import type { Metadata } from 'next';
import Link from 'next/link';
import { notFound, permanentRedirect } from 'next/navigation';
import { ExternalLink } from 'lucide-react';
import { PageHeader, Section, KV, Note } from '@/components/ui/section';
import { Badge } from '@/components/ui/badge';
import { EmptyState } from '@/components/ui/empty-state';
import { Freshness } from '@/components/ui/freshness';
import { Pager } from '@/components/ui/pager';
import { EvidenceTable } from '@/components/data/evidence-table';
import { GeneFrequencyTable } from '@/components/data/frequency-table';
import { getGeneBySymbol, variantsForGene, variantsForGeneCount, frequenciesForGene, VARIANT_PAGE_SIZE } from '@/lib/queries/genomics';
import { evidenceForGene, evidenceForGeneCount, evidenceCancersForGene, EVIDENCE_PAGE_SIZE } from '@/lib/queries/evidence';
import { loadProvenance } from '@/lib/queries/provenance';
import { recentPublicationsFor, recentPublicationsForCount, PUBLICATION_PAGE_SIZE } from '@/lib/queries/publications';
import { PublicationList } from '@/components/data/publication-list';
import { GraphLink } from '@/components/graph/graph-link';
import { fmtInt, humanize } from '@/lib/format';
import { pageInfo } from '@/lib/pagination';
import { int, withParams, type SP } from '@/lib/search-params';

export const revalidate = 3600;
/** Cancer chips above the evidence table: the most-cited contexts only (every row still names its cancer). */
const CANCER_CHIPS = 20;

export async function generateMetadata({ params }: { params: Promise<{ symbol: string }> }): Promise<Metadata> {
  const g = await getGeneBySymbol((await params).symbol);
  return g ? { title: `${g.symbol} — gene`, description: `${g.symbol}${g.name ? ` (${g.name})` : ''}: curated cancer evidence, variants and cohort alteration frequencies.`, alternates: { canonical: `/gene/${g.symbol}` } } : { title: 'Gene' };
}

export default async function GenePage({ params, searchParams }: { params: Promise<{ symbol: string }>; searchParams: Promise<SP> }) {
  const { symbol } = await params;
  const g = await getGeneBySymbol(symbol);
  if (!g) notFound();
  if (g.symbol !== symbol) permanentRedirect(`/gene/${g.symbol}`);
  const sp = await searchParams;
  const evPageReq = int(sp, 'evPage', 1, 1, 100_000);
  const vPageReq = int(sp, 'vPage', 1, 1, 100_000);
  const cPageReq = int(sp, 'cPage', 1, 1, 100_000);
  const pPageReq = int(sp, 'pPage', 1, 1, 100_000);

  const [evTotal, vTotal, pTotal] = await Promise.all([evidenceForGeneCount(g.id, g.symbol), variantsForGeneCount(g.id), recentPublicationsForCount('gene', [g.id])]);
  const ev = pageInfo(evPageReq, EVIDENCE_PAGE_SIZE, evTotal);
  const vp = pageInfo(vPageReq, VARIANT_PAGE_SIZE, vTotal);
  const pp = pageInfo(pPageReq, PUBLICATION_PAGE_SIZE, pTotal);
  const [variants, evidence, freqs, pubs, cancersInEvidence] = await Promise.all([
    vTotal ? variantsForGene(g.id, { page: vp.page, pageSize: vp.pageSize }) : Promise.resolve([]),
    evTotal ? evidenceForGene(g.id, g.symbol, { page: ev.page, pageSize: ev.pageSize }) : Promise.resolve([]),
    frequenciesForGene(g.id, g.symbol),
    pTotal ? recentPublicationsFor('gene', [g.id], { page: pp.page, pageSize: pp.pageSize }) : Promise.resolve([]),
    evTotal ? evidenceCancersForGene(g.id, g.symbol, CANCER_CHIPS) : Promise.resolve([]),
  ]);
  const prov = await loadProvenance([...evidence.map((e) => e.provenance_id), ...freqs.map((f) => f.provenance_id)]);

  const current = { evPage: ev.page > 1 ? ev.page : '', vPage: vp.page > 1 ? vp.page : '', pPage: pp.page > 1 ? pp.page : '', cPage: cPageReq > 1 ? cPageReq : '' };
  const href = (o: Record<string, string | number | null | undefined>, hash: string) => `/gene/${g.symbol}${withParams(current, o)}#${hash}`;

  return (
    <article>
      <PageHeader kicker="Gene" title={<span className="ci-mono font-sans">{g.symbol}</span>} lede={g.name ?? undefined}>
        <p className="mt-2 flex flex-wrap items-center gap-2 text-[12.5px]">
          <GraphLink type="gene" entityRef={g.symbol} />
          <span className="ci-mono text-ink-3">{g.id}</span>
          {g.hgnc_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/${g.hgnc_id}`} target="_blank" rel="noopener noreferrer">
              {g.hgnc_id} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {g.ensembl_gene_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=${g.ensembl_gene_id}`} target="_blank" rel="noopener noreferrer">
              {g.ensembl_gene_id} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {g.ncbi_gene_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://www.ncbi.nlm.nih.gov/gene/${g.ncbi_gene_id}`} target="_blank" rel="noopener noreferrer">
              NCBI {g.ncbi_gene_id} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {g.civic_gene_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://civicdb.org/genes/${g.civic_gene_id}/summary`} target="_blank" rel="noopener noreferrer">
              CIViC <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {g.is_cancer_gene ? <Badge tone="accent" title="Has at least one curated cancer edge (derived flag)">Cancer gene</Badge> : null}
          <Badge tone="outline">{g.status}</Badge>
        </p>
      </PageHeader>

