/* BIOTEN Observer V7.31.8-R8: hub preview limits, date-sorted pagination, language and PDF routing. */
(() => {
  'use strict';

  const DEFAULT_PAGE_SIZE = 12;
  const INDUSTRY_PAGE_SIZE = 8;
  const DEFAULT_COMPANY_COVER = 'assets/images/bioten-observer/company-news-default.jpg';
  const DEFAULT_INDUSTRY_COVER = 'assets/images/bioten-observer/industry-insights-default.jpg';
  const isEnglish = () => document.documentElement.lang.toLowerCase().startsWith('en');
  const text = (cn, en) => (isEnglish() ? en : cn);

  function updateLanguageAttributes(root = document) {
    root.querySelectorAll('[data-aria-cn][data-aria-en]').forEach((element) => {
      element.setAttribute('aria-label', isEnglish() ? element.dataset.ariaEn : element.dataset.ariaCn);
    });
    root.querySelectorAll('[data-v7301-en-review]').forEach((notice) => {
      notice.hidden = !isEnglish();
    });
  }

  function updateObserverChrome() {
    const title = document.querySelector('title[data-cn][data-en]');
    if (title) document.title = isEnglish() ? title.dataset.en : title.dataset.cn;

    const context = document.querySelector('.v500-context');
    if (!context) return;
    context.dataset.ariaCn = '博碳观察页面层级';
    context.dataset.ariaEn = 'BIOTEN Observer context';
    context.setAttribute('aria-label', text(context.dataset.ariaCn, context.dataset.ariaEn));

    const first = context.querySelector('ol > li:first-child :is(a, span)');
    if (first) {
      first.dataset.newsCn = '博碳观察';
      first.dataset.newsEn = 'BIOTEN Observer';
      first.textContent = text(first.dataset.newsCn, first.dataset.newsEn);
    }

    const current = context.querySelector('ol > li:last-child :is(a, span)');
    if (!current) return;
    const view = document.body.dataset.observerView;
    const labels = {
      hub: ['公司动态 · 行业洞察', 'Company News · Industry Insights'],
      company: ['公司动态', 'Company News'],
      industry: ['行业洞察', 'Industry Insights'],
      article: ['文章阅读', 'Article'],
      document: ['PDF 阅读', 'PDF Reader'],
      legacy: ['内容频道', 'Content Channels'],
    };
    const [cn, en] = labels[view] || labels.article;
    current.dataset.newsCn = cn;
    current.dataset.newsEn = en;
    current.textContent = text(cn, en);
  }

  function protectObserverTitle() {
    const title = document.querySelector('title[data-cn][data-en]');
    if (!title) return;
    const observer = new MutationObserver(() => {
      const preferred = isEnglish() ? title.dataset.en : title.dataset.cn;
      if (document.title !== preferred) document.title = preferred;
    });
    observer.observe(title, { childList: true, characterData: true, subtree: true });
  }

  function normalizeLegacyParameters() {
    const url = new URL(window.location.href);
    let changed = false;
    ['q', 'tag', 'category'].forEach((key) => {
      if (url.searchParams.has(key)) {
        url.searchParams.delete(key);
        changed = true;
      }
    });
    if (changed) window.history.replaceState({}, '', `${url.pathname}${url.search}${url.hash}`);
  }

  function installCoverFallbacks() {
    document.querySelectorAll('.observer-publication-card__media img, .observer-card__media img, .observer-home-card__media img, .observer-article-cover img').forEach((image) => {
      image.addEventListener('error', () => {
        const industry = image.closest('[data-observer-category="industry"], [data-observer-mode="industry"]');
        const fallback = industry ? DEFAULT_INDUSTRY_COVER : DEFAULT_COMPANY_COVER;
        if (!image.src.endsWith(fallback)) image.src = fallback;
      }, { once: true });
    });
  }

  function initializeHubPreviews() {
    const hub = document.querySelector('[data-observer-mode="hub"]');
    if (!hub) return;

    hub.querySelectorAll('[data-observer-preview-limit]').forEach((section) => {
      const grid = section.querySelector('.observer-home-publications');
      const limit = Math.max(1, Number.parseInt(section.dataset.observerPreviewLimit || '', 10) || 1);
      if (!grid) return;

      const observer = new MutationObserver(() => sortAndLimit());

