(() => {
  if (window.__qlearnPresenterBootstrapInstalled) return;
  window.__qlearnPresenterBootstrapInstalled = true;

  function startPresenter(config = {}) {
    if (window.__qlearnPresenter) {
      window.__qlearnPresenter.exit(false);
    }

    const presenterMode = config.mode || "single";
    const sessionId = config.sessionId || "standalone";

  const detectedPage = window.__hudraPageDetector?.resolve();

  if (!detectedPage?.supported) {
    window.__hudraPageDetector?.showNotice(
      "Hudra couldn’t start because this page does not contain a supported lesson."
    );
    return;
  }

  const { contentRoot, pageTitleElement } = detectedPage;

  let pageTitle = pageTitleElement?.textContent?.trim() || "";

  function isHidden(element) {
    if (!element || element.hidden) return true;

    const computedStyle = window.getComputedStyle(element);
    return (
      computedStyle.display === "none" ||
      computedStyle.visibility === "hidden"
    );
  }

  const visibleSlideHeadings = [
    ...contentRoot.querySelectorAll("h2, h3")
  ].filter((heading) => {
    const hasText = heading.textContent.trim().length > 0;
    const hasMedia = Boolean(
      heading.querySelector("img, video, iframe, svg, canvas, picture")
    );

    return (hasText || hasMedia) && !isHidden(heading);
  });

  const slideDefinitions = [];

  if (visibleSlideHeadings.length) {
    visibleSlideHeadings.forEach((heading, index) => {
      const nextHeading = visibleSlideHeadings[index + 1] || null;
      const range = document.createRange();

      range.setStartBefore(heading);

      if (nextHeading) {
        range.setEndBefore(nextHeading);
      } else {
        range.setEnd(contentRoot, contentRoot.childNodes.length);
      }

      slideDefinitions.push({
        index,
        headingLevel: heading.tagName,
        fragment: range.cloneContents()
      });

      if (typeof range.detach === "function") {
        range.detach();
      }
    });
  } else {
    const range = document.createRange();
    range.selectNodeContents(contentRoot);

    slideDefinitions.push({
      index: 0,
      headingLevel: null,
      fragment: range.cloneContents()
    });

    if (typeof range.detach === "function") {
      range.detach();
    }
  }

  const presentationLayer = document.createElement("div");
  presentationLayer.id = "qlearn-presenter-layer";
  document.body.appendChild(presentationLayer);

  const pageHeader = document.createElement("div");
  pageHeader.id = "qlearn-presenter-page-title";
  pageHeader.textContent = pageTitle;
  presentationLayer.appendChild(pageHeader);

  const presenterCredit = document.createElement("div");
  presenterCredit.id = "qlearn-presenter-credit";
  presenterCredit.textContent = "Hudra";
  presentationLayer.appendChild(presenterCredit);

  const gameCredit = document.createElement("div");
  gameCredit.id = "qlearn-presenter-game";
  gameCredit.textContent = "The Game";
  presentationLayer.appendChild(gameCredit);

  const slidesContainer = document.createElement("div");
  slidesContainer.id = "qlearn-presenter-slides";
  presentationLayer.appendChild(slidesContainer);

  const toast = document.createElement("div");
  toast.id = "qlearn-presenter-toast";
  presentationLayer.appendChild(toast);

  const audienceHiddenOverlay = document.createElement("div");
  audienceHiddenOverlay.id = "qlearn-presenter-audience-hidden";
  audienceHiddenOverlay.innerHTML = `<div>Audience Hidden</div>`;
  presentationLayer.appendChild(audienceHiddenOverlay);

  let slideWrappers = slideDefinitions.map((slide, index) => {
    const wrapper = document.createElement("div");
    wrapper.className = "qlearn-presenter-slide";
    wrapper.dataset.slideIndex = String(index);

    if (slide.headingLevel) {
      wrapper.dataset.headingLevel = slide.headingLevel.toLowerCase();
    }

    wrapper.appendChild(slide.fragment.cloneNode(true));
    slidesContainer.appendChild(wrapper);
    return wrapper;
  });

  slideWrappers.forEach((wrapper) => {
    wrapper
      .querySelectorAll(
        "script, style, noscript, [hidden], [aria-hidden='true']"
      )
      .forEach((element) => element.remove());

    wrapper.querySelectorAll("h1").forEach((element) => element.remove());
  });

  function isImageOnlySlide(wrapper) {
    const images = [...wrapper.querySelectorAll("img")].filter((image) => {
      const style = window.getComputedStyle(image);
      return style.display !== "none" && style.visibility !== "hidden";
    });

    if (images.length !== 1) return false;

    if (wrapper.querySelector("video, iframe, canvas, svg, table, pre, code, ul, ol")) {
      return false;
    }

    const walker = document.createTreeWalker(
      wrapper,
      NodeFilter.SHOW_TEXT,
      {
        acceptNode(node) {
          return node.textContent.trim()
            ? NodeFilter.FILTER_ACCEPT
            : NodeFilter.FILTER_REJECT;
        }
      }
    );

    return !walker.nextNode();
  }

  slideWrappers.forEach((wrapper) => {
    wrapper.classList.toggle("qlp-image-only", isImageOnlySlide(wrapper));
  });

  const style = document.createElement("style");
  style.id = "qlearn-presenter-style";
  style.textContent = `
    body.qlearn-presenting {
      overflow: hidden !important;
      background: #111 !important;
    }

    body.qlearn-presenting > *:not(#qlearn-presenter-layer):not(#qlearn-presenter-controls) {
      visibility: hidden !important;
    }

