/**
 * Stepping Stones — Codels 3D model library
 * License: CC0-1.0 · Units: meters · Y-up · Front: +Z · Origin: center of the base (y = 0)
 * Triangles: 388 · Size (W × H × D): 4.05 × 0.20 × 1.19 m
 *
 * Usage:
 *   import { createSteppingStones } from './stepping-stones.js';
 *   
 *   const model = createSteppingStones();
 *   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 createSteppingStones() {
  const root = new THREE.Group();
  root.name = 'SteppingStones';

  // Materials
  const stoneMat = new THREE.MeshStandardMaterial({ name: 'stone', color: 0x7c7a75, roughness: 0.9, flatShading: true });
  const stoneLightMat = new THREE.MeshStandardMaterial({ name: 'stoneLight', color: 0x918d84, roughness: 0.9, flatShading: true });
  const stoneDarkMat = new THREE.MeshStandardMaterial({ name: 'stoneDark', color: 0x5f5d5a, roughness: 0.95, flatShading: true });
  const stoneWarmMat = new THREE.MeshStandardMaterial({ name: 'stoneWarm', color: 0x8a7f70, roughness: 0.9, flatShading: true });
  const mossMat = new THREE.MeshStandardMaterial({ name: 'moss', color: 0x5f8a3a, roughness: 1, flatShading: true });

  // Parts
  const stone1 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2369, 0.2754, 0.1251, 9), 0.022, 148), stoneMat);
  stone1.name = 'stone1';
  stone1.position.set(-1.7978, 0.083, 0.2133);
  stone1.rotation.set(deg(-2.2227), deg(209.1714), deg(-2.878));
  stone1.scale.set(1, 1, 0.8191);
  root.add(stone1);
  const stone2 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2626, 0.3053, 0.1311, 9), 0.0244, 149), stoneLightMat);
  stone2.name = 'stone2';
  stone2.position.set(-1.085, 0.0897, -0.0371);
  stone2.rotation.set(deg(-0.7306), deg(337.4981), deg(1.1678));
  stone2.scale.set(1, 1, 0.7713);
  root.add(stone2);
  const stone3 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2246, 0.2612, 0.1222, 9), 0.0209, 150), stoneWarmMat);
  stone3.name = 'stone3';
  stone3.position.set(-0.3839, 0.0862, -0.3395);
  stone3.rotation.set(deg(2.7662), deg(304.9793), deg(2.2017));
  stone3.scale.set(1, 1, 0.7565);
  root.add(stone3);
  const stone4 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2377, 0.2764, 0.1253, 9), 0.0221, 151), stoneDarkMat);
  stone4.name = 'stone4';
  stone4.position.set(0.3666, 0.0944, -0.194);
  stone4.rotation.set(deg(0.1322), deg(12.8275), deg(2.6018));
  stone4.scale.set(1, 1, 0.7921);
  root.add(stone4);
  const moss4 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.1161, 0.152, 0.05, 7), 0.0138, 215), mossMat);
  moss4.name = 'moss4';
  moss4.position.set(0.4027, 0.169, -0.2048);
  moss4.rotation.set(0, deg(70.1365), 0);
  moss4.scale.set(1, 1, 0.7921);
  root.add(moss4);
  const stone5 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2292, 0.2665, 0.1233, 9), 0.0213, 152), stoneMat);
  stone5.name = 'stone5';
  stone5.position.set(1.1253, 0.0829, -0.1465);
  stone5.rotation.set(deg(-1.2977), deg(208.3471), deg(-1.5137));
  stone5.scale.set(1, 1, 0.6811);
  root.add(stone5);
  const stone6 = new THREE.Mesh(jitter(new THREE.CylinderGeometry(0.2884, 0.3353, 0.1371, 9), 0.0268, 153), stoneLightMat);
  stone6.name = 'stone6';
  stone6.position.set(1.7492, 0.0899, 0.2859);
  stone6.rotation.set(deg(-2.4748), deg(81.9641), deg(1.2852));
  stone6.scale.set(1, 1, 0.7548);
  root.add(stone6);
  const pebble1 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(0.0312, 0), 0.0047, 284), stoneLightMat);
  pebble1.name = 'pebble1';
  pebble1.position.set(-0.7496, 0.0188, -0.3989);
  pebble1.rotation.set(deg(16.8458), deg(270.8821), 0);
  pebble1.scale.set(1, 0.6, 1);
  root.add(pebble1);
  const pebble2 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(0.0506, 0), 0.0076, 285), stoneDarkMat);
  pebble2.name = 'pebble2';
  pebble2.position.set(-1.3619, 0.0446, 0.3126);
  pebble2.rotation.set(deg(79.4155), deg(192.6446), 0);
  pebble2.scale.set(1, 0.6, 1);
  root.add(pebble2);
  const pebble3 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(0.0495, 0), 0.0074, 286), stoneLightMat);
  pebble3.name = 'pebble3';
  pebble3.position.set(-1.56, 0.0369, -0.1732);
  pebble3.rotation.set(deg(43.9424), deg(332.7176), 0);
  pebble3.scale.set(1, 0.6, 1);
  root.add(pebble3);
  const pebble4 = new THREE.Mesh(jitter(new THREE.DodecahedronGeometry(0.0407, 0), 0.0061, 287), stoneDarkMat);
  pebble4.name = 'pebble4';
  pebble4.position.set(-1.5816, 0.0239, -0.061);
  pebble4.rotation.set(deg(28.5911), deg(272.8903), 0);
  pebble4.scale.set(1, 0.6, 1);
  root.add(pebble4);

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

export default createSteppingStones;