import { NextResponse } from "next/server";
import { isImgwNoProductsResponse, readImgwResponseBody } from "@/lib/imgw-empty-response";

const ALLOWED_PATHS = new Set(["synop", "hydro", "meteo", "warningsmeteo", "warningshydro", "product"]);
const IMGW_BASE_URL = "https://danepubliczne.imgw.pl/api/data";
const USER_AGENT = "wtr./1.0 (weather data proxy)";

export async function GET(_: Request, context: { params: Promise<{ path: string[] }> }) {
  const { path } = await context.params;
  const [resource, variant, value] = path;

  const isAllowedSynopDetail = resource === "synop" && variant === "id" && Boolean(value) && path.length === 3;
  const isAllowedCollection = ALLOWED_PATHS.has(resource) && path.length === 1;
  if (!isAllowedSynopDetail && !isAllowedCollection) {
    return NextResponse.json({ error: "Nieobsługiwana ścieżka IMGW." }, { status: 404 });
  }

  const upstreamPath = path.map(encodeURIComponent).join("/");
  try {
    const response = await fetch(`${IMGW_BASE_URL}/${upstreamPath}`, {
      next: { revalidate: 300 },
      headers: { Accept: "application/json", "User-Agent": USER_AGENT },
    });
    if (!response.ok) {
      const body = await readImgwResponseBody(response);
      if (
        (resource === "warningsmeteo" || resource === "warningshydro") &&
        response.status === 404 &&
        isImgwNoProductsResponse(body.json)
      ) {
        return NextResponse.json([], {
          headers: { "Cache-Control": "public, s-maxage=300, stale-while-revalidate=600" },
        });
      }
      return NextResponse.json({ error: "IMGW API jest chwilowo niedostępne." }, { status: response.status });
    }
    const data: unknown = await response.json();
    return NextResponse.json(data, {
      headers: { "Cache-Control": "public, s-maxage=300, stale-while-revalidate=600" },
    });
  } catch {
    return NextResponse.json({ error: "Nie udało się połączyć z IMGW API." }, { status: 502 });
  }
}