export function normalizeLinkedInInput(raw: string): string {
  let working = (raw || '').trim();
  if (!working) return '';
  working = working.replace(/^['"]|['"]$/g, '');
  const lower = working.toLowerCase();

  const buildFromHandle = (handleRaw: string) => {
    let handle = (handleRaw || '').trim();
    handle = handle.replace(/^@+/, '');
    handle = handle.replace(/^in\//i, '');
    handle = handle.replace(/^\/+/, '');
    handle = handle.split('?')[0].split('#')[0];
    handle = handle.replace(/[^a-zA-Z0-9._-]/g, '-');
    handle = handle.replace(/-+/g, '-').replace(/^-+|-+$/g, '');
    return handle ? `https://www.linkedin.com/in/${handle}` : 'https://www.linkedin.com/';
  };

  if (lower.includes('linkedin.com')) {
    let urlStr = working;
    if (!/^https?:\/\//i.test(urlStr)) {
      urlStr = 'https://' + urlStr.replace(/^\/+/, '');
    }
    try {
      const u = new URL(urlStr);
      const parts = (u.pathname || '').split('/').filter(Boolean);
      const reserved = new Set(['pub', 'mwlite', 'profile', 'redir', 'sales', 'company', 'school', 'feed', 'posts', 'pulse']);
      let handle = '';
      const inIndex = parts.findIndex(p => p.toLowerCase() === 'in');
      if (inIndex >= 0 && parts[inIndex + 1]) {
        handle = parts[inIndex + 1];
      } else {
        const candidates = parts.filter(p => !reserved.has(p.toLowerCase()));
        handle = candidates[candidates.length - 1] || '';
      }
      return buildFromHandle(handle);
    } catch {
      // fall through to handle mode
    }
  }

  if (/^https?:\/\//i.test(working) || /^www\./i.test(working)) {
    return working;
  }

  return buildFromHandle(working);
}