import { ExternalLink } from 'lucide-react';
import type { Metadata } from 'next';
import Link from 'next/link';
import { notFound } from 'next/navigation';
import { CompareTrayBar } from '@/components/compare/compare-tray-bar';
import { ModelsTable } from '@/components/entity/blocks';
import { Tri } from '@/components/models/badges';
import { LICENCE_DIMENSIONS, OpennessBlock } from '@/components/models/openness-block';
import { EntityBadge } from '@/components/ui/badges';
import { Hint } from '@/components/ui/hint';
import { Pagination } from '@/components/ui/pagination';
import { Container, Note } from '@/components/ui/section';
import { ApiError, apiD1, safe } from '@/lib/api';
import { fmtInt } from '@/lib/format';
import { SITE_NAME, SITE_URL } from '@/lib/site';
import type { LicenseDetail, ModelOpenness } from '@/lib/types';

type Params = { params: Promise<{ key: string }>; searchParams: Promise<{ offset?: string }> };
const LIMIT = 50;
export const revalidate = 3600;

async function load(key: string, offset: number): Promise<LicenseDetail> {
  try {
    return await apiD1.license(key, LIMIT, offset);
  } catch (e) {
    if (e instanceof ApiError && e.notFound) notFound();
    throw e;
  }
}

const tri = (v: boolean | null) => (v === true ? 'yes' : v === false ? 'no' : 'unknown');

export async function generateMetadata({ params }: Params): Promise<Metadata> {
  const { key } = await params;
  const l = await safe(apiD1.license(key, 1));
  if (!l) return { title: 'Licence', robots: { index: false } };
  const title = `${l.label} — Model licence terms & models using it`;
  const description = `${l.label} (${l.category}${l.spdx ? `, SPDX ${l.spdx}` : ''}): commercial use ${tri(l.commercial_use)}, redistribution ${tri(l.redistribution)}, derivatives ${tri(l.derivatives)}, hosting restrictions ${tri(l.hosting_restrictions)}, acceptable-use policy ${tri(l.acceptable_use)}. ${fmtInt(l.models.total)} canonical models use it. ${SITE_NAME}.`.slice(0, 300);
  const canonical = `/licenses/${encodeURIComponent(l.key)}`;
  return { title, description, alternates: { canonical }, openGraph: { title: `${title} | ${SITE_NAME}`, description, url: `${SITE_URL}${canonical}`, type: 'article' } };
}

/** Openness view derived from the licence permissions alone (weights downloadable · commercial · redistribution · derivatives). */
function opennessFromLicence(l: LicenseDetail): ModelOpenness {
  const category = !l.weights_downloadable ? 'proprietary' : l.commercial_use === false || l.hosting_restrictions === true || l.derivatives === false || l.category === 'community' || l.category === 'research-only' || l.category === 'responsible-ai' ? 'restricted-weights' : 'open-weights';
  const labels: Record<string, string> = { proprietary: 'Closed / proprietary', 'restricted-weights': 'Restricted weights', 'open-weights': 'Open weights' };
  const defs: Record<string, string> = {
    proprietary: 'Weights are not redistributable under this licence.',
    'restricted-weights': 'Weights downloadable, but the licence restricts commercial use, hosting, derivatives or field of use.',
    'open-weights': 'Weights downloadable under a permissive licence allowing commercial use; code or data may be missing.',
  };
  return {
    category,
    raw: l.key,
    label: labels[category] ?? category,
    definition: defs[category] ?? '',
    dimensions: { weights_available: l.weights_downloadable, source_code_available: null, training_code_available: null, training_data_disclosed: null, dataset_available: null, commercial_use_allowed: l.commercial_use, redistribution_allowed: l.redistribution, derivatives_allowed: l.derivatives },
    note: 'Derived from the licence text alone — a model under this licence may still publish code or data (see its page).',
  };
}

export default async function LicensePage({ params, searchParams }: Params) {
  const { key } = await params;
  const { offset: off } = await searchParams;
  const offset = Math.max(0, Number(off) || 0);
  const l = await load(key, offset);
  const canonical = `/licenses/${encodeURIComponent(l.key)}`;
  const ld = { '@context': 'https://schema.org', '@type': 'CreativeWork', name: l.label, url: `${SITE_URL}${canonical}`, alternateName: l.aliases, sameAs: l.url ?? undefined, identifier: l.spdx ?? l.key, description: `${l.category} licence · commercial use ${tri(l.commercial_use)} · redistribution ${tri(l.redistribution)} · derivatives ${tri(l.derivatives)}` };

