import { NextResponse, type NextRequest } from "next/server";
import { consume } from "@/lib/rate-limit";

const PUBLIC_PREFIXES = ["/api/auth/", "/s/", "/icon-", "/favicon"];
const PUBLIC_PATHS = new Set(["/login", "/manifest.webmanifest", "/offline.html"]);
const SESSION_COOKIE_NAMES = ["authjs.session-token", "__Secure-authjs.session-token"];

// Token-prefix length used as part of the rate-limit bucket key.
const RL_PREFIX_LEN = 8;

export function middleware(request: NextRequest) {
  const start = performance.now();
  const response = route(request);
  logRequest(request, response.status, Math.round(performance.now() - start));
  return response;
}

function withPathname(response: NextResponse, pathname: string): NextResponse {
  response.headers.set("x-pathname", pathname);
  return response;
}

function route(request: NextRequest): NextResponse {
  const { pathname } = request.nextUrl;

  // Rate-limit the public share-link viewer (/s/<token>).
  // The rate limiter runs in the Edge runtime and has its own module-level bucket
  // Map (separate from the Node.js runtime used by page components). All requests
  // to /s/<token> are counted here regardless of whether the token resolves; page
  // components additionally track per-failure counts via recordFailure() for
  // accurate auditing. Switch to Redis for cross-runtime / multi-replica accuracy.
  if (pathname.startsWith("/s/") && pathname.length > 3) {
    const token = pathname.slice(3); // strip "/s/"
    const ip = clientIp(request);
    const key = `${ip}:${token.slice(0, RL_PREFIX_LEN)}`;

    if (!consume(key)) {
      return new NextResponse("Too Many Requests", {
        status: 429,
        headers: { "Retry-After": "60", "Content-Type": "text/plain" },
      });
    }
  }

  if (PUBLIC_PATHS.has(pathname) || PUBLIC_PREFIXES.some((p) => pathname.startsWith(p))) {
    return withPathname(NextResponse.next(), pathname);
  }

  if (hasSessionCookie(request)) return withPathname(NextResponse.next(), pathname);

  const loginUrl = new URL("/login", request.url);
  loginUrl.searchParams.set("callbackUrl", request.url);
  return NextResponse.redirect(loginUrl);
}

function clientIp(request: NextRequest): string {
  return (
    request.headers.get("x-forwarded-for")?.split(",")[0]?.trim() ??
    request.headers.get("x-real-ip") ??
    "0.0.0.0"
  );
}

function hasSessionCookie(request: NextRequest) {
  return request.cookies
    .getAll()
    .some((cookie) =>
      SESSION_COOKIE_NAMES.some(
        (name) => cookie.name === name || cookie.name.startsWith(`${name}.`),
      ),
    );
}

// Structured request log — output as JSON so it's machine-readable in production.
// pino is not available in the Edge runtime; console.log goes to server stdout.
// userId is omitted: decoding the session token requires a DB lookup unavailable here.
function logRequest(request: NextRequest, status: number, ms: number) {
  const authenticated = hasSessionCookie(request);
  const entry = {
    level: "info",
    time: Date.now(),
    method: request.method,
    path: request.nextUrl.pathname,
    status,
    ms,
    authenticated,
  };
  console.log(JSON.stringify(entry));
}

export const config = {
  matcher: [
    // Skip Next.js internals and static files
    "/((?!_next/static|_next/image|favicon.ico).*)",
  ],
};