// Click-to-start gate.
//
// Browsers reject `audio.play()` without a user gesture. After a hard reload
// we want to resume playback automatically when possible and fall back to a
// "tap to start" modal otherwise. Inside the Electron shell autoplay is
// permitted, so a one-time "Don't show again" pref suppresses the modal.
//
// Usage:
//   const ok = await tryAutoplay(audioEl);     // best-effort attempt
//   if (!ok) {
//       await showStartModal({ stationName, onStart, onCancel });
//   }

const DISMISSED_KEY = 'oradio.autoplayDismissed';

function isElectron() {
    try { return !!(typeof window !== 'undefined' && window.oradioNative?.isElectron); }
    catch { return false; }
}

export function autoplayDismissed() {
    // Only honour the dismissal in Electron — plain browsers can't bypass
    // their autoplay policy regardless of any flag we set.
    if (!isElectron()) return false;
    try { return localStorage.getItem(DISMISSED_KEY) === '1'; }
    catch { return false; }
}

/** Try to start an <audio> element. Resolves true on success, false on rejection. */
export async function tryAutoplay(audio) {
    if (!audio) return false;
    try {
        const p = audio.play();
        if (p && typeof p.then === 'function') await p;
        return !audio.paused;
    } catch {
        return false;
    }
}

let _open = null;

/**
 * Show a blocking modal that captures a user gesture. Resolves when the user
 * taps Start (which fulfils browser autoplay rules for the subsequent
 * `audio.play()` the caller will perform). Rejects on Cancel.
 *
 * Returns a Promise. While the modal is open subsequent calls return the
 * same promise (idempotent).
 */
export function showStartModal({ stationName = 'Radio', subtitle = '', onStart, onCancel } = {}) {
    if (_open) return _open.promise;

    let resolve, reject;
    const promise = new Promise((res, rej) => { resolve = res; reject = rej; });

    const backdrop = document.createElement('div');
    backdrop.className = 'play-gate-backdrop';
    backdrop.setAttribute('role', 'dialog');
    backdrop.setAttribute('aria-modal', 'true');
    backdrop.setAttribute('aria-label', 'Tap to start audio');

    const card = document.createElement('div');
    card.className = 'play-gate-card';

    const h = document.createElement('h2');
    h.className = 'play-gate-title';
    h.textContent = 'Tap to start audio';
    card.appendChild(h);

    const name = document.createElement('div');
    name.className = 'play-gate-station';
    name.textContent = stationName;
    card.appendChild(name);

    if (subtitle) {
        const sub = document.createElement('div');
        sub.className = 'play-gate-sub';
        sub.textContent = subtitle;
        card.appendChild(sub);
    }

    const row = document.createElement('div');
    row.className = 'play-gate-row';
    const startBtn = document.createElement('button');
    startBtn.className = 'play-gate-start';
    startBtn.textContent = '▶ Start';
    const cancelBtn = document.createElement('button');
    cancelBtn.className = 'play-gate-cancel';
    cancelBtn.textContent = 'Cancel';
    row.appendChild(startBtn);
    row.appendChild(cancelBtn);
    card.appendChild(row);

    let dismissCheckbox = null;
    if (isElectron()) {
        const lbl = document.createElement('label');
        lbl.className = 'play-gate-dismiss';
        dismissCheckbox = document.createElement('input');
        dismissCheckbox.type = 'checkbox';
        dismissCheckbox.id = 'play-gate-dismiss-cb';
        lbl.appendChild(dismissCheckbox);
        const txt = document.createElement('span');
        txt.textContent = " Don't show again on this device";
        lbl.appendChild(txt);
        card.appendChild(lbl);
    }

    backdrop.appendChild(card);
    document.body.appendChild(backdrop);
    queueMicrotask(() => startBtn.focus());

    function close() {
        if (_open?.backdrop?.parentNode) _open.backdrop.parentNode.removeChild(_open.backdrop);
        _open = null;
    }

    function persistDismissal() {
        if (dismissCheckbox && dismissCheckbox.checked) {
            try { localStorage.setItem(DISMISSED_KEY, '1'); } catch { /* ignore */ }
        }
    }

    startBtn.addEventListener('click', () => {
        persistDismissal();
        close();
        try { onStart && onStart(); } catch { /* ignore */ }
        resolve();
    });
    cancelBtn.addEventListener('click', () => {
        close();
        try { onCancel && onCancel(); } catch { /* ignore */ }
        reject(new Error('autoplay-cancelled'));
    });
    backdrop.addEventListener('keydown', (e) => {
        if (e.key === 'Escape') cancelBtn.click();
    });

    _open = { backdrop, promise };
    return promise;
}

export function isStartModalOpen() { return !!_open; }