extends RefCounted

const MIN_SECONDS := 5
const BASE_SECONDS := 30
# Cumulative P(cooldown <= seconds); interpolate exponentially between anchors.
const SECONDS := [5, 10, 15, 20, 25, 30]
const CHANCES := [0.0002, 0.0015, 0.01, 0.05, 0.25, 1.0]

static func cumulative_chance(seconds: int) -> float:
	if seconds < MIN_SECONDS:
		return 0.0
	if seconds >= BASE_SECONDS:
		return 1.0
	for index in SECONDS.size() - 1:
		if seconds <= SECONDS[index + 1]:
			var progress := float(seconds - SECONDS[index]) / float(SECONDS[index + 1] - SECONDS[index])
			return exp(lerpf(log(CHANCES[index]), log(CHANCES[index + 1]), progress))
	return 1.0

static func from_roll(roll: float) -> int:
	for seconds in range(MIN_SECONDS, BASE_SECONDS):
		if roll < cumulative_chance(seconds):
			return seconds
	return BASE_SECONDS

static func roll_seconds() -> int:
	return from_roll(randf())