LegalMove.java

package com;

import java.util.LinkedList;
import java.util.stream.IntStream;

/**
 * @author KOTBI Abderrahmane
 * @version 1.1
 */
public class LegalMove {

  /**
   * @param b
   * @param r
   * @param c
   * @param round
   * @return linkedList for a selected direction in the matrix that start from the point(r,c) till
   *     the end of the matrix following on of the eight directions
   */
  public static LinkedList<Character> pickOneDirection(char[][] b, int r, int c, int round) {
    LinkedList<Character> linkedList = new LinkedList<>();
    switch (round) {
      case 0:
        IntStream.range(c, 8).forEach(i -> linkedList.add(b[r][i]));
        break;
      case 1:
        IntStream.range(7 - r, 8).forEach(i -> linkedList.add(b[7 - i][c]));
        break;
      case 2:
        IntStream.range(7 - c, 8).forEach(i -> linkedList.add(b[r][7 - i]));
        break;
      case 3:
        IntStream.range(r, 8).forEach(i -> linkedList.add(b[i][c]));
        break;
      case 4:
        IntStream.range(0, Math.min(r + 1, 8 - c)).forEach(i -> linkedList.add(b[r - i][c + i]));
        break;
      case 5:
        IntStream.range(0, Math.min(r + 1, c + 1)).forEach(i -> linkedList.add(b[r - i][c - i]));
        break;
      case 6:
        IntStream.range(0, Math.min(8 - r, c + 1)).forEach(i -> linkedList.add(b[r + i][c - i]));
        break;
      case 7:
        IntStream.range(0, Math.min(8 - r, 8 - c)).forEach(i -> linkedList.add(b[r + i][c + i]));
        break;
    }
    return linkedList;
  }

  /**
   * @param linkedList
   * @param r
   * @param c
   * @param color
   * @return boolean that checks if the move is legal for one direction
   */
  public static boolean checkMoveOneDirection(
      LinkedList<Character> linkedList, int r, int c, char color) {
    if (linkedList.size() < 3) {
      return false;
    } else {
      linkedList.removeFirst();
      char revColor = color == 'W' ? 'B' : 'W';
      if (linkedList.getFirst() == revColor) {
        linkedList.removeFirst();
        for (char v : linkedList) {
          if (v == '.') {
            return false;
          } else if (v == color) {
            return true;
          }
        }
      }
      return false;
    }
  }

  /**
   * @param b
   * @param r
   * @param c
   * @param color
   * @return boolean that checks if the move is legal for all the eight directions
   */
  public static boolean checkMove(char[][] b, int r, int c, char color) {
    boolean result0 = checkMoveOneDirection(pickOneDirection(b, r, c, 0), r, c, color);
    boolean result1 = checkMoveOneDirection(pickOneDirection(b, r, c, 1), r, c, color);
    boolean result2 = checkMoveOneDirection(pickOneDirection(b, r, c, 2), r, c, color);
    boolean result3 = checkMoveOneDirection(pickOneDirection(b, r, c, 3), r, c, color);
    boolean result4 = checkMoveOneDirection(pickOneDirection(b, r, c, 4), r, c, color);
    boolean result5 = checkMoveOneDirection(pickOneDirection(b, r, c, 5), r, c, color);
    boolean result6 = checkMoveOneDirection(pickOneDirection(b, r, c, 6), r, c, color);
    boolean result7 = checkMoveOneDirection(pickOneDirection(b, r, c, 7), r, c, color);
    boolean result =
        result0 || result2 || result1 || result3 || result4 || result6 || result5 || result7;
    return result;
  }
}