"""Simple one-pixel chase (uses preset c[0] for the dot, preset n3 as step)."""

import utime


class Chase:
    def __init__(self, presets):
        self.presets = presets

    def run(self, preset):
        n = self.presets.num_leds
        rgb = preset.c[0] if preset.c else (255, 64, 0)
        raw_step = int(getattr(preset, "n3", 1))
        step = raw_step if raw_step != 0 else 1
        pos = 0
        delay_ms = max(1, int(preset.d))
        while True:
            off = (0, 0, 0)
            for i in range(n):
                self.presets.n[i] = off
            self.presets.n[pos % n] = self.presets.apply_brightness(rgb, preset.b)
            self.presets.n.write()
            yield
            utime.sleep_ms(delay_ms)
            pos += step