public class Life implements ILife {

  private boolean[][] grid = new boolean[5][5];  // vorläufig 5x5 Raster

  public static void main(String[] args) {
    Life l = new Life(new String[] {  "     ",
                                      "     ",
                                      " *** ",
                                      "     ",
                                      "     " });
    l = (Life) l.nextGeneration();
  }


  public Life() {
    nukeAll();
  }

  public Life(String[] setup) {
    this();
    for (int y = 0; y < setup.length; y++)
      for (int x = 0; x < setup[y].length(); x++)
        if (setup[y].charAt(x) != ' ')
          setAlive(x, y);
  }


  @Override
  public void nukeAll() {
    // TODO Auto-generated method stub

  }

  @Override
  public void setAlive(int x, int y) {
    grid[x][y] = true;
  }

  @Override
  public void setDead(int x, int y) {
    grid[x][y] = false;
  }

  @Override
  public boolean isAlive(int x, int y) {
    return grid[x][y];
  }

  @Override
  public ILife nextGeneration() {
    Life next = new Life();

    for (int y = 0; y < grid.length; y++) {
      for (int x = 0; x < grid[y].length; x++) {
        if (countAliveNeighbours(x, y) == 3) {
          next.setAlive(x, y);
        } else if (countAliveNeighbours(x, y) < 2 || countAliveNeighbours(x, y) > 3) {
          next.setDead(x, y);
        }
      }
    }

    return next;
  }

  private int countAliveNeighbours(int x, int y) {
    int count = 0;

    for (int offset_X = -1; offset_X <= 1; offset_X++) {
      for (int offset_Y = -1; offset_Y <= 1; offset_Y++) {
        if (offset_X == 0 && offset_Y == 0) continue;  // eigene Zelle überspringen
        int neighbor_X = x + offset_X;
        int neighbor_Y = y + offset_Y;

        if (isValid(neighbor_X, neighbor_Y) && isAlive(neighbor_X, neighbor_Y)) {
          count++;
        }
      }
    }

    return count;
  }

  private boolean isValid(int x, int y) {
    return x >= 0 && x < grid.length && y >= 0 && y < grid[x].length;
  }
}