// middleware.ts (Next.js Edge Middleware for Vercel / Edge Runtime)
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export async function middleware(request: NextRequest) {
  const url = request.nextUrl;
  const rawRef = url.searchParams.get('ref') || url.searchParams.get('utm_source');

  // Sanitize referral code
  const sanitizedRef = rawRef ? rawRef.toLowerCase().replace(/[^a-z0-9_-]/g, '') : 'default';

  // Clone headers and inject normalized referral header for SSR hydration
  const requestHeaders = new Headers(request.headers);
  requestHeaders.set('x-referral-source', sanitizedRef);

  const response = NextResponse.next({
    request: { headers: requestHeaders },
  });

  // Enable CDN caching while keeping cache keys aligned
  response.headers.set('Vary', 'x-referral-source');
  return response;
}

export const config = {
  matcher: ['/((?!api|_next/static|_next/image|favicon.ico).*)'],
};

// cloudflare-worker.js (Cloudflare Workers + Edge KV)
export default {
  async fetch(request, env, ctx) {
    const url = new URL(request.url);
    const ref = (url.searchParams.get('ref') || 'default').toLowerCase().replace(/[^a-z0-9_-]/g, '');

    // 1. Check Edge KV cache
    let copy = await env.HEADLINES_KV.get(`ref:${ref}`, { type: 'json' });

    // 2. Cache miss -> query Supabase / Postgres REST API
    if (!copy) {
      const res = await fetch(`${env.SUPABASE_URL}/rest/v1/referral_headlines?referral_code=eq.${ref}&select=*`, {
        headers: { 'apikey': env.SUPABASE_ANON_KEY }
      });
      const rows = await res.json();
      copy = rows[0] || (await env.HEADLINES_KV.get('ref:default', { type: 'json' }));
      
      // Cache for 10 minutes
      ctx.waitUntil(env.HEADLINES_KV.put(`ref:${ref}`, JSON.stringify(copy), { expirationTtl: 600 }));
    }

    // 3. Inject into HTML stream via HTMLRewriter
    const originResponse = await fetch(request);
    return new HTMLRewriter()
      .on('#ch-title', { element(e) { e.setInnerContent(copy.headline); } })
      .on('#ch-desc', { element(e) { e.setInnerContent(copy.subheadline); } })
      .transform(originResponse);
  }
};

// Client-side Query Parameter Resolver
document.addEventListener('DOMContentLoaded', () => {
  // 1. Parse query parameter (The Clue)
  const params = new URLSearchParams(window.location.search);
  const refCode = (params.get('ref') || params.get('utm_source') || 'default')
    .toLowerCase()
    .trim()
    .replace(/[^a-z0-9_-]/g, '');

  // 2. Fetch copy from database or fallback
  fetch(`/api/referral?code=${encodeURIComponent(refCode)}`)
    .then(res => res.json())
    .then(data => {
      if (data && data.headline) {
        document.getElementById('ch-title').textContent = data.headline;
        document.getElementById('ch-desc').textContent = data.subheadline;
        if (data.cta_primary) document.getElementById('ch-cta-text').textContent = data.cta_primary;
      }
    })
    .catch(() => {
      // Graceful fallback to default copy
      console.warn('Referral lookup failed; maintaining default copy.');
    });
});