import Link from 'next/link';
import { Section, KV, Note } from '@/components/ui/section';
import { Badge, ClaimBadge } from '@/components/ui/badge';
import { EmptyState } from '@/components/ui/empty-state';
import { Freshness } from '@/components/ui/freshness';
import { SourceBadge } from '@/components/ui/source-badge';
import { gapComponentForCancer, gapScopeKey } from '@/lib/queries/research-gap';
import { fmtInt, fmtPct, fmtValue, humanize } from '@/lib/format';

function ratioText(v: number | null): string {
  if (v == null) return 'undefined (no activity)';
  const abs = Math.abs(v);
  const factor = 2 ** abs;
  const how = factor >= 10 ? `${fmtInt(factor)}×` : `${fmtValue(factor, 'ratio')}×`;
  if (abs < 0.15) return 'about proportional to its share of deaths';
  return v > 0 ? `death share ${how} its activity share` : `activity share ${how} its death share`;
}

/**
 * Small server component for a cancer page: that cancer's research-gap components in the latest
 * burden scope of a geography (default USA, both sexes). Shows the inputs behind each ratio and links
 * to the full index and the two ratio rankings. Renders an EmptyState when the cancer is not a
 * top-level entity of the scope (components exist only for top-level cancers with a mortality
 * observation — CLAUDE.md §246-247).
 */
export async function CancerGapCard({ cancerId, geography = 'USA' }: { cancerId: string; geography?: string }) {
  const res = await gapComponentForCancer(cancerId, geography);
  return (
    <Section
      id="research-gap"
      kicker="Unmet need · computed"
      title="Research gap"
      level={3}
      actions={
        <Link href="/research-gap" className="ci-link">
          Full index →
        </Link>
      }
    >
      {!res ? (
        <EmptyState compact title="No research-gap components for this entity" knows={[{ label: 'Research Gap Index (top-level cancers)', href: '/research-gap' }, { label: 'Methodology', href: '/methodology#research-gap' }]}>
          Components are computed for top-level cancers with a mortality observation in a burden scope (United States only for now). Entities below the top level inherit no value: shares would double-count their parent.
        </EmptyState>
      ) : (
        (() => {
          const { scope, row, sums } = res;
          const key = gapScopeKey(scope);
          const src = <SourceBadge p={{ sourceSlug: scope.source_slug, sourceName: scope.source_name, dataset: `mortality_count · ${scope.geography} · ${scope.year} · ${scope.sex}`, layer: 'normalized' }} compact />;
          return (
            <>
              <p className="mb-2 flex flex-wrap items-center gap-2 text-[12px] text-ink-3">
                <ClaimBadge kind="computed" />
                <span>
                  {scope.geography} · {scope.year} · {scope.sex === 'all' ? 'both sexes' : humanize(scope.sex)} · all ages · {fmtInt(sums.eligible)} eligible top-level cancers
                </span>
                {row.eligible ? (
                  <Badge tone="ok">eligible</Badge>
                ) : (
                  <Badge tone="outline" title={row.ineligible_reason ?? undefined}>
                    ineligible
                  </Badge>
                )}
              </p>
              <KV
                items={[
                  {
                    k: `Deaths ${scope.year}`,
                    v: (
                      <>
                        <span className="ci-num">{fmtInt(row.deaths)}</span> {src}
                        {row.death_share != null ? <span className="text-ink-3"> · {fmtPct(row.death_share, 1)} of {fmtInt(sums.deaths)} in the eligible set</span> : null}
                      </>
                    ),
                  },
                  {
                    k: 'Active trials',
                    v: (
                      <>
                        <span className="ci-num">{fmtInt(row.active_trials)}</span> <Link href="/source/clinicaltrials" className="ci-src">clinicaltrials</Link>
                        {row.trial_share != null ? <span className="text-ink-3"> · {fmtPct(row.trial_share, 1)} of {fmtInt(sums.activeTrials)}</span> : null}
                        <span className="text-ink-3"> · {fmtValue(row.trials_per_1000_deaths, 'per_1000_deaths')} per 1,000 deaths</span>
                      </>
                    ),
                  },
                  {
                    k: 'Publications 5 y',
                    v: (
                      <>
                        <span className="ci-num">{fmtInt(row.publications_5y)}</span> <Link href="/source/pubmed" className="ci-src">pubmed</Link>
                        {row.publication_share != null ? <span className="text-ink-3"> · {fmtPct(row.publication_share, 1)} of {fmtInt(sums.publications5y)}</span> : null}
                        <span className="text-ink-3"> · {fmtValue(row.publications_per_1000_deaths, 'per_1000_deaths')} per 1,000 deaths</span>
                      </>
                    ),
                  },
                  {
                    k: 'Trial gap ratio',
                    v: row.eligible ? (
                      <>
                        <span className={`ci-num font-medium ${(row.trial_gap_ratio ?? 0) >= 1 ? 'text-danger' : ''}`}>{fmtValue(row.trial_gap_ratio, 'log2_ratio')}</span>
                        <span className="text-ink-3"> log₂ · {ratioText(row.trial_gap_ratio)}</span>
                        {row.trial_gap_rank != null ? (
                          <>
                            {' '}
                            ·{' '}
                            <Link href={`/rankings/trial_gap_ratio?scope=${encodeURIComponent(key)}`} className="ci-link">
                              rank #{row.trial_gap_rank} of {fmtInt(sums.eligible)}
                            </Link>
                          </>
                        ) : null}
                      </>
                    ) : (
                      <span className="text-ink-3">not computed — {row.ineligible_reason?.replace(/_/g, ' ')}</span>
                    ),
                  },
                  {
                    k: 'Research gap ratio',
                    v: row.eligible ? (
                      <>
                        <span className={`ci-num font-medium ${(row.research_gap_ratio ?? 0) >= 1 ? 'text-danger' : ''}`}>{fmtValue(row.research_gap_ratio, 'log2_ratio')}</span>
                        <span className="text-ink-3"> log₂ · {ratioText(row.research_gap_ratio)}</span>
                        {row.research_gap_rank != null ? (
                          <>
                            {' '}
                            ·{' '}
                            <Link href={`/rankings/research_gap_ratio?scope=${encodeURIComponent(key)}`} className="ci-link">
                              rank #{row.research_gap_rank} of {fmtInt(sums.eligible)}
                            </Link>
                          </>
                        ) : null}
                      </>
                    ) : (
                      <span className="text-ink-3">not computed — {row.ineligible_reason?.replace(/_/g, ' ')}</span>
                    ),
                  },
                  { k: 'Formula', v: <span className="ci-mono text-[12px]">log2(death share ÷ activity share) · {row.formula_version}</span> },
                ]}
              />
              <Note>A gap ratio compares registered activity with deaths inside one scope. It is a signal, not a judgement of research quality; trial counts include NCIt descendants, literature counts are query-based per entity.</Note>
              <Freshness dataUpdatedAt={row.computed_at} extra={`scope ${key}`} />
            </>
          );
        })()
      )}
    </Section>
  );
}