import { NextResponse } from "next/server";

const REVERSE_GEOCODING_URL = "https://nominatim.openstreetmap.org/reverse";
const USER_AGENT = "wtr./1.0 (https://git.zvcloud.net/zv/wtr)";

interface RawReverseLocation {
  name?: string;
  display_name?: string;
  address?: {
    city?: string;
    town?: string;
    village?: string;
    municipality?: string;
    state?: string;
  };
}

function parseCoordinate(value: string | null, min: number, max: number) {
  if (!value?.trim()) return null;
  const coordinate = Number(value);
  return Number.isFinite(coordinate) && coordinate >= min && coordinate <= max ? Number(coordinate.toFixed(3)) : null;
}

export async function GET(request: Request) {
  const { searchParams } = new URL(request.url);
  const latitude = parseCoordinate(searchParams.get("latitude"), -90, 90);
  const longitude = parseCoordinate(searchParams.get("longitude"), -180, 180);
  const language = searchParams.get("language") === "en" ? "en" : "pl";
  if (latitude === null || longitude === null) {
    return NextResponse.json({ error: "Invalid coordinates." }, { status: 400 });
  }

  const params = new URLSearchParams({
    format: "jsonv2",
    lat: String(latitude),
    lon: String(longitude),
    zoom: "10",
    addressdetails: "1",
    "accept-language": language,
  });

  try {
    const response = await fetch(`${REVERSE_GEOCODING_URL}?${params}`, {
      next: { revalidate: 86400 },
      headers: { Accept: "application/json", "User-Agent": USER_AGENT },
    });
    if (!response.ok) return NextResponse.json({ error: "Reverse geocoding is unavailable." }, { status: 502 });
    const data = await response.json() as RawReverseLocation;
    const name = data.address?.city
      ?? data.address?.town
      ?? data.address?.village
      ?? data.address?.municipality
      ?? data.name
      ?? data.display_name?.split(",")[0]?.trim();
    if (!name) return NextResponse.json({ error: "Place name is unavailable." }, { status: 404 });
    return NextResponse.json({
      name,
      province: data.address?.state ?? null,
    }, {
      headers: { "Cache-Control": "public, s-maxage=86400, stale-while-revalidate=604800" },
    });
  } catch {
    return NextResponse.json({ error: "Reverse geocoding is unavailable." }, { status: 502 });
  }
}