import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import {
  ATTRIBUTION_COOKIE_NAME,
  buildAttributionSnapshot,
  serializeAttributionCookie,
} from '@/lib/revops';
import { verifySignedUserIdEdge } from '@/lib/session-edge';
import { getAuthCookieName, getCookieDomain } from '@/lib/cookieConfig';
import {
  getAppOrigin,
  getWwwOrigin,
  isAppPath,
  isHostSplitEnabled,
  wwwUrl,
} from '@/lib/hosts';

const isProduction = process.env.NODE_ENV === 'production';

function attachAttributionCookie(req: NextRequest, response: NextResponse) {
  if (req.cookies.get(ATTRIBUTION_COOKIE_NAME)?.value) {
    return response;
  }

  const path = req.nextUrl.pathname;

  if (path.startsWith('/api/') || path.startsWith('/_next') || path.startsWith('/r/') || path.includes('.')) {
    return response;
  }

  const snapshot = buildAttributionSnapshot({
    utmSource: req.nextUrl.searchParams.get('utm_source'),
    utmMedium: req.nextUrl.searchParams.get('utm_medium'),
    utmCampaign: req.nextUrl.searchParams.get('utm_campaign'),
    utmContent: req.nextUrl.searchParams.get('utm_content'),
    utmTerm: req.nextUrl.searchParams.get('utm_term'),
    referrer: req.headers.get('referer'),
    landingPath: path,
    firstSeenAt: new Date(),
  });

  response.cookies.set(ATTRIBUTION_COOKIE_NAME, serializeAttributionCookie(snapshot), {
    httpOnly: false,
    secure: isProduction,
    sameSite: 'lax',
    path: '/',
    maxAge: 60 * 60 * 24 * 90,
    domain: getCookieDomain(),
  });

  return response;
}

/** Hostname of the app host, or null when marketing and app share one origin (dev). */
function getAppHostname(): string | null {
  if (!isHostSplitEnabled()) {
    return null;
  }

  try {
    return new URL(getAppOrigin()).hostname;
  } catch {
    return null;
  }
}

/** Absolute target on the other host, preserving path and query. */
function crossHostUrl(origin: string, req: NextRequest): string {
  const url = new URL(req.nextUrl.pathname + req.nextUrl.search, origin);

  return url.toString();
}

/**
 * Route a request that arrived on the app host (app.qrmaster.net).
 *
 * The app host serves only the logged-in app; everything else belongs to the marketing
 * host and gets redirected so a stray link or an old bookmark still lands somewhere
 * sensible. Returns null when the request is an app path and should continue through the
 * normal auth handling below.
 */
function routeAppHost(req: NextRequest): NextResponse | null {
  const path = req.nextUrl.pathname;

  // Keep the app host out of search indexes entirely - the marketing host owns all SEO.
  if (path === '/robots.txt') {
    return NextResponse.rewrite(new URL('/robots-app.txt', req.url));
  }
  if (path === '/sitemap.xml') {
    return NextResponse.redirect(wwwUrl('/sitemap.xml'), 301);
  }

  // API and framework internals must be served on both hosts: the app calls its own
  // /api routes, and the Stripe webhook still points at the marketing host.
  if (path.startsWith('/api/') || path.startsWith('/_next')) {
    return NextResponse.next();
  }

  // QR redirects belong to the marketing host. Redirecting instead of 404ing keeps any
  // code that was generated with the wrong origin working.
  if (path.startsWith('/r/')) {
    return NextResponse.redirect(crossHostUrl(getWwwOrigin(), req), 301);
  }

  if (path.includes('.')) {
    return NextResponse.next();
  }

  if (isAppPath(path)) {
    return null;
  }

  return NextResponse.redirect(crossHostUrl(getWwwOrigin(), req), 301);
}

async function routeRequest(req: NextRequest): Promise<NextResponse> {
  const path = req.nextUrl.pathname;
  const hostname = req.headers.get('host')?.split(':')[0] || req.nextUrl.hostname;

  if (hostname === 'qrmaster.net') {
    const url = req.nextUrl.clone();
    url.protocol = 'https';
    url.port = '';
    url.hostname = 'www.qrmaster.net';
    return NextResponse.redirect(url, 301);
  }

  const appHostname = getAppHostname();

  if (appHostname) {
    if (hostname === appHostname) {
      const appHostResponse = routeAppHost(req);

      if (appHostResponse) {
        return appHostResponse;
      }
      // Falls through: app path on the app host, continue to the auth check below.
    } else if (isAppPath(path)) {
      // App path requested on the marketing host - move it to the app host. Keeps old
      // bookmarks and the dashboard link in email footers working.
      return NextResponse.redirect(crossHostUrl(getAppOrigin(), req), 301);
    }
  }

