// Title-screen stage using the same official Reachy Mini MJCF rig that the
// simulator renders. The game has already booted before the title is shown,
// so this is a render-only clone of the live rig: no second physics world is
// created and no invented illustration is used.
import { useEffect, useRef } from "react";
import Box from "@mui/material/Box";
import * as THREE from "three";
import { RoomEnvironment } from "three/addons/environments/RoomEnvironment.js";

let stagePromise = null;
let stageReady = false;

export const isMenuReachyReady = () => stageReady;
export const preloadMenuReachy = () => {
  if (!stagePromise) {
    stagePromise = new Promise((resolve, reject) => {
      const started = performance.now();
      const wait = () => {
        const root = window.rl?.reachyRig?.root;
        if (root) {
          stageReady = true;
          resolve(buildStage(root));
          return;
        }
        // The shared MuJoCo world may still be compiling when the title
        // preloader starts. Give the official rig enough time to arrive so
        // the Reachy stage is not silently replaced by an empty panel.
        if (performance.now() - started > 30000) {
          stageReady = true;
          reject(new Error("Reachy Mini title rig was not ready"));
          return;
        }
        requestAnimationFrame(wait);
      };
      wait();
    });
  }
  return stagePromise;
};

function buildStage(sourceRoot) {
  const scene = new THREE.Scene();
  const camera = new THREE.PerspectiveCamera(30, 1, 0.02, 20);
  camera.position.set(0, 0.28, 0.95);
  camera.lookAt(0, 0.25, 0);
  const renderer = new THREE.WebGLRenderer({ antialias: true, alpha: true });
  renderer.setClearColor(0x000000, 0);
  renderer.setPixelRatio(Math.min(2, window.devicePixelRatio));
  renderer.toneMapping = THREE.ACESFilmicToneMapping;
  const el = renderer.domElement;
  el.style.position = "absolute";
  el.style.inset = "0";
  el.style.width = "100%";
  el.style.height = "100%";
  el.style.opacity = "0";
  el.style.transition = "opacity .45s ease";

  const pmrem = new THREE.PMREMGenerator(renderer);
  scene.environment = pmrem.fromScene(new RoomEnvironment()).texture;
  scene.environmentIntensity = 0.35;
  scene.add(new THREE.HemisphereLight(0xffffff, 0x24232b, 1.8));
  const key = new THREE.DirectionalLight(0xffffff, 2.1);
  key.position.set(2, 4, 3);
  scene.add(key);
  const rim = new THREE.DirectionalLight(0xffb366, 0.8);
  rim.position.set(-2, 3, -2);
  scene.add(rim);

  const rig = sourceRoot.clone(true);
  rig.scale.setScalar(1.15);
  rig.traverse((node) => { if (node.isMesh) node.frustumCulled = false; });
  scene.add(rig);
  const bounds = new THREE.Box3().setFromObject(rig);
  const center = bounds.getCenter(new THREE.Vector3());
  rig.position.x -= center.x;
  rig.position.y -= bounds.min.y;
  rig.position.z -= center.z;
  // Fit the official model to its narrow half of the title stage instead of
  // relying on a hand-tuned camera distance. This keeps the whole robot
  // visible even when the MJCF mesh bounds change between releases.
  const fitted = new THREE.Box3().setFromObject(rig);
  const fittedCenter = fitted.getCenter(new THREE.Vector3());
  const radius = fitted.getSize(new THREE.Vector3()).length() * 0.5;
  camera.position.set(fittedCenter.x, fittedCenter.y + radius * 0.08, fittedCenter.z + Math.max(0.8, radius * 2.8));
  camera.lookAt(fittedCenter);
  rig.updateMatrixWorld(true);

  const sourceByName = new Map();
  // Meshes have an empty Three.js name. Do not map/copy those entries: the
  // live pose only belongs to the named MuJoCo body groups, while mesh-local
  // transforms must stay exactly as authored in the official MJCF rig.
  sourceRoot.traverse((node) => { if (node.name) sourceByName.set(node.name, node); });
  const head = [...rig.children].flatMap((node) => {
    const found = [];
    node.traverse((child) => { if (child.name.endsWith("/xl_330")) found.push(child); });
    return found;
  })[0] ?? rig.getObjectByName("reachy/xl_330");
  const leftAntenna = rig.getObjectByName("reachy/dc15_a01_horn_dummy_8");
  const rightAntenna = rig.getObjectByName("reachy/dc15_a01_horn_dummy_7");
  const headBase = new THREE.Quaternion();
  const leftBase = new THREE.Quaternion();
  const rightBase = new THREE.Quaternion();
  const copyLivePose = () => rig.traverse((node) => {
    const source = node.name ? sourceByName.get(node.name) : null;
    if (!source || node === rig) return;
    node.position.copy(source.position);
    node.quaternion.copy(source.quaternion);
  });

  let mount = null;
  let raf = 0;
  let previous = 0;
  const loop = (now) => {
    raf = requestAnimationFrame(loop);
    copyLivePose();
    if (head) {
      headBase.copy(head.quaternion);
      head.quaternion.multiply(new THREE.Quaternion().setFromEuler(new THREE.Euler(
        Math.sin(now * 0.0011) * 0.08,
        Math.sin(now * 0.0008) * 0.18,
        0,
      )));
    }
    if (leftAntenna && rightAntenna) {
      leftBase.copy(leftAntenna.quaternion);
      rightBase.copy(rightAntenna.quaternion);
      const antennaWave = Math.sin(now * 0.0022) * 0.28;
      leftAntenna.quaternion.multiply(new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(0, 0, 1), antennaWave));
      rightAntenna.quaternion.multiply(new THREE.Quaternion().setFromAxisAngle(new THREE.Vector3(0, 0, 1), -antennaWave));
    }
    renderer.render(scene, camera);
    previous = now;
    if (el.style.opacity === "0") el.style.opacity = "1";
  };
  const resize = () => {
    if (!mount) return;
    const width = mount.clientWidth, height = mount.clientHeight;
    if (!width || !height) return;
    camera.aspect = width / height;
    camera.updateProjectionMatrix();
    renderer.setSize(width, height);
  };
  const observer = new ResizeObserver(resize);
  return {
    attach(host) {
      if (mount) this.detach();
      mount = host;
      mount.appendChild(el);
      observer.observe(mount);
      resize();
      previous = performance.now();
      raf = requestAnimationFrame(loop);
    },
    detach() {
      cancelAnimationFrame(raf);
      observer.disconnect();
      el.remove();
      mount = null;
    },
  };
}

export default function MenuReachy({ sx }) {
  const hostRef = useRef(null);
  useEffect(() => {
    let disposed = false;
    preloadMenuReachy().then((stage) => {
      if (!disposed && hostRef.current) stage.attach(hostRef.current);
    }).catch((error) => console.warn("menu Reachy disabled:", error));
    return () => {
      disposed = true;
      stagePromise?.then((stage) => stage.detach()).catch(() => {});
    };
  }, []);
  return <Box ref={hostRef} aria-label="Reachy Mini" sx={{ position: "relative", touchAction: "none", userSelect: "none", ...sx }} />;
}