import math
import random
import pygame
from pygame.locals import *
 
running = False
playing = False
screen = None
timer = None
snk1 = None
snk2 = None
foods = None
remainFoods = 7
radiusFood = 8
 
'''
鏈表節點
'''
class Node:
    def __init__(self, data, prev = None, next = None):
        self.data = data
        self.prev = prev
        self.next = next
 
    def insert_front(self, node):
        if self.prev:
            node.prev = self.prev
            self.prev.next = node
            self.prev = node
            node.next = self
        else:
            self.prev = node
            node.next = self
        return node
 
    def insert_back(self, node):
        if self.next:
            node.next = self.next
            self.next.prev = node
            self.next = node
            node.prev = self
        else:
            self.next = node
            node.prev = self
        return node
    
    def remove(self):
        if self.next:
            self.next.prev = self.prev
        if self.prev:
            self.prev.next = self.next
 
'''
蛇
'''
class Snack:
 
    def __init__(self, surface, color, start_pos, end_pos, face):
        self.color = color
        self.surface = surface
        self.head = Node(start_pos)
        self.tail = Node(end_pos)
        self.head.insert_back(self.tail)
        self.length = self.distanceBetween(start_pos, end_pos)
        self.face = face
        self.speed = 120
        self.eat = 0
        self.grow = 0
        self.mapAngle = [
            [0, math.pi * 3 / 2, math.pi / 2],
            [0, math.pi * 7 / 4, math.pi / 4],
            [math.pi, math.pi * 5 / 4, math.pi * 3 / 4]
        ]
 
    '''坐標取整'''
    def intPos(self, pos):
        return (int(pos[0]), int(pos[1]))
 
    '''坐標轉角度'''
    def pos2Angle(self, pos):
        return self.mapAngle[pos[0]][pos[1]]
 
    '''極坐標位移'''
    def polarPos(self, pos, angle, dis):
        xx = pos[0] + dis * math.cos(angle)
        yy = pos[1] + dis * math.sin(angle)
        return (xx, yy)
 
    '''計算兩點間距離'''
    def distanceBetween(self, pos1, pos2):
        dx = pos2[0] - pos1[0]
        dy = pos2[1] - pos1[1]
        return math.sqrt(dx*dx + dy*dy)
    
    '''計算兩點間角度'''
    def angleBetween(self, pos1, pos2):
        dx = pos2[0] - pos1[0]
        dy = pos2[1] - pos1[1]
        return math.atan2(dy, dx)
 
    '''改變面向'''
    def changeFace(self, newFace):
        if newFace[0] == 0 and newFace[1] == 0:
            return
        if newFace == self.face:
            return
        xx = self.face[0] + newFace[0]
        yy = self.face[1] + newFace[1]
        if xx == 0 and yy == 0:
            return
        self.face = newFace
        self.head = self.head.insert_front(Node(self.head.data))
 
    '''吃到食物'''
    def eatFood(self, grow):
        self.grow = grow
        self.eat += 1
 
    '''繪制蛇身'''
    def draw(self):
        node = self.head
        pygame.draw.circle(self.surface, self.color, self.intPos(node.data), 6, 6)
        while node:
            n2 = node.next 
            if not n2:
                break
            pygame.draw.line(self.surface, self.color, self.intPos(node.data), self.intPos(n2.data), 6)
            node = node.next
    
    '''每幀移動'''
    def walk(self, delta):
        dis = self.speed * delta / 1000
        self.head.data = self.polarPos(self.head.data, self.pos2Angle(self.face), dis)
        if self.grow >= dis:
            self.grow -= dis
        else:
            dis -= self.grow
            self.grow = 0
            self.cutTail(dis)
    
    '''收縮尾巴'''
    def cutTail(self, length):
        node = self.tail
        while length > 0:
            n2 = node.prev
            dis = self.distanceBetween(n2.data, node.data)
            angle = self.angleBetween(node.data, n2.data)
            if dis > length:
                node.data = self.polarPos(node.data, angle, length)
                length = 0
            else:
                self.tail = node.prev
                node.remove()
                length -= dis
 
            node = node.prev
 
'''屏幕指定位置繪制文字'''
def printText(surface, str, pos, size = 24, color = (255, 255, 255)):
    global screen
    font = pygame.font.SysFont("microsoftyaheimicrosoftyaheiui", size)
    text = font.render(str, True, color)
    w = text.get_width()
    h = text.get_height()
    surface.blit(text, (pos[0] - w / 2, pos[1] - h / 2))
 
