/**
 * Screenshot Gallery / Lightbox functionality — the website's ONE picture viewer (2026-10-08).
 *
 * A set is DECLARED in the page, never guessed: every picture that opens the viewer is a real link to its full-size
 * file, `<a href="/assets/…webp" data-gallery="<set>">`, and a set is all links with the same name, in page order.
 * An app card's further pictures are hidden links in the same card. Nothing is probed, nothing outside the page is
 * requested. With JavaScript off the link simply opens the image, so the page keeps working.
 *
 * Closes on: the close button, Esc, a click beside the picture, and a click or tap ON the picture. A swipe changes the
 * picture and does not close. Labels follow <html lang>.
 */
(function () {
    'use strict';

    // Debug mode - set to true for console logging
    const DEBUG = false;
    function log(...args) {
        if (DEBUG) console.log('[Gallery]', ...args);
    }

    const LABELS = {
        hu: { close: 'Bezárás', prev: 'Előző', next: 'Következő', loading: 'Betöltés...', go: n => `Ugrás ${n}. képhez`, dialog: 'Képnézegető' },
        en: { close: 'Close', prev: 'Previous', next: 'Next', loading: 'Loading...', go: n => `Go to image ${n}`, dialog: 'Picture viewer' },
    };
    const lang = (document.documentElement.lang || 'hu').slice(0, 2);
    const L = LABELS[lang] || LABELS.hu;

    // The markup, built once.
    const box = document.createElement('div');
    box.className = 'lightbox-overlay';
    box.setAttribute('role', 'dialog');
    box.setAttribute('aria-modal', 'true');
    box.setAttribute('aria-label', L.dialog);
    box.tabIndex = -1;
    box.innerHTML =
        '<button type="button" class="lightbox-close"></button>' +
        '<div class="lightbox-content">' +
        '<button type="button" class="lightbox-nav lightbox-prev">‹</button>' +
        '<img class="lightbox-image" src="" alt="">' +
        '<button type="button" class="lightbox-nav lightbox-next">›</button>' +
        '</div>' +
        '<div class="lightbox-counter"></div>' +
        '<div class="lightbox-dots"></div>';
    const closeBtn = box.querySelector('.lightbox-close');
    const prevBtn = box.querySelector('.lightbox-prev');
    const nextBtn = box.querySelector('.lightbox-next');
    const img = box.querySelector('.lightbox-image');
    const counter = box.querySelector('.lightbox-counter');
    const dots = box.querySelector('.lightbox-dots');
    closeBtn.setAttribute('aria-label', L.close);
    closeBtn.innerHTML = '&times;';
    prevBtn.setAttribute('aria-label', L.prev);
    nextBtn.setAttribute('aria-label', L.next);

    const state = { items: [], index: 0, opener: null, swiped: false };

    function altOf(a, fallback) {
        const i = a.querySelector('img');
        return (i && i.getAttribute('alt')) || a.getAttribute('data-alt') || fallback || '';
    }

    function show() {
        const it = state.items[state.index];
        counter.textContent = L.loading;
        img.onload = () => update();
        img.src = it.src;
        img.alt = it.alt;
        update();
    }

    function update() {
        const n = state.items.length;
        counter.textContent = `${state.index + 1} / ${n}`;
        dots.querySelectorAll('.lightbox-dot').forEach((d, i) => d.classList.toggle('active', i === state.index));
        prevBtn.disabled = state.index === 0;
        nextBtn.disabled = state.index === n - 1;
        const single = n <= 1;
        prevBtn.style.display = single ? 'none' : 'flex';
        nextBtn.style.display = single ? 'none' : 'flex';
        dots.style.display = single ? 'none' : 'flex';
        counter.style.display = single ? 'none' : 'block';
        // a button that just turned off would drop the focus to the page behind the viewer
        if (document.activeElement && document.activeElement.disabled) closeBtn.focus();
    }

    function go(i) {
        if (i >= 0 && i < state.items.length && i !== state.index) {
            state.index = i;
            show();
        }
    }

    function open(link) {
        const name = link.getAttribute('data-gallery');
        const links = Array.from(document.querySelectorAll('a[data-gallery]')).filter(a => a.getAttribute('data-gallery') === name);
        const clickedAlt = altOf(link);
        state.items = links.map(a => ({ src: a.getAttribute('href'), alt: a === link ? clickedAlt : altOf(a, clickedAlt) }));
        state.index = Math.max(0, links.indexOf(link));
        state.opener = link;
        log('open', name, state.items.length, 'pictures');
        dots.innerHTML = '';
        state.items.forEach((_, i) => {
            const d = document.createElement('button');
            d.type = 'button';
            d.className = 'lightbox-dot';
            d.setAttribute('aria-label', L.go(i + 1));
            d.addEventListener('click', e => { e.stopPropagation(); go(i); });
            dots.appendChild(d);
        });
        if (!box.parentNode) document.body.appendChild(box);
        box.classList.add('active');
        document.body.style.overflow = 'hidden';
        show();
        closeBtn.focus();
    }

    function close() {
        if (!box.classList.contains('active')) return;
        box.classList.remove('active');
        document.body.style.overflow = '';
        img.removeAttribute('src');
        const back = state.opener;
        state.items = [];
        state.index = 0;
        state.opener = null;
        if (back) back.focus();
        log('closed');
    }

    // Openers: a plain click opens the viewer; a modified click (new tab, etc.) is left to the browser.
    document.addEventListener('click', e => {
        const a = e.target.closest('a[data-gallery]');
        if (!a || e.defaultPrevented || e.button !== 0 || e.metaKey || e.ctrlKey || e.shiftKey || e.altKey) return;
        e.preventDefault();
        open(a);
    });

    closeBtn.addEventListener('click', e => { e.stopPropagation(); close(); });
    prevBtn.addEventListener('click', e => { e.stopPropagation(); go(state.index - 1); });
    nextBtn.addEventListener('click', e => { e.stopPropagation(); go(state.index + 1); });

    // A click anywhere else closes: beside the picture, and on the picture itself — unless it ended a swipe.
    box.addEventListener('click', e => {
        if (state.swiped) { state.swiped = false; return; }
        if (e.target === box || e.target.classList.contains('lightbox-content') || e.target === img) close();
    });

    document.addEventListener('keydown', e => {
        if (!box.classList.contains('active')) return;
        if (e.key === 'Escape') close();
        else if (e.key === 'ArrowLeft') go(state.index - 1);
        else if (e.key === 'ArrowRight') go(state.index + 1);
    });

    // Swipe on a phone: changes the picture, never closes (the click that follows a swipe is swallowed above).
    let startX = 0, startY = 0;
    box.addEventListener('touchstart', e => {
        startX = e.changedTouches[0].screenX;
        startY = e.changedTouches[0].screenY;
        state.swiped = false;
    }, { passive: true });
    box.addEventListener('touchend', e => {
        const dx = startX - e.changedTouches[0].screenX;
        const dy = startY - e.changedTouches[0].screenY;
        if (Math.abs(dx) > 50 && Math.abs(dx) > Math.abs(dy)) {
            state.swiped = true;
            if (dx > 0) go(state.index + 1); else go(state.index - 1);
        }
    }, { passive: true });

    log('Gallery initialized');
})();