import { randomUUID } from "crypto";
import { NextRequest, NextResponse } from "next/server";
import { GeocodingClient } from "@/lib/geocoding-client";

// Module-level singleton — cache persists across requests
const client = new GeocodingClient();

/**
 * Maximum allowed query length.  Station/place names are typically
 * < 100 characters.  This prevents abuse with extremely long inputs.
 */
const MAX_QUERY_LENGTH = 256;

/**
 * Allowed country codes for narrowing the search.
 * Two-letter ISO 3166-1 alpha-2 codes.
 */
const ALLOWED_COUNTRY_CODES = /^[a-z]{2}(,[a-z]{2}){0,4}$/;

export async function GET(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const name = searchParams.get("name");
    const countrycodes = searchParams.get("countrycodes");

    if (!name) {
      return NextResponse.json({ error: "Missing 'name' parameter" }, { status: 400 });
    }

    if (name.length > MAX_QUERY_LENGTH) {
      return NextResponse.json(
        { error: "Query too long (max 256 characters)" },
        { status: 400 },
      );
    }

    if (countrycodes && !ALLOWED_COUNTRY_CODES.test(countrycodes.toLowerCase())) {
      return NextResponse.json(
        { error: "Invalid countrycodes (use up to 5 two-letter codes, comma-separated)" },
        { status: 400 },
      );
    }

    const results = await client.geocode(name, countrycodes || undefined);

    if (results.length === 0) {
      return NextResponse.json({ error: "No results found" }, { status: 404 });
    }

    return NextResponse.json(results[0]);
  } catch (error) {
    const corrId = randomUUID().slice(0, 8);
    console.error(`[${corrId}] Geocode API error:`, error);
    return NextResponse.json({ error: "Internal server error", correlationId: corrId }, { status: 500 });
  }
}