import type { MetadataRoute } from "next";
import { SITEMAP_KINDS, type SitemapKind } from "@/lib/dto";
import { routes } from "@/lib/routes";

/**
 * Shared by app/sitemap.ts (per-id sitemaps at /sitemap/<id>.xml) and app/sitemap.xml/route.ts (the index).
 * Ids are deterministic strings so the index never depends on the API being reachable at build time:
 *   static · <kind>-1 … <kind>-PAGES_PER_KIND   (5 000 URLs per API page; empty pages yield no URLs)
 */
export const PAGES_PER_KIND = 4;

type Freq = MetadataRoute.Sitemap[number]["changeFrequency"];

export const STATIC_PAGES: Array<{ path: string; changeFrequency: Freq; priority: number }> = [
  { path: routes.home(), changeFrequency: "hourly", priority: 1 },
  { path: routes.map(), changeFrequency: "daily", priority: 0.9 },
  { path: routes.datacenters(), changeFrequency: "daily", priority: 0.9 },
  { path: routes.markets(), changeFrequency: "daily", priority: 0.8 },
  { path: routes.operators(), changeFrequency: "daily", priority: 0.8 },
  { path: routes.countries(), changeFrequency: "daily", priority: 0.8 },
  { path: routes.projects(), changeFrequency: "daily", priority: 0.8 },
  { path: routes.rankings(), changeFrequency: "daily", priority: 0.7 },
  { path: routes.cloudRegions(), changeFrequency: "weekly", priority: 0.7 },
  { path: routes.ixps(), changeFrequency: "weekly", priority: 0.5 },
  { path: routes.live(), changeFrequency: "hourly", priority: 0.7 },
  { path: routes.sources(), changeFrequency: "weekly", priority: 0.5 },
  { path: routes.methodology(), changeFrequency: "monthly", priority: 0.5 },
  { path: routes.bot(), changeFrequency: "monthly", priority: 0.3 },
  { path: routes.about(), changeFrequency: "monthly", priority: 0.4 },
  { path: routes.search(), changeFrequency: "monthly", priority: 0.3 },
];

export const KIND_HREF: Record<SitemapKind, (slug: string) => string> = {
  facilities: routes.facility,
  operators: routes.operator,
  countries: routes.country,
  metros: routes.market,
  projects: routes.project,
  "cloud-regions": routes.cloudRegion,
};

export const KIND_FREQ: Record<SitemapKind, Freq> = {
  facilities: "weekly",
  operators: "weekly",
  countries: "daily",
  metros: "daily",
  projects: "weekly",
  "cloud-regions": "monthly",
};

export function sitemapIds(): string[] {
  const ids = ["static"];
  for (const kind of SITEMAP_KINDS) for (let p = 1; p <= PAGES_PER_KIND; p++) ids.push(`${kind}-${p}`);
  return ids;
}

export function parseSitemapId(id: string): { kind: SitemapKind; page: number } | "static" | null {
  if (id === "static") return "static";
  const m = /^(.+)-(\d+)$/.exec(id);
  if (!m) return null;
  const kind = m[1] as SitemapKind;
  if (!(SITEMAP_KINDS as readonly string[]).includes(kind)) return null;
  const page = Number(m[2]);
  return page >= 1 && page <= PAGES_PER_KIND ? { kind, page } : null;
}