import type { Metadata } from 'next';
import Link from 'next/link';
import { notFound } from 'next/navigation';
import { ExternalLink } from 'lucide-react';
import { GraphLink } from '@/components/graph/graph-link';
import { PageHeader, 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 { Pager } from '@/components/ui/pager';
import { SourceBadge } from '@/components/ui/source-badge';
import { ApprovalsTable } from '@/components/data/approvals-table';
import { EvidenceTable } from '@/components/data/evidence-table';
import { TrialTable } from '@/components/data/trial-list';
import { getDrugBySlug, approvalsForDrug, codesForDrug, pipelineForDrug, type DrugCodeRow } from '@/lib/queries/drugs';
import { evidenceForDrug, evidenceForDrugCount, EVIDENCE_PAGE_SIZE } from '@/lib/queries/evidence';
import { trialsForDrug, trialsForDrugCount, TRIAL_PAGE_SIZE } from '@/lib/queries/trials';
import { loadProvenance } from '@/lib/queries/provenance';
import { jsonLd, drugLd } from '@/lib/seo';
import { fmtDate, fmtInt, humanize, phaseLabel } from '@/lib/format';
import { pageInfo } from '@/lib/pagination';
import { str, int, withParams, type SP } from '@/lib/search-params';

export const revalidate = 3600;

const CODE_SYSTEMS: Record<string, string> = {
  atc: 'ATC (WHO)',
  din: 'DIN (Health Canada)',
  hc_drug_code: 'DPD drug code',
  unii: 'UNII (FDA GSRS)',
  rxcui: 'RxCUI (RxNorm)',
  ncit: 'NCIt',
  chembl: 'ChEMBL',
  drugbank: 'DrugBank',
  pubchem_cid: 'PubChem CID',
  civic_therapy: 'CIViC therapy',
  ema_product: 'EMA product',
  mhra: 'MHRA',
  tga: 'TGA',
};
function codeSystemLabel(system: string): string {
  return CODE_SYSTEMS[system] ?? humanize(system);
}

/** External link for code systems with a stable public URL pattern; plain text otherwise. */
function CodeLink({ c, codes }: { c: DrugCodeRow; codes: DrugCodeRow[] }) {
  let url: string | null = null;
  if (c.system === 'atc') url = `https://atcddd.fhi.no/atc_ddd_index/?code=${encodeURIComponent(c.code)}`;
  else if (c.system === 'hc_drug_code') url = `https://health-products.canada.ca/dpd-bdpp/info?lang=eng&code=${encodeURIComponent(c.code)}`;
  else if (c.system === 'din') {
    // The DPD public page is keyed by drug code, not DIN: reuse the hc_drug_code row that carries the same brand label.
    const dc = codes.find((k) => k.system === 'hc_drug_code' && k.label === c.label);
    url = dc ? `https://health-products.canada.ca/dpd-bdpp/info?lang=eng&code=${encodeURIComponent(dc.code)}` : null;
  } else if (c.system === 'chembl') url = `https://www.ebi.ac.uk/chembl/compound_report_card/${encodeURIComponent(c.code)}/`;
  else if (c.system === 'ncit') url = `https://evsexplore.semantics.cancer.gov/evsexplore/concept/ncit/${encodeURIComponent(c.code)}`;
  else if (c.system === 'pubchem_cid') url = `https://pubchem.ncbi.nlm.nih.gov/compound/${encodeURIComponent(c.code)}`;
  else if (c.system === 'drugbank') url = `https://go.drugbank.com/drugs/${encodeURIComponent(c.code)}`;
  if (!url) return <>{c.code}</>;
  return (
    <a className="ci-link inline-flex items-center gap-1" href={url} target="_blank" rel="noopener noreferrer">
      {c.code} <ExternalLink className="h-3 w-3" aria-hidden />
    </a>
  );
}

export async function generateMetadata({ params }: { params: Promise<{ slug: string }> }): Promise<Metadata> {
  const d = await getDrugBySlug((await params).slug);
  return d ? { title: `${d.name} — drug`, description: d.description ?? `${d.name}: regulatory approvals by jurisdiction, curated evidence and clinical trials.`, alternates: { canonical: `/drug/${d.slug}` } } : { title: 'Drug' };
}

