function escapeRegex(s) {
  return s.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
}

function highlightWords(lists) {
  const textNodes = [];
  const walker = document.createTreeWalker(document.body, NodeFilter.SHOW_TEXT, {
    acceptNode: node => {
      if (node.parentNode && ['SCRIPT', 'STYLE', 'NOSCRIPT', 'IFRAME'].includes(node.parentNode.nodeName)) return NodeFilter.FILTER_REJECT;
      if (!node.nodeValue.trim()) return NodeFilter.FILTER_SKIP;
      return NodeFilter.FILTER_ACCEPT;
    }
  });

  while (walker.nextNode()) textNodes.push(walker.currentNode);

  const activeWords = [];

  for (const list of lists) {
    if (!list.active) continue;
    for (const word of list.words) {
      if (!word.active) continue;
      activeWords.push({
        text: word.wordStr,
        background: word.background || list.background,
        foreground: word.foreground || list.foreground
      });
    }
  }

  if (activeWords.length === 0) return;

  const wordMap = new Map();
  for (const word of activeWords) wordMap.set(word.text.toLowerCase(), word);

  const pattern = new RegExp(`(${Array.from(wordMap.keys()).map(escapeRegex).join('|')})`, 'gi');

  for (const node of textNodes) {
    if (!pattern.test(node.nodeValue)) continue;

    const span = document.createElement('span');
    span.innerHTML = node.nodeValue.replace(pattern, match => {
      const word = wordMap.get(match.toLowerCase()) || { background: '#ffff00', foreground: '#000000' };
      return `<mark style="background:${word.background};color:${word.foreground};padding:0 2px;">${match}</mark>`;
    });

    node.parentNode.replaceChild(span, node);
  }
}

chrome.storage.local.get("lists", ({ lists }) => {
  if (Array.isArray(lists)) highlightWords(lists);
});