// 程序化生成简化人体化身 GLB（脸型/体型/肤色三参数组合）。
// 用法: node gen-templates.js --out <dir> [--faces 6] [--bodies 6] [--skins 5]
// 索引对齐 MatchTemplates：face 0 起、body/skin 1 起；已存在的 GLB 跳过（幂等）。
import { argv } from 'node:process';
import fs from 'node:fs';
import path from 'node:path';
import * as THREE from 'three';
import { GLTFExporter } from 'three/addons/exporters/GLTFExporter.js';

// Node 无 FileReader，GLTFExporter 二进制导出需要它（onloadend 回调风格）
if (typeof globalThis.FileReader === 'undefined') {
  globalThis.FileReader = class {
    constructor() { this.result = null; }
    set onloadend(fn) { this._onloadend = fn; }
    get onloadend() { return this._onloadend; }
    readAsArrayBuffer(blob) {
      blob.arrayBuffer().then((buf) => {
        this.result = buf;
        this._onloadend && this._onloadend();
      });
    }
  };
}

function parseArgs() {
  const a = { faces: 6, bodies: 6, skins: 5 };
  for (let i = 2; i < argv.length; i++) {
    if (argv[i].startsWith('--')) {
      const key = argv[i].slice(2);
      const val = argv[i + 1] !== undefined && !argv[i + 1].startsWith('--') ? argv[++i] : true;
      a[key] = val;
    }
  }
  a.out = a.out || '.';
  return a;
}

// 5 档肤色（PBR base color）
const SKIN_TONES = ['#FDE4CF', '#F3C39B', '#D99B6C', '#A96B3F', '#6B4226'];

// 脸型变体：发型形状/颜色差异
const FACE_HAIR = [
  { style: 'short', color: '#2B2B2B' },   // 短发
  { style: 'fringe', color: '#4A3728' },  // 刘海长发
  { style: 'bob', color: '#8C5A2B' },     // 波波头
];

// 体型变体：宽度/高度比例
const BODY_VARIANTS = [
  { name: 'slim', width: 0.85, height: 1.0 },
  { name: 'normal', width: 1.0, height: 1.0 },
  { name: 'broad', width: 1.18, height: 0.96 },
];

function buildAvatar(faceIdx, bodyIdx, skinIdx) {
  const face = FACE_HAIR[faceIdx % FACE_HAIR.length];
  const body = BODY_VARIANTS[bodyIdx % BODY_VARIANTS.length];
  const skin = SKIN_TONES[skinIdx % SKIN_TONES.length];

  const root = new THREE.Group();
  const skinMat = new THREE.MeshStandardMaterial({ color: skin, roughness: 0.7 });
  const hairMat = new THREE.MeshStandardMaterial({ color: face.color, roughness: 0.85 });
  const clothMat = new THREE.MeshStandardMaterial({ color: '#3D5A80', roughness: 0.8 });

  const W = body.width;
  const H = body.height;

  // 躯干：胶囊体
  const torso = new THREE.Mesh(new THREE.CapsuleGeometry(0.22 * W, 0.5, 8, 16), clothMat);
  torso.position.y = 1.12 * H;
  root.add(torso);

  // 头：球体
  const head = new THREE.Mesh(new THREE.SphereGeometry(0.16 * W, 24, 18), skinMat);
  head.position.y = 1.68 * H;
  root.add(head);

  // 发型：覆盖头顶的半球壳（按脸型变体）
  const hair = new THREE.Mesh(new THREE.SphereGeometry(0.175 * W, 24, 12, 0, Math.PI * 2, 0, Math.PI * 0.52), hairMat);
  hair.position.y = 1.68 * H + 0.03;
  root.add(hair);
  if (face.style === 'fringe') {
    const fringe = new THREE.Mesh(new THREE.BoxGeometry(0.16 * W, 0.05, 0.2 * W), hairMat);
    fringe.position.y = 1.7 * H;
    fringe.position.z = -0.12 * W;
    fringe.rotation.x = -0.25;
    root.add(fringe);
  } else if (face.style === 'bob') {
    const back = new THREE.Mesh(new THREE.BoxGeometry(0.3 * W, 0.3, 0.06), hairMat);
    back.position.y = 1.52 * H;
    back.position.z = 0.14 * W;
    root.add(back);
  }

  // 上肢
  for (const side of [-1, 1]) {
    const arm = new THREE.Mesh(new THREE.CapsuleGeometry(0.075 * W, 0.42, 6, 10), skinMat);
    arm.position.set(side * 0.32 * W, 1.32 * H, 0);
    arm.rotation.z = side * 0.06;
    root.add(arm);
  }

  // 下肢
  for (const side of [-1, 1]) {
    const leg = new THREE.Mesh(new THREE.CapsuleGeometry(0.1 * W, 0.62, 6, 10), clothMat);
    leg.position.set(side * 0.12 * W, 0.55 * H, 0);
    root.add(leg);
  }

  return root;
}

const args = parseArgs();
fs.mkdirSync(args.out, { recursive: true });
const exporter = new GLTFExporter();

let generated = 0;
for (let f = 0; f < args.faces; f++) {
  for (let b = 1; b <= args.bodies; b++) {
    for (let s = 1; s <= args.skins; s++) {
      const name = `avatar_f${f}_b${b}_s${s}.glb`;
      const outPath = path.join(args.out, name);
      if (fs.existsSync(outPath)) continue;
      const scene = buildAvatar(f, b, s);
      const buf = await new Promise((resolve, reject) => {
        exporter.parse(
          scene,
          (result) => resolve(Buffer.from(result)),
          (err) => reject(err),
          { binary: true }
        );
      });
      fs.writeFileSync(outPath, buf);
      generated++;
    }
  }
}
console.log(`generated ${generated} GLB (skipped existing) -> ${args.out}`);