import { cache } from "react";
import { api } from "@/lib/api";
import { routes } from "@/lib/routes";

/** iso2 → canonical country slug (from /countries?all=1), memoised per request. */
export const countrySlugMap = cache(async (): Promise<Map<string, string>> => {
  const r = await api.countries({ all: 1 });
  const m = new Map<string, string>();
  for (const c of r.items) m.set(c.iso2.toUpperCase(), c.slug);
  return m;
});

/** Fallback slug when the registry is unreachable: ASCII-folded, hyphenated name (matches the API's slugs for most countries). */
export function slugifyCountryName(name: string | null | undefined, iso2: string): string {
  if (!name) return iso2.toLowerCase();
  const folded = name
    .normalize("NFD")
    .replace(/[̀-ͯ]/g, "")
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/(^-|-$)/g, "");
  return folded || iso2.toLowerCase();
}

/** Href of the country page for an iso2 (canonical slug when known). */
export async function countryHref(iso2: string | null | undefined, name?: string | null): Promise<string | null> {
  if (!iso2) return null;
  const m = await countrySlugMap();
  return routes.country(m.get(iso2.toUpperCase()) ?? slugifyCountryName(name, iso2));
}