// usage: NODE_PATH=~/tools-gltf/node_modules node rotate_y180.cjs in.glb out.glb
// Rotates the model 180 deg about Y by baking it into POSITION/NORMAL/TANGENT (x,z -> -x,-z) and node translations.
const { NodeIO } = require('@gltf-transform/core');
const { ALL_EXTENSIONS } = require('@gltf-transform/extensions');
(async () => {
  const io = new NodeIO().registerExtensions(ALL_EXTENSIONS);
  const doc = await io.read(process.argv[2]);
  const seen = new Set();
  for (const mesh of doc.getRoot().listMeshes())
    for (const prim of mesh.listPrimitives()) {
      for (const sem of ['POSITION', 'NORMAL', 'TANGENT']) {
        const acc = prim.getAttribute(sem);
        if (!acc || seen.has(acc)) continue;
        seen.add(acc);
        const v = [0, 0, 0, 0];
        for (let i = 0; i < acc.getCount(); i++) { acc.getElement(i, v); v[0] = -v[0]; v[2] = -v[2]; acc.setElement(i, v); }
      }
      for (const t of prim.listTargets()) for (const sem of ['POSITION', 'NORMAL', 'TANGENT']) {
        const acc = t.getAttribute(sem); if (!acc || seen.has(acc)) continue; seen.add(acc);
        const v = [0, 0, 0, 0]; for (let i = 0; i < acc.getCount(); i++) { acc.getElement(i, v); v[0] = -v[0]; v[2] = -v[2]; acc.setElement(i, v); }
      }
    }
  let nodeNote = [];
  for (const n of doc.getRoot().listNodes()) {
    const t = n.getTranslation(), r = n.getRotation(), s = n.getScale();
    if (t.some(x => x) || r[3] !== 1 || s.some(x => x !== 1)) nodeNote.push([n.getName(), t, r, s]);
  }
  console.error('non-identity node transforms:', JSON.stringify(nodeNote));
  await io.write(process.argv[3], doc);
})();