import random

import pygame


class Cell:
    def __init__(self,pos,size):
        self.pos = pos
        self.size = size

    def grow(self):
        self.size = self.size + 1

    def movement(self):
       keys_pressed = pygame.key.get_pressed()
       if keys_pressed[pygame.K_UP]:
           pos = (cell.pos[0], cell.pos[1] - 1)
           self.pos = pos
       if keys_pressed[pygame.K_DOWN]:
           pos = (cell.pos[0], cell.pos[1] + 1)
           self.pos = pos
       if keys_pressed[pygame.K_LEFT]:
           pos = (cell.pos[0] - 1, cell.pos[1])
           self.pos = pos
       if keys_pressed[pygame.K_RIGHT]:
           pos = (cell.pos[0] + 1, cell.pos[1])
           self.pos = pos

    def appearance(self,screen):
        pygame.draw.circle(screen, RED, self.pos, self.size)


class Nutrient:
    def __init__(self,visible,pos,size):
        self.visible = visible
        self.pos = pos
        self.size = size

    def appear(self,screen):
        pygame.draw.circle(screen, BLUE, self.pos, CIRCLE_RADIUS)

    def consumed(self,pos):
        del self
        del nutrients[pos]
        cell.grow()

    def check_collision(self):
        if ((cell.pos[0] - self.pos[0]) ** 2) + ((cell.pos[1] - self.pos[1]) ** 2) <= (cell.size + self.size) ** 2:
            self.consumed(self.pos)

nutrients = {}
width = 640
height = 600
SIZE = (width, height)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
BLUE = (0, 0, 255)
CIRCLE_RADIUS = 2
BLACK = (0, 0, 0)

def main():
    screen = init_game()
    game_loop(screen)
    exit_game()

def init_game():
    global clock
    clock = pygame.time.Clock()
    pygame.init()
    screen = pygame.display.set_mode(SIZE)
    return screen

def game_loop(screen):
    global cell
    cell = Cell((300,300),5)
    spawn_nutrition()
    while True:
        if not event_handling():
            break
        if not update_game():
            break
        event = event_handling()
        update_game()
        draw_screen(screen)



def event_handling():
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            return False
    return True

def update_game():
    n_copy = nutrients.copy()
    for x,y in n_copy:
        nutrients[(x,y)].check_collision()
    del n_copy
    cell.movement()
    clock.tick(60)
    return True

def draw_screen(screen):
    screen.fill(WHITE)
    x = 0
    cell.appearance(screen)
    for x,y in nutrients:
        if nutrients[x,y].visible:
            nutrients[x,y].appear(screen)
        x+=1
    pygame.display.flip()

def spawn_nutrition():
    for _ in range(100):
        pos = (random.randint(0, SIZE[0]), random.randint(0, SIZE[1]))
        nutrients[pos]=(Nutrient(True, pos,2))

def exit_game():
    pygame.quit()

main()