      function sortAndLimit() {
        observer.disconnect();
        const cards = Array.from(grid.querySelectorAll(':scope > [data-observer-item]'))
          .map((card, sourceIndex) => {
            const publishedAt = Date.parse(card.querySelector('time[datetime]')?.getAttribute('datetime') || '');
            return {
              card,
              sourceIndex,
              publishedAt: Number.isFinite(publishedAt) ? publishedAt : 0,
            };
          })
          .sort((left, right) => right.publishedAt - left.publishedAt || left.sourceIndex - right.sourceIndex);

        cards.forEach(({ card }, index) => {
          card.hidden = index >= limit;
          card.setAttribute('aria-posinset', String(index + 1));
          card.setAttribute('aria-setsize', String(Math.min(cards.length, limit)));
          grid.append(card);
        });
        observer.observe(grid, { childList: true });
      }

      sortAndLimit();
    });
  }

  function pageButton(labelCn, labelEn, pageNumber, options = {}) {
    const control = document.createElement('button');
    control.type = 'button';
    control.textContent = text(labelCn, labelEn);
    control.dataset.labelCn = labelCn;
    control.dataset.labelEn = labelEn;
    control.dataset.page = String(pageNumber);
    if (options.current) control.setAttribute('aria-current', 'page');
    if (options.disabled) control.disabled = true;
    if (options.ariaCn) {
      control.dataset.ariaCn = options.ariaCn;
      control.dataset.ariaEn = options.ariaEn;
      control.setAttribute('aria-label', text(options.ariaCn, options.ariaEn));
    }
    return control;
  }

  function initializeList(page) {
    const pagination = page.querySelector('[data-observer-pagination]');
    const status = page.querySelector('[data-observer-status]');
    const grid = page.querySelector('[data-observer-grid]');
    if (!pagination || !grid) return;

    const items = Array.from(grid.querySelectorAll(':scope > [data-observer-item]'))
      .map((item, sourceIndex) => {
        const publishedAt = Date.parse(item.querySelector('time[datetime]')?.getAttribute('datetime') || '');
        return {
          item,
          sourceIndex,
          publishedAt: Number.isFinite(publishedAt) ? publishedAt : 0,
        };
      })
      .sort((left, right) => right.publishedAt - left.publishedAt || left.sourceIndex - right.sourceIndex)
      .map(({ item }) => item);

    if (!items.length || !pagination || !grid) return;

    items.forEach((item) => grid.append(item));
    const configuredPageSize = Math.max(
      1,
      Number.parseInt(page.dataset.observerPageSize || String(DEFAULT_PAGE_SIZE), 10) || DEFAULT_PAGE_SIZE,
    );
    const pageSize = page.dataset.observerMode === 'industry'
      ? INDUSTRY_PAGE_SIZE
      : configuredPageSize;
    page.dataset.observerPageSize = String(pageSize);
    const state = { page: 1 };

    function readUrlState() {
      const params = new URLSearchParams(window.location.search);
      state.page = Math.max(1, Number.parseInt(params.get('page') || '1', 10) || 1);
    }

    function writeUrlState() {
      const url = new URL(window.location.href);
      if (state.page > 1) url.searchParams.set('page', String(state.page));
      else url.searchParams.delete('page');
      window.history.pushState({}, '', `${url.pathname}${url.search}#observer-list`);
    }

    function renderPagination(totalPages) {
      pagination.replaceChildren();
      pagination.hidden = totalPages <= 1;
      if (totalPages <= 1) return;

      pagination.append(pageButton('上一页', 'Previous', Math.max(1, state.page - 1), {
        disabled: state.page === 1,
        ariaCn: '上一页',
        ariaEn: 'Previous page',
      }));

      const values = totalPages <= 7
        ? Array.from({ length: totalPages }, (_, index) => index + 1)
        : Array.from(new Set([1, totalPages, state.page - 1, state.page, state.page + 1]))
          .filter((value) => value > 0 && value <= totalPages)
          .sort((left, right) => left - right);

      let previous = 0;
      values.forEach((value) => {
        if (previous && value - previous > 1) {
          const gap = document.createElement('span');
          gap.textContent = '…';
          gap.setAttribute('aria-hidden', 'true');
          pagination.append(gap);
        }
        pagination.append(pageButton(String(value), String(value), value, {
          current: value === state.page,
          ariaCn: `第${value}页`,
          ariaEn: `Page ${value}`,
        }));
        previous = value;
      });

      pagination.append(pageButton('下一页', 'Next', Math.min(totalPages, state.page + 1), {
        disabled: state.page === totalPages,
        ariaCn: '下一页',
        ariaEn: 'Next page',
      }));
    }

