class_name Luck
extends RefCounted
## Numeric Luck (charter §7). Lives in GameState; only descriptor() reaches the
## log. Deterministic given a seeded RNG (charter §10). Die/range/bands are
## TUNABLE constants — not final values.

const MIN := 1
const MAX := 20
const DRIFT := 3

const BANDS := [
	{"max": 4, "text": "Fortune spits on you"},
	{"max": 8, "text": "The world is not on your side"},
	{"max": 12, "text": "The dice are indifferent"},
	{"max": 16, "text": "Luck rides with you"},
	{"max": 20, "text": "The dice are kind today"},
]


static func roll_base(rng: RandomNumberGenerator, modifier: int) -> int:
	var total := 0
	for i in 5:
		total += rng.randi_range(1, 20)
	return clampi(roundi(total / 5.0) + modifier, MIN, MAX)


static func drift(current: int, base: int, delta: int) -> int:
	return clampi(clampi(current + delta, base - DRIFT, base + DRIFT), MIN, MAX)


static func descriptor(luck: int) -> String:
	for band in BANDS:
		if luck <= band["max"]:
			return band["text"]
	return BANDS[-1]["text"]