// room3d.js — loaders + Mixamo retarget, ported from MESHGOD rigroom.html.
// Pure module: no DOM, no globals, no toast — throw Errors, callers handle UI.
// The bake algorithm is byte-for-byte rigroom's; only the target is now a
// parameter instead of a closed-over global.
import * as THREE from 'three';
import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
import { FBXLoader } from 'three/addons/loaders/FBXLoader.js';
import { OBJLoader } from 'three/addons/loaders/OBJLoader.js';
import { BVHLoader } from 'three/addons/loaders/BVHLoader.js';

export async function parseAny(buf, name){
  name = (name||'').toLowerCase();
  // extensionless routes (gallery/<id>/glb) + magic-byte fallback: gltf binary starts "glTF"
  if(!/\.(glb|gltf|fbx|obj|bvh)$/.test(name)){
    const head = new TextDecoder().decode(new Uint8Array(buf, 0, Math.min(16, buf.byteLength)));
    if(head.startsWith('glTF')) name += '.glb';
    else if(head.includes('Kaydara')) name += '.fbx';
    else if(head.includes('HIERARCHY')) name += '.bvh';
    else name += '.glb';   // worst case the loader throws a clear error
  }
  if(name.endsWith('.glb') || name.endsWith('.gltf')){
    const g = await new GLTFLoader().parseAsync(buf, ''); return {root:g.scene, anims:g.animations||[]}; }
  if(name.endsWith('.fbx')){ const r = new FBXLoader().parse(buf, ''); return {root:r, anims:r.animations||[]}; }
  if(name.endsWith('.obj')){ const r = new OBJLoader().parse(new TextDecoder().decode(buf));
    r.traverse(o=>{ if(o.isMesh && !o.material.map) o.material = new THREE.MeshStandardMaterial({color:0x9aa4af, roughness:.7}); });
    return {root:r, anims:[]}; }
  if(name.endsWith('.bvh')){ const r = new BVHLoader().parse(new TextDecoder().decode(buf));
    const root = new THREE.Object3D(); root.add(r.skeleton.bones[0]);
    return {root, anims:[r.clip]}; }
  throw new Error('unsupported type: '+name);
}

export function stats(root){
  let tris=0, meshes=0, bones=0;
  root.traverse(o=>{ if(o.isMesh){ meshes++; const g=o.geometry;
    tris += (g.index ? g.index.count : g.attributes.position.count)/3; } if(o.isBone) bones++; });
  return {tris:Math.round(tris), meshes, bones};
}

export function disposeRoot(root){
  root.traverse(o=>{ if(o.geometry) o.geometry.dispose();
    const m=o.material; if(m)(Array.isArray(m)?m:[m]).forEach(mt=>{ for(const k in mt){ const v=mt[k];
      if(v && v.isTexture) v.dispose(); } mt.dispose(); }); });
}

// canonical bone key: "mixamorig:LeftUpLeg" / "mixamorig_LeftUpLeg" / "mixamorig4LeftUpLeg" → "leftupleg"
// (mixamo numbers the namespace per-download — strip digits too). Encodes real Mixamo quirks; keep as-is.
export const canon = n => n.replace(/^.*?mixamorig\d*[:_]?/i,'').replace(/[^a-z0-9]/gi,'').toLowerCase();
export function boneMap(root){
  const m={}; root.traverse(o=>{ if(o.isBone && !(canon(o.name) in m)) m[canon(o.name)] = o; }); return m;
}
const hipsOf = map => map['hips'] || null;

// bind-pose snapshot — retargets are world-space deltas against THIS. Capture BEFORE any clip poses it.
export function captureRest(root){
  root.updateMatrixWorld(true);
  const rest = new Map(), order = [];
  root.traverse(o=>{ if(o.isBone){ order.push(o);
    rest.set(o, { wq:o.getWorldQuaternion(new THREE.Quaternion()),
                  lq:o.quaternion.clone(), lp:o.position.clone() }); } });
  return {rest, order};
}

