import pygame

# pygame setup
pygame.init()
screen = pygame.display.set_mode((1280, 720))
clock = pygame.time.Clock()
running = True
dt = 0

force_coef = 10
player_applied_force = pygame.Vector2(0, 0)
player_mass = 1
player_pos = pygame.Vector2(screen.get_width() / 2, screen.get_height() / 2)
player_speed = pygame.Vector2(0, 0)


def draw_arrow(surface, color, start, end, width=3):
    pygame.draw.line(surface, color, start, end, width)
    direction = (end - start).normalize()
    arrow_size = 10
    perpendicular = pygame.Vector2(-direction.y, direction.x)
    point1 = end - direction * arrow_size + perpendicular * arrow_size / 2
    point2 = end - direction * arrow_size - perpendicular * arrow_size / 2
    pygame.draw.polygon(surface, color, [end, point1, point2])


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

    screen.fill("purple")

    pygame.draw.circle(screen, "red", player_pos, 40)

    player_applied_force = pygame.Vector2(0, 0)

    keys = pygame.key.get_pressed()
    if keys[pygame.K_w]:
        player_applied_force.y -= force_coef
    if keys[pygame.K_s]:
        player_applied_force.y += force_coef
    if keys[pygame.K_a]:
        player_applied_force.x -= force_coef
    if keys[pygame.K_d]:
        player_applied_force.x += force_coef

    acceleration = player_applied_force / player_mass
    player_speed += acceleration * dt
    player_pos += player_speed * dt

    # Draw force arrow
    if player_applied_force.length() > 0:
        arrow_end = player_pos + player_applied_force * 2
        draw_arrow(screen, "yellow", player_pos, arrow_end)

    # Draw speed arrow
    if player_speed.length() > 0:
        arrow_end = player_pos + player_speed * 2
        draw_arrow(screen, "cyan", player_pos, arrow_end)

    pygame.display.flip()
    dt = clock.tick(60) / 1000

pygame.quit()