const DESKTOP_ORIGIN_PATTERNS = [
  /^https?:\/\/tauri\.localhost(:\d+)?$/,
  /^https?:\/\/[a-z0-9-]+\.tauri\.localhost(:\d+)?$/i,
  /^tauri:\/\/localhost$/,
  /^asset:\/\/localhost$/,
];

const BROWSER_ORIGIN_PATTERNS = [
  /^https:\/\/(.*\.)?worldmonitor\.app$/,
  /^https:\/\/worldmonitor-[a-z0-9-]+-elie-[a-z0-9]+\.vercel\.app$/,
  ...(process.env.NODE_ENV === 'production' ? [] : [
    /^https?:\/\/localhost(:\d+)?$/,
    /^https?:\/\/127\.0\.0\.1(:\d+)?$/,
  ]),
];

function isDesktopOrigin(origin) {
  return Boolean(origin) && DESKTOP_ORIGIN_PATTERNS.some(p => p.test(origin));
}

function isTrustedBrowserOrigin(origin) {
  return Boolean(origin) && BROWSER_ORIGIN_PATTERNS.some(p => p.test(origin));
}

function extractOriginFromReferer(referer) {
  if (!referer) return '';
  try {
    return new URL(referer).origin;
  } catch {
    return '';
  }
}

export function validateApiKey(req, options = {}) {
  const forceKey = options.forceKey === true;
  const key = req.headers.get('X-WorldMonitor-Key');
  // Same-origin browser requests don't send Origin (per CORS spec).
  // Fall back to Referer to identify trusted same-origin callers.
  const origin = req.headers.get('Origin') || extractOriginFromReferer(req.headers.get('Referer')) || '';

  // Desktop app — always require API key
  if (isDesktopOrigin(origin)) {
    if (!key) return { valid: false, required: true, error: 'API key required for desktop access' };
    const validKeys = (process.env.WORLDMONITOR_VALID_KEYS || '').split(',').filter(Boolean);
    if (!validKeys.includes(key)) return { valid: false, required: true, error: 'Invalid API key' };
    return { valid: true, required: true };
  }

  // Trusted browser origin (worldmonitor.app, Vercel previews, localhost dev) — no key needed
  if (isTrustedBrowserOrigin(origin)) {
    if (forceKey && !key) {
      return { valid: false, required: true, error: 'API key required' };
    }
    if (key) {
      const rawEnv = process.env.WORLDMONITOR_VALID_KEYS || '';
      const validKeys = rawEnv.split(',').filter(Boolean);
      if (!validKeys.includes(key)) return {
        valid: false, required: true, error: 'Invalid API key',
        _debug: {
          receivedKey: key,
          receivedKeyLen: key.length,
          envVarRaw: rawEnv,
          parsedKeys: validKeys,
          envVarLen: rawEnv.length,
        },
      };
    }
    return { valid: true, required: forceKey };
  }

  // Explicit key provided from unknown origin — validate it
  if (key) {
    const validKeys = (process.env.WORLDMONITOR_VALID_KEYS || '').split(',').filter(Boolean);
    if (!validKeys.includes(key)) return { valid: false, required: true, error: 'Invalid API key' };
    return { valid: true, required: true };
  }

  // No origin, no key — require API key (blocks unauthenticated curl/scripts)
  return { valid: false, required: true, error: 'API key required' };
}