// Trusted parent-side measurement; template scripts stay disabled by sandbox and CSP.
(() => {
    const frame = document.getElementById('previewHtmlFrame');
    let observer;
    let scheduled = 0;

    function resizePreview() {
        scheduled = 0;
        const document = frame.contentDocument;
        if (!document?.body) return;
        frame.style.height = '0px';
        const height = Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
        frame.style.height = `${Math.max(80, Math.ceil(height) + 2)}px`;
    }

    function scheduleResize() {
        cancelAnimationFrame(scheduled);
        scheduled = requestAnimationFrame(resizePreview);
    }

    function preventLinkNavigation(event) {
        if (event.target?.closest?.('a, area')) event.preventDefault();
    }

    frame.addEventListener('load', () => {
        observer?.disconnect();
        const document = frame.contentDocument;
        if (!document?.body) return;
        document.addEventListener('click', preventLinkNavigation, true);
        document.addEventListener('submit', event => event.preventDefault(), true);
        observer = new ResizeObserver(scheduleResize);
        observer.observe(document.body);
        scheduleResize();
    });
    window.addEventListener('resize', scheduleResize);
    window.addEventListener('pagehide', () => {
        observer?.disconnect();
        cancelAnimationFrame(scheduled);
    });
})();