// Build a multi-clip GLB from the pack's single baked Take: extract a chosen set of
// clips (by frame range from angelfish-clips.json) into SEPARATE named animations, each
// rebased to start at 0, then drop the original 75s Take. This is what the Zen Den's
// behavior engine crossfades between. Usage: node build-clips.mjs in.glb out.glb
import { NodeIO } from '@gltf-transform/core';
import { ALL_EXTENSIONS } from '@gltf-transform/extensions';
import { prune } from '@gltf-transform/functions';
import fs from 'node:fs';

const [, , inPath, outPath] = process.argv;
const io = new NodeIO().registerExtensions(ALL_EXTENSIONS);
const doc = await io.read(inPath);
const root = doc.getRoot();
const buffer = root.listBuffers()[0];
const meta = JSON.parse(fs.readFileSync(new URL('./angelfish-clips.json', import.meta.url))).clips;

// output-clip-name -> source clip in the pack. Full turn SEQUENCES (in→loop→out) so the
// controller can play a real turn; swim intensities for cadence/zoomies; eats for forage.
const MAP = {
  idle:     'Idle',
  cruise:   'Swim1_norm',
  fast:     'Swim2_Fast',
  turnLin:  'Turn_L_in',  turnLloop: 'Turn_L_loop',  turnLout: 'Turn_L_out',
  turnRin:  'Turn_R_in',  turnRloop: 'Turn_R_loop',  turnRout: 'Turn_R_out',
  eatswim:  'Eat_Swim',   eatground: 'Eat_Ground',
};

const src = root.listAnimations()[0];
const srcChannels = src.listChannels();
const EPS = 1e-4;
// The original Take's time/value accessors — captured now, disposed after we've copied
// the windows we need (new clips create their own fresh accessors, so these become dead).
const oldAccessors = new Set();
for (const sm of src.listSamplers()) { oldAccessors.add(sm.getInput()); oldAccessors.add(sm.getOutput()); }

for (const [outName, srcName] of Object.entries(MAP)) {
  const [s0, s1] = meta[srcName].seconds;
  const anim = doc.createAnimation(outName);
  for (const ch of srcChannels) {
    const sm = ch.getSampler();
    const times = sm.getInput().getArray();
    let a = 0; while (a < times.length - 1 && times[a] < s0 - EPS) a++;
    let b = times.length - 1; while (b > a && times[b] > s1 + EPS) b--;
    const base = times[a];
    const nTimes = Float32Array.from(times.slice(a, b + 1), (x) => x - base);
    const out = sm.getOutput();
    const c = out.getElementSize();
    const nOut = out.getArray().slice(a * c, (b + 1) * c);
    const inAcc = doc.createAccessor().setType('SCALAR').setArray(nTimes).setBuffer(buffer);
    const outAcc = doc.createAccessor().setType(out.getType()).setArray(nOut).setBuffer(buffer);
    const ns = doc.createAnimationSampler().setInput(inAcc).setOutput(outAcc).setInterpolation(sm.getInterpolation());
    anim.addSampler(ns);
    anim.addChannel(doc.createAnimationChannel().setTargetNode(ch.getTargetNode()).setTargetPath(ch.getTargetPath()).setSampler(ns));
  }
}
src.dispose();                          // remove the original 75s Take
for (const acc of oldAccessors) acc.dispose();   // free its ~10MB of keyframe data
await doc.transform(prune());
await io.write(outPath, doc);
console.log('clips:', root.listAnimations().map((a) => `${a.getName()}(${a.listChannels().length}ch)`).join(', '));