"""16x16 matrix-style rain animation."""

from machine import Pin
import neopixel
import random
import time

from panel16_utils import PANEL_H, PANEL_W, clamp8, xy_to_index


np = neopixel.NeoPixel(Pin(4), PANEL_W * PANEL_H)
rng = random.Random(42)

heads = [rng.randrange(-PANEL_H, 0) for _ in range(PANEL_W)]

for _frame in range(320):
    for y in range(PANEL_H):
        for x in range(PANEL_W):
            np[xy_to_index(x, y)] = (0, 0, 0)

    for x in range(PANEL_W):
        heads[x] += 1
        if heads[x] > PANEL_H + 6:
            heads[x] = rng.randrange(-PANEL_H, 0)

        head_y = heads[x]
        for tail in range(8):
            y = head_y - tail
            if 0 <= y < PANEL_H:
                brightness = clamp8(255 - tail * 36)
                np[xy_to_index(x, y)] = (0, brightness, 0)

    np.write()
    time.sleep(0.045)

np.fill((0, 0, 0))
np.write()