next.config.js

const withBundleAnalyzer = require("@next/bundle-analyzer")({
  enabled: process.env.ANALYZE === "true",
});

/**
 * @docs
 * - https://scotthelme.co.uk/content-security-policy-an-introduction/
 * - https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
 */
// script-src 'self' 'unsafe-inline' 'unsafe-eval' umami.sznm.dev;
// default-src 'self';
// style-src 'self' 'unsafe-inline';
// img-src * blob: data: *.freepik.com;
// media-src 'none';
// connect-src *;
// font-src 'self';

const ContentSecurityPolicy = `
  frame-src giscus.app;
`;

/**
 * @docs
 * - https://nextjs.org/docs/advanced-features/security-headers
 */
const securityHeaders = [
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP
  {
    key: "Content-Security-Policy",
    value: ContentSecurityPolicy.replace(/\n/g, ""),
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy
  {
    key: "Referrer-Policy",
    value: "origin-when-cross-origin",
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
  {
    key: "X-Frame-Options",
    value: "DENY",
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options
  {
    key: "X-Content-Type-Options",
    value: "nosniff",
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-DNS-Prefetch-Control
  {
    key: "X-DNS-Prefetch-Control",
    value: "on",
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security
  {
    key: "Strict-Transport-Security",
    value: "max-age=31536000; includeSubDomains; preload",
  },
  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Feature-Policy
  {
    key: "Permissions-Policy",
    value: "geolocation=()",
  },
];

/** @type {import('next').NextConfig} */
module.exports = withBundleAnalyzer({
  reactStrictMode: true,
  swcMinify: true,
  headers: async () => {
    return [
      {
        source: "/",
        headers: securityHeaders,
      },
      {
        source: "/:path*",
        headers: securityHeaders,
      },
    ];
  },
  webpack: (config, { dev, isServer }) => {
    // Replace React with Preact only in client production build
    if (!dev && !isServer) {
      Object.assign(config.resolve.alias, {
        react: "preact/compat",
        "react-dom/test-utils": "preact/test-utils",
        "react-dom": "preact/compat",
      });
    }

    return config;
  },
});