  // 301 Redirects for /guide -> /learn to avoid duplicate content and consolidate authority
  if (path === '/guide/tracking-analytics') {
    return attachAttributionCookie(req, NextResponse.redirect(new URL('/learn/tracking', req.url), 301));
  }
  if (path === '/guide/bulk-qr-code-generation') {
    return attachAttributionCookie(req, NextResponse.redirect(new URL('/learn/developer', req.url), 301));
  }
  if (path === '/guide/qr-code-best-practices') {
    return attachAttributionCookie(req, NextResponse.redirect(new URL('/learn/basics', req.url), 301));
  }
  if (path === '/create-qr') {
    return attachAttributionCookie(req, NextResponse.redirect(new URL('/dynamic-qr-code-generator', req.url), 301));
  }
  if (path === '/bar-code-generator' || path === '/barcode-generator') {
    return attachAttributionCookie(req, NextResponse.redirect(new URL('/tools/barcode-generator', req.url), 301));
  }

  // Public routes that don't require authentication
  const publicPaths = [
    '/',
    '/pricing',
    '/faq',
    '/blog',
    '/login',
    '/signup',
    '/privacy',
    '/newsletter',
    '/restaurants',
    '/tools',
    '/features',
    // '/guide', // Redirected to /learn/*
    '/de',
    '/qr-code-erstellen',
    '/dynamic-qr-code-generator',
    '/dynamic-barcode-generator',
    '/bulk-qr-code-generator',
    '/qr-code-tracking',
    '/qr-code-analytics',
    '/reprint-calculator',
    '/custom-qr-code-generator',
    '/manage-qr-codes',
    '/coupon',
    '/feedback',
    '/vcard',
    '/display',
    '/contact',
    '/about',
    '/learn',
    '/use-cases',
    '/authors',
    '/press',
    '/testimonials',
    '/qr-code-for-marketing-campaigns',
    '/qr-code-for',
    '/qr-code-print-size-guide',
    '/use-cases/flyer-qr-codes',
    '/use-cases/packaging-qr-codes',
    '/use-cases/real-estate-sign-qr-codes',
    '/use-cases/feedback-qr-codes',
    '/use-cases/payment-qr-codes',
    '/use-cases/coupon-qr-codes',
    '/alternatives',
    '/vs',
  ];

  // Check if path is public
  const isPublicPath = publicPaths.some(p => path === p || path.startsWith(p + '/'));

  // Allow API routes
  if (path.startsWith('/api/')) {
    return attachAttributionCookie(req, NextResponse.next());
  }

  // Allow redirect routes (QR code redirects)
  if (path.startsWith('/r/')) {
    return attachAttributionCookie(req, NextResponse.next());
  }

  // Allow static files
  if (path.includes('.') || path.startsWith('/_next')) {
    return attachAttributionCookie(req, NextResponse.next());
  }

  // Allow public paths
  if (isPublicPath) {
    return attachAttributionCookie(req, NextResponse.next());
  }

  const protectedPaths = [
    '/analytics',
    '/bulk-creation',
    '/create',
    '/dashboard',
    '/integrations',
    '/onboarding',
    '/qr',
    '/settings',
  ];
  const isProtectedPath = protectedPaths.some(p => path === p || path.startsWith(p + '/'));

  if (!isProtectedPath) {
    return attachAttributionCookie(req, NextResponse.next());
  }

  // For protected routes, require a validly signed userId cookie
  const userId = await verifySignedUserIdEdge(req.cookies.get(getAuthCookieName())?.value);

  if (!userId) {
    // Not authenticated - redirect to signup, which lives on the marketing host.
    const signupUrl = new URL(wwwUrl('/signup'));
    const redirectTarget = `${path}${req.nextUrl.search}`;
    signupUrl.searchParams.set('redirect', redirectTarget);
    return attachAttributionCookie(req, NextResponse.redirect(signupUrl));
  }

  // Authenticated - allow access
  return attachAttributionCookie(req, NextResponse.next());
}

export async function middleware(req: NextRequest) {
  const response = await routeRequest(req);
  const appHostname = getAppHostname();
  const hostname = req.headers.get('host')?.split(':')[0] || req.nextUrl.hostname;

  // Belt and braces alongside robots-app.txt: the app host must never be indexed, and
  // setting the header here covers every response the routing above can produce.
  if (appHostname && hostname === appHostname) {
    response.headers.set('X-Robots-Tag', 'noindex, nofollow');
  }

  return response;
}

export const config = {
  matcher: [
    /*
     * Match all request paths except for the ones starting with:
     * - _next/static (static files)
     * - _next/image (image optimization files)
     * - favicon.ico (favicon file)
     * - public folder
     */
    '/((?!_next/static|_next/image|favicon.ico|logo.svg|og-image.png).*)',
  ],
};