    #qlearn-presenter-layer {
      visibility: visible !important;
      position: fixed !important;
      inset: 0 !important;
      z-index: 2147483646 !important;
      overflow: hidden !important;
      background: white !important;
      --qlp-slide-pad-top: 11vh;
      --qlp-slide-pad-side: 7vw;
      --qlp-slide-pad-bottom: 13vh;
      --qlp-body-size: clamp(21px, 2.1vw, 33px);
      --qlp-h2-size: clamp(44px, 5.8vw, 78px);
      --qlp-h3-size: clamp(38px, 4.8vw, 66px);
      --qlp-media-height: 58vh;
    }

    #qlearn-presenter-layer.qlp-aspect-16-10 {
      --qlp-slide-pad-top: 10vh;
      --qlp-slide-pad-side: 6.5vw;
      --qlp-slide-pad-bottom: 11vh;
      --qlp-body-size: clamp(20px, 1.95vw, 31px);
      --qlp-h2-size: clamp(42px, 5.2vw, 72px);
      --qlp-h3-size: clamp(36px, 4.3vw, 60px);
      --qlp-media-height: 62vh;
    }

    #qlearn-presenter-layer,
    #qlearn-presenter-layer * {
      visibility: visible !important;
    }

    #qlearn-presenter-page-title {
      position: absolute !important;
      top: 0 !important;
      left: 0 !important;
      right: 0 !important;
      z-index: 10 !important;
      box-sizing: border-box !important;
      min-height: 48px !important;
      padding: 12px 7vw 10px !important;
      overflow: hidden !important;
      border-bottom: 1px solid rgba(0, 0, 0, 0.12) !important;
      background: rgba(255, 255, 255, 0.97) !important;
      color: #3a3a3a !important;
      font-family: Arial, sans-serif !important;
      font-size: clamp(16px, 1.4vw, 22px) !important;
      font-weight: 600 !important;
      line-height: 1.2 !important;
      text-overflow: ellipsis !important;
      white-space: nowrap !important;
    }

    #qlearn-presenter-credit {
      position: absolute !important;
      right: 18px !important;
      bottom: 12px !important;
      z-index: 20 !important;
      color: rgba(0, 0, 0, 0.52) !important;
      font-family: Arial, sans-serif !important;
      font-size: 11px !important;
      font-weight: 400 !important;
      line-height: 1 !important;
      pointer-events: none !important;
      white-space: nowrap !important;
    }

    #qlearn-presenter-game {
      position: absolute !important;
      left: 18px !important;
      bottom: 12px !important;
      z-index: 95 !important;
      color: rgba(255, 255, 255, 0.72) !important;
      mix-blend-mode: difference !important;
      font-family: Arial, sans-serif !important;
      font-size: 11px !important;
      font-weight: 400 !important;
      line-height: 1 !important;
      pointer-events: none !important;
      white-space: nowrap !important;
      opacity: 1 !important;
      transition: opacity 700ms ease !important;
    }

    #qlearn-presenter-game.qlearn-presenter-game-hidden {
      opacity: 0 !important;
    }

    #qlearn-presenter-slides {
      position: absolute !important;
      inset: 0 !important;
      overflow: hidden !important;
    }

    .qlearn-presenter-slide {
      display: block !important;
      position: absolute !important;
      inset: 0 !important;
      z-index: 0 !important;
      box-sizing: border-box !important;
      overflow-x: hidden !important;
      overflow-y: auto !important;
      padding: var(--qlp-slide-pad-top) var(--qlp-slide-pad-side) var(--qlp-slide-pad-bottom) !important;
      background: white !important;
      color: #222 !important;
      font-family: Arial, sans-serif !important;
      font-size: var(--qlp-body-size) !important;
      line-height: 1.4 !important;
      opacity: 0 !important;
      visibility: hidden !important;
      transform: translateY(8px) !important;
      pointer-events: none !important;
      transition:
        opacity 220ms ease,
        transform 220ms ease,
        visibility 0s linear 220ms !important;
    }

    .qlearn-presenter-slide.qlearn-slide-active {
      z-index: 1 !important;
      opacity: 1 !important;
      visibility: visible !important;
      transform: translateY(0) !important;
      pointer-events: auto !important;
      transition:
        opacity 220ms ease,
        transform 220ms ease,
        visibility 0s linear 0s !important;
    }

    @media (prefers-reduced-motion: reduce) {
      .qlearn-presenter-slide {
        transform: none !important;
        transition: none !important;
      }
    }

    .qlearn-presenter-slide > div,
    .qlearn-presenter-slide section,
    .qlearn-presenter-slide article {
      max-width: none !important;
    }

    .qlearn-presenter-slide h2 {
      margin: 0 0 0.7em !important;
      padding: 0 !important;
      color: #222 !important;
      font-family: Arial, sans-serif !important;
      font-size: var(--qlp-h2-size) !important;
      font-weight: 700 !important;
      line-height: 1.06 !important;
    }

    .qlearn-presenter-slide h3 {
      margin: 0 0 0.7em !important;
      padding: 0 !important;
      color: #222 !important;
      font-family: Arial, sans-serif !important;
      font-size: var(--qlp-h3-size) !important;
      font-weight: 700 !important;
      line-height: 1.1 !important;
    }

    .qlearn-presenter-slide h4 {
      margin: 1em 0 0.45em !important;
      color: #222 !important;
      font-family: Arial, sans-serif !important;
      font-size: clamp(27px, 3vw, 42px) !important;
      font-weight: 700 !important;
      line-height: 1.15 !important;
    }

