/* Copyright 1996 Rujith de Silva.
   Modified 2002-03-07
   */

package rujith.pentominoes;

/**
 * A piece composed of adjoining squares on a rectangular grid that
 * can be rotated or swapped (flipped over).
 */
public class Piece 
{
    // Multiplier to get the x-coordinate for each of the four
    // directions
    static private final int xmul[][] =
    { { 1, 0 },
      { 0, -1 }, 
      { -1, 0 }, 
      { 0, 1 }
    };

    // Multiplier to get the y-coordinate for each of the four
    // directions
    static private final int ymul[][] =
    { { 0, 1 },
      { 1, 0 },
      { 0, -1 },
      { -1, 0 }
    };
    
    // Initial (x,y) positions of the five squares
    private final int init[][] = new int[5][2];

    // Initial direction of the piece.
    private int direction = 0;

    // Is the piece flipped or not.
    private boolean swap = false;

    /**
     * Current (x,y) positions of the five squares.  Do not update
     * these values directly.
     */
    final protected int current[][] = new int[5][2];

    /**
     * Create a new Piece.
     *
     * @param init Initial (x,y) positions of the five squares.  A
     * (5x2) array.
     */
    public Piece (int init[][])
    {
        for (int i = 0; i < 5; ++i)
        {
            for (int j = 0; j < 2; ++j)
            {
                this.init[i][j] = init[i][j];
                this.current[i][j] = init[i][j];
            }
        }
    }

    /**
     * @return Current direction of the piece
     */
    public int getDirection ()
    {
        return this.direction;
    }

    /**
     * Update the direction of the piece
     *
     * @param i New direction.  Varies between 0 and 3.
     */
    synchronized public void setDirection (int i)
    {
        i %= 4;
        if (this.direction != i)
        {
            this.direction = i;
            this.update ();
        }
    }

    /**
     * @return Current swap (flip) setting of the piece
     */
    public boolean getSwap ()
    {
        return this.swap;
    }

    /**
     * Update whether the piece is flipped or not
     *
     * @param sw True if piece should be flipped
     */
    synchronized public void setSwap (boolean sw)
    {
        if (this.swap != sw)
        {
            this.swap = sw;
            this.update ();
        }
    }

    // Update the current positions of the squares
    synchronized private void update ()
    {
        int dir = this.direction;
        int xm1 = xmul[dir][0];
        int xm2 = xmul[dir][1];
        int ym1 = ymul[dir][0];
        int ym2 = ymul[dir][1];

        // Perform simple matrix multiplication to get the new squares
        for (int i = 0; i < 5; ++i)
        {
            int i0 = this.init[i][0];
            int i1 = this.init[i][1];
            if (this.swap) i1 = - i1;
            this.current[i][0] = i0 * xm1 + i1 * xm2;
            this.current[i][1] = i0 * ym1 + i1 * ym2;
        }
    }
}