// SOLARGOD moons layer (Stage 3) — every moon in the registry as a lit sphere,
// positioned by ctx.bodyWorld (main.js computes the local compressed offset in the
// parent's equatorial plane; retrograde via negative period). Moons draw at the
// SAME exaggeration as their parent, so the true radius ratio (e.g. Io/Jupiter
// ≈ 0.026) is preserved. Labels appear only when the parent (or the moon) is the
// focus, to keep the wide view clean (brief §5).

export default function create(ctx) {
  const { THREE, scene, CONFIG, ui, scale, bodies, focus, toLocal, effectiveE, makeLabel, registerPick } = ctx;

  const entries = [];
  for (const id in bodies) {
    const b = bodies[id];
    if (b.type !== 'moon') continue;
    const mat = new THREE.MeshStandardMaterial({ color: new THREE.Color(b.color), roughness: 1, metalness: 0 });
    const mesh = new THREE.Mesh(new THREE.SphereGeometry(1, 24, 16), mat);
    mesh.visible = true;
    scene.add(mesh);
    registerPick(mesh, id);
    const lbl = makeLabel(mesh, b.name, 'body-label moon');
    lbl.obj.visible = false; // CSS2DRenderer honors obj.visible (not div.style.display)
    entries.push({ id, b, mesh, lbl });
  }

  let show = true;
  ui.addLayer('moons', 'Moons', true, (on) => { show = on; for (const e of entries) e.mesh.visible = on; });
  ui.setStatus('moons', `${entries.length} moons`, 'ok');

  return {
    id: 'moons',
    onClockTick(simMs, jd) {
      for (const e of entries) {
        const abs = ctx.bodyWorld[e.id];
        if (!abs) continue;
        toLocal(abs, e.mesh.position);
        e.mesh.scale.setScalar(scale.drawRadius(e.b.radiusKm, effectiveE(e.b.parent)));
        const near = focus.id === e.b.parent || focus.id === e.id;
        e.lbl.obj.visible = show && near;
        e.lbl.div.classList.toggle('focused', e.id === focus.id);
      }
    },
  };
}