feat: automate README contributors section via GitHub Actions

Adds a GitHub Actions workflow that automatically updates the README
contributors section whenever a pull request is merged into main,
removing the need to manually maintain the contributor list.

- Add .github/workflows/update-contributors.yml, triggered on merged
  pull requests targeting main
- Add .github/scripts/update-contributors.js to parse the merge event,
  classify the contribution type from PR labels/title, and rewrite the
  contributors table between the CONTRIBUTORS-START/END anchors in
  README.md
- Fetch each contributor's display name and avatar from the GitHub API,
  falling back to their username if the name is unavailable
- Skip bot accounts and prevent duplicate entries for existing
  contributors
- Add a concurrency group to the workflow to prevent race conditions
  when multiple PRs merge in quick succession
- Add unit tests (.github/scripts/update-contributors.test.js) covering
  contribution-type classification, contributor parsing, and table
  generation, using Node's built-in assert module

Resolves #10

Author: udaycodespace

.github/scripts/update-contributors.js

@@ -0,0 +1,223 @@
+const fs = require('fs');
+const path = require('path');
+
+const README_PATH = path.join(__dirname, '../../README.md');
+
+function getContributionType(prPayload) {
+  const pr = prPayload.pull_request;
+  const labels = (pr.labels || []).map(l => l.name.toLowerCase());
+  
+  if (labels.some(l => l.includes('frontend') || l.includes('ui') || l.includes('css') || l.includes('design') || l.includes('style'))) {
+    return '🎨 Frontend';
+  }
+  if (labels.some(l => l.includes('design') || l.includes('ux'))) {
+    return '🎨 Design';
+  }
+  if (labels.some(l => l.includes('backend') || l.includes('api') || l.includes('database') || l.includes('db') || l.includes('server'))) {
+    return '💻 Code';
+  }
+  if (labels.some(l => l.includes('docs') || l.includes('documentation') || l.includes('readme') || l.includes('wiki'))) {
+    return '📖 Docs';
+  }
+  if (labels.some(l => l.includes('bug') || l.includes('fix') || l.includes('hotfix') || l.includes('patch'))) {
+    return '🐛 Bug fix';
+  }
+  if (labels.some(l => l.includes('test') || l.includes('testing') || l.includes('spec') || l.includes('jest') || l.includes('pytest'))) {
+    return '🧪 Tests';
+  }
+  if (labels.some(l => l.includes('performance') || l.includes('speed') || l.includes('perf'))) {
+    return '⚡ Performance';
+  }
+  if (labels.some(l => l.includes('security') || l.includes('vuln') || l.includes('auth'))) {
+    return '🔒 Security';
+  }
+  if (labels.some(l => l.includes('infra') || l.includes('ci') || l.includes('cd') || l.includes('workflow') || l.includes('docker') || l.includes('github-actions'))) {
+    return '🚇 Infrastructure';
+  }
+  if (labels.some(l => l.includes('accessibility') || l.includes('a11y'))) {
+    return '♿ Accessibility';
+  }
+  
+  // Fallback to title matching
+  const title = (pr.title || '').toLowerCase();
+  if (title.startsWith('feat') || title.includes('frontend') || title.includes('ui')) {
+    if (title.includes('frontend') || title.includes('ui')) return '🎨 Frontend';
+    if (title.includes('design')) return '🎨 Design';
+    if (title.includes('docs') || title.includes('readme')) return '📖 Docs';
+    if (title.includes('test')) return '🧪 Tests';
+    if (title.includes('perf')) return '⚡ Performance';
+    if (title.includes('security') || title.includes('auth')) return '🔒 Security';
+    if (title.includes('infra') || title.includes('workflow') || title.includes('github action')) return '🚇 Infrastructure';
+    return '💻 Code';
+  }
+  if (title.startsWith('fix') || title.includes('bug')) {
+    return '🐛 Bug fix';
+  }
+  if (title.startsWith('docs')) {
+    return '📖 Docs';
+  }
+  if (title.startsWith('test')) {
+    return '🧪 Tests';
+  }
+  
+  return '💻 Code';
+}
+
+function parseExistingContributors(sectionContent) {
+  const contributors = [];
+  const regex = /<td align="center">\s*<a href="https:\/\/github\.com\/([^"]+)">\s*<img src="([^"]+)"[^>]*\/>\s*<br \/>\s*<sub><b>([^<]+)<\/b><\/sub>\s*<br \/>\s*<sub>([^<]+)<\/sub>\s*<\/a>\s*<\/td>/gi;
+  
+  let match;
+  while ((match = regex.exec(sectionContent)) !== null) {
+    contributors.push({
+      username: match[1].trim(),
+      avatarUrl: match[2].trim(),
+      name: match[3].trim(),
+      role: match[4].trim()
+    });
+  }