    function render({ updateUrl = false, focusList = false } = {}) {
      const totalPages = Math.max(1, Math.ceil(items.length / pageSize));
      state.page = Math.min(state.page, totalPages);
      const first = (state.page - 1) * pageSize;
      const visibleItems = items.slice(first, first + pageSize);
      const visible = new Set(visibleItems);
      items.forEach((item) => { item.hidden = !visible.has(item); });

      if (status) {
        const start = items.length ? first + 1 : 0;
        const end = Math.min(first + pageSize, items.length);
        const statusCn = `第 ${start}-${end} 篇 · 共 ${items.length} 篇`;
        const statusEn = `${start}-${end} of ${items.length}`;
        status.dataset.newsCn = statusCn;
        status.dataset.newsEn = statusEn;
        status.textContent = text(statusCn, statusEn);
      }

      renderPagination(totalPages);
      updateLanguageAttributes(page);
      if (updateUrl) writeUrlState();
      if (focusList) visibleItems[0]?.querySelector('h2 a, h3 a')?.focus({ preventScroll: false });
    }

    pagination.addEventListener('click', (event) => {
      const button = event.target.closest('button[data-page]');
      if (!button || button.disabled) return;
      state.page = Number.parseInt(button.dataset.page, 10) || 1;
      render({ updateUrl: true, focusList: true });
    });
    window.addEventListener('popstate', () => { readUrlState(); render(); });
    document.addEventListener('dbc:languagechange', () => render());
    readUrlState();
    render();
  }

  function initializeDocument() {
    const main = document.querySelector('[data-observer-view="document"], .observer-document-main');
    if (!main) return;
    const slug = new URLSearchParams(window.location.search).get('doc');
    const catalog = Array.isArray(window.BiotenObserverCatalogV7318) ? window.BiotenObserverCatalogV7318 : [];
    const article = catalog.find((entry) => entry.slug === slug);
    const error = document.querySelector('[data-document-error]');
    if (!article) {
      if (error) error.hidden = false;
      return;
    }

    const categoryPage = article.observerCategory === 'industry' ? 'news-insights.html' : 'news-company.html';
    const categoryLink = document.querySelector('[data-document-category-link]');
    const articleLink = document.querySelector('[data-document-article-link]');
    const back = document.querySelector('[data-document-back]');
    const open = document.querySelector('[data-document-open]');
    const download = document.querySelector('[data-document-download]');
    const frame = document.querySelector('[data-document-frame]');
    const title = document.querySelector('[data-document-title]');
    const category = document.querySelector('[data-document-category]');
    if (categoryLink) categoryLink.href = categoryPage;
    if (articleLink) articleLink.href = article.file;
    if (back) back.href = article.file;
    if (open) open.href = article.pdf;
    if (download) {
      download.href = article.pdf;
      download.download = article.pdfDownloadName;
    }
    if (frame) frame.data = article.pdf;
    if (title) {
      title.dataset.newsCn = article.title;
      title.dataset.newsEn = article.titleEn;
      title.textContent = text(article.title, article.titleEn);
    }
    if (category) {
      category.dataset.newsCn = article.observerCategoryCn;
      category.dataset.newsEn = article.observerCategoryEn;
      category.textContent = text(article.observerCategoryCn, article.observerCategoryEn);
    }
    if (error) error.hidden = true;
  }

  function initializeArticleShare(main) {
    const meta = main.querySelector('.observer-article-hero__meta');
    const pdfAction = meta?.querySelector('.observer-article-hero__pdf-action');
    if (!meta || !pdfAction) return;

    let button = meta.querySelector('[data-article-share]');
    if (!button) {
      button = document.createElement('button');
      button.className = 'observer-article-hero__share-action';
      button.type = 'button';
      button.dataset.articleShare = '';
      button.dataset.ariaCn = '分享阅读';
      button.dataset.ariaEn = 'Share article';
      button.setAttribute('aria-label', text('分享阅读', 'Share article'));
      button.setAttribute('title', text('分享阅读', 'Share article'));
      button.innerHTML = '<span class="observer-article-hero__share-label" data-article-share-label data-news-cn="分享阅读" data-news-en="Share article">分享阅读</span><svg viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path class="share-arrow-box" d="M7.5 4.1H6.7A3.7 3.7 0 0 0 3 7.8v8.4a3.7 3.7 0 0 0 3.7 3.7h9.1a3.7 3.7 0 0 0 3.7-3.7v-2.5"></path><path class="share-arrow" d="M8.7 15.6c-.98-3.47-.29-6.22 2.04-7.74 1.52-.99 3.22-1.16 5.41-1.12V3.5l5.9 5.82-5.9 5.8v-3.17c-2.99-.27-5.04.9-7.46 3.65Z"></path></svg>';
      pdfAction.insertAdjacentElement('afterend', button);
    }

