middleware.js

// middleware.js
import { createMiddlewareClient } from '@supabase/auth-helpers-nextjs';
import { NextResponse } from 'next/server';

function isProtectedRoute(pathname) {
  return ['/dashboard', '/exam', '/plan'].some(prefix => 
    pathname.startsWith(prefix)
  );
}

export async function middleware(req) {
  const res = NextResponse.next();
  const supabase = createMiddlewareClient({ req, res });

  try {
    // Get session from both cookie and Supabase client
    const { data: { session }, error } = await supabase.auth.getSession();
    const { data: { user: cookieUser } } = await supabase.auth.getUser();

    console.log('Middleware session check:', {
      hasSession: !!session || !!cookieUser,
      user: session?.user?.id || cookieUser?.id,
      path: req.nextUrl.pathname
    });

    if (error && !cookieUser) {
      console.error('Auth session error:', error.message);
      return NextResponse.json({ error: 'Authentication error' }, { status: 500 });
    }

    // Use combined session check
    const hasValidSession = !!session || !!cookieUser;

    // Handle API routes
    if (req.nextUrl.pathname.startsWith('/api/')) {
      // Clone the request headers and add Supabase auth headers
      const requestHeaders = new Headers(req.headers);
      requestHeaders.set('x-user-id', session?.user?.id || '');
      requestHeaders.set('authorization', `Bearer ${session?.access_token || ''}`);
      
      // Create a response that propagates cookies
      const response = NextResponse.next({
        request: {
          headers: requestHeaders,
        },
      });

      // Ensure cookies are preserved
      res.headers.forEach((value, key) => {
        if (key.toLowerCase() === 'set-cookie') {
          response.headers.append(key, value);
        }
      });

      // Example: Express.js cookie settings
        res.cookie('token', token, {
            httpOnly: true,
            secure: process.env.NODE_ENV === 'production', // Enable in prod
            sameSite: process.env.NODE_ENV === 'production' ? 'None' : 'Lax',
        });

      return response;
    }

    // Protected routes handling
    if (!hasValidSession && isProtectedRoute(req.nextUrl.pathname)) {
      const redirectUrl = new URL('/auth', req.url);
      redirectUrl.searchParams.set('redirectedFrom', req.nextUrl.pathname);
      return NextResponse.redirect(redirectUrl);
    }

    // Important: Return the response with potentially modified headers
    return res;
  } catch (error) {
    console.error('Middleware error:', error);
    return NextResponse.redirect(new URL('/auth', req.url));
  }
}

export const config = {
  matcher: [
    '/api/:path*',
    '/dashboard/:path*',
    '/exam/:path*',
    '/plan/:path*'
  ]
}