = true;
	    }
	}
	else if ( (c1 + r1) % 2 == 1 && (c2 + r2) % 2 == 1 ) {
	    if ( c1 + r1 == c2 + r2 ) {
		bOK = true;
	    }
	    else if ( c1 - r1 == c2 - r2 ) {
		bOK = true;
	    }
	}
	if ( bOK ) {
	    int cd;
	    if ( c1 < c2 )
		cd = 1;
	    else
		cd = -1;
	    int rd;
	    if ( r1 < r2 )
		rd = 1;
	    else
		rd = -1;

	    int r = r1 + rd;
	    int c = c1 + cd;
	    for ( ; c != c2; r += rd, c += cd ) {
		if ( anBoard[ r ][ c ] != -1 ) {
		    bOK = false;
		    break;
		}
	    }
	}

	return bOK;
    }

    boolean checkMove( int c1, int r1, int c2, int r2 ) {
	if ( c1 == c2 && r1 == r2 )
	    return false;

	boolean bOK = false;
	int nPiece = anBoard[ r1 ][ c1 ];
	int nPType = nPiece % 6;
	int nDestPiece = anBoard[ r2 ][ c2 ];
	int nDestPType = nDestPiece % 6;

	switch ( nPType ) {
	case PawnB:
	    if ( nPiece < 6 ) {
		if ( c1 == c2 ) {
		    if ( r1 == r2 - 1 )	{
			if ( nDestPiece == -1 )
			    bOK = true;
		    }
		    else if ( r1 == r2 - 2 && r1 == 1 ) {
			if ( anBoard[ r2 - 1 ][ c1 ] == -1 )
			    bOK = true;
		    }
		}
		else if ( c1 == c2 + 1 || c1 == c2 - 1 ) {
		    if ( r1 == r2 - 1 )	{
			if ( nDestPiece != -1 && nDestPiece > 5 )
			    bOK = true;
		    }
		}
	    }
	    else {
		if ( c1 == c2 ) {
		    if ( r1 == r2 + 1 )	{
			if ( nDestPiece == -1 )
			    bOK = true;
		    }
		    else if ( r1 == r2 + 2 && r1 == 6 ) {
			if ( anBoard[ r2 + 1 ][ c1 ] == -1 )
			    bOK = true;
		    }
		}
		else if ( c1 == c2 + 1 || c1 == c2 - 1 ) {
		    if ( r1 == r2 + 1 )	{
			if ( nDestPiece != -1 && nDestPiece < 6 )
			    bOK = true;
		    }
		}
	    }
	    break;
	case RookeB:
	    bOK = checkMoveLat( c1, r1, c2, r2 );
	    break;
	case KnightB:
	    if ( r1 == r2 - 2 || r1 == r2 + 2 ) {
		if ( c1 == c2 - 1 || c1 == c2 + 1 ) {
		    bOK = true;
		}
	    }
	    else if ( c1 == c2 - 2 || c1 == c2 + 2 ) {
		if ( r1 == r2 - 1 || r1 == r2 + 1 ) {
		    bOK = true;
		}
	    }
	    break;
	case BishopB:
	    bOK = checkMoveDiag( c1, r1, c2, r2 );
	    break;
	case QueenB:
	    bOK = checkMoveLat( c1, r1, c2, r2 );
	    if ( bOK == false )
		bOK = checkMoveDiag( c1, r1, c2, r2 );
	    break;
	case KingB:
	    if ( Math.abs( r1 - r2 ) < 2
		 && Math.abs( c1 - c2 ) < 2
		 && (Math.abs( r1 - r2 ) != 0
		     || Math.abs( c1 - c2 ) != 0) )
		bOK = true;
	    break;
	default:
	    break;
	}

	if ( bOK == true ) {
	    if ( nPiece < 6 && (nDestPiece == -1 || nDestPiece > 5) )
		bOK = true;
	    else if ( nPiece > 5 && (nDestPiece == -1 || nDestPiece < 6) )
		bOK = true;
	    else
		bOK = false;
	}

	return bOK;
    }

    public void mouseReleased( MouseEvent e ) {
    }

    public void mousePressed( MouseEvent e ) {
    }

    public void mouseClicked( MouseEvent e ) {
	if ( nActivePiece[0] >= 0 ) {
	    int x = e.getX();
	    int y = e.getY();

	    // Figure out the row/column
	    Dimension d = getSize();
	    int c = (x * 8) / d.width;
	    int r = (y * 8) / d.height;
	    if ( c < 0 || c > 7 )
		return;
	    if ( r < 0 || r > 7 )
		return;

	    if ( checkMove( nActivePiece[0], nActivePiece[1], c, r ) ) {
		anBoard[ r ][ c ] = anBoard[ nActivePiece[1] ][ nActivePiece[0] ];
		anBoard[ nActivePiece[1] ][ nActivePiece[0] ] = -1;
		nPlayer = (nPlayer + 1) % 2;
	    }

	    nActivePiece[0] = -1;
	    nActivePiece[1] = -1;
	}
	else {
	    int x = e.getX();
	    int y = e.getY();

	    // Figure out the row/column
	    Dimension d = getSize();
	    int c = (x * 8) / d.width;
	    int r = (y * 8) / d.height;
	    if ( c < 0 || c > 7 )
		return;
	    if ( r < 0 || r > 7 )
		return;

	    // Check to see if there's a piece there.
	    // If so, set active piece to it.
	    if ( anBoard[ r ][ c ] != -1 ) {
		// Check to see who's turn it is
		if ( (anBoard[ r ][ c ] < 6 && nPlayer == 0)
		     || (anBoard[ r ][ c ] > 5 && nPlayer == 1)
		     ) {
		    nActivePiece[0] = c;
		    nActivePiece[1] = r;
		}
	    }
	}

	repaint();
    }

    public void mouseEntered( MouseEvent e ) {
    }

    public void mouseExited( MouseEvent e ) {
    }
}