import { NextResponse } from "next/server";
import { cacheGet, cacheSet } from "@/lib/cache";
import type { GeofabrikIndex } from "@transportationer/shared";

export const runtime = "nodejs";

const GEOFABRIK_INDEX_URL = "https://download.geofabrik.de/index-v1.json";
const CACHE_KEY = "geofabrik:index";

export async function GET() {
  const cached = await cacheGet<GeofabrikIndex>(CACHE_KEY);
  if (cached) {
    return NextResponse.json(cached, { headers: { "X-Cache": "HIT" } });
  }

  let data: GeofabrikIndex;
  try {
    const res = await fetch(GEOFABRIK_INDEX_URL, {
      headers: { "User-Agent": "Transportationer/1.0 15-min-city-analyzer" },
      signal: AbortSignal.timeout(30_000),
    });
    if (!res.ok) {
      return NextResponse.json(
        { error: `Geofabrik returned ${res.status}` },
        { status: 502 },
      );
    }
    data = await res.json();
  } catch (err) {
    return NextResponse.json(
      { error: "Failed to fetch Geofabrik index", detail: String(err) },
      { status: 502 },
    );
  }

  await cacheSet(CACHE_KEY, data, "GEOFABRIK_INDEX");
  return NextResponse.json(data, { headers: { "X-Cache": "MISS" } });
}