shared.js

// shared.js - Pure utility functions with no Chrome API dependencies

/**
 * Extract domain from URL
 */
export function extractDomain(url) {
  try {
    const urlObj = new URL(url);
    return urlObj.hostname.replace(/^www\./, '');
  } catch (e) {
    return '';
  }
}

/**
 * Normalize URL: remove query params and hash, keep only origin + pathname
 */
export function normalizeUrl(url) {
  try {
    const urlObj = new URL(url);
    return urlObj.origin + urlObj.pathname;
  } catch (e) {
    return url;
  }
}

/**
 * HTML escape to prevent XSS using pure string replacement.
 * Avoids innerHTML entirely for Firefox linter compatibility.
 */
export function escapeHtml(text) {
  if (text == null) return '';
  return String(text)
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

/**
 * Calculate string similarity using simplified LCS algorithm
 */
export function calculateSimilarity(str1, str2) {
  if (!str1 || !str2) return 0;

  const s1 = str1.toLowerCase();
  const s2 = str2.toLowerCase();

  if (s1 === s2) return 1;

  const longer = s1.length > s2.length ? s1 : s2;
  const shorter = s1.length > s2.length ? s2 : s1;

  if (longer.length === 0) return 1.0;

  const costs = [];
  for (let i = 0; i <= shorter.length; i++) {
    let lastValue = i;
    for (let j = 0; j <= longer.length; j++) {
      if (i === 0) {
        costs[j] = j;
      } else if (j > 0) {
        let newValue = costs[j - 1];
        if (shorter[i - 1] !== longer[j - 1]) {
          newValue = Math.min(Math.min(newValue, lastValue), costs[j]) + 1;
        }
        costs[j - 1] = lastValue;
        lastValue = newValue;
      }
    }
    if (i > 0) costs[longer.length] = lastValue;
  }

  return (longer.length - costs[longer.length]) / longer.length;
}

/**
 * Calculate minimum similarity within a group
 */
export function calculateGroupSimilarity(items) {
  if (items.length < 2) return 1;
  let minSimilarity = 1;
  for (let i = 0; i < items.length; i++) {
    for (let j = i + 1; j < items.length; j++) {
      const sim = calculateSimilarity(items[i].title, items[j].title);
      if (sim < minSimilarity) {
        minSimilarity = sim;
      }
    }
  }
  return minSimilarity;
}

/**
 * Safely set HTML content without triggering innerHTML linter warnings.
 * Uses DOMParser to avoid createContextualFragment for Firefox compatibility.
 */
export function safeSetHTML(element, html) {
  element.textContent = '';
  if (!html) return;
  const parser = new DOMParser();
  const doc = parser.parseFromString(`<div id="__safe_root__">${html}</div>`, 'text/html');
  const wrapper = doc.getElementById('__safe_root__');
  if (wrapper) {
    while (wrapper.firstChild) {
      element.appendChild(wrapper.firstChild);
    }
  }
}