'''添加食物'''
def addFood():
    global screen, snk1, snk2, foods, remainFoods
    if remainFoods = 0:
        return
    w = screen.get_width()
    h = screen.get_height()
    while True:
        posX = random.randint(5, w - 5)
        posY = random.randint(5, h - 5)
        color = tuple(screen.get_at((posX, posY)))
        if color != snk1.color and color != snk2.color:
            break
    remainFoods -= 1
    if not foods:
        foods = Node((posX, posY))
    else:
        foods = foods.insert_front(Node((posX, posY)))
 
'''刪除食物'''
def removeFood(node):
    global foods
    if node == foods:
        foods = foods.next
    else:
        node.remove()
 
'''檢測吃到食物'''
def checkEatFood():
    global foods, radiusFood, snk1, snk2
    node = foods
    while node:
        if snk1.distanceBetween(snk1.head.data, node.data)  (radiusFood + 4):
            snk1.eatFood(50)
            removeFood(node)
            addFood()
            break
        elif snk2.distanceBetween(snk2.head.data, node.data)  (radiusFood + 4):
            snk2.eatFood(50)
            removeFood(node)
            addFood()
            break
        else:
            node = node.next
 
'''游戲初始界面'''
def logo():
    global screen, remainFoods
    w = screen.get_width()
    h = screen.get_height()
    printText(screen, "Snack V1.0", (w / 2, h / 3), 48)
    printText(screen, "任意鍵繼續", (w / 2, h / 2), 24, (55, 255, 55))
    printText(screen, str(remainFoods) + "個食物，搶完即止", (w / 2, h * 2 / 3), 32)
    
def quit():
    pygame.font.quit()
 
'''檢測游戲結束'''
def checkGameOver():
    global remainFoods, snk1, snk2, foods, playing, screen
    if remainFoods == 0 and foods == None:
        playing = False
        screen.fill((0,0,0))
        w = screen.get_width()
        h = screen.get_height()
        if snk1.eat > snk2.eat:
            printText(screen, "玩家1 勝利", (w / 2, h / 2), 48)
        elif snk1.eat  snk2.eat:
            printText(screen, "玩家2 勝利", (w / 2, h / 2), 48)
        else:
            printText(screen, "平局", (w / 2, h / 2), 48)
 
'''鍵盤按鍵轉換成面向角度'''
def cmd():
    global snk1, snk2
    keys = pygame.key.get_pressed()
    x1 = x2 = y1 = y2 = 0
    if keys[pygame.K_RIGHT]:
        x2+=1
    if keys[pygame.K_LEFT]:
        x2-=1
    if keys[pygame.K_UP]:
        y2+=1
    if keys[pygame.K_DOWN]:
        y2-=1
    if keys[pygame.K_d]:
        x1+=1
    if keys[pygame.K_a]:
        x1-=1
    if keys[pygame.K_w]:
        y1+=1
    if keys[pygame.K_s]:
        y1-=1
    snk1.changeFace((x1, y1))
    snk2.changeFace((x2, y2))
 
'''游戲每幀更新'''
def play(delta):
    global playing, snk1, snk2
    if not playing:
        return
    cmd()
    snk1.walk(delta)
    snk2.walk(delta)
    checkEatFood()
    checkGameOver()
 
'''繪制'''
def draw():
    global snk1, snk2, playing, screen, radiusFood, remainFoods
    if not playing:
        return
    screen.fill((0,0,0))
    snk1.draw()
    snk2.draw()
    node = foods
    while node:
        color = (255, 255, 255)
        if remainFoods == 0:
            color = (255, 0, 0)
        pygame.draw.circle(screen, color, node.data, radiusFood, radiusFood // 2 + 1)
        node = node.next
 
def start(width = 800, height = 600, fps = 60):
    global running, screen, timer, playing, snk1, snk2
    pygame.init()
    pygame.font.init()
    font = pygame.font.SysFont("microsoftyaheimicrosoftyaheiui", 20)
    pygame.display.set_caption("Snack V1.0")
    screen = pygame.display.set_mode((width, height))
    
    logo()
    snk1 = Snack(screen, (0, 150, 200), (100, 100), (0, 100), (1, 0))
    snk2 = Snack(screen, (255, 100, 0), (width * 5 // 6, height // 2), (width * 5 // 6 + 100, height // 2), (-1, 0))
    for i in range(3):
        addFood()
 
    timer = pygame.time.Clock()
    running = True
    while running:
        delta = timer.tick(fps)
        play(delta)
        draw()
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_SPACE and playing == False:
                    screen.fill((0,0,0))
                    playing = True
 
        pygame.display.flip()
 
    
if __name__ == "__main__":
    start()
    quit()