/**
 * Rock Cluster — Codels 3D model library
 * License: CC0-1.0 · Units: meters · Y-up · Front: +Z · Origin: center of the base (y = 0)
 * Triangles: 288 · Size (W × H × D): 1.92 × 0.90 × 2.29 m
 *
 * Usage:
 *   import { createRockCluster } from './rock-cluster.js';
 *   
 *   const model = createRockCluster();
 *   model.position.set(0, 0, 0);
 *   scene.add(model);
 */
import * as THREE from 'three';

const deg = THREE.MathUtils.degToRad;

// Deterministic vertex displacement (organic low-poly look).
function jitter(geometry, amount, seed) {
  const pos = geometry.attributes.position;
  const h = (a, b, c, s) => {
    let x = Math.imul(a, 73856093) ^ Math.imul(b, 19349663) ^ Math.imul(c, 83492791) ^ Math.imul(s, 2654435761);
    x = Math.imul(x ^ (x >>> 16), 2246822507);
    x = Math.imul(x ^ (x >>> 13), 3266489909);
    return ((x ^ (x >>> 16)) >>> 0) / 4294967295 - 0.5;
  };
  for (let i = 0; i < pos.count; i++) {
    const x = pos.getX(i), y = pos.getY(i), z = pos.getZ(i);
    const qx = Math.round(x * 1000), qy = Math.round(y * 1000), qz = Math.round(z * 1000);
    pos.setXYZ(i, x + h(qx, qy, qz, seed) * 2 * amount, y + h(qx, qy, qz, seed + 1) * 2 * amount, z + h(qx, qy, qz, seed + 2) * 2 * amount);
  }
  pos.needsUpdate = true;
  geometry.computeVertexNormals();
  return geometry;
}

export function createRockCluster() {
  const root = new THREE.Group();
  root.name = 'RockCluster';

  // Materials
  const stoneMat = new THREE.MeshStandardMaterial({ name: 'stone', color: 0x625f5a, roughness: 0.92, flatShading: true });
  const stoneLightMat = new THREE.MeshStandardMaterial({ name: 'stoneLight', color: 0x75726e, roughness: 0.9, flatShading: true });
  const stoneDarkMat = new THREE.MeshStandardMaterial({ name: 'stoneDark', color: 0x52504c, roughness: 0.95, flatShading: true });

  // Parts
  const mainRock = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(1, 1), 0.13, 26), stoneMat);
  mainRock.name = 'mainRock';
  mainRock.position.set(0, 0.3656, 0);
  mainRock.rotation.set(deg(6.7859), deg(147.8987), deg(-0.2767));
  mainRock.scale.set(0.6102, 0.3523, 0.4004);
  root.add(mainRock);
  const rock2 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(1, 0), 0.22, 27), stoneLightMat);
  rock2.name = 'rock2';
  rock2.position.set(-0.6805, 0.4363, -0.1155);
  rock2.rotation.set(deg(8.3837), deg(138.705), deg(-9.104));
  rock2.scale.set(0.4146, 0.4098, 0.2945);
  root.add(rock2);
  const rock3 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(1, 0), 0.22, 28), stoneDarkMat);
  rock3.name = 'rock3';
  rock3.position.set(0.672, 0.3318, -0.4341);
  rock3.rotation.set(deg(-3.5391), deg(144.9353), deg(-10.1288));
  rock3.scale.set(0.3679, 0.3676, 0.2224);
  root.add(rock3);
  const rock4 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(1, 0), 0.22, 29), stoneMat);
  rock4.name = 'rock4';
  rock4.position.set(-0.2377, 0.3015, 0.9094);
  rock4.rotation.set(deg(7.1479), deg(42.6035), deg(-1.0222));
  rock4.scale.set(0.2584, 0.2766, 0.1984);
  root.add(rock4);
  const rock5 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(1, 0), 0.22, 30), stoneLightMat);
  rock5.name = 'rock5';
  rock5.position.set(-0.4928, 0.2758, -0.933);
  rock5.rotation.set(deg(5.1674), deg(274.8037), deg(-3.9933));
  rock5.scale.set(0.2148, 0.2309, 0.1443);
  root.add(rock5);

  root.traverse((o) => {
    if (o.isMesh) {
      o.castShadow = true;
      o.receiveShadow = true;
    }
  });
  return root;
}

export default createRockCluster;