import { NextResponse, type NextRequest } from "next/server";

const WINDOW_MS = 60_000;

const MAX_REQ = 120;

type Bucket = { count: number; resetAt: number };

const g = globalThis as unknown as { __docketBuckets?: Map<string, Bucket> };

const buckets: Map<string, Bucket> = (g.__docketBuckets ??= new Map());

function clientIp(req: NextRequest): string {

  const cf = req.headers.get("cf-connecting-ip");

  if (cf) return cf.trim();

  const real = req.headers.get("x-real-ip");

  if (real) return real.trim();

  const xff = req.headers.get("x-forwarded-for");

  if (xff) return xff.split(",")[0].trim();

  return "unknown";

}

export function middleware(req: NextRequest) {

  if (buckets.size > 10_000) {

    const now = Date.now();

    for (const [k, b] of buckets) if (b.resetAt < now) buckets.delete(k);

  }

  const ip = clientIp(req);

  const now = Date.now();

  const b = buckets.get(ip);

  if (!b || b.resetAt < now) {

    buckets.set(ip, { count: 1, resetAt: now + WINDOW_MS });

    return NextResponse.next();

  }

  b.count += 1;

  if (b.count > MAX_REQ) {

    const retry = Math.ceil((b.resetAt - now) / 1000);

    return new NextResponse(

      JSON.stringify({ error: "Rate limit exceeded. Slow down." }),

      {

        status: 429,

        headers: {

          "Content-Type": "application/json",

          "Retry-After": String(retry),

          "X-RateLimit-Limit": String(MAX_REQ),

          "X-RateLimit-Remaining": "0",

        },

      }

    );

  }

  return NextResponse.next();

}

export const config = {

  matcher: ["/api/:path*"],

};