import { useEffect, useState } from "react";
import { COUNTDOWN_ENABLED, REGISTRATION_OPENS_AT } from "./opening";

interface RegistrationOpenState {
	isOpen: boolean;
	days: number;
	hours: number;
	minutes: number;
	seconds: number;
}

function compute(): RegistrationOpenState {
	if (!COUNTDOWN_ENABLED) {
		return { isOpen: true, days: 0, hours: 0, minutes: 0, seconds: 0 };
	}
	const diff = REGISTRATION_OPENS_AT.getTime() - Date.now();
	if (diff <= 0) {
		return { isOpen: true, days: 0, hours: 0, minutes: 0, seconds: 0 };
	}
	const totalSeconds = Math.floor(diff / 1000);
	const days = Math.floor(totalSeconds / 86400);
	const hours = Math.floor((totalSeconds % 86400) / 3600);
	const minutes = Math.floor((totalSeconds % 3600) / 60);
	const seconds = totalSeconds % 60;
	return { isOpen: false, days, hours, minutes, seconds };
}

/**
 * Returns live countdown state to {@link REGISTRATION_OPENS_AT}.
 * Ticks every second; clears the interval once registration is open.
 */
export function useRegistrationOpen(): RegistrationOpenState {
	const [state, setState] = useState<RegistrationOpenState>(compute);

	useEffect(() => {
		if (state.isOpen) return;

		const id = setInterval(() => {
			const next = compute();
			setState(next);
			if (next.isOpen) clearInterval(id);
		}, 1000);

		return () => clearInterval(id);
	}, [state.isOpen]);

	return state;
}