    .qlearn-presenter-slide h5,
    .qlearn-presenter-slide h6 {
      margin: 0.9em 0 0.4em !important;
      color: #222 !important;
      font-family: Arial, sans-serif !important;
      font-size: 1.05em !important;
      font-weight: 700 !important;
      line-height: 1.2 !important;
    }

    .qlearn-presenter-slide h2:has(img),
    .qlearn-presenter-slide h3:has(img) {
      margin: 0 0 0.7em !important;
      padding: 0 !important;
      line-height: 1 !important;
    }

    .qlearn-presenter-slide h2 img,
    .qlearn-presenter-slide h3 img {
      display: block !important;
      width: 100% !important;
      max-width: 100% !important;
      height: auto !important;
      max-height: 28vh !important;
      object-fit: contain !important;
    }

    .qlearn-presenter-slide p {
      margin-top: 0 !important;
      margin-bottom: 0.8em !important;
    }

    .qlearn-presenter-slide ul,
    .qlearn-presenter-slide ol {
      margin-top: 0.4em !important;
      margin-bottom: 0.8em !important;
      padding-left: 1.5em !important;
    }

    .qlearn-presenter-slide li {
      margin-bottom: 0.3em !important;
    }

    .qlearn-presenter-slide a {
      color: #0068a8 !important;
      text-decoration: underline !important;
    }

    .qlearn-presenter-slide img {
      max-width: 100% !important;
      max-height: calc(var(--qlp-media-height) * var(--qlp-media-scale, 1)) !important;
      width: auto !important;
      height: auto !important;
      object-fit: contain !important;
    }

    .qlearn-presenter-slide video {
      display: block !important;
      max-width: 100% !important;
      max-height: calc(var(--qlp-media-height) * var(--qlp-media-scale, 1)) !important;
      width: auto !important;
      height: auto !important;
      object-fit: contain !important;
    }

    .qlearn-presenter-slide iframe {
      display: block !important;
      width: min(90vw, 1200px) !important;
      height: min(65vh, 720px) !important;
      max-width: 100% !important;
      border: 0 !important;
    }

    .qlearn-presenter-slide table {
      width: 100% !important;
      max-width: 100% !important;
      height: auto !important;
      border-collapse: collapse !important;
      table-layout: auto !important;
    }

    .qlearn-presenter-slide tbody,
    .qlearn-presenter-slide tr,
    .qlearn-presenter-slide td,
    .qlearn-presenter-slide th {
      height: auto !important;
      max-width: 100% !important;
    }

    .qlearn-presenter-slide td,
    .qlearn-presenter-slide th {
      box-sizing: border-box !important;
      padding: 0.35em !important;
      vertical-align: top !important;
    }

    .qlearn-presenter-slide [style*="width"] {
      max-width: 100% !important;
    }

    .qlearn-presenter-slide-content {
      width: 100% !important;
      box-sizing: border-box !important;
      zoom: var(--qlp-content-scale, 1);
    }

    .qlearn-presenter-slide.qlp-tight {
      padding-top: 8vh !important;
      padding-bottom: 9vh !important;
    }

    .qlearn-presenter-slide.qlp-very-tight {
      padding-top: 7vh !important;
      padding-right: 5vw !important;
      padding-bottom: 8vh !important;
      padding-left: 5vw !important;
    }

    .qlearn-presenter-slide .qlp-continuation-title::after {
      content: "  ·  continued";
      font-size: 0.42em;
      font-weight: 500;
      opacity: 0.62;
      white-space: nowrap;
    }

    .qlearn-presenter-slide .qlp-compact-block {
      font-size: 0.82em !important;
    }

    /* A slide containing exactly one image uses the full audience viewport. */
    .qlearn-presenter-slide.qlp-image-only {
      padding: 0 !important;
      overflow: hidden !important;
      background: #fff !important;
    }

    .qlearn-presenter-slide.qlp-image-only .qlearn-presenter-slide-content {
      width: 100vw !important;
      height: 100vh !important;
      zoom: 1 !important;
    }

    .qlearn-presenter-slide.qlp-image-only img {
      position: absolute !important;
      inset: 0 !important;
      display: block !important;
      width: 100vw !important;
      height: 100vh !important;
      max-width: none !important;
      max-height: none !important;
      margin: auto !important;
      object-fit: contain !important;
    }

    #qlearn-presenter-layer.qlp-showing-image-only #qlearn-presenter-page-title {
      display: none !important;
    }

    #qlearn-presenter-audience-hidden {
      position: absolute !important;
      inset: 0 !important;
      z-index: 80 !important;
      display: flex !important;
      align-items: center !important;
      justify-content: center !important;
      background: #000 !important;
      color: rgba(255, 255, 255, 0.92) !important;
      font: 600 clamp(24px, 3vw, 44px)/1.2 Arial, sans-serif !important;
      letter-spacing: 0.02em !important;
      opacity: 0 !important;
      visibility: hidden !important;
      pointer-events: none !important;
      transition: opacity 180ms ease, visibility 0s linear 180ms !important;
    }

    #qlearn-presenter-audience-hidden.qlearn-presenter-audience-hidden-visible {
      opacity: 1 !important;
      visibility: visible !important;
      transition: opacity 180ms ease, visibility 0s linear 0s !important;
    }

    #qlearn-presenter-toast {
      position: absolute !important;
      left: 50% !important;
      bottom: 78px !important;
      transform: translateX(-50%) translateY(10px) !important;
      z-index: 30 !important;
      padding: 9px 14px !important;
      border-radius: 999px !important;
      background: rgba(0, 0, 0, 0.78) !important;
      color: white !important;
      font: 14px Arial, sans-serif !important;
      opacity: 0 !important;
      transition: opacity 140ms ease, transform 140ms ease !important;
      pointer-events: none !important;
      white-space: nowrap !important;
    }

