# Implementation of classic arcade game Pong

import simplegui
import random

# 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
RIGHT = True

#position[x,y] and velocity[x,y] of ball
ball_pos=[0,0]
ball_vel=[0,0]

#position[x,y] and velocity[x,y] of paddles
paddle_pos=[HEIGHT/2,HEIGHT/2]
paddle_vel=[0,0]

#score[left,rigth]
score=[0,0]

# 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]
    ball_vel[0]=random.randrange(2, 4);
    ball_vel[1]=-1*random.randrange(1, 3);
    if direction==LEFT:
        ball_vel[0] =-1*ball_vel[0]


# define event handlers
def new_game():
    global score, paddle_pos
    score=[0,0]
    paddle_pos=[HEIGHT/2,HEIGHT/2]
    spawn_ball(LEFT)

#draw
def draw(c):
    # draw mid line and gutters
    c.draw_line([WIDTH / 2, 0],[WIDTH / 2, HEIGHT], 1, "White")
    c.draw_line([PAD_WIDTH, 0],[PAD_WIDTH, HEIGHT], 1, "White")
    c.draw_line([WIDTH - PAD_WIDTH, 0],[WIDTH - PAD_WIDTH, HEIGHT], 1, "White")     
    # update ball
    new_position_ball()
            
    # draw ball
    c.draw_circle(ball_pos,BALL_RADIUS,2,"White","White")
    
    # update paddle's vertical position, keep paddle on the screen
    modify_paddle(0)
    modify_paddle(1)
    
    # draw paddles
    c.draw_polygon(rectangle_paddle(0,paddle_pos[0]), 1, "White", "White")
    c.draw_polygon(rectangle_paddle(1,paddle_pos[1]), 1, "White", "White")
    
    #check the colision
    colision()
    
    # draw scores
    c.draw_text(str(score[0]),[WIDTH*(1/3.0),120],50, "Green")
    c.draw_text(str(score[1]),[WIDTH*(2/3.0),120],50, "Green")
     
#increase and decrease the velocity of paddles
def keydown(key):
    if key==simplegui.KEY_MAP["s"]:
        paddle_vel[0]+=5
    elif key==simplegui.KEY_MAP["w"]:
        paddle_vel[0]-=5
    elif key==simplegui.KEY_MAP["down"]:
        paddle_vel[1]+=5
    elif key==simplegui.KEY_MAP["up"]:
        paddle_vel[1]-=5
   
def keyup(key):
    if key==simplegui.KEY_MAP["s"]:
        paddle_vel[0]-=5
    elif key==simplegui.KEY_MAP["w"]:
        paddle_vel[0]+=5
    elif key==simplegui.KEY_MAP["down"]:
        paddle_vel[1]-=5
    elif key==simplegui.KEY_MAP["up"]:
        paddle_vel[1]+=5
        
#check if ball have colision with the paddle or the edge
def colision():
    #get the limits of paddle
    rigth_limit=WIDTH-PAD_WIDTH-BALL_RADIUS
    left_limit=PAD_WIDTH+BALL_RADIUS
    
    #check if ball colide with the edge
    if ball_pos[0]>=rigth_limit:
        #if yes, check the position of the paddle to increase velocity or score
        if colision_with_ball(paddle_pos[1])==1:
            ball_vel[0]+=ball_vel[0]*0.10
            ball_vel[1]+=ball_vel[1]*0.10
        else:
            score[0]+=1
            spawn_ball(LEFT)
        
    #check if ball colide with the edge
    elif ball_pos[0]<= left_limit:
        #if yes, check the position of the paddle to increase velocity or score
        if colision_with_ball(paddle_pos[0])==1:
            ball_vel[0]+=ball_vel[0]*0.10
            ball_vel[1]+=ball_vel[1]*0.10
        else:
            score[1]+=1
            spawn_ball(RIGHT)
            
#check if ball colides with the paddle
#return 1 if colides, 0 otherwise
def colision_with_ball(y):
    if ball_pos[1]<=y+HALF_PAD_HEIGHT and ball_pos[1]>=y-HALF_PAD_HEIGHT:
        return 1
    else:
        return 0

#move the paddle
def modify_paddle(paddle):
    upperPosition=paddle_pos[paddle]+paddle_vel[paddle]-HALF_PAD_HEIGHT
    downPosition=paddle_pos[paddle]+paddle_vel[paddle]+HALF_PAD_HEIGHT
    if not(upperPosition<0 or downPosition>HEIGHT):
            paddle_pos[paddle]+=paddle_vel[paddle]

#get the rectangle of paddle
def rectangle_paddle(position,y):
    point = [[0,0],[0,0],[0,0],[0,0]]
    side=0
    if position>0:
        side=WIDTH-PAD_WIDTH
        
    point[0] = [side, y-HALF_PAD_HEIGHT]
    point[1] = [side+PAD_WIDTH, y-HALF_PAD_HEIGHT]
    point[2] = [side+PAD_WIDTH, y+HALF_PAD_HEIGHT]
    point[3] = [side, y+HALF_PAD_HEIGHT]
    
    return point   

#update position ball
def new_position_ball():
    ball_pos[0] += ball_vel[0]
    ball_pos[1] += ball_vel[1]
    
    under_limit=HEIGHT-BALL_RADIUS
    upper_limit=BALL_RADIUS
    rigth_limit=WIDTH-PAD_WIDTH-BALL_RADIUS
    left_limit=PAD_WIDTH+BALL_RADIUS
    
    if ball_pos[0]>=rigth_limit:
        ball_vel[0]*=-1
        ball_pos[0]=rigth_limit
    elif ball_pos[0]<= left_limit:
        ball_vel[0]*=-1
        ball_pos[0]=left_limit
        
    if ball_pos[1]>=under_limit:
        ball_vel[1]*=-1
        ball_pos[1]=under_limit
    elif ball_pos[1]<=upper_limit:
        ball_pos[1]=upper_limit
        ball_vel[1]*=-1
            


# 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("Reset", new_game)


# start frame
new_game()
frame.start()