import type { NextConfig } from "next";

// Report-only rather than enforcing, deliberately: the policy is derived from
// what this app is known to load — its own bundle, the self-hosted Nunito
// files from next/font, and nothing else — but an unenforced policy that logs
// violations is worth more than a guessed one that blanks the app for every
// HR user. Promote it to `Content-Security-Policy` once the reports come back
// clean.
//
// 'unsafe-inline' on script-src is not laziness: Next.js inlines its
// bootstrap and hydration payload as inline <script> tags, so a nonce-based
// policy means threading a per-request nonce through proxy.ts — a separate
// change, and the reason this starts in report-only.
function contentSecurityPolicy(): string {
  // Die Anmeldung schickt ein Formular an /api/auth/signin/…, und von dort
  // geht es per Weiterleitung zum Anmeldeserver. `form-action` gilt auch für
  // die Weiterleitungen nach einem Formularversand — steht der Aussteller
  // nicht darin, bricht der Browser die Anmeldung ab. Genau hier wäre die
  // Nur-Bericht-Fassung später eine böse Überraschung.
  let issuerOrigin = "";
  try {
    issuerOrigin = new URL(process.env.AUTH_MICROSOFT_ENTRA_ID_ISSUER ?? "").origin;
  } catch {
    issuerOrigin = "";
  }
  const formAction = ["'self'", issuerOrigin].filter(Boolean).join(" ");

  return [
    "default-src 'self'",
    "script-src 'self' 'unsafe-inline'",
    "style-src 'self' 'unsafe-inline'",
    "img-src 'self' data: blob:",
    "font-src 'self'",
    // Die Anwendung spricht im Browser mit niemandem ausser sich selbst: die
    // Datenbank erreicht nur der Server, und seit die API-Schicht weg ist,
    // gibt es keine Gegenstelle mehr, die von aussen angesprochen würde.
    "connect-src 'self'",
    "frame-ancestors 'self'",
    "base-uri 'self'",
    `form-action ${formAction}`,
    "object-src 'none'",
  ].join("; ");
}

const nextConfig: NextConfig = {
  // Emits a self-contained .next/standalone server (only the deps actually
  // used at runtime, no full node_modules) - what the Dockerfile copies in.
  output: "standalone",
  // Baseline security headers (clickjacking, MIME-sniffing, referrer leakage,
  // browser feature access) plus the report-only CSP described above.
  async headers() {
    return [
      {
        source: "/:path*",
        headers: [
          { key: "X-Frame-Options", value: "SAMEORIGIN" },
          { key: "X-Content-Type-Options", value: "nosniff" },
          { key: "Referrer-Policy", value: "strict-origin-when-cross-origin" },
          { key: "Permissions-Policy", value: "camera=(), microphone=(), geolocation=()" },
          { key: "Strict-Transport-Security", value: "max-age=63072000; includeSubDomains" },
          { key: "Content-Security-Policy-Report-Only", value: contentSecurityPolicy() },
        ],
      },
    ];
  },
};

export default nextConfig;