extends RefCounted

const CHANCES := [1.0, 0.25, 0.05, 0.01, 0.0015, 0.0002]

static func tail_chance(quality: float) -> float:
	var scaled := clampf(quality, 0.0, 1.0) * 5.0
	var index := mini(4, floori(scaled))
	return exp(lerpf(log(CHANCES[index]), log(CHANCES[index + 1]), scaled - index))

static func rank_from_roll(steps: int, roll: float) -> int:
	for rank in range(steps, 0, -1):
		if roll < tail_chance(float(rank) / steps):
			return rank
	return 0

static func roll_value(effect: String, roll: float = -1.0) -> float:
	var chance := randf() if roll < 0.0 else roll
	match effect:
		"recycler": return 0.5 + rank_from_roll(79, chance) * 0.5
		"virus": return 1.0 + rank_from_roll(19, chance)
		"titanium_armor": return 5.0 + rank_from_roll(45, chance)
	return 0.0