export default class SessionTicker {
    constructor({ duration, onTick, onExpire, tickInterval = 1 }) {
        this.duration = duration;
        this.onTick = onTick;
        this.onExpire = onExpire;
        this.tickInterval = tickInterval;
        this.expiresAt = null;
        this._interval = null;
        this._onVisibility = this._onVisibility.bind(this);
        this._onPageShow = this._onPageShow.bind(this);
    }

    start() {
        this.expiresAt = Date.now() + this.duration * 1000;
        this._attachListeners();
        this._tick();
        this._interval = setInterval(() => this._tick(), this.tickInterval * 1000);
        return this;
    }

    stop() {
        clearInterval(this._interval);
        this._interval = null;
        this._detachListeners();
        return this;
    }

    reset(newDuration) {
        if (newDuration != null) this.duration = newDuration;
        this.stop();
        return this.start();
    }

    getRemaining() {
        if (!this.expiresAt) return 0;
        return Math.max(0, Math.ceil((this.expiresAt - Date.now()) / 1000));
    }

    _tick() {
        const remaining = this.getRemaining();
        this.onTick?.(remaining);
        if (remaining <= 0) {
            this.stop();
            this.onExpire?.();
        }
    }

    _onVisibility() {
        if (document.visibilityState === 'visible') this._tick();
    }

    _onPageShow(e) {
        if (e.persisted) this._tick();
    }

    _attachListeners() {
        document.addEventListener('visibilitychange', this._onVisibility);
        window.addEventListener('pageshow', this._onPageShow);
    }

    _detachListeners() {
        document.removeEventListener('visibilitychange', this._onVisibility);
        window.removeEventListener('pageshow', this._onPageShow);
    }
}