    if (button.dataset.shareReady === 'true') return;
    button.dataset.shareReady = 'true';
    const label = button.querySelector('[data-article-share-label]');
    const setLabel = (cn, en) => {
      const value = text(cn, en);
      if (label) label.textContent = value;
      button.setAttribute('aria-label', value);
      button.setAttribute('title', value);
    };
    const restoreLabel = () => setLabel('分享阅读', 'Share article');
    const flashLabel = (cn, en) => {
      setLabel(cn, en);
      button.dataset.shareMessage = text(cn, en);
      window.setTimeout(() => {
        delete button.dataset.shareMessage;
        restoreLabel();
      }, 2200);
    };
    const copyCurrentUrl = async () => {
      const url = window.location.href;
      try {
        if (navigator.clipboard?.writeText) {
          await navigator.clipboard.writeText(url);
          return true;
        }
      } catch (_) {
        // Continue to the browser-compatible copy fallback.
      }
      const field = document.createElement('textarea');
      field.value = url;
      field.setAttribute('readonly', '');
      field.style.cssText = 'position:fixed;left:-9999px;top:0;opacity:0;';
      document.body.appendChild(field);
      field.select();
      const copied = document.execCommand('copy');
      field.remove();
      return copied;
    };

    button.addEventListener('click', async () => {
      const title = main.querySelector('.observer-article-hero h1')?.textContent?.trim() || document.title;
      const url = window.location.href;
      if (navigator.share) {
        try {
          await navigator.share({ title, url });
          return;
        } catch (error) {
          if (error instanceof DOMException && error.name === 'AbortError') return;
        }
      }
      const copied = await copyCurrentUrl();
      flashLabel(copied ? '链接已复制' : '请复制当前链接', copied ? 'Link copied' : 'Copy this page URL');
    });
    document.addEventListener('dbc:languagechange', restoreLabel);
  }

  function initializeArticle() {
    const main = document.querySelector('[data-observer-article]');
    if (!main) return;
    initializeArticleShare(main);
    const catalog = Array.isArray(window.BiotenObserverCatalogV7318) ? window.BiotenObserverCatalogV7318 : [];
    const article = catalog.find((entry) => entry.slug === main.dataset.observerArticle);
    if (!article) return;

    const publisher = main.querySelector('.observer-article-hero__meta > span:nth-child(2)');
    if (publisher) {
      const label = publisher.querySelector('b');
      Array.from(publisher.childNodes).forEach((node) => { if (node !== label) node.remove(); });
      const value = document.createElement('span');
      value.dataset.observerAuthor = '';
      value.dataset.newsCn = article.authorCn;
      value.dataset.newsEn = article.authorEn;
      value.textContent = text(article.authorCn, article.authorEn);
      publisher.append(value);
    }

    const authorLabel = Array.from(main.querySelectorAll('.observer-article-data th')).find((cell) => cell.dataset.newsCn === '发布主体');
    const authorCell = authorLabel?.closest('tr')?.querySelector('td');
    if (authorCell) {
      authorCell.dataset.newsCn = article.authorCn;
      authorCell.dataset.newsEn = article.authorEn;
      authorCell.textContent = text(article.authorCn, article.authorEn);
    }
  }

  function initialize() {
    normalizeLegacyParameters();
    updateLanguageAttributes();
    updateObserverChrome();
    protectObserverTitle();
    installCoverFallbacks();
    initializeHubPreviews();
    const list = document.querySelector('[data-observer-list-page]');
    if (list) initializeList(list);
    initializeDocument();
    initializeArticle();
    document.addEventListener('dbc:languagechange', () => {
      updateLanguageAttributes();
      updateObserverChrome();
      initializeDocument();
      initializeArticle();
    });
    window.addEventListener('load', updateObserverChrome, { once: true });
  }

  if (document.readyState === 'loading') document.addEventListener('DOMContentLoaded', initialize, { once: true });
  else initialize();
})();