import type { MetadataRoute } from 'next';
import { api, safe } from '@/lib/api';
import { apiCompare } from '@/lib/api-compare';
import { apiExplore } from '@/lib/api-explore';
import { SITE_URL, routes } from '@/lib/site';
import { STORIES } from '@/lib/stories';
import { TOPICS } from '@/lib/topics';

/**
 * Sharded sitemap (Next `generateSitemaps`): one file per URL family so no shard grows past a few thousand URLs.
 * Emitted at /sitemap/<id>.xml; robots.ts lists every shard. Parameterised analytical views (/explore?…,
 * /scatter?…, /finder?…) are deliberately absent: they are noindex and their canonical is the bare path.
 */
export const SITEMAP_IDS = ['core', 'countries', 'country-topics', 'indicators', 'rankings', 'regions', 'stories'] as const;
export type SitemapId = (typeof SITEMAP_IDS)[number];

export async function generateSitemaps(): Promise<Array<{ id: SitemapId }>> {
  return SITEMAP_IDS.map((id) => ({ id }));
}

export default async function sitemap(props: { id: Promise<string> | string }): Promise<MetadataRoute.Sitemap> {
  const id = (await props.id) as SitemapId;
  const health = await safe(api.health());
  const lastModified = health?.built_at ? new Date(health.built_at) : new Date();
  const entry = (path: string, changeFrequency: MetadataRoute.Sitemap[number]['changeFrequency'], priority: number): MetadataRoute.Sitemap[number] => ({ url: `${SITE_URL}${path}`, lastModified, changeFrequency, priority });

  switch (id) {
    case 'core':
      return [
        entry('/', 'daily', 1),
        entry(routes.explore(), 'daily', 0.9),
        entry(routes.countries(), 'daily', 0.9),
        entry(routes.compare(), 'monthly', 0.7),
        entry(routes.rankings(), 'daily', 0.9),
        entry(routes.indicators(), 'daily', 0.9),
        entry(routes.changes(), 'daily', 0.6),
        entry(routes.regions(), 'weekly', 0.7),
        entry(routes.trajectories(), 'monthly', 0.6),
        entry(routes.scatter(), 'monthly', 0.6),
        entry(routes.finder(), 'monthly', 0.6),
        entry(routes.extremes(), 'weekly', 0.6),
        entry(routes.peers(), 'monthly', 0.5),
        entry(routes.stories(), 'weekly', 0.7),
        entry(routes.download(), 'monthly', 0.5),
        entry(routes.updates(), 'daily', 0.4),
        entry(routes.sources(), 'weekly', 0.5),
        entry(routes.methodology(), 'monthly', 0.5),
        entry(routes.api(), 'monthly', 0.5),
        ...((await safe(apiExplore.sources()))?.items ?? []).map((s) => entry(routes.source(s.id), 'weekly', 0.4)),
      ];
    case 'countries': {
      const res = await safe(api.countries());
      return (res?.items ?? []).map((c) => entry(routes.country(c.slug ?? c.id), 'weekly', 0.8));
    }
    case 'country-topics': {
      const res = await safe(api.countries());
      return (res?.items ?? []).flatMap((c) => TOPICS.map((tp) => entry(routes.countryTopic(c.slug ?? c.id, tp.id), 'weekly', 0.6)));
    }
    case 'indicators': {
      const res = await safe(apiExplore.indicators());
      return (res?.items ?? []).map((i) => entry(routes.indicator(i.slug), 'weekly', 0.7));
    }
    case 'rankings': {
      const res = await safe(apiCompare.rankings());
      return (res?.items ?? []).map((i) => entry(routes.ranking(i.slug), 'weekly', 0.7));
    }
    case 'regions': {
      const res = await safe(apiExplore.regions());
      return (res?.items ?? []).map((g) => entry(routes.region(g.slug ?? g.id), 'weekly', 0.6));
    }
    case 'stories':
      return STORIES.map((s) => entry(routes.story(s.slug), 'weekly', 0.7));
    default:
      return [];
  }
}