import type { Metadata } from 'next';
import { t } from '@/i18n';
import { api, isNotBuilt, safe } from '@/lib/api';
import { apiAnalytics } from '@/lib/api-analytics';
import { apiExplore } from '@/lib/api-explore';
import { routes } from '@/lib/site';
import { NotBuiltState } from '@/components/data/empty-state';
import { WorldExplorer } from '@/components/explorer/world-explorer';
import { baseFeatures } from '@/components/indicators/map-geometry';
import { DEFAULT_EXPLORER_INDICATOR, EXPLORER_VIEWS, explorerIndicators, parseYearParam, type ExplorerView } from '@/components/explorer/options';

export const revalidate = 900;

type SP = Record<string, string | string[] | undefined>;
const SLUG = /^[a-z0-9][a-z0-9-]*$/;

function first(sp: SP, k: string): string | null {
  const v = sp[k];
  return (Array.isArray(v) ? v[0] : v) ?? null;
}

function parseState(sp: SP) {
  const ind = (first(sp, 'indicator') ?? '').toLowerCase();
  const view = first(sp, 'view') as ExplorerView | null;
  const country = (first(sp, 'country') ?? '').toLowerCase();
  const group = (first(sp, 'group') ?? 'world').toLowerCase();
  return {
    indicator: SLUG.test(ind) ? ind : DEFAULT_EXPLORER_INDICATOR,
    year: parseYearParam(first(sp, 'year')),
    view: view && EXPLORER_VIEWS.includes(view) ? view : ('map' as ExplorerView),
    country: /^[a-z]{3}$/.test(country) ? country : null,
    group: SLUG.test(group) ? group : 'world',
  };
}

export async function generateMetadata({ searchParams }: { searchParams: Promise<SP> }): Promise<Metadata> {
  const sp = await searchParams;
  const parameterized = Object.keys(sp).length > 0;
  return {
    title: t('explorer.metaTitle'),
    description: t('explorer.description'),
    alternates: { canonical: routes.explore() },
    robots: parameterized ? { index: false, follow: true } : undefined,
    openGraph: { title: `${t('explorer.metaTitle')} — ${t('site.name')}`, description: t('explorer.description'), url: routes.explore(), type: 'website' },
  };
}

export default async function ExplorePage({ searchParams }: { searchParams: Promise<SP> }) {
  const sp = await searchParams;
  const state = parseState(sp);
  let countriesRes;
  try {
    countriesRes = await api.countries();
  } catch (e) {
    if (isNotBuilt(e)) return <NotBuiltState />;
    throw e;
  }
  const [indicatorsRes, groupsRes, frames] = await Promise.all([
    safe(apiExplore.indicators({ with_data: true })),
    safe(apiExplore.regions()),
    safe(apiAnalytics.indicatorFrames(state.indicator, { group: state.group !== 'world' ? state.group : null })),
  ]);
  const countries = countriesRes.items.filter((c) => (c.kind ?? 'country') === 'country');
  const { features, sphere } = baseFeatures(countriesRes.items);
  const indicators = explorerIndicators(indicatorsRes?.items ?? []);
  return (
    <WorldExplorer
      features={features}
      sphere={sphere}
      countries={countries.map((c) => ({ id: c.id, slug: c.slug, name: c.name, flag: c.flag, region: c.region, income: c.income }))}
      indicators={indicators}
      groups={groupsRes?.items ?? []}
      initial={frames}
      initialState={state}
    />
  );
}