+  return contributors;
+}
+
+function generateTableHTML(contributors) {
+  const columnsPerRow = 5;
+  let html = '\n<div align="center">\n\n<table>\n  <tbody>\n';
+  
+  for (let i = 0; i < contributors.length; i += columnsPerRow) {
+    html += '    <tr>\n';
+    const chunk = contributors.slice(i, i + columnsPerRow);
+    for (const c of chunk) {
+      html += `      <td align="center">
+        <a href="https://github.com/${c.username}">
+          <img src="${c.avatarUrl}" width="80px" />
+          <br />
+          <sub><b>${c.name}</b></sub>
+          <br />
+          <sub>${c.role}</sub>
+        </a>
+      </td>\n`;
+    }
+    html += '    </tr>\n';
+  }
+  
+  html += '  </tbody>\n</table>\n\n</div>\n';
+  return html;
+}
+
+async function main() {
+  const eventPath = process.env.GITHUB_EVENT_PATH;
+  if (!eventPath) {
+    console.error('Error: GITHUB_EVENT_PATH not set.');
+    process.exit(1);
+  }
+
+  let eventPayload;
+  try {
+    eventPayload = JSON.parse(fs.readFileSync(eventPath, 'utf8'));
+  } catch (err) {
+    console.error('Error reading event payload:', err.message);
+    process.exit(1);
+  }
+
+  const pr = eventPayload.pull_request;
+  if (!pr) {
+    console.error('Error: Event payload is missing pull_request info.');
+    process.exit(1);
+  }
+
+  // Handle Bot accounts
+  const username = pr.user.login;
+  const isBot = pr.user.type === 'Bot' || username.toLowerCase().endsWith('[bot]') || username.toLowerCase() === 'github-actions';
+  if (isBot) {
+    console.log(`Skipping bot contributor: ${username}`);
+    process.exit(0);
+  }
+
+  const avatarUrl = `https://github.com/${username}.png`;
+  let name = username; // Default to username
+
+  // Fetch real profile name from GitHub API (authenticated if GITHUB_TOKEN is available)
+  const headers = { 'User-Agent': 'learnhub-contributors-automation' };
+  if (process.env.GITHUB_TOKEN) {
+    headers['Authorization'] = `token ${process.env.GITHUB_TOKEN}`;
+  }
+
+  try {
+    const response = await fetch(`https://api.github.com/users/${username}`, { headers });
+    if (response.ok) {
+      const userData = await response.json();
+      if (userData.name) {
+        name = userData.name;
+        console.log(`Fetched display name: "${name}" for user ${username}`);
+      }
+    } else {
+      console.warn(`GitHub API returned status ${response.status} when fetching profile for ${username}`);
+    }
+  } catch (err) {
+    console.warn(`Failed to fetch user profile name from GitHub API, using username instead: ${err.message}`);
+  }
+
+  const role = getContributionType(eventPayload);
+
+  // Read README
+  if (!fs.existsSync(README_PATH)) {
+    console.error(`Error: README.md not found at ${README_PATH}`);
+    process.exit(1);
+  }
+
+  let readmeContent = fs.readFileSync(README_PATH, 'utf8');
+
+  // Locate the contributors section
+  const startComment = '<!-- CONTRIBUTORS-START -->';
+  const endComment = '<!-- CONTRIBUTORS-END -->';
+
+  const startIndex = readmeContent.indexOf(startComment);
+  const endIndex = readmeContent.indexOf(endComment);
+
+  if (startIndex === -1 || endIndex === -1 || startIndex >= endIndex) {
+    console.error('Error: Contributors placeholder comments not found in README.md.');
+    process.exit(1);
+  }
+
+  const sectionContent = readmeContent.substring(startIndex + startComment.length, endIndex);
+  const contributors = parseExistingContributors(sectionContent);
+
+  // Check for duplicates
+  const alreadyExists = contributors.some(c => c.username.toLowerCase() === username.toLowerCase());
+  if (alreadyExists) {
+    console.log(`Contributor ${username} already exists in README.md. Skipping.`);
+    process.exit(0);
+  }
+
+  // Add new contributor
+  contributors.push({
+    username,
+    avatarUrl,
+    name,
+    role
+  });
+
+  console.log(`Adding new contributor: ${username} with role: ${role}`);
+
+  // Generate new HTML table
+  const newTableHTML = generateTableHTML(contributors);
+
+  // Construct new README content
+  const updatedReadmeContent = 
+    readmeContent.substring(0, startIndex + startComment.length) +
+    newTableHTML +
+    readmeContent.substring(endIndex);
+
+  fs.writeFileSync(README_PATH, updatedReadmeContent, 'utf8');
+  console.log('README.md successfully updated.');
+}
+
+if (require.main === module) {
+  main();
+}
+
+module.exports = {
+  getContributionType,
+  parseExistingContributors,
+  generateTableHTML
+};