export default async function DrugPage({ params, searchParams }: { params: Promise<{ slug: string }>; searchParams: Promise<SP> }) {
  const { slug } = await params;
  const d = await getDrugBySlug(slug);
  if (!d) notFound();
  const sp = await searchParams;
  const [evTotal, tTotal] = await Promise.all([evidenceForDrugCount(d.id), trialsForDrugCount(d.id)]);
  const ev = pageInfo(int(sp, 'evPage', 1, 1, 100_000), EVIDENCE_PAGE_SIZE, evTotal);
  const tp = pageInfo(int(sp, 'tPage', 1, 1, 100_000), TRIAL_PAGE_SIZE, tTotal);
  const aPage = int(sp, 'aPage', 1, 1, 100_000);
  const [approvals, evidence, trials, codes, pipeline] = await Promise.all([approvalsForDrug(d.id), evTotal ? evidenceForDrug(d.id, { page: ev.page, pageSize: ev.pageSize }) : Promise.resolve([]), tTotal ? trialsForDrug(d.id, { page: tp.page, pageSize: tp.pageSize }) : Promise.resolve([]), codesForDrug(d.id), pipelineForDrug(d.id)]);
  const hasCanada = approvals.some((a) => a.jurisdiction === 'CA');
  const prov = await loadProvenance([...approvals.map((a) => a.provenance_id), ...evidence.map((e) => e.provenance_id)]);
  const jurisdictions = [...new Set(approvals.map((a) => a.jurisdiction))].sort();
  const wanted = approvals.length ? str(sp, 'jurisdiction') : '';
  const selected = jurisdictions.includes(wanted) ? wanted : null;
  const shown = selected ? approvals.filter((a) => a.jurisdiction === selected) : approvals;
  const aliases = d.aliases ?? [];
  const current = { jurisdiction: selected ?? '', evPage: ev.page > 1 ? ev.page : '', tPage: tp.page > 1 ? tp.page : '', aPage: aPage > 1 ? aPage : '' };
  const href = (o: Record<string, string | number | null | undefined>, hash?: string) => `/drug/${d.slug}${withParams(current, o)}${hash ? `#${hash}` : ''}`;

  return (
    <article>
      <script type="application/ld+json" dangerouslySetInnerHTML={{ __html: jsonLd(drugLd({ slug: d.slug, name: d.name, description: d.description, mechanism: d.mechanism, aliases })) }} />
      <PageHeader kicker={`Drug${d.kind ? ` · ${humanize(d.kind)}` : ''}`} title={d.name} lede={d.description ?? undefined}>
        <p className="mt-2 flex flex-wrap items-center gap-2 text-[12.5px]">
          <span className="ci-mono text-ink-3">{d.id}</span>
          <GraphLink type="drug" entityRef={d.slug} />
          {d.ncit_code ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://evsexplore.semantics.cancer.gov/evsexplore/concept/ncit/${d.ncit_code}`} target="_blank" rel="noopener noreferrer">
              NCIt {d.ncit_code} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {d.chembl_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://www.ebi.ac.uk/chembl/compound_report_card/${d.chembl_id}/`} target="_blank" rel="noopener noreferrer">
              {d.chembl_id} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {d.drugbank_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://go.drugbank.com/drugs/${d.drugbank_id}`} target="_blank" rel="noopener noreferrer">
              {d.drugbank_id} <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {d.civic_therapy_id ? (
            <a className="ci-link inline-flex items-center gap-1" href={`https://civicdb.org/therapies/${d.civic_therapy_id}/summary`} target="_blank" rel="noopener noreferrer">
              CIViC <ExternalLink className="h-3 w-3" aria-hidden />
            </a>
          ) : null}
          {d.development_status ? <Badge tone="outline">{humanize(d.development_status)}</Badge> : null}
        </p>
      </PageHeader>