    #qlearn-presenter-toast.qlearn-presenter-toast-visible {
      opacity: 1 !important;
      transform: translateX(-50%) translateY(0) !important;
    }

    body.qlearn-presenter-audience #qlearn-presenter-controls {
      display: none !important;
    }

    #qlearn-presenter-controls {
      visibility: visible !important;
      position: fixed !important;
      left: 50% !important;
      bottom: 20px !important;
      transform: translateX(-50%) !important;
      z-index: 2147483647 !important;
      display: flex !important;
      align-items: center !important;
      gap: 12px !important;
      padding: 10px 16px !important;
      border-radius: 999px !important;
      background: rgba(0, 0, 0, 0.8) !important;
      color: white !important;
      font: 16px Arial, sans-serif !important;
      box-shadow: 0 4px 18px rgba(0, 0, 0, 0.3) !important;
    }

    #qlearn-presenter-controls,
    #qlearn-presenter-controls * {
      visibility: visible !important;
    }

    #qlearn-presenter-controls button {
      border: 0 !important;
      border-radius: 7px !important;
      padding: 8px 13px !important;
      background: white !important;
      color: #222 !important;
      cursor: pointer !important;
      font: inherit !important;
    }

    #qlearn-presenter-controls button:hover:not(:disabled) {
      background: #e8e8e8 !important;
    }

    #qlearn-presenter-controls button:disabled {
      cursor: default !important;
      opacity: 0.4 !important;
    }

    #qlearn-presenter-controls [data-role="counter"] {
      min-width: 110px !important;
      text-align: center !important;
      white-space: nowrap !important;
    }
  `;

  document.head.appendChild(style);

  function applyAspectMode() {
    const ratio = window.innerWidth / Math.max(window.innerHeight, 1);
    // Only two supported layouts: 16:9 (1.778) and 16:10 (1.6).
    const isSixteenTen = Math.abs(ratio - 1.6) < Math.abs(ratio - 16 / 9);
    presentationLayer.classList.toggle("qlp-aspect-16-10", isSixteenTen);
    presentationLayer.classList.toggle("qlp-aspect-16-9", !isSixteenTen);
    presentationLayer.dataset.aspect = isSixteenTen ? "16:10" : "16:9";
  }

  function wrapSlideContent(wrapper) {
    let content = wrapper.querySelector(":scope > .qlearn-presenter-slide-content");
    if (content) return content;
    content = document.createElement("div");
    content.className = "qlearn-presenter-slide-content";
    while (wrapper.firstChild) content.appendChild(wrapper.firstChild);
    wrapper.appendChild(content);
    return content;
  }

  function slideOverflows(wrapper) {
    const content = wrapSlideContent(wrapper);
    return (
      content.getBoundingClientRect().bottom >
        wrapper.getBoundingClientRect().bottom - 4 ||
      wrapper.scrollHeight > wrapper.clientHeight + 4
    );
  }

  function resetFit(wrapper) {
    wrapper.classList.remove("qlp-tight", "qlp-very-tight");
    wrapper.style.setProperty("--qlp-content-scale", "1");
    wrapper.style.setProperty("--qlp-media-scale", "1");
  }

  function fitSlide(wrapper, allowSmall = true) {
    resetFit(wrapper);
    if (wrapper.classList.contains("qlp-image-only")) return true;
    if (!slideOverflows(wrapper)) return true;

    wrapper.style.setProperty("--qlp-media-scale", "0.86");
    if (!slideOverflows(wrapper)) return true;

    wrapper.classList.add("qlp-tight");
    if (!slideOverflows(wrapper)) return true;

    wrapper.classList.add("qlp-very-tight");
    if (!slideOverflows(wrapper)) return true;

    const scales = allowSmall
      ? [0.96, 0.92, 0.88, 0.84, 0.80]
      : [0.96, 0.92, 0.88];
    for (const scale of scales) {
      wrapper.style.setProperty("--qlp-content-scale", String(scale));
      if (!slideOverflows(wrapper)) return true;
    }
    return false;
  }

  function makeContinuationHeading(sourceHeading) {
    const heading = sourceHeading.cloneNode(true);
    heading.classList.add("qlp-continuation-title");
    return heading;
  }

  function splitList(list) {
    const items = [...list.children].filter((item) => item.tagName === "LI");
    if (items.length < 2) return [list.cloneNode(true)];
    const midpoint = Math.ceil(items.length / 2);
    return [items.slice(0, midpoint), items.slice(midpoint)].map((group) => {
      const copy = list.cloneNode(false);
      group.forEach((item) => copy.appendChild(item.cloneNode(true)));
      return copy;
    });
  }

  function divideOversizedBlock(block) {
    if (block.matches("ul, ol")) return splitList(block);
    return [block.cloneNode(true)];
  }

  function createGeneratedSlide(template, heading, continued) {
    const wrapper = document.createElement("div");
    wrapper.className = "qlearn-presenter-slide";
    wrapper.dataset.headingLevel = template.dataset.headingLevel || "h2";
    const content = document.createElement("div");
    content.className = "qlearn-presenter-slide-content";
    if (heading) {
      content.appendChild(continued ? makeContinuationHeading(heading) : heading.cloneNode(true));
    }
    wrapper.appendChild(content);
    return wrapper;
  }

  function paginateWrapper(original) {
    const originalContent = wrapSlideContent(original);
    const blocks = [...originalContent.children];
    if (!blocks.length || fitSlide(original, false)) return [original];

