import { useEffect, useState } from 'react';

// A ready sandbox opens before its refreshed copy lands, so the sandbox says the latest setup changes
// are on their way for as long as that is true. Read, never consumed: a remount must not swallow it.
const LANDING_KEY = 'akashic_sandbox_landing';
const SHOWN_MS = 90_000;

export const LANDING_COPY = 'Your latest setup changes arrive in about a minute.';

type NoticeStorage = Pick<Storage, 'getItem' | 'setItem' | 'removeItem'>;

export const markLanding = (storage: NoticeStorage, at: number = Date.now()): void => {
    try {
        storage.setItem(LANDING_KEY, String(at));
    } catch {
        // Storage refused: entry still works, it just says nothing about the copy.
    }
};

// Milliseconds left to show the notice; zero when unmarked, stale or unreadable.
const landingLeft = (storage: NoticeStorage, now: number): number => {
    try {
        const at = Number(storage.getItem(LANDING_KEY));
        const left = at ? at + SHOWN_MS - now : 0;
        return left > 0 && left <= SHOWN_MS ? left : 0;
    } catch {
        return 0;
    }
};

export const SandboxLandingNotice = () => {
    const [left] = useState(() => landingLeft(sessionStorage, Date.now()));
    const [shown, setShown] = useState(left > 0);

    useEffect(() => {
        if (!shown) return;
        const timer = setTimeout(() => setShown(false), left);
        return () => clearTimeout(timer);
    }, [shown, left]);

    return shown ? <span>{LANDING_COPY}</span> : null;
};

export default SandboxLandingNotice;