import pygame
from pygame.locals import *

import os, math

SCREEN_SIZE_X = 800
SCREEN_SIZE_Y = 600

SPEED = 2
TURN_SPEED = 3

RIGHT = 0
LEFT = 1

class Car():
        def __init__(self):
                self.sprite = pygame.image.load(os.path.join('img', 'car.png')).convert()
                self.rect = self.sprite.get_rect()

                self.rect.center = SCREEN_SIZE_X/2, SCREEN_SIZE_Y - self.rect.height * 2

                self.sprite.set_colorkey((255, 255, 255))

                self.angle = 0

                self.original = self.sprite

        def change_direction(self, direction):
                """
                Set the orientation of the car.
                """

                if direction == RIGHT:
                        self.angle += TURN_SPEED

                elif direction == LEFT:
                        self.angle -= TURN_SPEED

        def update(self):
                """
                Update the position of car regarding the current orientation and the SPEED value.
                """

                speedx = math.sin(self.angle * (math.pi/180)) * SPEED
                speedy = math.cos(self.angle * (math.pi/180)) * SPEED * -1

                #rotate the car
                a_rad = math.asin(speedx/SPEED)
                a_deg = math.degrees(a_rad)

                self.sprite = pygame.transform.rotate(self.original, a_deg * -1)
                self.rect = self.sprite.get_rect(center = self.rect.center)

                #move the car
                self.rect.center = self.rect.center[0] + speedx, self.rect.center[1] + speedy

        def draw(self, screen):
                """
                Draw the car on the screen.
                """

                screen.blit(self.sprite, self.rect.center)

def main():
        pygame.init()

        screen = pygame.display.set_mode((SCREEN_SIZE_X, SCREEN_SIZE_Y), HWSURFACE|DOUBLEBUF)

        car = Car()

        clock = pygame.time.Clock()

        loop = True
        while loop:
                clock.tick(60)

                for event in pygame.event.get():
                        if event.type == QUIT:
                                loop = False

                        if event.type == KEYDOWN:
                                if event.key == K_ESCAPE:
                                        loop = False


                pygame.event.pump()

                key = pygame.key.get_pressed()

                #set the orientation of the car with the RIGHT and LEFT button
                if key[K_RIGHT]:
                        car.change_direction(RIGHT)

                if key[K_LEFT]:
                        car.change_direction(LEFT)

                car.update()

                screen.fill((255, 255, 255))

                car.draw(screen)

                pygame.display.flip()

if __name__ == '__main__':
        main()