/* ============================================================================
 * TIL search — merges the Docusaurus TIL site's results into the WordPress
 * search-results page.
 *
 * The TIL site (/til/, a separate Docusaurus build) uses docusaurus-lunr-search,
 * which ships a prebuilt lunr 2.3.9 index (/til/lunr-index.json) + a document
 * store (/til/search-doc.json). This module loads both client-side and queries
 * them exactly the way the TIL search bar does, so the results match, then
 * renders a labeled "From TIL" section on the WP search page.
 *
 * SELF-CONTAINED / REMOVABLE. Depends only on the vendored global `lunr`
 * (js/vendor/lunr.min.js) and config in window.dwTilSearch (localized in
 * functions.php). Fills #dw-til-results (placeholder in templates/search.html).
 * To remove the feature entirely, delete:
 *   - this file + js/vendor/lunr.min.js
 *   - the "TIL search" enqueue block in functions.php (is_search())
 *   - the <!-- wp:html --> #dw-til-results block in templates/search.html
 *   - the "TIL search results" CSS block in style.css
 * ==========================================================================*/
(function () {
  'use strict';

  var cfg = window.dwTilSearch;
  if (!cfg || !cfg.query || typeof lunr === 'undefined') return;
  var mount = document.getElementById('dw-til-results');
  if (!mount) return;

  // docusaurus-lunr-search overrides the tokenizer separator; match it so our
  // client-side tokenizing (and therefore the matches) line up with the index.
  lunr.tokenizer.separator = /[\s\-/]+/;

  Promise.all([
    fetch(cfg.index).then(function (r) { return r.json(); }),
    fetch(cfg.docs).then(function (r) { return r.json(); })
  ]).then(function (res) {
    var index = lunr.Index.load(res[0]);
    var docs = (res[1] && res[1].searchDocs) || [];
    var input = String(cfg.query);

    // Same query the plugin's LunrSearchAdapter builds: exact terms (boosted)
    // plus trailing-wildcard terms for prefix matches.
    var results = index.query(function (query) {
      var tokens = lunr.tokenizer(input);
      query.term(tokens, { boost: 10 });
      query.term(tokens, { wildcard: lunr.Query.wildcard.TRAILING });
    });

    // Map hits to docs, dedupe by URL (a page can match on title + content),
    // keep lunr's ranking order, cap to maxHits.
    var seen = {}, hits = [];
    for (var i = 0; i < results.length && hits.length < cfg.maxHits; i++) {
      var doc = docs[results[i].ref];
      if (!doc || seen[doc.url]) continue;
      seen[doc.url] = 1;
      hits.push(doc);
    }
    render(hits, input);
  }).catch(function () {
    /* TIL index unreachable (e.g. /til not deployed) — skip silently. */
  });

  function esc(s) {
    return String(s).replace(/[&<>"]/g, function (c) {
      return { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;' }[c];
    });
  }

  // A short excerpt centered on the first query term, with the terms highlighted.
  function snippet(content, input) {
    if (!content) return '';
    var tokens = lunr.tokenizer(input).map(String);
    var lc = content.toLowerCase();
    var pos = tokens.length ? lc.indexOf(tokens[0]) : -1;
    var start = pos < 0 ? 0 : Math.max(0, pos - 60);
    var slice = content.substring(start, start + 200);
    var out = (start > 0 ? '… ' : '') + esc(slice) +
              (start + 200 < content.length ? ' …' : '');
    tokens.forEach(function (t) {
      if (!t) return;
      var re = new RegExp('(' + t.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + ')', 'ig');
      out = out.replace(re, '<mark>$1</mark>');
    });
    return out;
  }

  function render(hits, input) {
    if (!hits.length) { mount.hidden = true; return; }
    var html = '<ul class="dw-til-list">';
    hits.forEach(function (d) {
      html += '<li class="dw-til-item">' +
                '<a class="dw-til-link" href="' + esc(d.url) + '">' + esc(d.title) + '</a>' +
                '<p class="dw-til-snippet">' + snippet(d.content, input) + '</p>' +
              '</li>';
    });
    html += '</ul>';
    mount.innerHTML = html;
    mount.hidden = false;
  }
})();