  return (
    <Container wide>
      <script type="application/ld+json" dangerouslySetInnerHTML={{ __html: JSON.stringify(ld) }} />
      <nav aria-label="Breadcrumb" className="pt-5 text-xs text-ink-3">
        <ol className="flex flex-wrap items-center gap-1.5">
          <li>
            <Link href="/" className="hover:text-ink">
              AI Atlas
            </Link>
          </li>
          <li aria-hidden>/</li>
          <li>
            <Link href="/licenses" className="hover:text-ink">
              Licences
            </Link>
          </li>
          <li aria-hidden>/</li>
          <li>
            <Link href={`/licenses?category=${encodeURIComponent(l.category)}`} className="hover:text-ink">
              {l.category}
            </Link>
          </li>
          <li aria-hidden>/</li>
          <li className="text-ink-2">{l.label}</li>
        </ol>
      </nav>
      <header className="pb-6 pt-4 md:pt-5" data-license-header>
        <div className="flex flex-wrap items-center gap-2">
          <EntityBadge type="license" />
          <span className="rounded-[3px] bg-surface-2 px-1.5 text-[11px] font-medium text-ink-2">{l.category}</span>
          {l.osi_approved && <span className="rounded-[3px] bg-positive-soft px-1.5 text-[11px] font-medium text-positive">OSI approved</span>}
          {l.spdx && <span className="mono text-xs text-ink-3">SPDX {l.spdx}</span>}
        </div>
        <div className="mt-3 flex flex-col gap-4 lg:flex-row lg:items-end lg:justify-between">
          <div className="min-w-0">
            <h1 className="display text-[30px] md:text-[44px]">{l.label}</h1>
            <p className="mt-2 flex flex-wrap items-center gap-x-3 gap-y-1 text-[15px] text-ink-2">
              <span className="mono text-ink">{l.key}</span>
              {l.url && (
                <a href={l.url} target="_blank" rel="noopener noreferrer" className="inline-flex max-w-full min-w-0 items-center gap-1 text-ink-3 hover:text-accent">
                  <span className="truncate">{l.url.replace(/^https?:\/\/(www\.)?/, '').replace(/\/$/, '').slice(0, 56)}</span> <ExternalLink className="size-3.5 shrink-0" aria-hidden />
                </a>
              )}
            </p>
          </div>
          <p className="tnum text-sm text-ink-2">
            <span className="font-semibold text-ink">{fmtInt(l.models.total)}</span> canonical models{' '}
            <Link href={`/models?license=${encodeURIComponent(l.key)}`} className="link">
              open in the terminal →
            </Link>
          </p>
        </div>
      </header>

      <div className="grid gap-10 pb-16 lg:grid-cols-[minmax(0,1fr)_24rem]">
        <div className="min-w-0 space-y-10">
          <section>
            <p className="eyebrow mb-2">Dimensions</p>
            <dl className="kv" data-license-dimensions>
              {LICENCE_DIMENSIONS.map((d) => (
                <div key={d.key}>
                  <dt>{d.label}</dt>
                  <dd className="flex items-start justify-between gap-2 text-ink">
                    <span>
                      <Tri v={l[d.key] as boolean | null} yes={d.invert ? 'Yes — restrictions apply' : 'Yes'} no={d.invert ? 'None' : 'No'} />
                    </span>
                    <Hint text={d.hint} align="right" className="-my-1 shrink-0" />
                  </dd>
                </div>
              ))}
              <div>
                <dt>Weights downloadable</dt>
                <dd className="text-ink">
                  <Tri v={l.weights_downloadable} />
                </dd>
              </div>
              <div>
                <dt>OSI approved</dt>
                <dd className="text-ink">
                  <Tri v={l.osi_approved} />
                </dd>
              </div>
            </dl>
            <Note className="mt-2">Read from the licence text by the ontology; a dash means the text is ambiguous and nothing is assumed. Not legal advice.</Note>
          </section>
          <section>
            <p className="eyebrow mb-2">What this means for openness</p>
            <OpennessBlock openness={opennessFromLicence(l)} compact />
          </section>
          <section id="models">
            <p className="eyebrow mb-2">
              Models under this licence <span className="tnum text-ink-3">{fmtInt(l.models.total)}</span>
            </p>
            <ModelsTable items={l.models.items} />
            <Pagination total={l.models.total} limit={LIMIT} offset={offset} makeHref={(o) => `${canonical}${o ? `?offset=${o}#models` : '#models'}`} className="mt-4" />
          </section>
        </div>
        <aside className="min-w-0 space-y-8">
          {l.aliases?.length > 0 && (
            <section>
              <p className="eyebrow mb-2">
                Aliases mapped to this licence <span className="tnum text-ink-3">{fmtInt(l.aliases.length)}</span>
              </p>
              <ul className="flex flex-wrap gap-1.5 text-xs">
                {l.aliases.map((a) => (
                  <li key={a} className="mono border border-rule px-1.5 py-0.5 text-ink-2">
                    {a}
                  </li>
                ))}
              </ul>
              <Note className="mt-2">Raw labels stated by sources that the ontology maps to this canonical key.</Note>
            </section>
          )}
          <section>
            <p className="eyebrow mb-2">Category</p>
            <p className="text-sm text-ink-2">
              <Link href={`/licenses?category=${encodeURIComponent(l.category)}`} className="link">
                {l.category}
              </Link>{' '}
              — see the other licences of this category and the <Link href="/methodology" className="link">openness methodology</Link>.
            </p>
          </section>
        </aside>
      </div>
      <CompareTrayBar />
    </Container>
  );
}