import sys
import pygame

pygame.init()

screen_width = 640
screen_height = 480
screen = pygame.display.set_mode((screen_width, screen_height))
screen_rect = screen.get_rect()

clock = pygame.time.Clock()

fps = 30


class Character(object):
    def __init__(self, surface, accel, gravity):
        self.surface = surface
        self.accel = accel
        self.gravity = gravity
        self.vel = (0, 0)
        self.pos = ((screen_width / 2),(screen_height / 2))
        self.size = (10, 10)

    def move_right(self):
        self.vel = (self.vel[0] + self.accel, self.vel[1])
        self.pos = (self.pos[0] + self.vel[0],self.pos[1])

    def move_left(self):
        self.vel = (self.vel[0] - self.accel, self.vel[1])
        self.pos = (self.pos[0] + self.vel[0],self.pos[1])

    def move_up(self):
        self.vel = (self.vel[0], self.vel[1] - self.accel)
        self.pos = (self.pos[0],self.pos[1] + self.vel[1])

    def move_down(self):
        self.vel = (self.vel[0], self.vel[1] + self.accel)
        self.pos = (self.pos[0],self.pos[1] + self.vel[1])

    def move(self):
        keys = pygame.key.get_pressed()
        if keys[pygame.K_w]:
            self.move_up()
        if keys[pygame.K_a]:
            self.move_left()
        if keys[pygame.K_s]:
            self.move_down()
        if keys[pygame.K_d]:
            self.move_right()

        if self.pos[0] <= 0 or self.pos[0] >= screen_width:
            self.vel = (self.vel[0] * -1, self.vel[1])

        if self.pos[1] <= 0 or self.pos[1] >= screen_height:
            self.vel = (self.vel[0], self.vel[1] * -1)

        self.character = pygame.Rect((self.pos[0], self.pos[1]), self.size)
        self.character.clamp_ip(screen_rect)

    def display(self):
        pygame.draw.rect(self.surface, (255, 255, 255), self.character)

    def reset(self):
        (x_pos, y_pos) = pygame.mouse.get_pos()
        self.pos = (x_pos, self.pos[1])
        self.pos = (self.pos[0], y_pos)
        self.x_vel = 0
        self.y_vel = 0

    def apply_gravity(self):
        self.timestep = 1/fps # or something else to your liking
        self.vel = (self.vel[0], self.vel[1] + self.gravity * self.timestep)
        self.pos = (self.pos[0], self.pos[1] + self.vel[1] * self.timestep + 0.5* self.gravity * self.timestep**2)

def main():
    player1 = Character(screen, 10, .5)
    while True:
        for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    pygame.quit()
                    sys.exit()
                elif event.type == pygame.MOUSEBUTTONDOWN:
                    player1.reset()

        player1.apply_gravity()
        player1.move()

        screen.fill((0, 0, 0))

        player1.display()

        pygame.display.update(screen_rect)
        clock.tick(fps)

if __name__ == "__main__":
    main()