// Collect unique webpage URLs from the slide list.
function getWebpageUrls(sourceSlides) {
  const urls = [];
  (Array.isArray(sourceSlides) ? sourceSlides : []).forEach(function (slide) {
    const content = slide && slide.content ? slide.content : {};
    const regions = slide && slide.template && Array.isArray(slide.template.regions) ? slide.template.regions : [];
    regions.forEach(function (region) {
      if (region.region_type !== 'webpage') {
        return;
      }
      const regionContent = content[region.region_key] || {};
      const url = String(regionContent.value || '').trim();
      if (url && urls.indexOf(url) === -1) {
        urls.push(url);
      }
    });
  });
  return urls;
}

// Filter the slides down to those that are active right now.
function getActiveSlidesFrom(sourceSlides) {
  const now = new Date();
  return (Array.isArray(sourceSlides) ? sourceSlides : []).filter(function (slide) {
    return isSlideActive(slide, now);
  });
}

// Build a cache key for the active slide set.
function getActiveSlidesCacheKey() {
  const now = new Date();
  return [
    currentPlaylistSignature || '',
    now.getFullYear(),
    now.getMonth(),
    now.getDate(),
    now.getHours(),
    now.getMinutes(),
    now.getSeconds()
  ].join('|');
}

// Return the cached active slide set for the current playlist and second.
function getCurrentActiveSlides() {
  const cacheKey = getActiveSlidesCacheKey();
  if (cacheKey !== activeSlidesCacheKey) {
    activeSlidesCacheValue = getActiveSlidesFrom(slides);
    activeSlidesCacheKey = cacheKey;
  }
  return activeSlidesCacheValue;
}

// Clear the cached active slide set.
function clearActiveSlidesCache() {
  activeSlidesCacheKey = '';
  activeSlidesCacheValue = [];
}

// Reset render caches when the viewport changes.
function syncRenderCacheViewport() {
  var viewportKey = window.innerWidth + 'x' + window.innerHeight;
  if (renderCacheViewportKey === viewportKey) {
    return;
  }

  renderCacheViewportKey = viewportKey;
  slideMarkupCache = Object.create(null);
  templateLayoutCache = Object.create(null);
  templateRenderPlanCache = Object.create(null);
}

// Build a signature for the currently rendered view.
function getCurrentRenderKey(activeSlides) {
  const viewportKey = window.innerWidth + 'x' + window.innerHeight;
  const availableSlides = Array.isArray(activeSlides) ? activeSlides : [];
  if (!availableSlides.length) {
    return [currentPlaylistSignature || '', viewportKey, 'empty', slides.length ? 'scheduled' : 'assigned'].join('|');
  }
  let normalizedIndex = Number(index || 0);
  if (!Number.isFinite(normalizedIndex) || normalizedIndex < 0 || normalizedIndex >= availableSlides.length) {
    normalizedIndex = 0;
  }
  const slide = availableSlides[normalizedIndex];
  return [currentPlaylistSignature || '', viewportKey, 'slide', slide && slide.id ? slide.id : ''].join('|');
}

// Pick the current slide and the next slide for webpage preloading.
function getWebpagePreloadSlides(sourceSlides, targetIndex) {
  const availableSlides = Array.isArray(sourceSlides) ? sourceSlides : [];
  if (!availableSlides.length) {
    return [];
  }

  let normalizedIndex = Number(targetIndex || 0);
  if (!Number.isFinite(normalizedIndex) || normalizedIndex < 0 || normalizedIndex >= availableSlides.length) {
    normalizedIndex = 0;
  }

  const preloadSlides = [];
  const currentSlide = availableSlides[normalizedIndex];
  const nextSlide = availableSlides[normalizedIndex + 1];

  if (currentSlide) {
    preloadSlides.push(currentSlide);
  }
  if (nextSlide && nextSlide !== currentSlide) {
    preloadSlides.push(nextSlide);
  }

  return preloadSlides;
}

// Mount hidden iframe preloads for the chosen webpage URLs.
function syncWebpagePreloads(sourceSlides, targetIndex) {
  const urls = getWebpageUrls(getWebpagePreloadSlides(sourceSlides, targetIndex));
  const signature = urls.join('\n');
  if (signature === preloadSignature) {
    return;
  }
  if (!urls.length) {
    preloadSignature = '';
    if (preloadContainer) {
      preloadContainer.innerHTML = '';
    }
    return;
  }
  if (!preloadContainer) {
    preloadContainer = document.createElement('div');
    preloadContainer.className = 'webpage-preloads';
    preloadContainer.setAttribute('aria-hidden', 'true');
    document.body.appendChild(preloadContainer);
  }
  preloadContainer.innerHTML = urls.map(function (url) {
    return '<iframe class="webpage-preload-frame" src="' + escapeHtml(url) + '" title="Webpage preload" tabindex="-1" loading="eager" referrerpolicy="no-referrer" scrolling="no"></iframe>';
  }).join('');
  preloadSignature = signature;
}

// Return a stable client id for this browser session.
function getCommandClientId() {
  if (commandClientId) {
    return commandClientId;
  }
  try {
    var storedClientId = window.localStorage.getItem(commandClientStorageKey);
    if (storedClientId) {
      commandClientId = storedClientId;
      return commandClientId;
    }
  } catch (_error) {
    // fall through to ephemeral ID generation
  }
  commandClientId = (window.crypto && window.crypto.randomUUID ? window.crypto.randomUUID() : 'client-' + Date.now() + '-' + Math.random().toString(16).slice(2));
  try {
    window.localStorage.setItem(commandClientStorageKey, commandClientId);
  } catch (_error2) {
    // ignore storage errors
  }
  return commandClientId;
}

// Load the most recent playlist snapshot from browser storage.
function loadPlaylistSnapshot() {
  try {
    var raw = window.localStorage.getItem(playlistSnapshotStorageKey);
    if (!raw) {
      return null;
    }
    var parsed = JSON.parse(raw);
    if (!parsed || !Array.isArray(parsed.slides)) {
      return null;
    }
    return {
      slides: parsed.slides.map(normalizeSlide),
      signature: String(parsed.signature || ''),
      fadeBetweenSlides: Boolean(parsed.fadeBetweenSlides),
      etag: String(parsed.etag || '')
    };
  } catch (_error) {
    return null;
  }
}

// Save the latest playlist snapshot for offline recovery.
function savePlaylistSnapshot(data) {
  try {
    window.localStorage.setItem(playlistSnapshotStorageKey, JSON.stringify({
      slides: Array.isArray(data && data.slides) ? data.slides : [],
      signature: String(data && data.signature || ''),
      fadeBetweenSlides: Boolean(data && data.fadeBetweenSlides),
      etag: String(data && data.etag || ''),
      savedAt: new Date().toISOString()
    }));
  } catch (_error) {
    // ignore storage errors
  }
}

// Apply a playlist snapshot to the current in-memory state.
function applyPlaylistSnapshot(data) {
  if (!data || !Array.isArray(data.slides)) {
    return false;
  }
  slides = data.slides.map(normalizeSlide);
  currentPlaylistSignature = String(data.signature || '');
  currentPlaylistFadeBetweenSlides = Boolean(data.fadeBetweenSlides);
  currentPlaylistEtag = String(data.etag || '');
  pendingPlaylistUpdate = null;
  clearActiveSlidesCache();
  slideMarkupCache = Object.create(null);
  templateLayoutCache = Object.create(null);
  templateRenderPlanCache = Object.create(null);
  renderCacheViewportKey = '';
  index = 0;
  return true;
}