import random
import utime

from patterns.pattern_modes import style_mode

_LEGACY = {"starfall": 1}


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

    def _run_snowfall(self, preset, colors, flakes, last):
        density = max(1, int(preset.n1) if int(preset.n1) > 0 else 20)
        speed = max(1, int(preset.n2) if int(preset.n2) > 0 else 1)
        d = max(1, int(preset.d))
        now = utime.ticks_ms()
        if utime.ticks_diff(now, last) < d:
            return flakes, last, False
        bg_color = self.driver.apply_brightness(preset.background_or(colors), preset.b)
        if random.randint(0, 255) < density:
            flakes.append([self.driver.num_leds - 1, random.randint(0, len(colors) - 1)])
        for i in range(self.driver.num_leds):
            self.driver.n[i] = bg_color
        nf = []
        for pos, ci in flakes:
            if 0 <= pos < self.driver.num_leds:
                self.driver.n[pos] = self.driver.apply_brightness(colors[ci], preset.b)
            pos -= speed
            if pos >= -1:
                nf.append([pos, ci])
        self.driver.n.write()
        return nf, utime.ticks_add(last, d), True

    def _run_starfall(self, preset, colors, stars, last):
        rate = max(1, min(255, int(preset.n1) if int(preset.n1) > 0 else 14))
        speed = max(1, int(preset.n2) if int(preset.n2) > 0 else 2)
        tail = max(2, int(preset.n3) if int(preset.n3) > 0 else 10)
        max_stars = 4
        d = max(1, int(preset.d))
        now = utime.ticks_ms()
        if utime.ticks_diff(now, last) < d:
            return stars, last, False
        bg = self.driver.apply_brightness(preset.background_or(colors), preset.b)
        for i in range(self.driver.num_leds):
            self.driver.n[i] = bg
        if len(stars) < max_stars and random.randint(0, 255) < rate:
            top = self.driver.num_leds - 1 + random.randint(
                0, min(8, self.driver.num_leds // 2)
            )
            stars.append({"h": float(top), "ci": random.randint(0, len(colors) - 1)})
        ns = []
        for s in stars:
            h = s["h"]
            ci = s["ci"]
            ih = int(h)
            for t in range(tail):
                idx = ih + t
                if 0 <= idx < self.driver.num_leds:
                    fade = 255 - (t * 255 // max(1, tail - 1))
                    base = colors[ci]
                    lit = (
                        (base[0] * fade) // 255,
                        (base[1] * fade) // 255,
                        (base[2] * fade) // 255,
                    )
                    lit = self.driver.apply_brightness(lit, preset.b)
                    o = self.driver.n[idx]
                    self.driver.n[idx] = (
                        max(o[0], lit[0]),
                        max(o[1], lit[1]),
                        max(o[2], lit[2]),
                    )
            h -= speed
            if h >= -tail:
                s["h"] = h
                ns.append(s)
        stars = ns
        self.driver.n.write()
        return stars, utime.ticks_add(last, d), True

    def run(self, preset):
        """Falling particles: n6 0 snowfall flakes, 1 starfall streaks."""
        mode = style_mode(preset, 0, _LEGACY)
        colors = preset.c if preset.c else [(255, 255, 255), (180, 220, 255)]
        last = utime.ticks_ms()

        if mode == 1:
            colors = preset.c if preset.c else [
                (255, 255, 255),
                (200, 230, 255),
                (255, 248, 220),
            ]
            stars = []
            while True:
                stars, last, stepped = self._run_starfall(preset, colors, stars, last)
                if stepped and not preset.a:
                    yield
                    return
                yield

        flakes = []
        while True:
            flakes, last, stepped = self._run_snowfall(preset, colors, flakes, last)
            if stepped and not preset.a:
                yield
                return
            yield