import type { NextConfig } from "next";

const nextConfig: NextConfig = {
  /**
   * Cache-Control policy.
   *
   * Why this exists:
   *   Hostinger's CDN was applying `s-maxage=31536000` (1 year) to
   *   prerendered HTML pages by default. When a new deploy shipped
   *   fresh Turbopack chunk hashes, the edge kept serving year-old
   *   HTML referencing chunk filenames that no longer existed on
   *   disk — result: HTML 200, every /_next/static/*.js and .css
   *   came back 404, the page rendered unstyled. Private/incognito
   *   did nothing because the cache is server-side.
   *
   * Strategy:
   *   - /_next/static/* — immutable for a year. Filenames are
   *     content-hashed, so a new build produces new filenames; the
   *     old ones are safe to keep indefinitely in caches.
   *   - /api/*          — no-store. API responses are per-user and
   *     must never be shared across requests at the edge.
   *   - Everything else — public, brief s-maxage + generous
   *     stale-while-revalidate. The edge serves instantly from cache
   *     for the first 5 min, then returns cached content while
   *     refreshing in the background for up to 24 h. A deploy's
   *     chunk-hash drift self-heals within ~5 min with no user-
   *     visible latency.
   *
   *   Note: dynamic dashboard routes (/inbox, /contacts, /pipelines,
   *   /broadcasts, etc.) are server-rendered per request — Next.js
   *   and Supabase auth already prevent them from being served
   *   from a shared cache. The s-maxage here is a ceiling; Next.js
   *   and auth middleware still set `private` / `no-store` for
   *   per-user responses.
   */
  async headers() {
    return [
      {
        source: "/_next/static/:path*",
        headers: [
          {
            key: "Cache-Control",
            value: "public, max-age=31536000, immutable",
          },
        ],
      },
      {
        source: "/api/:path*",
        headers: [{ key: "Cache-Control", value: "no-store" }],
      },
      {
        source: "/:path*",
        headers: [
          {
            key: "Cache-Control",
            value:
              "public, max-age=0, s-maxage=300, stale-while-revalidate=86400",
          },
        ],
      },
    ];
  },
};

export default nextConfig;