import pygame as pg

from dataclasses import dataclass
from pygame import QUIT, KEYDOWN, K_ESCAPE
from pygame.font import Font
from pygame.math import Vector2
from pygame.surface import Surface
from pygame.time import Clock
from random import randint


WINDOW_SIZE = (800, 450)

BG_COLOR = (200, 200, 200)

SPEED = Vector2(0, -3)

FPS = 60


@dataclass()
class Letter:
    position: Vector2
    surface: Surface


def next_position(surf):
    return Vector2(
        randint(0, WINDOW_SIZE[0] - surf.get_width()),
        WINDOW_SIZE[1] + surf.get_height()
    )


def main():
    pg.init()

    surface = pg.display.set_mode(WINDOW_SIZE)
    font = Font('Boxy-Bold.ttf', 24)

    items = []
    clock = Clock()

    working = True
    while working:
        # Handle events
        for e in pg.event.get():
            if e.type == QUIT:
                working = False
                continue

            if e.type != KEYDOWN:
                continue

            if e.key == K_ESCAPE:
                working = False

            char = e.unicode.strip()
            if char:
                surf = font.render(char, False, (50, 50, 50))
                items.append(Letter(next_position(surf), surf))

        # Update
        for i in items:
            i.position += SPEED
        items = [i for i in items if i.position.y > -i.surface.get_height()]

        # Render
        surface.fill(BG_COLOR)
        for i in items:
            surface.blit(i.surface, i.position)
        pg.display.update()

        clock.tick(FPS)

    pg.quit()


if __name__ == "__main__":
    main()