/**
 * Navigation controller for Remark.js presentations in iframes.
 * 
 * Looks for elements with class 'html-viewer-container'.
 */

document$.subscribe(({ body }) => {
    const containers = body.querySelectorAll('.html-viewer-container');
    
    containers.forEach(container => {
        const iframe = container.querySelector('iframe');
        const prevBtn = container.querySelector('.prev-btn');
        const nextBtn = container.querySelector('.next-btn');
        const pageNumDisplay = container.querySelector('.page-num');
        const pageCountDisplay = container.querySelector('.page-count');

        if (!iframe || !prevBtn || !nextBtn) return;

        function updatePageInfo() {
            try {
                if (iframe.contentWindow && iframe.contentWindow.slideshow) {
                    const slideshow = iframe.contentWindow.slideshow;
                    const currentIndex = slideshow.getCurrentSlideIndex() + 1;
                    const totalSlides = slideshow.getSlides().length;

                    if (pageNumDisplay) pageNumDisplay.textContent = currentIndex;
                    if (pageCountDisplay) pageCountDisplay.textContent = totalSlides;
                }
            } catch (e) {
                // Silently fail if cross-origin or slideshow not yet loaded
            }
        }

        prevBtn.addEventListener('click', () => {
            try {
                if (iframe.contentWindow && iframe.contentWindow.slideshow) {
                    iframe.contentWindow.slideshow.gotoPreviousSlide();
                    updatePageInfo();
                } else {
                    iframe.contentWindow.dispatchEvent(new KeyboardEvent('keydown', { 'keyCode': 37 }));
                }
            } catch (e) {
                console.error("Could not navigate slideshow:", e);
            }
        });

        nextBtn.addEventListener('click', () => {
            try {
                if (iframe.contentWindow && iframe.contentWindow.slideshow) {
                    iframe.contentWindow.slideshow.gotoNextSlide();
                    updatePageInfo();
                } else {
                    iframe.contentWindow.dispatchEvent(new KeyboardEvent('keydown', { 'keyCode': 39 }));
                }
            } catch (e) {
                console.error("Could not navigate slideshow:", e);
            }
        });

        // Update info when iframe loads
        iframe.addEventListener('load', updatePageInfo);

        // Periodically update in case the user navigates using the keyboard inside the iframe
        setInterval(updatePageInfo, 500);
    });
});