    const first = blocks[0]?.matches("h2, h3") ? blocks.shift() : null;
    const generated = [];
    let currentWrapper = createGeneratedSlide(original, first, false);
    slidesContainer.appendChild(currentWrapper);
    generated.push(currentWrapper);

    function currentContent() {
      return currentWrapper.querySelector(".qlearn-presenter-slide-content");
    }

    function newContinuation() {
      currentWrapper = createGeneratedSlide(original, first, true);
      slidesContainer.appendChild(currentWrapper);
      generated.push(currentWrapper);
    }

    for (const sourceBlock of blocks) {
      const pieces = divideOversizedBlock(sourceBlock);
      for (const piece of pieces) {
        currentContent().appendChild(piece);
        resetFit(currentWrapper);
        if (!slideOverflows(currentWrapper)) continue;

        piece.remove();
        const hasBody = [...currentContent().children].some((el) => !el.matches("h2, h3"));
        if (hasBody) newContinuation();
        currentContent().appendChild(piece);

        if (!fitSlide(currentWrapper, false)) {
          if (piece.matches("table, pre, iframe, video, img, div")) {
            piece.classList.add("qlp-compact-block");
          }
          fitSlide(currentWrapper, true);
        }
      }
    }

    original.remove();
    return generated;
  }

  function paginateAndFitSlides() {
    applyAspectMode();
    const originals = [...slideWrappers];
    const rebuilt = [];
    originals.forEach((wrapper) => rebuilt.push(...paginateWrapper(wrapper)));
    slideWrappers = rebuilt;
    slideWrappers.forEach((wrapper, index) => {
      wrapper.dataset.slideIndex = String(index);
      fitSlide(wrapper, true);
    });
  }

  let resizeTimer = null;
  function refitAfterResize() {
    clearTimeout(resizeTimer);
    resizeTimer = setTimeout(() => {
      applyAspectMode();
      slideWrappers.forEach((wrapper) => fitSlide(wrapper, true));
      if (slideWrappers[current]) slideWrappers[current].scrollTop = 0;
    }, 160);
  }

  applyAspectMode();
  paginateAndFitSlides();
  window.addEventListener("resize", refitAfterResize);

  const controls = document.createElement("div");
  controls.id = "qlearn-presenter-controls";
  controls.innerHTML = `
    <button type="button" data-action="prev">← Previous</button>
    <span data-role="counter"></span>
    <button type="button" data-action="next">Next →</button>
    <button type="button" data-action="exit">Exit</button>
  `;

  document.body.appendChild(controls);

  const previousButton = controls.querySelector('[data-action="prev"]');
  const nextButton = controls.querySelector('[data-action="next"]');
  const counter = controls.querySelector('[data-role="counter"]');

  let current = 0;
  let toastTimer = null;
  let audienceHidden = false;
  let audienceZoom = 100;
  let audienceScrollY = 0;

  function applyAudienceView() {
    const slide = slideWrappers[current];
    if (!slide) return;
    slide.style.zoom = `${audienceZoom}%`;
    slide.scrollTop = audienceScrollY;
    requestAnimationFrame(() => { audienceScrollY = slide.scrollTop; });
  }

  function setAudienceZoom(value, announce = true) {
    audienceZoom = Math.max(70, Math.min(150, Math.round(Number(value) / 5) * 5));
    applyAudienceView();
    if (announce) showToast(`Audience zoom ${audienceZoom}%`);
    sendPresenterState();
  }

  function adjustAudienceZoom(delta) { setAudienceZoom(audienceZoom + Number(delta || 0)); }

  function scrollAudience(delta) {
    const slide = slideWrappers[current];
    if (!slide) return;
    slide.scrollBy({ top: Number(delta || 0), behavior: "smooth" });
    setTimeout(() => { audienceScrollY = slide.scrollTop; sendPresenterState(); }, 180);
  }

  function resetAudienceView(announce = true) {
    audienceZoom = 100;
    audienceScrollY = 0;
    applyAudienceView();
    if (announce) showToast("Audience view reset");
    sendPresenterState();
  }

  function setAudienceHidden(hidden, announce = true) {
    audienceHidden = Boolean(hidden);
    audienceHiddenOverlay.classList.toggle(
      "qlearn-presenter-audience-hidden-visible",
      audienceHidden
    );

    if (announce) {
      showToast(audienceHidden ? "Audience hidden" : "Audience restored");
    }

    sendPresenterState();
  }

  function toggleAudienceHidden() {
    if (videoModeActive) {
      showToast("Pause the video before hiding the audience screen");
      return;
    }
    setAudienceHidden(!audienceHidden);
  }

  function showToast(message) {
    toast.textContent = message;
    toast.classList.add("qlearn-presenter-toast-visible");
    clearTimeout(toastTimer);
    toastTimer = setTimeout(() => {
      toast.classList.remove("qlearn-presenter-toast-visible");
    }, 1200);
  }

  function isVisibleMedia(element) {
    if (!element) return false;
    const mediaStyle = window.getComputedStyle(element);
    return mediaStyle.display !== "none" && mediaStyle.visibility !== "hidden";
  }

  function findPlayableVideo(slide) {
    if (!slide) return null;

    const directVideos = [...slide.querySelectorAll("video")];
    const directVideo = directVideos.find(isVisibleMedia);
    if (directVideo) {
      return { video: directVideo, frame: null };
    }

    const videoFrames = [
      ...slide.querySelectorAll(
        'iframe[data-media-type="video"], iframe[title*="video" i], iframe[src*="media_attachments_iframe"]'
      )
    ].filter(isVisibleMedia);

