src/lib/cors.ts

// ═══════════════════════════════════════════════════════════════════════════
// CORS HELPER - Shared CORS headers and OPTIONS preflight handler
// Use this in every API route for cross-origin frontend support
// ═══════════════════════════════════════════════════════════════════════════

export const CORS_HEADERS = {
  'Access-Control-Allow-Origin': '*',
  'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, PATCH, OPTIONS',
  'Access-Control-Allow-Headers':
    'Content-Type, Authorization, X-Requested-With, Accept, Origin',
  'Access-Control-Max-Age': '86400',
};

/**
 * Returns a 204 No Content response for OPTIONS preflight requests.
 * Add `export { OPTIONS } from '@/lib/cors'` in every route file.
 */
export function OPTIONS() {
  return new Response(null, { status: 204, headers: CORS_HEADERS });
}

/**
 * Wraps a NextResponse with CORS headers.
 */
export function withCors(response: Response): Response {
  const headers = new Headers(response.headers);
  Object.entries(CORS_HEADERS).forEach(([k, v]) => headers.set(k, v));
  return new Response(response.body, {
    status: response.status,
    statusText: response.statusText,
    headers,
  });
}