import { GeocodingError, type GeocodeAddress, type GeocodeResult, type GeocodingProvider } from "@/server/services/geo/provider";
import { nominatimLimiter } from "@/server/services/geo/rate-limit";

/**
 * Nominatim (OpenStreetMap) provider. Usage policy: server side only, max. 1 request/s process-wide,
 * identifying User-Agent, results are cached in Site.latitude/longitude by the caller, no bulk
 * geocoding inside requests (only the geocode-site job and scripts/geocode-backfill.ts call this).
 */

type Config = { url: string; userAgent: string; timeoutMs: number };
type Deps = { fetch: typeof fetch; limiter: { acquire(): Promise<number> } };

/** Structured search URL (no free text → fewer ambiguous hits). */
export function buildNominatimUrl(baseUrl: string, address: GeocodeAddress): URL {
  const url = new URL(`${baseUrl.replace(/\/+$/, "")}/search`);
  url.searchParams.set("format", "jsonv2");
  url.searchParams.set("limit", "1");
  url.searchParams.set("addressdetails", "0");
  const street = [address.houseNumber, address.street].map((s) => s?.trim()).filter(Boolean).join(" ");
  if (street) url.searchParams.set("street", street);
  if (address.postalCode?.trim()) url.searchParams.set("postalcode", address.postalCode.trim());
  if (address.city?.trim()) url.searchParams.set("city", address.city.trim());
  const country = (address.country ?? "DE").trim().toLowerCase();
  if (/^[a-z]{2}$/.test(country)) url.searchParams.set("countrycodes", country);
  return url;
}

export function createNominatimProvider(config: Config, deps: Deps = { fetch: globalThis.fetch, limiter: nominatimLimiter }): GeocodingProvider {
  return {
    name: "nominatim",
    async geocode(address: GeocodeAddress): Promise<GeocodeResult> {
      await deps.limiter.acquire();
      let res: Response;
      try {
        res = await deps.fetch(buildNominatimUrl(config.url, address), {
          headers: { "User-Agent": config.userAgent, "Accept-Language": "de", Accept: "application/json" },
          signal: AbortSignal.timeout(config.timeoutMs),
        });
      } catch (err) {
        throw new GeocodingError(`request failed: ${(err as Error).name}`);
      }
      if (!res.ok) throw new GeocodingError(`http ${res.status}`);
      let body: unknown;
      try {
        body = await res.json();
      } catch {
        throw new GeocodingError("invalid response");
      }
      const hit = Array.isArray(body) ? (body[0] as { lat?: unknown; lon?: unknown } | undefined) : undefined;
      const latitude = Number(hit?.lat);
      const longitude = Number(hit?.lon);
      if (!hit || !Number.isFinite(latitude) || !Number.isFinite(longitude) || Math.abs(latitude) > 90 || Math.abs(longitude) > 180) {
        return { status: "not_found" };
      }
      return { status: "ok", latitude, longitude };
    },
  };
}