    for (const frame of videoFrames) {
      try {
        const frameDocument = frame.contentDocument || frame.contentWindow?.document;
        const frameVideo = frameDocument?.querySelector("video");
        if (frameVideo) return { video: frameVideo, frame };
      } catch (error) {
        // Cross-origin players cannot be controlled directly.
      }
    }

    return null;
  }

  let activeVideo = null;
  let activeVideoFrame = null;
  let activeFullscreenDocument = null;
  let videoModeActive = false;
  let videoFullscreenActive = false;
  let deliberatelyLeavingVideoFullscreen = false;

  function getFullscreenElement(doc) {
    return doc?.fullscreenElement || doc?.webkitFullscreenElement || null;
  }

  async function requestElementFullscreen(element) {
    if (!element) return false;
    try {
      if (element.requestFullscreen) {
        await element.requestFullscreen();
        return true;
      }
      if (element.webkitRequestFullscreen) {
        element.webkitRequestFullscreen();
        return true;
      }
    } catch (error) {
      console.warn("Hudra fullscreen request failed:", error);
    }
    return false;
  }

  async function exitDocumentFullscreen(doc) {
    if (!doc || !getFullscreenElement(doc)) return;
    try {
      if (doc.exitFullscreen) {
        await doc.exitFullscreen();
      } else if (doc.webkitExitFullscreen) {
        doc.webkitExitFullscreen();
      }
    } catch (error) {
      console.warn("Hudra could not exit video fullscreen:", error);
    }
  }

  function removeVideoListeners() {
    if (activeVideo) {
      activeVideo.removeEventListener("ended", onActiveVideoEnded);
    }
    if (activeFullscreenDocument && activeFullscreenDocument !== document) {
      activeFullscreenDocument.removeEventListener("fullscreenchange", onVideoFullscreenChange);
      activeFullscreenDocument.removeEventListener("webkitfullscreenchange", onVideoFullscreenChange);
    }
    document.removeEventListener("fullscreenchange", onVideoFullscreenChange);
    document.removeEventListener("webkitfullscreenchange", onVideoFullscreenChange);
  }

  function clearVideoState() {
    removeVideoListeners();
    activeVideo = null;
    activeVideoFrame = null;
    activeFullscreenDocument = null;
    videoModeActive = false;
    videoFullscreenActive = false;
    deliberatelyLeavingVideoFullscreen = false;
  }

  async function stopActiveVideo({ pause = true, toastMessage = "⏸ Video paused" } = {}) {
    if (!videoModeActive) return false;

    const video = activeVideo;
    const fullscreenDoc = activeFullscreenDocument;

    deliberatelyLeavingVideoFullscreen = true;
    if (pause && video && !video.paused) video.pause();

    await exitDocumentFullscreen(fullscreenDoc);
    if (fullscreenDoc !== document) {
      await exitDocumentFullscreen(document);
    }

    clearVideoState();
    if (toastMessage) showToast(toastMessage);
    return true;
  }

  async function onActiveVideoEnded() {
    await stopActiveVideo({
      pause: false,
      toastMessage: "↩ Video finished · returning to slide"
    });
  }

  function onVideoFullscreenChange() {
    if (!videoModeActive || deliberatelyLeavingVideoFullscreen) return;

    const ownerFullscreen = getFullscreenElement(activeFullscreenDocument);
    const parentFullscreen = getFullscreenElement(document);

    if (videoFullscreenActive && !ownerFullscreen && !parentFullscreen) {
      if (activeVideo && !activeVideo.paused) activeVideo.pause();
      clearVideoState();
      showToast("⏸ Video paused · returned to slide");
    }
  }

  async function startCurrentSlideVideo() {
    const slide = slideWrappers[current];
    const playable = findPlayableVideo(slide);

    if (!playable) {
      showToast("No controllable video on this slide");
      return false;
    }

    const { video, frame } = playable;
    activeVideo = video;
    activeVideoFrame = frame;
    activeFullscreenDocument = video.ownerDocument || document;
    videoModeActive = true;
    deliberatelyLeavingVideoFullscreen = false;

    video.addEventListener("ended", onActiveVideoEnded);
    document.addEventListener("fullscreenchange", onVideoFullscreenChange);
    document.addEventListener("webkitfullscreenchange", onVideoFullscreenChange);
    if (activeFullscreenDocument !== document) {
      activeFullscreenDocument.addEventListener("fullscreenchange", onVideoFullscreenChange);
      activeFullscreenDocument.addEventListener("webkitfullscreenchange", onVideoFullscreenChange);
    }

    try {
      if (video.ended) video.currentTime = 0;

      // Prefer the actual video. If Canvas blocks that, fullscreen its iframe.
      videoFullscreenActive = await requestElementFullscreen(video);
      if (!videoFullscreenActive && frame) {
        activeFullscreenDocument = document;
        videoFullscreenActive = await requestElementFullscreen(frame);
      }

      await video.play();
      showToast(
        videoFullscreenActive
          ? "▶ Video playing fullscreen"
          : "▶ Video playing · fullscreen unavailable"
      );
      return true;
    } catch (error) {
      console.warn("Hudra could not control this video:", error);
      await stopActiveVideo({ pause: true, toastMessage: null });
      showToast("Video player could not be controlled");
      return false;
    }
  }

  async function toggleCurrentSlideVideo() {
    if (videoModeActive) {
      return stopActiveVideo({
        pause: true,
        toastMessage: "⏸ Video paused · returning to slide"
      });
    }
    return startCurrentSlideVideo();
  }

  function makePreviewDocument(index) {
    const slide = slideWrappers[index];
    if (!slide) return "";

