import { ExternalLink } from 'lucide-react';
import Link from 'next/link';
import { hostOf, fmtInt, num, plural } from '@/lib/format';
import { routes } from '@/lib/site';
import type { TodayItem, TodaySection } from '@/lib/types';
import { ChangeRow } from './change-row';

/** Fixed order of the Today in AI 2.0 sections (API keys) — sections absent from the payload are listed as quiet. */
export const TODAY_ORDER = ['MAJOR_RELEASES', 'PRICE_MOVES', 'BENCHMARK_MOVES', 'MODEL_CHANGES', 'RESEARCH', 'OPEN_WEIGHT_RELEASES', 'DEPRECATIONS', 'PROVIDER_CHANGES', 'HARDWARE'] as const;
export const TODAY_LABELS: Record<string, string> = {
  MAJOR_RELEASES: 'Major releases',
  PRICE_MOVES: 'Price moves',
  BENCHMARK_MOVES: 'Benchmark moves',
  MODEL_CHANGES: 'Model changes',
  RESEARCH: 'Research',
  OPEN_WEIGHT_RELEASES: 'Open-weight releases',
  DEPRECATIONS: 'Deprecations',
  PROVIDER_CHANGES: 'Provider changes',
  HARDWARE: 'Hardware',
};
/** Section key → the `/changes` filter that lists everything behind it. */
export const TODAY_FEED_HREF: Record<string, (date: string) => string> = {
  MAJOR_RELEASES: (d) => `/changes?importance_min=3&since=${d}&until=${d}`,
  PRICE_MOVES: (d) => `/changes?category=price&since=${d}&until=${d}`,
  BENCHMARK_MOVES: (d) => `/changes?category=benchmark&since=${d}&until=${d}`,
  MODEL_CHANGES: (d) => `/changes?category=model&since=${d}&until=${d}`,
  RESEARCH: (d) => `/changes?category=paper&since=${d}&until=${d}`,
  OPEN_WEIGHT_RELEASES: (d) => `/changes?type=NEW_MODEL&since=${d}&until=${d}`,
  DEPRECATIONS: (d) => `/changes?type=DEPRECATION_ANNOUNCED&since=${d}&until=${d}`,
  PROVIDER_CHANGES: (d) => `/changes?category=provider&since=${d}&until=${d}`,
  HARDWARE: (d) => `/changes?category=hardware&since=${d}&until=${d}`,
};

export function orderedSections(today: TodaySection[] | undefined): { present: TodaySection[]; quiet: string[] } {
  const byKey = new Map((today ?? []).map((s) => [s.key, s]));
  const present: TodaySection[] = [];
  const quiet: string[] = [];
  for (const k of TODAY_ORDER) {
    const s = byKey.get(k);
    if (s && s.items.length) present.push(s);
    else quiet.push(k);
  }
  for (const s of today ?? []) if (!(TODAY_ORDER as readonly string[]).includes(s.key) && s.items.length) present.push(s);
  return { present, quiet };
}

/** "1 release · 4 documents" + expandable source list for grouped items (events sharing a group_key). */
export function GroupedSources({ it }: { it: TodayItem }) {
  const grouped = num(it.grouped_events) ?? 1;
  const docs = it.documents ?? [];
  const sources = num(it.sources) ?? docs.length;
  if (grouped <= 1 && docs.length <= 1) return null;
  const noun = it.event_type === 'RELEASE' || it.event_type === 'NEW_MODEL' ? 'release' : it.event_type === 'NEW_PAPER' ? 'paper' : 'event';
  return (
    <details className="mt-1 text-xs text-ink-3" data-grouped>
      <summary className="cursor-pointer select-none hover:text-ink">
        1 {noun} · {fmtInt(grouped)} {plural(grouped, 'event')} · {fmtInt(docs.length || sources)} {plural(docs.length || sources, 'document')}
        {sources > 1 && docs.length !== sources ? ` · ${fmtInt(sources)} sources` : ''}
      </summary>
      <ul className="mt-1 space-y-0.5 pl-3">
        {docs.map((u) => (
          <li key={u}>
            <a href={u} target="_blank" rel="noopener noreferrer" className="inline-flex items-center gap-1 text-ink-2 hover:text-accent">
              {hostOf(u) ?? u} <ExternalLink className="size-3" aria-hidden />
              <span className="truncate text-ink-3">{u.replace(/^https?:\/\/[^/]+/, '').slice(0, 60)}</span>
            </a>
          </li>
        ))}
        {docs.length === 0 && <li>Documents not listed by the API for this group.</li>}
      </ul>
    </details>
  );
}

export function TodayItemRow({ it }: { it: TodayItem }) {
  return <ChangeRow e={it} showDate live={false} trailing={<GroupedSources it={it} />} />;
}

export function QuietLine({ quiet, labels }: { quiet: string[]; labels?: Record<string, string> }) {
  if (!quiet.length) return null;
  return (
    <p className="mt-6 text-xs text-ink-3">
      Quiet today: {quiet.map((k, i) => (
        <span key={k}>
          {i > 0 && ' · '}
          {labels?.[k] ?? TODAY_LABELS[k] ?? k}
        </span>
      ))}
      . <Link href={routes.timeline()} className="link">Timeline →</Link>
    </p>
  );
}