# A program that simulates a two-player game of pong.
# Author: Nicholas Coleman
# The 'a' and 'z' keys are used to move player 1 (left)
# The up and down arrows are used to move player 2 (right)
# The space bar is used to serve
# The program does not currently keep track of points

from turtle import *

class TurtlePong:

    # Create a new TurtlePong object
    def __init__(game):
        # Create Turtle object for player 1
        game.player1 = makePlayer(-300, 0)

        # Create Turtle object for player 2
        game.player2 = makePlayer(300, 0)

        # Create Turtle object for the ball
        game.ball = makeBall(30)

        # Set player 1 as the first server
        game.setServer(game.player1)

        # Use 'a' and 'z' to move player1
        onkey(game.p1up, "a")
        onkey(game.p1down, "z")

        # Use up and down arrows to move player 2
        onkey(game.p2up, "Up")
        onkey(game.p2down, "Down")

        # Use space bar to serve
        onkey(game.serve, " ")

        listen()

    # Give the ball to the player who will serve next
    def setServer(game, server):
        game.ball.speed("fastest")
        if server == game.player1:
            offset = 25
        else: # server == player 2
            offset = -25
        game.ball.goto(server.xcor() + offset, server.ycor())
        game.server = server
        game.holding = True

    # move player 1 up
    def p1up(game):
        moveUp(game.player1)
        if game.server == game.player1 and game.holding:
            moveUp(game.ball)

    # move player 1 down
    def p1down(game):
        moveDown(game.player1)
        if game.server == game.player1 and game.holding:
            moveDown(game.ball)

    # move player 2 up
    def p2up(game):
        moveUp(game.player2)
        if game.server == game.player2 and game.holding:
            moveUp(game.ball)

    # move player 2 down
    def p2down(game):
        moveDown(game.player2)
        if game.server == game.player2 and game.holding:
            moveDown(game.ball)

    # serve the ball if it is ready to be served
    def serve(game):

        # only serve if a player is holding the ball
        if(game.holding):
            game.holding = False

            # keep going until the ball is out of bounds
            while game.ball.xcor() > -300 and game.ball.xcor() < 300:

                # if the ball hits the top or bottom wall, change direction
                if game.ball.ycor() > 300 or game.ball.ycor() < -300:
                    game.ball.speed("fastest")
                    game.ball.setheading(360 - game.ball.heading())

                # if the ball hits player 1 or 2, change direction
                if touching(game.player1, game.ball) or \
                   touching(game.player2, game.ball):
                    game.ball.speed("fastest")
                    game.ball.setheading(180 - game.ball.heading())

                # move the ball forward
                game.ball.speed("slowest")
                game.ball.forward(10)

            # if the ball is out on player 1's side, serve goes to player 2
            if game.ball.xcor() < -300:
                game.setServer(game.player2)

            # if the ball is out on player 2's side, serve goes to player 1
            if game.ball.xcor() > 300:
                game.setServer(game.player1)
            
# make a turtle that looks like a pong player
def makePlayer(xPos, yPos):
    player = Turtle()
    player.shape("square")
    player.shapesize(4.0, 1.0)
    player.speed("fastest")
    player.penup()
    player.goto(xPos, yPos)
    return player

# make a turtle that looks like a turtle, but acts like a ball
def makeBall(heading):
    ball = Turtle()
    ball.shape("turtle")
    ball.penup()
    ball.setheading(heading)
    return ball

# move a turtle up by 25 pixels
def moveUp(turtle):
    turtle.goto(turtle.xcor(), turtle.ycor() + 25)

# move a turtle down by 25 pixels
def moveDown(turtle):
    turtle.goto(turtle.xcor(), turtle.ycor() - 25)

# determine if a player is touching the ball
def touching(player, ball):
    return abs(ball.xcor() - player.xcor()) < 25 and \
           abs(ball.ycor() - player.ycor()) < 50

# Create a new game and keep it going until the user clicks on the window
def main():
    game = TurtlePong()
    exitonclick()

main()