import pygame
import sys
from pygame.locals import *

pygame.init()
vec = pygame.math.Vector2  # 2 for two dimensional

HEIGHT = 450
WIDTH = 400
ACC = 0.5
FRIC = -0.12
FPS = 60

FramePerSec = pygame.time.Clock()

display_surface = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("game")


class Player(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.surf = pygame.Surface((30, 30))
        self.surf.fill((128, 255, 40))
        self.rect = self.surf.get_rect(center=(50, 420))
        self.pos = vec(50, 420)
        self.vel = vec(0, 0)
        self.acc = vec(0, 0)

    def move(self):
        self.acc = vec(0, 0.5)
        keys = pygame.key.get_pressed()
        if keys[K_LEFT]:
            self.acc.x = -ACC
        if keys[K_RIGHT]:
            self.acc.x = ACC

        # equations of motion
        self.acc.x += self.vel.x * FRIC
        self.vel += self.acc
        self.pos += self.vel + 0.5 * self.acc

        # wrap around the sides of the screen
        if self.pos.x > WIDTH:
            self.pos.x = 0
        if self.pos.x < 0:
            self.pos.x = WIDTH

        self.rect.midbottom = self.pos

    def check_collision(self, platforms):
        hits = pygame.sprite.spritecollide(self, platforms, False)
        if hits:
            self.vel.y = 0
            self.pos.y = hits[0].rect.top + 1
            self.rect.midbottom = self.pos


class Platform(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.surf = pygame.Surface((WIDTH, 20))
        self.surf.fill((255, 0, 0))
        self.rect = self.surf.get_rect(center=(WIDTH / 2, HEIGHT - 10))


PT1 = Platform()
P1 = Player()

all_sprites = pygame.sprite.Group()
all_sprites.add(PT1)
all_sprites.add(P1)

platforms = pygame.sprite.Group()
platforms.add(PT1)

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()

    display_surface.fill((0, 0, 0))

    P1.move()
    P1.check_collision(platforms)

    # Draw all sprites
    for entity in all_sprites:
        display_surface.blit(entity.surf, entity.rect)

    pygame.display.update()
    FramePerSec.tick(FPS)