import type { Metadata } from 'next';
import Link from 'next/link';
import { ATTRIBUTION, DISCLAIMER, FIELD_PRIORITY } from '@/components/meta/legal';
import { FreshnessSection, LimitationsSection, MissionLaunchSection, OrbitCalcSection, OrbitClassSection, PipelineSection, ResolutionSection, StatusSection } from '@/components/meta/methodology-sections';
import { ConstellationRulesSection, MetricsSection, OwnerCodesSection } from '@/components/meta/methodology-tables';
import { Callout, DocLayout, DocSection, Prose } from '@/components/meta/prose';
import { Container, PageHeader } from '@/components/ui/section';
import { api, safe } from '@/lib/api';
import { fmtDateTime } from '@/lib/format';
import { SITE_URL, routes } from '@/lib/site';

export const metadata: Metadata = {
  title: 'Methodology — how SatelliteIndex builds and derives its data',
  description: 'Ingestion pipeline, source priorities, entity resolution, SGP4 orbit calculation, status and orbit-class rules, constellation membership, versioned derived metrics, freshness thresholds and known limitations.',
  alternates: { canonical: `${SITE_URL}/methodology` },
  openGraph: { title: 'Methodology | SatelliteIndex', description: 'How every value on SatelliteIndex is sourced, resolved, computed and labelled.', url: `${SITE_URL}/methodology` },
  twitter: { card: 'summary', title: 'Methodology | SatelliteIndex', description: 'How every value on SatelliteIndex is sourced, resolved, computed and labelled.' },
};

const TOC = [
  { id: 'pipeline', label: 'Data pipeline' },
  { id: 'source-priority', label: 'Source priorities' },
  { id: 'entity-resolution', label: 'Entity resolution' },
  { id: 'orbit-calculation', label: 'Orbit calculation' },
  { id: 'status', label: 'Status classification' },
  { id: 'orbit-class', label: 'Orbit class' },
  { id: 'constellations', label: 'Constellation membership' },
  { id: 'mission-type', label: 'Mission type' },
  { id: 'launches', label: 'Launches' },
  { id: 'owner-codes', label: 'Owner codes' },
  { id: 'metrics', label: 'Derived metrics' },
  { id: 'freshness', label: 'Freshness' },
  { id: 'limitations', label: 'Limitations' },
  { id: 'disclaimer', label: 'Disclaimer' },
];

export default async function MethodologyPage() {
  const res = await safe(api.methodology());
  const payload = res?.data ?? null;
  const metric = (key: string) => payload?.metrics.find((m) => m.key === key)?.methodology ?? null;
  return (
    <Container>
      <PageHeader eyebrow="Methodology" title="How the index is built" lede="Every value on SatelliteIndex is either a sourced fact with provenance or a derived label with a versioned rule. This page documents the rules — from the raw upstream payload to the position drawn on the globe — so you can decide how much to trust each number.">
        <p className="mt-4 text-sm text-ink-3">
          Sources and licenses: <Link href={routes.sources()} className="link">/sources</Link> · Live freshness: <Link href={routes.statusData()} className="link">/status/data</Link> · Machine-readable: <a href="/api/v1/methodology" className="link mono">/api/v1/methodology</a>
          {res && <span className="ml-2">· definitions fetched {fmtDateTime(res.meta.generated_at)}</span>}
        </p>
      </PageHeader>

      <DocLayout toc={TOC}>
        <div>
          <PipelineSection />

          <DocSection id="source-priority" eyebrow="02" title="Source priorities">
            <Prose>
              <p>
                Sources carry a numeric priority; when two sources describe the same field the higher-priority value is kept and the other is still recorded in provenance. In practice each field family has one primary source today:
              </p>
            </Prose>
            <div className="mt-4 overflow-x-auto">
              <table className="data-table stack md:min-w-[640px]">
                <thead>
                  <tr>
                    <th>Field</th>
                    <th>Primary source</th>
                    <th>Note</th>
                  </tr>
                </thead>
                <tbody>
                  {FIELD_PRIORITY.map((f) => (
                    <tr key={f.field}>
                      <td className="primary text-sm text-ink">{f.field}</td>
                      <td data-label="Primary source" className="text-sm">
                        <Link href={`${routes.sources()}#${f.sourceId}`} className="link">
                          {f.source}
                        </Link>
                      </td>
                      <td data-label="Note" className="text-sm text-ink-2">
                        {f.note}
                      </td>
                    </tr>
                  ))}
                </tbody>
              </table>
            </div>
          </DocSection>

          <ResolutionSection />
          <OrbitCalcSection />
          <StatusSection methodologyText={metric('status')} />
          <OrbitClassSection methodologyText={metric('orbit_class')} />
          <ConstellationRulesSection rules={payload?.constellation_rules ?? null} />
          <MissionLaunchSection />
          <OwnerCodesSection owners={payload?.owner_codes ?? null} />
          <MetricsSection metrics={payload?.metrics ?? null} />
          <FreshnessSection methodologyText={metric('freshness')} />
          <LimitationsSection />

          <DocSection id="disclaimer" eyebrow="14" title="Disclaimer">
            <Callout tone="warn" className="mt-0">
              {DISCLAIMER}
            </Callout>
            <Prose className="mt-4">
              <p>{ATTRIBUTION}</p>
              <p className="text-ink-3">
                See the <Link href={routes.terms()} className="link">terms of use</Link>. Corrections and questions: <Link href={routes.about()} className="link">about</Link>.
              </p>
            </Prose>
          </DocSection>
        </div>
      </DocLayout>
    </Container>
  );
}