      <div className="grid gap-8 lg:grid-cols-[1fr_320px]">
        <div className="space-y-8">
          <Section id="approvals" kicker="Regulatory" title={`Approvals (${fmtInt(approvals.length)})`} description="Each record names the authority, jurisdiction, indication text and status. A drug approved in one jurisdiction for one indication is not 'approved' in general.">
            {approvals.length ? (
              <>
                <nav aria-label="Jurisdiction" className="mb-3 flex flex-wrap gap-1.5 text-[12.5px]">
                  <Link href={href({ jurisdiction: '' }, 'approvals')} aria-current={!selected ? 'page' : undefined} className="ci-chip">
                    All
                  </Link>
                  {jurisdictions.map((j) => (
                    <Link key={j} href={href({ jurisdiction: j }, 'approvals')} aria-current={selected === j ? 'page' : undefined} className="ci-chip ci-mono">
                      {j}
                    </Link>
                  ))}
                </nav>
                <ApprovalsTable rows={shown} prov={prov} showDrug={false} page={aPage} hrefFor={(p) => href({ aPage: p > 1 ? p : '' }, 'approvals')} />
                {hasCanada ? (
                  <p className="mt-2 text-[12px] text-ink-3">
                    Health Canada records are DIN-level: one row per marketed product (brand, strength, form). The Drug Product Database does not publish indications, so no cancer is stated for these rows, and a cancelled or dormant DIN is the status of that one product — not a withdrawal of the molecule.
                  </p>
                ) : null}
                <Freshness dataUpdatedAt={approvals.reduce<Date | string | null>((m, a) => (m == null || String(a.updated_at) > String(m) ? a.updated_at : m), null)} />
              </>
            ) : (
              <EmptyState compact knows={[{ label: 'Curated evidence below', href: '#evidence' }, { label: 'Sources', href: '/sources' }]}>
                No regulatory approval recorded. Absence here is not evidence of absence: only ingested jurisdictions are covered.
              </EmptyState>
            )}
          </Section>

          <Section id="pipeline" kicker="Derived" title="Development pipeline" description="Most advanced stage across all cancers, then per top-level cancer reached through trial conditions or approval indications. Approval in any ingested jurisdiction outranks trial phase; counts are interventional studies.">
            {pipeline.length ? (
              <>
                <div className="ci-table-wrap">
                  <table className="ci-table">
                    <thead>
                      <tr>
                        <th scope="col">Scope</th>
                        <th scope="col">Stage</th>
                        <th scope="col">Max phase</th>
                        <th scope="col" className="num">Active</th>
                        <th scope="col" className="num">Recruiting</th>
                        <th scope="col" className="num">Phase 3</th>
                        <th scope="col" className="num">Trials</th>
                        <th scope="col" className="num">Approvals</th>
                        <th scope="col">Jurisdictions</th>
                        <th scope="col">First approval</th>
                        <th scope="col">First trial</th>
                      </tr>
                    </thead>
                    <tbody>
                      {pipeline.map((p) => (
                        <tr key={p.id}>
                          <td className="min-w-[160px]">
                            {p.cancer_slug ? (
                              <Link className="ci-link" href={`/pipeline?cancer=${p.cancer_slug}`}>
                                {p.cancer_name}
                              </Link>
                            ) : (
                              <span className="font-medium">All cancers</span>
                            )}
                          </td>
                          <td>
                            <Badge tone={p.stage === 'approved' ? 'ok' : p.stage === 'withdrawn' ? 'danger' : p.stage === 'phase_not_stated' ? 'outline' : 'neutral'}>{humanize(p.stage)}</Badge>
                          </td>
                          <td className="text-[12.5px] text-ink-2">{p.max_phase ? phaseLabel(p.max_phase) : '—'}</td>
                          <td className="num">{fmtInt(p.active_trials)}</td>
                          <td className="num">{fmtInt(p.recruiting_trials)}</td>
                          <td className="num">{fmtInt(p.phase3_trials)}</td>
                          <td className="num">{fmtInt(p.total_trials)}</td>
                          <td className="num">{fmtInt(p.approvals)}</td>
                          <td className="ci-mono text-[12px]">{p.jurisdictions.length ? p.jurisdictions.join(', ') : '—'}</td>
                          <td className="whitespace-nowrap">{fmtDate(p.first_approval_date)}</td>
                          <td className="whitespace-nowrap">{p.first_trial_date ? (p.first_trial_date.length >= 10 ? fmtDate(p.first_trial_date) : p.first_trial_date) : '—'}</td>
                        </tr>
                      ))}
                    </tbody>
                  </table>
                </div>
                <div className="mt-2 flex flex-wrap items-center gap-1.5 text-[12px] text-ink-3">
                  <ClaimBadge kind="computed" />
                  <SourceBadge p={{ sourceSlug: 'clinicaltrials', layer: 'derived', note: 'Inputs: interventional trials linking this drug (trial_interventions × trial_conditions) and its approval records.' }} />
                  <span className="ci-mono">{pipeline[0]!.formula_version}</span>
                  <Link className="ci-link" href="/methodology/pipeline">
                    Stage rules
                  </Link>
                </div>
                <Freshness dataUpdatedAt={pipeline[0]!.computed_at} />
              </>
            ) : (
              <EmptyState compact>No registered interventional trial or approval record places this drug in the pipeline yet.</EmptyState>
            )}
          </Section>