// WORLD-SPACE rotation-delta transfer, baked at 30fps. Raw quaternion copying only works when both
// rests share bone axes (fbx→fbx). Blender-exported GLB rigs orient bones differently, so we sample
// the SOURCE through the clip and move each target bone by the source bone's world-space delta.
export function bakeRetarget(clip, srcRoot, srcRest, tgtRoot, tgtRest, opts={}){
  const tgt = boneMap(tgtRoot), src = boneMap(srcRoot);
  const tHips = hipsOf(tgt), sHips = hipsOf(src);
  if(!tHips || !sHips) throw new Error('retarget: missing hips (mixamorig skeleton?)');
  const sRest = srcRest.rest, tRest = tgtRest.rest, tOrder = tgtRest.order;
  const pairs = new Map();   // target bone → source bone. Dedupe by canon key: fbx files often
  const used = new Set();    // carry a DUPLICATE hierarchy — bind only the first (what boneMap picks)
  for(const tb of tOrder){ const k=canon(tb.name), sb=src[k];
    if(sb && sRest.has(sb) && !used.has(k)){ pairs.set(tb, sb); used.add(k); } }
  if(!pairs.size) throw new Error('retarget: no matching bones');
  let ratio=1;   // hips travel: local hip-height ratio (cm fbx vs m glb sorts itself out)
  if(sHips.position.y > 1e-6) ratio = tHips.position.y / sHips.position.y;
  const fps=30, n=Math.max(2, Math.ceil(clip.duration*fps)+1);
  const times = new Float32Array(n);
  const qData = new Map([...pairs.keys()].map(tb=>[tb, new Float32Array(n*4)]));
  const pData = new Float32Array(n*3);
  const mixerS = new THREE.AnimationMixer(srcRoot);
  mixerS.clipAction(clip).play();
  const q1=new THREE.Quaternion(), q2=new THREE.Quaternion(), q3=new THREE.Quaternion();
  for(let i=0;i<n;i++){
    const t = Math.min(clip.duration, i/fps); times[i]=t;
    mixerS.setTime(t); srcRoot.updateMatrixWorld(true);
    const world = new Map();   // this frame's target world quats, parent-first (traverse order)
    for(const tb of tOrder){
      const parent = tb.parent;
      const pw = world.get(parent) || parent.getWorldQuaternion(q3);   // non-bone parents are static
      let lq;
      const sb = pairs.get(tb);
      if(sb){
        const sw = sb.getWorldQuaternion(q1);                          // source now
        const delta = sw.multiply(q2.copy(sRest.get(sb).wq).invert()); // world delta from source rest
        const tw = delta.multiply(tRest.get(tb).wq);                   // applied to target rest
        lq = q2.copy(pw).invert().multiply(tw);                        // back to local
        // hemisphere continuity: keep each bone on the same side as its last frame, else slerp garbage
        const qd = qData.get(tb);
        if(i && qd[(i-1)*4]*lq.x + qd[(i-1)*4+1]*lq.y + qd[(i-1)*4+2]*lq.z + qd[(i-1)*4+3]*lq.w < 0)
          lq.set(-lq.x,-lq.y,-lq.z,-lq.w);
        qd.set([lq.x,lq.y,lq.z,lq.w], i*4);
        lq = new THREE.Quaternion(lq.x,lq.y,lq.z,lq.w);
      } else lq = tRest.get(tb).lq;
      world.set(tb, new THREE.Quaternion().multiplyQuaternions(pw, lq));
    }
    const hl = tRest.get(tHips).lp, sl = sRest.get(sHips).lp;
    pData.set([ hl.x + (sHips.position.x - sl.x)*ratio, hl.y + (sHips.position.y - sl.y)*ratio,
                hl.z + (sHips.position.z - sl.z)*ratio ], i*3);
  }
  mixerS.stopAllAction();
  for(const [sb,r] of sRest){ sb.quaternion.copy(r.lq); sb.position.copy(r.lp); }   // un-pose the source
  if(opts.inPlace) for(let i=3;i<pData.length;i+=3){ pData[i]=pData[0]; pData[i+2]=pData[2]; }
  const tracks = [...pairs.keys()].map(tb =>
    new THREE.QuaternionKeyframeTrack(`${tb.name}.quaternion`, times, qData.get(tb)));
  tracks.push(new THREE.VectorKeyframeTrack(`${tHips.name}.position`, times, pData));
  return new THREE.AnimationClip(clip.name, clip.duration, tracks);
}

