import curses #控制字符界面
from random import  randrange, choice
#random.randrange([start], stop[, step])，
# 从指定范围内，按指定基数递增的集合中 获取一个随机数。
#random.choice从序列中获取一个随机元素。
from collections import  defaultdict#默认字典



letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']#ord函数以一个字符为参数，返回对应的ASCII数值，或者Unicode数值
actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']
actions_dict = dict(zip(letter_codes,actions*2)) #zip() 函数用于将可迭代的对象作为参数，将对象中对应的元素打包成一个个元组，然后返回由这些元组组成的对象，这样做的好处是节约了不少的内存。
#[(W,Up),(A,Left),..(q,Exit)]-->{W:Up, A:Left,...q:Exit}

#用户输入
def get_user_action(keyboard):
    char = 'N'
    while char not in actions_dict:
        char = keyboard.getch()
    return  actions_dict[char]
#矩阵转置
def transpose(field):#进行一个二维列表的转换
    return [list(row) for row in zip(*field)]

#矩阵逆转
def invert(field):
    return [row[::-1] for row in field]

#创建棋盘
class GameField(object):#class:类的关键字；GameField：自定义类的标识符；object；要继承的类名（是一个更大的类，可以从这个父类中继承一些功能和特性），object是默认值。
    def __init__(self, height=4, width=4, win=2048):#__init__是超类object下的一个初始化对象数据的函数
        self.height = height    #高
        self.width = width      #宽
        self.win_value = win    #过关分数
        self.score = 0          #当前分数
        self.highscore = 0      #最高分数
        self.reset()            #棋盘重置
    #重置棋盘
    def reset(self):
        if self.score > self.highscore:
            self.highscore = self.score
        self.score = 0
        self.field = [[0 for i in range(self.width)] for j in range(self.height)]#嵌套的列表，四行四列
        self.spawn()
        self.spawn()#在嵌套的列表里随机的生成元素

    def move(self,direction):#合并
        #一行向左合并
        def move_row_left(row):
            def tighten(row): #把零散的非零单元挤到一起
                new_row = [i for i in row if i !=0]
                new_row += [0 for i in range(len(row)-len(new_row))]
                return new_row
            def merge(row): #对邻近元素进行合并
                pair = False
                new_row = []
                for i in range(len(row)):
                    if pair:
                        new_row.append(2 * row[i])#合并
                        self.score += 2 * row[i]#记录分数
                        pair = False
                    else:
                        if i +1 < len(row) and row[i] == row[i + 1]:
                            pair = True
                            new_row.append(0)
                        else:
                            new_row.append(row[i])
                assert  len(new_row) == len(row)
                return  new_row
            #先挤到一块再合并再挤到一起
            return tighten(merge(tighten(row)))
        #通过对矩阵进行转置和逆转，可以直接从左移得到其余三个方向的移动操作
        moves = {}
        moves['Left'] = lambda field:                   \
            [move_row_left(row) for row in field]
        moves['Right'] = lambda field:                   \
            invert(moves['Left'](invert(field)))
        moves['Up'] = lambda field:                 \
            transpose(moves['Left'](transpose(field)))
        moves['Down'] = lambda field:                   \
            transpose(moves['Right'](transpose(field)))

        if direction in  moves:
            if self.move_is_possible(direction):
                self.field = moves[direction](self.field)
                self.spawn()
                return True
            else:
                return False
    #判断输赢
    def is_win(self):
        return any(any(i >= self.win_value for i in row) for row in self.field)

    def is_gameover(self):
        return not any(self.move_is_possible(move) for move in actions)

    #绘制游戏界面
    def draw(self,screen):
        help_string1 = '(W)Up (S)Down (A)Left (D)Right'
        help_string2 = '      (R)Restart (Q)Exit'
        gameover_string = '            GAME OVER'
        win_string = '                YOU WIN!'
        def cast(string):
            screen.addstr(string + '\n')#调用方法把字符串打印到屏幕

        #绘制水平分割线
        def draw_hor_separator():
            line = '+' + ('+------' * self.width + '+')[1:]
            separator = defaultdict(lambda: line)
            if not hasattr(draw_hor_separator, 'counter'):
                draw_hor_separator.counter = 0
            cast(separator[draw_hor_separator.counter])
            draw_hor_separator.counter += 1
        def draw_row(row):
            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row)+ '|')

        screen.clear()
        cast('SCORE: ' + str(self.score))#绘制当前分数和最高分
        if 0 != self.highscore:
            cast('HIGHSCORE：' + str(self.highscore))
        for row in self.field:
            draw_hor_separator()#绘制分割线
            draw_row(row)#绘制行
        draw_hor_separator()#绘制底边的线
        if self.is_win():
            cast(win_string)
        else:
            if self.is_gameover():
                cast(gameover_string)
            else:
                cast(help_string1)
        cast(help_string2)

    #棋盘操作
    #随机生成一个2或者4
    def spawn(self):
        new_element = 4 if randrange(100) > 89 else 2#9:1的比例生成4和2
        (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] ==0])#通过choice选择一个未被占领的位置
        self.field[i][j] = new_element

    #判断能否移动
    def move_is_possible(self,diretion):
            def row_is_left_movable(row):#判断是否可以向左移动
                def change(i):
                    if row[i] == 0 and row[i + 1] !=0:
                        return True
                    if row[i] !=0 and row[i + 1] == row[i]:
                        return  True
                    return False
                return any(change(i) for i in range(len(row) - 1))#any,只要有一个是ture结果就是ture
            check = {}
            check['Left'] = lambda field:                   \
                any(row_is_left_movable(row) for row in field)
            check['Right'] = lambda field:                  \
                check['Left'](invert(field))
            check['Up']     =lambda  field:                 \
                check['Left'](transpose(field))
            check['Down'] =lambda field:                    \
                check['Right'](transpose(field))
            if diretion in check:
                return check[diretion](self.field)
            else:
                return False
#主逻辑
def main(stdscr):#标准屏幕，curses模块
    def init():
        #重置游戏棋盘
        game_field.reset()
        return  'Game'
    def not_game(state):
        #画出 GameOver 或者 Win 的界面
        game_field.draw(stdscr)
        #读取用户输入得到的action，判断是重启游戏还是结束游戏
        action = get_user_action(stdscr)
        responses = defaultdict(lambda : state)#默认是当前状态，没有行为就会一直在当前界面循环
        #collections.defaultdict可以接受一个函数作为参数来初始化
        responses['Restart'],responses['Exit']='Init','Exit'#对应不同的行为转换到不同的状态
        return responses[action]
    def game():
        #画出当前棋盘的状态
        game_field.draw(stdscr)
        #读取用户输入得到的action
        action = get_user_action(stdscr)
        if action == 'Restart':
            return  'Init'
        if action == 'Exit':
            return  'Exit'
        if game_field.move(action):
            if game_field.is_win():
                return 'Win'
            if game_field.is_gameover():
                return 'Gameover'
        return 'Game'
    state_actions = {
        'Init': init,
        'Win': lambda: not_game('Win'),
        'Gameover': lambda : not_game('Gameover'),
        'Game': game
    }
    curses.use_default_colors()

    game_field = GameField(win=2048)


    state = 'Init'
    #状态机开始循环
    while state != 'Exit':
        state = state_actions[state]()
curses.wrapper(main)#把stdscr对象传入main函数里，wrapper接口