oglimmer/ggo

package de.oglimmer.ggo.logic.util;

import de.oglimmer.ggo.logic.Field;

public class FieldUtil {

    /**
     * @formatter:off
     * 
     *   even(x) && even(y)
     *   x y
      *   - -
     *   0 -
     *   - 0
     *   + 0
     *   - +
     *   0 +
     *   
     *   even(x) && odd(y)
     *   0 -
     *   + -
     *   - 0
     *   + 0
     *   0 +
     *   + +
     *   
     *   odd(x) && even(y) 
     *   - -
     *   0 -
     *   - 0
     *   + 0
     *   - +
     *   0 +
     *   
     *   odd(x) && odd(y) 
     *   0 -
     *   + -
     *   - 0
     *   + 0
     *   0 +
     *   + +
     *   
     *  @formatter:on
     */
    public static boolean adjacent(Field a, Field b) {
        int thisX = (int) a.getPos().getX();
        int thisY = (int) a.getPos().getY();
        int fx = (int) b.getPos().getX();
        int fy = (int) b.getPos().getY();

        if (minus(thisX, fx) && zero(thisY, fy) || plus(thisX, fx) && zero(thisY, fy)) {
            return true;
        }

        if (even(thisX) && even(thisY) || odd(thisX) && even(thisY)) {
            if (minus(thisX, fx) && minus(thisY, fy) || zero(thisX, fx) && minus(thisY, fy)
                    || minus(thisX, fx) && plus(thisY, fy) || zero(thisX, fx) && plus(thisY, fy)) {
                return true;
            }
        } else {
            if (zero(thisX, fx) && minus(thisY, fy) || plus(thisX, fx) && minus(thisY, fy)
                    || zero(thisX, fx) && plus(thisY, fy) || plus(thisX, fx) && plus(thisY, fy)) {
                return true;
            }
        }

        return false;
    }

    private static boolean minus(int a, int b) {
        return b - a == -1;
    }

    private static boolean zero(int a, int b) {
        return b - a == 0;
    }

    private static boolean plus(int a, int b) {
        return b - a == 1;
    }

    private static boolean odd(int i) {
        return i % 2 != 0;
    }

    private static boolean even(int i) {
        return i % 2 == 0;
    }

}