          <Section id="evidence" kicker="Curated evidence" title={`Clinical evidence (${fmtInt(evTotal)})`} description={`CIViC items in which this therapy appears, grouped by cancer context, then molecular profile. ${EVIDENCE_PAGE_SIZE} items per page.`}>
            {evidence.length ? (
              <>
                <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 mentions this therapy yet.</EmptyState>
            )}
          </Section>

          <Section id="trials" kicker="Clinical trials" title={`Trials with this intervention (${fmtInt(tTotal)})`} description={tTotal ? `Most recently updated first, ${TRIAL_PAGE_SIZE} per page.` : undefined}>
            {trials.length ? (
              <>
                <TrialTable
                  rows={trials}
                  summary={
                    <>
                      Showing {fmtInt(tp.from)}–{fmtInt(tp.to)} of {fmtInt(tTotal)} studies
                    </>
                  }
                />
                <Pager total={tTotal} pageSize={tp.pageSize} page={tp.page} hrefFor={(p) => href({ tPage: p > 1 ? p : '' }, 'trials')} label="Trial pages" noun="studies" />
              </>
            ) : (
              <EmptyState compact>No registered study lists this drug as an intervention yet.</EmptyState>
            )}
          </Section>
        </div>

        <aside className="space-y-8">
          <Section id="record" kicker="Molecule" title="Record" level={3}>
            <KV
              items={[
                { k: 'Kind', v: d.kind ? humanize(d.kind) : null },
                { k: 'Mechanism', v: d.mechanism },
                { k: 'Targets', v: d.target_gene_ids.length ? `${d.target_gene_ids.length} gene${d.target_gene_ids.length === 1 ? '' : 's'}` : null },
                { k: 'UNII', v: d.unii ? <span className="ci-mono">{d.unii}</span> : null },
                { k: 'PubChem CID', v: d.pubchem_cid ? <a className="ci-link ci-mono" href={`https://pubchem.ncbi.nlm.nih.gov/compound/${d.pubchem_cid}`} target="_blank" rel="noopener noreferrer">{d.pubchem_cid}</a> : null },
                { k: 'Aliases', v: aliases.length ? aliases.slice(0, 30).join(', ') + (aliases.length > 30 ? ` … (+${aliases.length - 30})` : '') : null },
              ]}
            />
            <Freshness dataUpdatedAt={d.updated_at} />
          </Section>
          <Section id="identifiers" kicker="Identifiers" title={`Codes (${fmtInt(codes.length)})`} level={3} description="Upstream identifiers kept as first-class codes; each links to its registry where a stable public URL exists.">
            {codes.length ? (
              <div className="ci-table-wrap">
                <table className="ci-table">
                  <thead>
                    <tr>
                      <th scope="col">System</th>
                      <th scope="col">Code</th>
                      <th scope="col">Label</th>
                    </tr>
                  </thead>
                  <tbody>
                    {codes.map((c) => (
                      <tr key={c.id}>
                        <td className="whitespace-nowrap text-[12.5px] text-ink-2">{codeSystemLabel(c.system)}</td>
                        <td className="ci-mono text-[12px]">
                          <CodeLink c={c} codes={codes} />
                        </td>
                        <td className="max-w-[200px] text-[12.5px] text-ink-2">{c.label ?? '—'}</td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              </div>
            ) : (
              <EmptyState compact>No cross-reference code recorded yet beyond the record identifiers above.</EmptyState>
            )}
          </Section>
          <Note tone="warn">Regulatory status is jurisdiction-specific and time-bound. Nothing on this page is a treatment recommendation.</Note>
        </aside>
      </div>
    </article>
  );
}