""" PONG: In this project, we will build a version of Pong, one of the first arcade video games (1972) """
# use following link to test the program in 'codeskulptor': http://www.codeskulptor.org/#user45_LkGAT2Amnf_2.py

import random
try:
    import simplegui  # access to drawing operations for interactive applications
except ImportError:
    import SimpleGUICS2Pygame.simpleguics2pygame as simplegui  # CodeSkulptor GUI module stand alone version


# initialize globals - pos and vel encode vertical info for paddles
WIDTH = 600
HEIGHT = 400
BALL_RADIUS = 20
PAD_WIDTH = 8
PAD_HEIGHT = 80
HALF_PAD_WIDTH = PAD_WIDTH / 2
HALF_PAD_HEIGHT = PAD_HEIGHT / 2
LEFT = False  # 'LEFT' and 'RIGHT' are predefined as BOOLEAN
RIGHT = True


# initialize ball_pos and ball_vel for new bal in middle of table if direction is RIGHT, the ball's velocity is upper right, else upper left
def spawn_ball(direction):
    global ball_pos, ball_vel  # these are vectors stored as lists
    ball_pos = [WIDTH / 2, HEIGHT / 2]  # this is just the initial position in the middle of the screen
    if direction is RIGHT:
        ball_vel = [random.randrange(2, 4), -random.randrange(1, 3)]  # [random.randrange(120, 240)/60, -random.randrange(60, 180)/60]
    else:
        ball_vel = [-random.randrange(2, 4), -random.randrange(1, 3)]  # pixels per tick [sideways, up/downwards] - this defines by how much

def increase_speed():  # this is a separate helper function that incrases the speed when a ball hits the pad
    ball_vel[0] = ball_vel[0] * 1.1
    ball_vel[1] = ball_vel[1] * 1.1


# define event handlers
def new_game():
    global paddle1_pos, paddle2_pos, paddle1_vel, paddle2_vel  # these are numbers
    global score1, score2  # these are ints
    paddle1_pos = HEIGHT / 2
    paddle2_pos = HEIGHT / 2
    paddle1_vel = 0
    paddle2_vel = 0
    score1 = 0
    score2 = 0
    spawn_ball(LEFT)


def draw(canvas):
    global score1, score2, paddle1_pos, paddle2_pos, ball_pos, ball_vel

    # draw mid line and gutters
    canvas.draw_line([WIDTH / 2, 0], [WIDTH / 2, HEIGHT], 1, "White")
    canvas.draw_line([PAD_WIDTH, 0], [PAD_WIDTH, HEIGHT], 1, "White")
    canvas.draw_line([WIDTH - PAD_WIDTH, 0], [WIDTH - PAD_WIDTH, HEIGHT], 1, "White")

    # update ball
    ball_pos[0] += ball_vel[0]
    ball_pos[1] += ball_vel[1]

    # draw ball
    canvas.draw_circle(ball_pos, BALL_RADIUS, 1, "White", "White")

    # update paddle's vertical position, keep paddle on the screen
    if paddle1_pos + paddle1_vel >= HALF_PAD_HEIGHT and paddle1_pos + paddle1_vel <= HEIGHT - HALF_PAD_HEIGHT:
        paddle1_pos += paddle1_vel
    if paddle2_pos + paddle2_vel >= HALF_PAD_HEIGHT and paddle2_pos + paddle2_vel <= HEIGHT - HALF_PAD_HEIGHT:
        paddle2_pos += paddle2_vel

    # draw paddles
    canvas.draw_polygon([[0, paddle1_pos - HALF_PAD_HEIGHT], [PAD_WIDTH, paddle1_pos - HALF_PAD_HEIGHT],
                         [PAD_WIDTH, paddle1_pos + HALF_PAD_HEIGHT], [0, paddle1_pos + HALF_PAD_HEIGHT]], 1, "White", "White")
    canvas.draw_polygon([[WIDTH - PAD_WIDTH, paddle2_pos - HALF_PAD_HEIGHT], [WIDTH, paddle2_pos - HALF_PAD_HEIGHT],
                         [WIDTH, paddle2_pos + HALF_PAD_HEIGHT], [WIDTH - PAD_WIDTH, paddle2_pos + HALF_PAD_HEIGHT]], 1, "White", "White")

    # determine whether paddle and ball collide
    if ball_pos[0] <= BALL_RADIUS + PAD_WIDTH:  # vertical reflection - left side
        if ball_pos[1] > paddle1_pos - HALF_PAD_HEIGHT and ball_pos[1] < paddle1_pos + HALF_PAD_HEIGHT:
            ball_vel[0] = - ball_vel[0]
            increase_speed()
        else:
            score2 += 1
            spawn_ball(RIGHT)

    if ball_pos[0] >= WIDTH - BALL_RADIUS - PAD_WIDTH:  # vertical reflection - right side
        if ball_pos[1] > paddle2_pos - HALF_PAD_HEIGHT and ball_pos[1] < paddle2_pos + HALF_PAD_HEIGHT:
            ball_vel[0] = - ball_vel[0]
            increase_speed()
        else:
            score1 +=1
            spawn_ball(LEFT)

    if ball_pos[1] <= BALL_RADIUS:  # these two are for the horizontal reflection
        ball_vel[1] = - ball_vel[1]
    elif ball_pos[1] >= HEIGHT - BALL_RADIUS:
        ball_vel[1] = - ball_vel[1]

    # draw scores
    canvas.draw_text(str(score1), [140, 50], 44, 'White')
    canvas.draw_text(str(score2), [440, 50], 44, 'White')


def keydown(key):
    global paddle1_vel, paddle2_vel
    if key == simplegui.KEY_MAP["w"]:
        paddle1_vel = -8
    elif key == simplegui.KEY_MAP["s"]:
        paddle1_vel = 8
    if key == simplegui.KEY_MAP["up"]:
        paddle2_vel = -8
    elif key == simplegui.KEY_MAP["down"]:
        paddle2_vel = 8

def keyup(key):
    global paddle1_vel, paddle2_vel
    if key == simplegui.KEY_MAP["w"]:
        paddle1_vel = 0
    elif key == simplegui.KEY_MAP["s"]:
        paddle1_vel = 0
    if key == simplegui.KEY_MAP["up"]:
        paddle2_vel = 0
    elif key == simplegui.KEY_MAP["down"]:
        paddle2_vel = 0


# create frame
frame = simplegui.create_frame("Pong", WIDTH, HEIGHT)
frame.set_draw_handler(draw)
frame.set_keydown_handler(keydown)
frame.set_keyup_handler(keyup)
frame.add_button("Restart", new_game, 150)

# start frame
new_game()
frame.start()
