"""
元胞自动机 Python 实现
"""
import numpy as np
import matplotlib.pyplot as plt


class GameOfLife(object):

  def __init__(self, cells_shape):
    """
    Parameters
    ----------
    cells_shape : 一个元组，表示画布的大小。

    Examples
    --------
    建立一个高20，宽30的画布
    game = GameOfLife((20, 30))
    
    """

    # 矩阵的四周不参与运算
    self.cells = np.zeros(cells_shape)

    real_width = cells_shape[0] - 2
    real_height = cells_shape[1] - 2
    
    self.cells[1:-1, 1:-1] = np.random.randint(2, size=(real_width, real_height))
    self.timer = 0
    self.mask = np.ones(9)
    self.mask[4] = 0
  
  def update_state(self):
    """更新一次状态"""
    buf = np.zeros(self.cells.shape)
    cells = self.cells
    for i in range(1, cells.shape[0] - 1):
      for j in range(1, cells.shape[0] - 1):
        # 计算该细胞周围的存活细胞数
        neighbor = cells[i-1:i+2, j-1:j+2].reshape((-1, ))
        neighbor_num = np.convolve(self.mask, neighbor, 'valid')[0]
        if neighbor_num == 3:
          buf[i, j] = 1
        elif neighbor_num == 2:
          buf[i, j] = cells[i, j]
        else:
          buf[i, j] = 0
    self.cells = buf
    self.timer += 1
  
  def plot_state(self):
    """画出当前的状态"""
    plt.title('Iter :{}'.format(self.timer))
    plt.imshow(self.cells)
    plt.show()

  def update_and_plot(self, n_iter):
    """更新状态并画图
    Parameters
    ----------
    n_iter : 更新的轮数
    """
    plt.ion()
    for _ in range(n_iter):
      plt.title('Iter :{}'.format(self.timer))
      plt.imshow(self.cells)
      self.update_state()
      plt.pause(0.2)
    plt.ioff()
          

if __name__ == '__main__':
  game = GameOfLife(cells_shape=(60, 60))
  game.update_and_plot(200)