/**
 * Open Graph：复用 <title> / meta[name=description]，补齐绝对 og:url / og:image。
 * 爬虫可读 head 内静态 meta；本脚本在浏览器中按当前域名校正。
 */
(function () {
  var PROD_ORIGIN = 'https://ideship.com';
  var OG_IMAGE_PATH = '/site/assets/img/og-cover.png';
  var OG_IMAGE_REL = 'assets/img/og-cover.png';

  function truncate(text, max) {
    var value = String(text || '')
      .replace(/\s+/g, ' ')
      .trim();
    if (value.length <= max) return value;
    return value.slice(0, max);
  }

  function ensureMeta(property, content) {
    if (!content) return;
    var node = document.querySelector('meta[property="' + property + '"]');
    if (!node) {
      node = document.createElement('meta');
      node.setAttribute('property', property);
      document.head.appendChild(node);
    }
    node.setAttribute('content', content);
  }

  function resolveOrigin() {
    if (location.protocol === 'http:' || location.protocol === 'https:') {
      return location.origin;
    }
    return PROD_ORIGIN;
  }

  function resolvePageUrl(origin) {
    if (location.protocol === 'file:') {
      return /9610\.html$/i.test(location.pathname || '')
        ? PROD_ORIGIN + '/9610.html'
        : PROD_ORIGIN + '/';
    }
    var path = location.pathname || '/';
    if (/\/index\.html$/i.test(path)) {
      path = path.replace(/\/index\.html$/i, '/') || '/';
    }
    if (path === '/site' || path === '/site/' || path === '/site/index.html') {
      path = '/';
    }
    return origin + path + (location.search || '');
  }

  function resolveImageUrl(origin) {
    if (origin === PROD_ORIGIN || /(^|\.)ideship\.com$/i.test(location.hostname || '')) {
      return origin + OG_IMAGE_PATH;
    }
    try {
      return new URL(OG_IMAGE_REL, location.href).href;
    } catch (e) {
      return origin + '/assets/img/og-cover.png';
    }
  }

  function applyOpenGraph() {
    var title = truncate(document.title, 30);
    var descNode = document.querySelector('meta[name="description"]');
    var description = truncate(descNode && descNode.getAttribute('content'), 60);
    var origin = resolveOrigin();

    ensureMeta('og:title', title);
    if (description) ensureMeta('og:description', description);
    ensureMeta('og:image', resolveImageUrl(origin));
    ensureMeta('og:url', resolvePageUrl(origin));
    ensureMeta('og:type', 'website');
  }

  applyOpenGraph();
  window.IDEOpenGraph = { refresh: applyOpenGraph };
})();