      <div className="grid gap-8 lg:grid-cols-[1fr_320px]">
        <div className="space-y-8">
          {g.description ? (
            <Section id="summary" kicker="Summary" title="Description">
              <p className="max-w-3xl text-[15px] leading-relaxed">{g.description}</p>
            </Section>
          ) : null}

          <Section id="evidence" kicker="Curated evidence" title={`Clinical evidence (${fmtInt(evTotal)})`} description={`CIViC items involving this gene, grouped by molecular profile and therapy, with native levels and directions. ${EVIDENCE_PAGE_SIZE} items per page.`}>
            {evTotal ? (
              <>
                {cancersInEvidence.length ? (
                  <nav aria-label="Cancers in evidence" className="mb-3">
                    <ul className="m-0 flex list-none flex-wrap gap-1.5 p-0 text-[12.5px]">
                      <li className="ci-kicker mr-1 self-center">{cancersInEvidence.length >= CANCER_CHIPS ? `Top ${CANCER_CHIPS} cancers` : 'Cancers'}</li>
                      {cancersInEvidence.map((c) => (
                        <li key={c.slug}>
                          <Link href={`/cancer/${c.slug}/evidence`} className="ci-chip">
                            {c.name} <span className="ci-num text-ink-3">{c.n}</span>
                          </Link>
                        </li>
                      ))}
                    </ul>
                  </nav>
                ) : null}
                <EvidenceTable
                  items={evidence}
                  prov={prov}
                  showCancer
                  summary={
                    <>
                      Showing {fmtInt(ev.from)}–{fmtInt(ev.to)} of {fmtInt(evTotal)} evidence items
                    </>
                  }
                />
                <Pager total={evTotal} pageSize={ev.pageSize} page={ev.page} hrefFor={(p) => href({ evPage: p > 1 ? p : '' }, 'evidence')} label="Evidence pages" noun="evidence items" />
              </>
            ) : (
              <EmptyState compact>No curated evidence item involves this gene yet.</EmptyState>
            )}
          </Section>

          <Section id="frequencies" kicker="Cohorts" title={`Alteration frequency by cohort (${fmtInt(freqs.length)})`} description="Frequency = cases affected / cases profiled within one cohort. Cohorts are never pooled.">
            {freqs.length ? <GeneFrequencyTable rows={freqs} prov={prov} page={cPageReq} hrefFor={(p) => href({ cPage: p > 1 ? p : '' }, 'frequencies')} /> : <EmptyState compact>No cohort frequency recorded for this gene.</EmptyState>}
          </Section>

          <Section id="publications" kicker="Literature" title={`Linked publications (${fmtInt(pTotal)})`} description={pTotal ? `${PUBLICATION_PAGE_SIZE} per page, newest first.` : undefined}>
            {pubs.length ? (
              <>
                <PublicationList
                  rows={pubs}
                  summary={
                    <>
                      Showing {fmtInt(pp.from)}–{fmtInt(pp.to)} of {fmtInt(pTotal)} publications
                    </>
                  }
                />
                <Pager total={pTotal} pageSize={pp.pageSize} page={pp.page} hrefFor={(p) => href({ pPage: p > 1 ? p : '' }, 'publications')} label="Publication pages" noun="publications" />
              </>
            ) : (
              <EmptyState compact>No publication linked to this gene yet.</EmptyState>
            )}
          </Section>
        </div>

        <aside className="space-y-8">
          <Section id="identity" kicker="HGNC" title="Record" level={3}>
            <KV
              items={[
                { k: 'Location', v: g.location ? <span className="ci-mono">{g.location}</span> : null },
                { k: 'Chromosome', v: g.chromosome },
                { k: 'Locus type', v: g.locus_type },
                { k: 'Locus group', v: g.locus_group },
                { k: 'Previous symbols', v: g.prev_symbols.length ? g.prev_symbols.join(', ') : null },
                { k: 'Alias symbols', v: g.alias_symbols.length ? g.alias_symbols.join(', ') : null },
                { k: 'Gene families', v: g.gene_families.length ? g.gene_families.join('; ') : null },
                { k: 'UniProt', v: g.uniprot_ids.length ? g.uniprot_ids.join(', ') : null },
                { k: 'OMIM', v: g.omim_ids.length ? g.omim_ids.join(', ') : null },
                { k: 'RefSeq', v: g.refseq_accession },
              ]}
            />
            <Freshness dataUpdatedAt={g.updated_at} extra="source: hgnc" />
          </Section>
          <Section id="variants" kicker="Variants" title={`Variants (${fmtInt(vTotal)})`} description={vTotal > VARIANT_PAGE_SIZE ? `Sorted by evidence count, ${VARIANT_PAGE_SIZE} per page.` : undefined} level={3}>
            {variants.length ? (
              <>
                <ul className="ci-rows">
                  {variants.map((v) => (
                    <li key={v.id}>
                      <Link className="ci-link" href={`/variant/${v.slug}`}>
                        {v.name}
                      </Link>
                      <span>
                        {v.variant_type ? humanize(v.variant_type) : ''}
                        {v.evidence_count ? ` · ${v.evidence_count} ev.` : ''}
                      </span>
                    </li>
                  ))}
                </ul>
                <Pager total={vTotal} pageSize={vp.pageSize} page={vp.page} hrefFor={(p) => href({ vPage: p > 1 ? p : '' }, 'variants')} label="Variant pages" noun="variants" className="text-[12px]" />
              </>
            ) : (
              <p className="text-[13px] text-ink-3">No variant entity recorded for this gene.</p>
            )}
          </Section>
          <Note>Gene-level pages aggregate curated evidence across cancers; the cancer context of each item is shown in the table and must not be generalized.</Note>
        </aside>
      </div>
    </article>
  );
}