    const clone = slide.cloneNode(true);
    clone.classList.add("qlearn-slide-active");
    clone.style.position = "relative";
    clone.style.inset = "auto";
    clone.style.width = "100%";
    clone.style.height = "100%";
    clone.style.opacity = "1";
    clone.style.visibility = "visible";
    clone.style.transform = "none";
    clone.style.overflow = "hidden";
    if (index === current) {
      clone.style.zoom = `${audienceZoom}%`;
      clone.dataset.hudraScrollY = String(audienceScrollY);
    }

    clone.querySelectorAll("video").forEach((video) => {
      const replacement = document.createElement("div");
      replacement.className = "hudra-preview-media";
      replacement.textContent = "Video";
      if (video.getAttribute("poster")) {
        replacement.style.backgroundImage = `url('${video.getAttribute("poster").replace(/'/g, "%27")}')`;
      }
      video.replaceWith(replacement);
    });

    clone.querySelectorAll("iframe").forEach((frame) => {
      const replacement = document.createElement("div");
      replacement.className = "hudra-preview-media";
      replacement.textContent = frame.title || "Embedded content";
      frame.replaceWith(replacement);
    });

    return `<!doctype html><html><head><meta charset="utf-8"><base href="${location.href.replace(/"/g, "&quot;")}"><style>
      html,body{margin:0;width:100%;height:100%;overflow:hidden;background:#fff;}
      body{font-family:Arial,sans-serif;}
      .qlearn-presenter-slide{box-sizing:border-box;width:100%;height:100%;padding:7vh 6vw 9vh;background:white;color:#222;font-size:clamp(14px,2vw,30px);line-height:1.38;overflow:hidden;}
      h2{margin:0 0 .65em;font-size:clamp(25px,5vw,66px);line-height:1.06;}
      h3{margin:0 0 .65em;font-size:clamp(22px,4vw,52px);line-height:1.1;}
      h4{font-size:clamp(18px,3vw,38px);}
      p{margin-top:0;margin-bottom:.75em;} ul,ol{margin-top:.3em;margin-bottom:.7em;padding-left:1.4em;}
      img,video{max-width:100%;max-height:56vh;width:auto;height:auto;object-fit:contain;}
      .qlearn-presenter-slide.qlp-image-only{padding:0;position:relative;}
      .qlearn-presenter-slide.qlp-image-only .qlearn-presenter-slide-content{width:100%;height:100%;}
      .qlearn-presenter-slide.qlp-image-only img{position:absolute;inset:0;width:100%;height:100%;max-width:none;max-height:none;object-fit:contain;}
      iframe{max-width:100%;height:54vh;border:0;} .hudra-preview-media{display:grid;place-items:center;min-height:34vh;border-radius:14px;background:#111722 center/cover no-repeat;color:#d7ddeb;font:700 clamp(16px,2vw,28px) system-ui;} table{width:100%;border-collapse:collapse;font-size:.78em;} td,th{padding:.3em;} pre{overflow:hidden;font-size:.7em;}
      .qlp-continuation-title::after{content:" · continued";font-size:.42em;font-weight:500;opacity:.62;}
    </style></head><body>${clone.outerHTML}<script>const s=document.querySelector('[data-hudra-scroll-y]');if(s)s.scrollTop=Number(s.dataset.hudraScrollY)||0;<\/script></body></html>`;
  }

  function sendPresenterState() {
    chrome.runtime.sendMessage({
      type: "QLEARN_PRESENTER_STATE",
      sessionId,
      current,
      count: slideWrappers.length,
      pageTitle,
      audienceHidden,
      audienceZoom,
      audienceScrollY,
      currentPreview: makePreviewDocument(current),
      nextPreview: makePreviewDocument(current + 1)
    }).catch(() => {});
  }

  function showSlide(index) {
    if (videoModeActive) {
      stopActiveVideo({ pause: true, toastMessage: null }).catch(() => {});
    }

    current = Math.max(0, Math.min(index, slideWrappers.length - 1));

    slideWrappers.forEach((wrapper, wrapperIndex) => {
      wrapper.classList.toggle(
        "qlearn-slide-active",
        wrapperIndex === current
      );
    });

    presentationLayer.classList.toggle(
      "qlp-showing-image-only",
      slideWrappers[current]?.classList.contains("qlp-image-only")
    );

    audienceZoom = 100;
    audienceScrollY = 0;
    slideWrappers.forEach((wrapper) => { wrapper.style.zoom = "100%"; wrapper.scrollTop = 0; });
    applyAudienceView();
    counter.textContent = `Slide ${current + 1} of ${slideWrappers.length}`;
    previousButton.disabled = current === 0;
    nextButton.disabled = current === slideWrappers.length - 1;

    sendPresenterState();
  }

  function exit(notifyBackground = true) {
    document.removeEventListener("keydown", onKey);
    window.removeEventListener("resize", refitAfterResize);
    clearTimeout(resizeTimer);
    clearTimeout(toastTimer);
    clearTimeout(gameTimer);
    if (activeVideo && !activeVideo.paused) activeVideo.pause();
    if (videoModeActive) {
      deliberatelyLeavingVideoFullscreen = true;
      exitDocumentFullscreen(activeFullscreenDocument).catch(() => {});
      clearVideoState();
    }
    presentationLayer.remove();
    controls.remove();
    style.remove();
    document.body.classList.remove("qlearn-presenting", "qlearn-presenter-audience");
    delete window.__qlearnPresenter;

    if (notifyBackground) {
      chrome.runtime.sendMessage({
        type: "QLEARN_PRESENTER_ENDED",
        sessionId
      }).catch(() => {});
    }
  }

