/** This is the GameOfLife class as it stood at the
 *  end of the 9:30 lecture 6/2/2003, with minor name
 *  changes, and added comments.
 *  The game is essentially complete, except for having
 *  a driver that repeatedly calls update (and print).
 *  You can do this directly from DrJava and observe the result.
 */
public class GameOfLife_NineThirty {
  
  /** Number of rows on the board.*/
  final private int ROWS = 6;
  /** Number of columns on the board. */
  final private int COLS = 6;
  
  /** The board itself, as an array of "cells".
   *  Each cell has a status: ALIVE or DEAD.
   */
  private int[][] board;
  
  /** Cell values */
  final private int ALIVE = 1;
  final private int DEAD = 2;
  
  /** Construct a board with all cells "dead".
   */
  public GameOfLife_NineThirty() {
    board = new int[ROWS][COLS];
    for (int r = 0; r < ROWS; r++) {
      for (int c = 0; c < COLS; c++) {
        board[r][c] = DEAD;
      }
    }  
  }
  
  /** ASCII art display of the board. */
  public void print() {
    for (int r = 0; r < ROWS; r++) {
      for (int c = 0; c < COLS; c++) {
        System.out.print(board[r][c]);
      }
      System.out.println();
    }  
   }
  
  /** See how many living neighbor a cell has.*/
  public int countNb(int row, int col) {
    int count = 0;
    for (int r = row-1; r <= row+1; r++) {
      for (int c = col-1; c<= col+1; c++) {
        //Make sure the cell is one that we can and should check.
        if ( !((r == row) && (c == col))
            && r >= 0 && r < ROWS &&
            c >= 0 && c < COLS) {
          if (board[r][c] == ALIVE) {
            count = count +1;
          }
        }
      }
    }
    return count;    
  }
  
  /** Update each cell on the board.
     (Code in lecture had literal 3 and 6, which have
     been replaced by constants.)
  */
  public void update() {
    final int goAliveLimit = 3;
    final int goDeadLimit = 6;
    int[][] newBoard = new int[ROWS][COLS];
    for (int r = 0; r < ROWS; r++) {
      for (int c = 0; c < COLS; c++) {
        int ncount = countNb(r, c);
        //Following line was missing in the 9:30 code
        newBoard[r][c] = board[r][c];
        
        if (ncount < goAliveLimit) {
          //go alive
          newBoard[r][c] = ALIVE;
        }
        if (ncount > goDeadLimit) {
          //become dead
          newBoard[r][c] = DEAD;
        }
      }
    }
    board = newBoard;    
  }
  
//end class  
}