import NextAuth from "next-auth";
import { NextResponse } from "next/server";
import { authConfig } from "@/auth.config";
import { isInstalledForRequest } from "@/lib/installation/installation-state";

// /home, /appointments and /settings are intentionally NOT hard-gated here
// as of Phase 4 — Home must work for guests (public business browsing +
// booking), and /appointments and /settings each show their own friendly
// in-context sign-in prompt for a guest rather than a silent redirect with
// no explanation. Only /staff and /owner remain hard-gated: those are
// permission-based tooling with no meaningful "guest" experience at all.
const PROTECTED_PREFIXES = ["/staff", "/owner"];

// Reachable before installation completes: the installer itself, and the
// small set of static/manifest assets a browser requests independently of
// the page it's rendering (favicon, PWA manifest/icons, the offline
// fallback, the service worker script). Everything else redirects to
// /install until ApplicationInstallation flips to INSTALLED — see
// src/lib/installation/installation-state.ts. `/api/*` never reaches this
// file at all (excluded by `config.matcher` below); API routes that need
// business data guard themselves (see /api/health and
// /api/cron/process-notifications).
const INSTALL_EXEMPT_PREFIXES = [
  "/install",
  "/offline",
  "/manifest.webmanifest",
  "/icon.png",
  "/apple-icon.png",
  "/icons/",
  "/sw.js",
];

// Lightweight instance built from the DB-free config — see auth.config.ts.
// Next.js 16 renamed this file convention from `middleware` to `proxy`
// (https://nextjs.org/docs/messages/middleware-to-proxy); it now always
// runs on the Node.js runtime rather than Edge, but this stays split from
// the full `@/auth` regardless, so checking "is there a session" doesn't
// spin up a Postgres connection pool on every request.
const { auth } = NextAuth(authConfig);

/**
 * Nonce-gated 'strict-dynamic' script-src (Next's own documented pattern)
 * was tried here first and reverted: verified live against a production
 * build, it broke every page — Next's own inline RSC-hydration payload
 * scripts (the `self.__next_f.push(...)` chunks each page ships to
 * stream in its data) never actually receive the nonce this generates,
 * so 'strict-dynamic' refuses to run them and the app never hydrates
 * (confirmed via BAILOUT_TO_CLIENT_SIDE_RENDERING markers with
 * `"nonce":"$undefined"` in the served HTML). `script-src 'self'
 * 'unsafe-inline'` is the reliable fallback: Next's own *code* all loads
 * via external `<script src="/_next/static/...">` tags, which `'self'`
 * already covers — 'unsafe-inline' is only there for those small inline
 * data-streaming scripts. `style-src` needs 'unsafe-inline' for the same
 * reason as ever: this app uses plain React `style={{...}}` props
 * (progress bars, dynamic widths) throughout, and CSP has no nonce
 * mechanism for style *attributes* (only for <style> elements).
 */
function buildCsp(): string {
  // Fast Refresh/React DevTools' dev-mode debugging needs eval() — React
  // itself confirms it "will never use eval() in production mode", so
  // this only loosens the policy for local development, never a real
  // deployment.
  const scriptSrc = process.env.NODE_ENV === "production" ? "'self' 'unsafe-inline'" : "'self' 'unsafe-inline' 'unsafe-eval'";
  return [
    "default-src 'self'",
    `script-src ${scriptSrc}`,
    "style-src 'self' 'unsafe-inline'",
    // 'https:' (not just 'self' data:) — business logos/cover images are
    // arbitrary externally-hosted URLs an owner pastes into Business
    // Settings or the installer (see src/lib/business/branding.ts); there
    // is no fixed set of allowed hosts to enumerate. Scoped to https: only
    // (never http:), so this doesn't reopen the door to insecure image
    // loads generally.
    "img-src 'self' data: https:",
    "font-src 'self'",
    "connect-src 'self'",
    "worker-src 'self'",
    "manifest-src 'self'",
    "object-src 'none'",
    "base-uri 'self'",
    "form-action 'self'",
    "frame-ancestors 'none'",
  ].join("; ");
}

export default auth(async (req) => {
  const { pathname } = req.nextUrl;
  const csp = buildCsp();

  const isInstallExempt = INSTALL_EXEMPT_PREFIXES.some(
    (prefix) => pathname === prefix || pathname.startsWith(prefix.endsWith("/") ? prefix : `${prefix}/`),
  );
  const installed = await isInstalledForRequest();

  if (!installed && !isInstallExempt) {
    const response = NextResponse.redirect(new URL("/install", req.nextUrl.origin));
    response.headers.set("Content-Security-Policy", csp);
    return response;
  }
  if (installed && pathname === "/install") {
    // The wizard itself also refuses to render/submit once installed (see
    // src/app/install/page.tsx and the installer Server Action) — this
    // redirect is a convenience for direct navigation, not the actual
    // enforcement boundary.
    const response = NextResponse.redirect(new URL("/", req.nextUrl.origin));
    response.headers.set("Content-Security-Policy", csp);
    return response;
  }

  const isProtected = PROTECTED_PREFIXES.some(
    (prefix) => pathname === prefix || pathname.startsWith(`${prefix}/`),
  );

  if (isProtected && !req.auth) {
    const signInUrl = new URL("/sign-in", req.nextUrl.origin);
    signInUrl.searchParams.set("callbackUrl", pathname);
    const response = NextResponse.redirect(signInUrl);
    response.headers.set("Content-Security-Policy", csp);
    return response;
  }

  const response = NextResponse.next();
  response.headers.set("Content-Security-Policy", csp);
  return response;
});

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