'''
Function:
	定义bird类
Author:
	Charles
微信公众号:
	Charles的皮卡丘
'''
import pygame
import itertools


'''bird类'''
class Bird(pygame.sprite.Sprite):
	def __init__(self, images, idx, position, **kwargs):
		pygame.sprite.Sprite.__init__(self)
		self.images = images
		self.image = list(images.values())[idx]
		self.rect = self.image.get_rect()
		self.mask = pygame.mask.from_surface(self.image)
		self.rect.left, self.rect.top = position
		# 竖直方向运动所需变量
		self.is_flapped = False
		self.down_speed = 0
		self.up_speed = 9
		# 切换bird形态
		self.bird_idx = idx
		self.bird_idx_cycle = itertools.cycle([0, 1, 2, 1])
		self.bird_idx_change_count = 0
	'''更新'''
	def update(self, boundary_values, time_passed):
		# 竖直方向的位置更新
		if self.is_flapped:
			self.up_speed -= 60 * time_passed
			self.rect.top -= self.up_speed
			if self.up_speed <= 0:
				self.unsetFlapped()
				self.up_speed = 9
				self.down_speed = 0
		else:
			self.down_speed += 40 * time_passed
			self.rect.bottom += self.down_speed
		# 判断bird是否因为撞到上下边界而挂掉了
		is_dead = False
		if self.rect.bottom > boundary_values[1]:
			is_dead = True
			self.up_speed = 0
			self.down_speed = 0
			self.rect.bottom = boundary_values[1]
		if self.rect.top < boundary_values[0]:
			is_dead = True
			self.up_speed = 0
			self.down_speed = 0
			self.rect.top = boundary_values[0]
		# 切换bird形态模拟以模拟扇翅膀效果
		self.bird_idx_change_count += 1
		if self.bird_idx_change_count % 5 == 0:
			self.bird_idx = next(self.bird_idx_cycle)
			self.image = list(self.images.values())[self.bird_idx]
			self.bird_idx_change_count = 0
		return is_dead
	'''设置为飞行模式'''
	def setFlapped(self):
		if self.is_flapped:
			self.up_speed = max(12, self.up_speed+1)
		else:
			self.is_flapped = True
	'''设置为下落模式'''
	def unsetFlapped(self):
		self.is_flapped = False
	'''绑定到屏幕'''
	def draw(self, screen):
		screen.blit(self.image, self.rect)