// SOLARGOD asteroids layer (Stage 5) — a main-belt sample from JPL SBDB, each rock
// propagated by the SAME Kepler core as the planets (ephem.smallBodyEcl over epoch
// elements). One Points cloud, positions refreshed ≤10 Hz. Off by default; additive
// and fail-soft (brief §5, §11). Gate: the belt sits as a torus between Mars and
// Jupiter — not a sphere, not a line.

export default function create(ctx) {
  const { THREE, CONFIG, ui, scale, ephem, worldGroup } = ctx;
  const CAP = 1500;

  let elements = [];
  let geo = null, points = null, positions = null;
  let on = false, lastWall = 0;
  const _e = {}, _v = {};

  ui.addLayer('asteroids', 'Main belt', false, (v) => { on = v; if (points) points.visible = v; if (v) refresh(ctx.clock.jd, true); });
  ui.setStatus('asteroids', 'off', 'off');
  load();

  async function load() {
    ui.setStatus('asteroids', 'fetching SBDB…', 'warn');
    try {
      const q = `fields=full_name,a,e,i,om,w,ma,epoch&sb-kind=a&sb-class=MBA&limit=${CAP}`;
      const j = await (await fetch(`${CONFIG.proxy.sbdb}?${q}`)).json();
      const F = j.fields, ix = (k) => F.indexOf(k);
      elements = j.data.map((r) => ({
        a: +r[ix('a')], e: +r[ix('e')], i: +r[ix('i')], om: +r[ix('om')], w: +r[ix('w')], ma: +r[ix('ma')], epoch: +r[ix('epoch')],
      })).filter((el) => el.a > 0 && el.e < 0.98 && Number.isFinite(el.a) && Number.isFinite(el.ma));
      build();
      ui.setStatus('asteroids', `${elements.length} main-belt · SBDB`, on ? 'ok' : 'off');
    } catch (err) {
      console.warn('[solargod] asteroids', err.message);
      ui.setStatus('asteroids', 'SBDB unavailable', 'err');
    }
  }

  function build() {
    geo = new THREE.BufferGeometry();
    positions = new Float32Array(elements.length * 3);
    geo.setAttribute('position', new THREE.BufferAttribute(positions, 3));
    points = new THREE.Points(geo, new THREE.PointsMaterial({ color: 0x9a8464, size: 0.16, sizeAttenuation: true, transparent: true, opacity: 0.85, depthWrite: false }));
    points.frustumCulled = false;
    points.visible = on;
    worldGroup.add(points);
    if (on) refresh(ctx.clock.jd, true);
  }

  function refresh(jd) {
    for (let k = 0; k < elements.length; k++) {
      ephem.smallBodyEcl(elements[k], jd, _e);
      scale.viewFromEcl(_e, _v);
      positions[k * 3] = _v.x; positions[k * 3 + 1] = _v.y; positions[k * 3 + 2] = _v.z;
    }
    geo.attributes.position.needsUpdate = true;
  }

  return {
    id: 'asteroids',
    onClockTick(simMs, jd) {
      if (!on || !points) return;
      const now = performance.now();
      if (now - lastWall < 100) return; // ≤10 Hz
      lastWall = now;
      refresh(jd);
    },
  };
}