import pygame
import pygame.locals
import random

pygame.init()
screen=pygame.display.set_mode((300,300))
pygame.display.set_caption('Fountain')

numBalls = 10
gravity = 0.1

class Ball:
  def __init__(self):
    self.radius = 5
    self.x = 150
    self.y = 260
    self.vx = random.uniform(-1, 1)
    self.vy = random.uniform(-7, -3)
    # https://www.pygame.org/docs/ref/color.html
    c = pygame.Color(0, 0, 0)
    # hue saturation lightness alpha
    c.hsla = (colour, 100, 50, 100)
    self.color = c;

  def go(self):
    # move
    self.vy += gravity;
    self.x += self.vx;
    self.y += self.vy;

    # fallen off bottom of the screen, fire it off again
    if self.y > 300:
      self.__init__()

    # draw
    # https://www.pygame.org/docs/ref/draw.html
    # circle(surface, color, center, radius)
    pygame.draw.circle(screen, self.color, (int(self.x), int(self.y)), self.radius)

colour = 0

# make a list of balls
listballs = [Ball() for i in range(numBalls)]

clock = pygame.time.Clock()

running = True

while running:
  # get one event off the event queue
  # without waiting until there is one
  event = pygame.event.poll()
  if event.type == pygame.locals.QUIT:
    running = False
  # ignore all other events

  colour += 1
  if colour == 360:
    colour = 0

  # clear screen
  screen.fill((255,255,255))

  # draw all the balls
  [b.go() for b in listballs]

  pygame.display.update()

  # time delay
  # from the raspberry spoon game
  # https://www.pygame.org/docs/ref/time.html
  clock.tick(30)

pygame.quit()