import random
import utime


class SparkleTrail:
    def __init__(self, driver):
        self.driver = driver

    def run(self, preset):
        colors = preset.c if preset.c else [(120, 120, 255)]
        density = max(1, int(preset.n1) if int(preset.n1) > 0 else 24)
        decay = max(1, min(255, int(preset.n2) if int(preset.n2) > 0 else 210))
        last = utime.ticks_ms()
        while True:
            d = max(1, int(preset.d))
            now = utime.ticks_ms()
            if utime.ticks_diff(now, last) >= d:
                for i in range(self.driver.num_leds):
                    r,g,b = self.driver.n[i]
                    self.driver.n[i] = ((r*decay)//255, (g*decay)//255, (b*decay)//255)
                sparks = max(1, self.driver.num_leds * density // 255)
                for _ in range(sparks):
                    idx = random.randint(0, max(0, self.driver.num_leds - 1))
                    c = self.driver.apply_brightness(colors[random.randint(0, len(colors)-1)], preset.b)
                    self.driver.n[idx] = c
                self.driver.n.write()
                last = utime.ticks_add(last, d)
                if not preset.a:
                    yield
                    return
            yield