import Link from 'next/link';
import { HBars, Histogram } from '@/components/charts/charts';
import { Unavailable } from '@/components/ui/unavailable';
import { fmtInt, num } from '@/lib/format';
import { ORBIT_CLASS_COLORS, routes } from '@/lib/site';
import type { BucketStat, DensityPayload } from '@/lib/types';
import { GroupedHistogram } from './local-charts';
import { ChartBlock, Note, TwoCol } from './shared';

const BUCKET_ORDER = ['0-200', '200-300', '300-400', '400-500', '500-600', '600-700', '700-800', '800-900', '900-1000', '1000-2000', 'MEO', 'GEO', 'HEO', 'OTHER', 'UNKNOWN'];

export function sortBuckets<T extends { bucket: string }>(buckets: T[]): T[] {
  const idx = (b: string) => {
    const i = BUCKET_ORDER.indexOf(b);
    return i === -1 ? BUCKET_ORDER.length : i;
  };
  return [...buckets].sort((a, b) => idx(a.bucket) - idx(b.bucket));
}

function bucketLabel(b: string): string {
  if (/^\d+-\d+$/.test(b)) return `LEO ${b} km`;
  return b === 'UNKNOWN' ? 'Unclassified' : b;
}
function bucketColor(b: string): string {
  if (/^\d+-\d+$/.test(b)) return ORBIT_CLASS_COLORS.LEO ?? 'var(--leo)';
  return ORBIT_CLASS_COLORS[b] ?? 'var(--other)';
}

/** Orbital density section (informational object counts). `density` null → Unavailable. */
export function StatsDensity({ density, fallbackBuckets }: { density: DensityPayload | null; fallbackBuckets?: BucketStat[] }) {
  const buckets = sortBuckets(density?.buckets ?? fallbackBuckets ?? []);
  const bucketBars = buckets.map((b) => ({ label: bucketLabel(b.bucket), value: num(b.objects) ?? 0, color: bucketColor(b.bucket) }));

  const leo = density ? [...density.leo_profile_25km].map((r) => ({ bin: num(r.alt_km) ?? 0, values: [num(r.active_payloads) ?? 0, num(r.debris) ?? 0] })).sort((a, b) => a.bin - b.bin) : [];
  const incl = density ? [...density.inclination_profile_5deg].map((r) => ({ bin: num(r.incl_deg) ?? 0, value: num(r.objects) ?? 0 })).sort((a, b) => a.bin - b.bin) : [];
  const inclActive = density ? [...density.inclination_profile_5deg].map((r) => ({ bin: num(r.incl_deg) ?? 0, values: [num(r.active_payloads) ?? 0, (num(r.objects) ?? 0) - (num(r.active_payloads) ?? 0)] })).sort((a, b) => a.bin - b.bin) : [];

  return (
    <div className="space-y-12">
      <Note tone="warn">
        {density?.methodology ?? 'Objects on orbit by perigee altitude. Informational density, not a collision-risk metric.'} SatelliteIndex publishes object counts only — never collision probabilities.{' '}
        <Link href={routes.methodology()} className="text-accent hover:underline">Methodology</Link>
      </Note>

      <TwoCol>
        <ChartBlock title="Objects on orbit by altitude band" hint="Perigee altitude" derived>
          {bucketBars.length ? <HBars data={bucketBars} /> : <Unavailable what="Altitude bands" />}
          <table className="data-table stack mt-5 text-sm">
            <thead>
              <tr>
                <th>Band</th>
                <th className="num">Objects</th>
                <th className="num">Active payloads</th>
                <th className="num">Debris</th>
                <th className="num">Rocket bodies</th>
              </tr>
            </thead>
            <tbody>
              {buckets.map((b) => (
                <tr key={b.bucket}>
                  <td className="primary" data-label="Band">{bucketLabel(b.bucket)}</td>
                  <td className="num tnum" data-label="Objects">{fmtInt(b.objects)}</td>
                  <td className="num tnum" data-label="Active payloads">{fmtInt(b.active_payloads)}</td>
                  <td className="num tnum" data-label="Debris">{fmtInt(b.debris)}</td>
                  <td className="num tnum" data-label="Rocket bodies">{fmtInt(b.rocket_bodies)}</td>
                </tr>
              ))}
            </tbody>
          </table>
        </ChartBlock>

        <div className="space-y-10">
          <ChartBlock title="LEO altitude profile" hint="25 km bins · perigee" derived>
            {leo.length ? <GroupedHistogram data={leo} series={[{ label: 'Active payloads', color: 'var(--series-1)' }, { label: 'Debris', color: 'var(--series-4)' }]} title="LEO altitude profile: active payloads vs debris per 25 km" unit=" km" height={180} /> : <Unavailable what="LEO profile" />}
          </ChartBlock>
          <ChartBlock title="Inclination profile" hint="5° bins · all objects on orbit" derived>
            {incl.length ? <Histogram data={incl} title="Objects on orbit by inclination (5° bins)" unit="°" color="var(--series-2)" height={150} xTicks={8} /> : <Unavailable what="Inclination profile" />}
            {inclActive.length > 0 && <GroupedHistogram data={inclActive} series={[{ label: 'Active payloads', color: 'var(--series-3)' }, { label: 'Other objects', color: 'var(--inactive)' }]} title="Inclination profile: active payloads vs other objects" unit="°" height={150} className="mt-4" />}
          </ChartBlock>
        </div>
      </TwoCol>

      <Note>
        Debris growth by launch year, fragmentation sources and the largest tracked objects are on <Link href={routes.debris()} className="text-accent hover:underline">/debris</Link>. The most populated 50 km shells are listed under{' '}
        <Link href={routes.rankings('congested-shells')} className="text-accent hover:underline">Rankings → LEO shells</Link>.
      </Note>
    </div>
  );
}