  function onKey(event) {
    const activeElement = document.activeElement;
    const isTyping =
      activeElement &&
      ["INPUT", "TEXTAREA", "SELECT"].includes(activeElement.tagName);

    if (isTyping) return;

    if (event.key.toLowerCase() === "b") {
      event.preventDefault();
      event.stopPropagation();
      if (!event.repeat) toggleAudienceHidden();
      return;
    }

    if (event.key === "Tab") {
      event.preventDefault();
      event.stopPropagation();
      if (!event.repeat) toggleCurrentSlideVideo();
      return;
    }

    if (["ArrowRight", "PageDown", " ", "Enter"].includes(event.key)) {
      event.preventDefault();
      if (videoModeActive) {
        if (!event.repeat) showToast("Pause the video before changing slides");
        return;
      }
      if (current < slideWrappers.length - 1) showSlide(current + 1);
      return;
    }

    if (["ArrowLeft", "PageUp", "Backspace"].includes(event.key)) {
      event.preventDefault();
      if (videoModeActive) {
        if (!event.repeat) showToast("Pause the video before changing slides");
        return;
      }
      if (current > 0) showSlide(current - 1);
      return;
    }

    if (event.key === "Home") {
      event.preventDefault();
      showSlide(0);
      return;
    }

    if (event.key === "End") {
      event.preventDefault();
      showSlide(slideWrappers.length - 1);
      return;
    }

    if (event.key === "Escape") {
      event.preventDefault();
      if (videoModeActive) {
        stopActiveVideo({
          pause: true,
          toastMessage: "⏸ Video paused · returned to slide"
        }).catch(() => {});
      } else {
        exit();
      }
    }
  }

  controls.addEventListener("click", (event) => {
    const button = event.target.closest("button[data-action]");
    if (!button) return;

    const action = button.dataset.action;

    if (action === "next" && current < slideWrappers.length - 1) {
      if (videoModeActive) {
        showToast("Pause the video before changing slides");
      } else {
        showSlide(current + 1);
      }
      return;
    }

    if (action === "prev" && current > 0) {
      if (videoModeActive) {
        showToast("Pause the video before changing slides");
      } else {
        showSlide(current - 1);
      }
      return;
    }

    if (action === "exit") exit();
  });

  document.body.classList.add("qlearn-presenting");
  if (presenterMode === "audience") {
    document.body.classList.add("qlearn-presenter-audience");
  }
  document.addEventListener("keydown", onKey);

  const gameTimer = setTimeout(() => {
    gameCredit.classList.add("qlearn-presenter-game-hidden");
    setTimeout(() => gameCredit.remove(), 800);
  }, 5000);

  window.__qlearnPresenter = {
    exit,
    next() {
      if (videoModeActive) {
        showToast("Pause the video before changing slides");
      } else if (current < slideWrappers.length - 1) {
        showSlide(current + 1);
      }
    },
    previous() {
      if (videoModeActive) {
        showToast("Pause the video before changing slides");
      } else if (current > 0) {
        showSlide(current - 1);
      }
    },
    first() {
      if (videoModeActive) showToast("Pause the video before changing slides");
      else showSlide(0);
    },
    last() {
      if (videoModeActive) showToast("Pause the video before changing slides");
      else showSlide(slideWrappers.length - 1);
    },
    toggleVideo() {
      return toggleCurrentSlideVideo();
    },
    toggleAudienceHidden() {
      toggleAudienceHidden();
    },
    zoomIn() { adjustAudienceZoom(5); },
    zoomOut() { adjustAudienceZoom(-5); },
    setZoom(value) { setAudienceZoom(value); },
    scrollUp() { scrollAudience(-140); },
    scrollDown() { scrollAudience(140); },
    scrollBy(value) { scrollAudience(value); },
    resetView() { resetAudienceView(); },
    goTo(index) {
      const slideNumber = Number(index);
      if (Number.isFinite(slideNumber)) showSlide(slideNumber);
    },
    getCurrentSlide() {
      return current + 1;
    },
    getSlideCount() {
      return slideWrappers.length;
    },
    reportState() {
      sendPresenterState();
    }
  };

  showSlide(0);
  }

  chrome.runtime.onMessage.addListener((message) => {
    if (message?.type === "QLEARN_PRESENTER_START") {
      startPresenter(message.config || {});
      return;
    }

    if (message?.type === "QLEARN_PRESENTER_COMMAND" && window.__qlearnPresenter) {
      const command = message.command;
      if (command === "next") window.__qlearnPresenter.next();
      if (command === "previous") window.__qlearnPresenter.previous();
      if (command === "first") window.__qlearnPresenter.first();
      if (command === "last") window.__qlearnPresenter.last();
      if (command === "toggleVideo") window.__qlearnPresenter.toggleVideo();
      if (command === "toggleAudienceHidden") window.__qlearnPresenter.toggleAudienceHidden();
      if (command === "zoomIn") window.__qlearnPresenter.zoomIn();
      if (command === "zoomOut") window.__qlearnPresenter.zoomOut();
      if (command === "setZoom") window.__qlearnPresenter.setZoom(message.value);
      if (command === "scrollUp") window.__qlearnPresenter.scrollUp();
      if (command === "scrollDown") window.__qlearnPresenter.scrollDown();
      if (command === "scrollBy") window.__qlearnPresenter.scrollBy(message.value);
      if (command === "resetView") window.__qlearnPresenter.resetView();
      if (command === "goTo") window.__qlearnPresenter.goTo(message.value);
      if (command === "reportState") window.__qlearnPresenter.reportState();
      if (command === "exit") window.__qlearnPresenter.exit(false);
    }
  });
})();