// ---- self-check: two 3-bone skeletons with DIFFERENT rests, bake a 1s clip across, assert the
// world-space rotation DELTA the target reproduces matches the source's, within 1e-3. --------------
function _mkSkel(prefix, restEuler){
  // hips -> spine -> head, each 1 unit up its parent. restEuler tilts each bone's rest differently.
  const names = ['Hips','Spine','Head'];
  let parent=null, root=null; const bones=[];
  names.forEach((nm,i)=>{
    const b = new THREE.Bone(); b.name = prefix+nm;
    b.position.set(0, i===0 ? 1.0 : 1.0, 0);          // hips at y=1 so ratio is well-defined
    b.rotation.set(restEuler[i][0], restEuler[i][1], restEuler[i][2]);
    if(parent) parent.add(b); else root=b;
    parent=b; bones.push(b);
  });
  const wrap = new THREE.Object3D(); wrap.add(root); wrap.updateMatrixWorld(true);
  return {wrap, bones};
}
export function _selftest(){
  // underscore namespaces (not colon) so three's PropertyBinding binds the clips; canon() still
  // strips "mixamorig1_" / "mixamorig4_" to the same key, which is what we're actually testing.
  const src = _mkSkel('mixamorig1_', [[0,0,0],[0.1,0,0.2],[0,0.15,0]]);
  const tgt = _mkSkel('mixamorig4_', [[0,0.3,0],[-0.2,0,0.1],[0.05,0,-0.1]]);  // different namespace + rests
  const srcRest = captureRest(src.wrap), tgtRest = captureRest(tgt.wrap);
  // source clip: rotate the spine over 1s
  const times = new Float32Array([0, 0.5, 1.0]);
  const q0=new THREE.Quaternion(), q1=new THREE.Quaternion().setFromEuler(new THREE.Euler(0.6,0,0.3));
  const qm=q0.clone().slerp(q1,0.5);
  const vals=new Float32Array([q0.x,q0.y,q0.z,q0.w, qm.x,qm.y,qm.z,qm.w, q1.x,q1.y,q1.z,q1.w]);
  const clip = new THREE.AnimationClip('t', 1.0,
    [new THREE.QuaternionKeyframeTrack(src.bones[1].name+'.quaternion', times, vals)]);
  const baked = bakeRetarget(clip, src.wrap, srcRest, tgt.wrap, tgtRest);

  const srcMix = new THREE.AnimationMixer(src.wrap); srcMix.clipAction(clip).play();
  const tgtMix = new THREE.AnimationMixer(tgt.wrap); tgtMix.clipAction(baked).play();
  const delta=(bone,rest)=>bone.getWorldQuaternion(new THREE.Quaternion())
    .multiply(rest.wq.clone().invert());
  let maxErr=0, srcMoved=0;
  for(const t of [0, 0.5, 1.0]){
    srcMix.setTime(t); src.wrap.updateMatrixWorld(true);
    tgtMix.setTime(t); tgt.wrap.updateMatrixWorld(true);
    for(let i=0;i<3;i++){
      const ds=delta(src.bones[i], srcRest.rest.get(src.bones[i]));
      const dt=delta(tgt.bones[i], tgtRest.rest.get(tgt.bones[i]));
      let d = Math.abs(ds.x*dt.x + ds.y*dt.y + ds.z*dt.z + ds.w*dt.w);  // |dot|→1 when equal (mod sign)
      maxErr = Math.max(maxErr, 1 - d);
      srcMoved = Math.max(srcMoved, 2*Math.acos(Math.min(1, Math.abs(ds.w))));  // world-delta angle (rad)
    }
  }
  const ok = maxErr < 1e-3 && srcMoved > 0.05;   // guard: a non-posing source (e.g. unbound clip) would pass trivially
  return {ok, maxErr, srcMoved};
}