import * as THREE from 'three';
import { EffectComposer } from 'three/examples/jsm/postprocessing/EffectComposer.js';
import { RenderPass } from 'three/examples/jsm/postprocessing/RenderPass.js';
import { UnrealBloomPass } from 'three/examples/jsm/postprocessing/UnrealBloomPass.js';
import { OutputPass } from 'three/examples/jsm/postprocessing/OutputPass.js';
import { clamp, lerp, easeInOut } from '../util.js';

// ============================================================
// RENDER ENGINE — renderer, scene, camera rig, post fx
// ============================================================
export const scene = new THREE.Scene();
export let renderer = null;
export let composer = null;
let bloomPass = null;

export const camera = new THREE.PerspectiveCamera(42, 1, 0.1, 300);

// --- camera orbit rig ---
const rig = {
  target: new THREE.Vector3(0, 0.6, 0),
  tTarget: new THREE.Vector3(0, 0.6, 0),
  radius: 16, tRadius: 16,
  azimuth: Math.PI * 0.08, tAzimuth: Math.PI * 0.08,
  polar: 0.98, tPolar: 0.98,
  vRadius: 0,
};
const FOCUS_STACK = [];

export function initEngine(container) {
  renderer = new THREE.WebGLRenderer({ antialias: true, powerPreference: 'high-performance' });
  renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.shadowMap.enabled = true;
  renderer.shadowMap.type = THREE.PCFSoftShadowMap;
  renderer.toneMapping = THREE.ACESFilmicToneMapping;
  renderer.toneMappingExposure = 1.12;
  renderer.outputColorSpace = THREE.SRGBColorSpace;
  container.appendChild(renderer.domElement);

  composer = new EffectComposer(renderer);
  composer.addPass(new RenderPass(scene, camera));
  bloomPass = new UnrealBloomPass(new THREE.Vector2(window.innerWidth, window.innerHeight), 0.38, 0.55, 0.86);
  composer.addPass(bloomPass);
  composer.addPass(new OutputPass());

  window.addEventListener('resize', () => {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
    composer.setSize(window.innerWidth, window.innerHeight);
  });
  return renderer;
}

export function applyQuality(q) {
  if (!renderer) return;
  const high = q !== 'low';
  renderer.shadowMap.enabled = high;
  bloomPass.enabled = high;
  renderer.setPixelRatio(high ? Math.min(window.devicePixelRatio, 2) : 1);
  scene.traverse(o => { if (o.isMesh && o.material) o.material.needsUpdate = true; });
}

// ---------- camera control ----------
export function orbitRotate(dx, dy) {
  rig.tAzimuth -= dx * 0.005;
  rig.tPolar = clamp(rig.tPolar - dy * 0.004, 0.32, 1.35);
}
export function orbitZoom(delta) {
  rig.tRadius = clamp(rig.tRadius * (1 + delta * 0.0012), 6, 46);
}
export function orbitPan(dx, dz) {
  // pan in camera space
  const s = rig.radius * 0.0016;
  const cos = Math.cos(rig.azimuth), sin = Math.sin(rig.azimuth);
  rig.tTarget.x += (-dx * cos - dz * sin) * s * -1;
  rig.tTarget.z += (dx * sin - dz * cos) * s * -1;
  clampTarget();
}
export function setOrbit(target, radius, azimuth, polar, instant = false) {
  rig.tTarget.copy(target);
  rig.tRadius = radius;
  if (azimuth !== undefined) rig.tAzimuth = azimuth;
  if (polar !== undefined) rig.tPolar = polar;
  if (instant) {
    rig.target.copy(rig.tTarget); rig.radius = rig.tRadius;
    rig.azimuth = rig.tAzimuth; rig.polar = rig.tPolar;
  }
}
export function pushFocus(name) { if (!FOCUS_STACK.includes(name)) FOCUS_STACK.push(name); }
export function popFocus(name) { const i = FOCUS_STACK.indexOf(name); if (i >= 0) FOCUS_STACK.splice(i, 1); }

function clampTarget() {
  const lim = 26;
  rig.tTarget.x = clamp(rig.tTarget.x, -lim, lim);
  rig.tTarget.z = clamp(rig.tTarget.z, -lim, lim);
}

export function updateCamera(dt) {
  const k = 1 - Math.pow(0.0001, dt);   // smooth exponential approach
  rig.target.lerp(rig.tTarget, k * 0.9);
  rig.radius = lerp(rig.radius, rig.tRadius, k * 0.9);
  rig.azimuth = lerp(rig.azimuth, rig.tAzimuth, k * 0.85);
  rig.polar = lerp(rig.polar, rig.tPolar, k * 0.85);

  const sinP = Math.sin(rig.polar), cosP = Math.cos(rig.polar);
  camera.position.set(
    rig.target.x + rig.radius * sinP * Math.sin(rig.azimuth),
    rig.target.y + rig.radius * cosP,
    rig.target.z + rig.radius * sinP * Math.cos(rig.azimuth)
  );
  camera.lookAt(rig.target);
  camera.userData.lookTarget = rig.target;
  return { polar: rig.polar, azimuth: rig.azimuth };
}

export function renderFrame() {
  if (composer) composer.render();
}

// ---------- raycasting helper ----------
const raycaster = new THREE.Raycaster();
const ndc = new THREE.Vector2();
export function pickAt(clientX, clientY, objects, recursive = true) {
  ndc.x = (clientX / window.innerWidth) * 2 - 1;
  ndc.y = -(clientY / window.innerHeight) * 2 + 1;
  raycaster.setFromCamera(ndc, camera);
  const hits = raycaster.intersectObjects(objects, recursive);
  return hits.length ? hits[0] : null;
}
export function screenRay(clientX, clientY) {
  ndc.x = (clientX / window.innerWidth) * 2 - 1;
  ndc.y = -(clientY / window.innerHeight) * 2 + 1;
  raycaster.setFromCamera(ndc, camera);
  return raycaster.ray;
}

// ---------- shared material cache ----------
const matCache = new Map();
export function mat(color, opts = {}) {
  const key = `${color}|${opts.rough ?? .8}|${opts.metal ?? 0}|${opts.flat ?? 1}|${opts.emissive ?? 0}|${opts.emissiveIntensity ?? 1}|${opts.transparent ?? 0}|${opts.opacity ?? 1}`;
  if (!matCache.has(key)) {
    const m = new THREE.MeshStandardMaterial({
      color, roughness: opts.rough ?? 0.8, metalness: opts.metal ?? 0,
      flatShading: opts.flat ?? true,
      emissive: opts.emissive || 0x000000,
      emissiveIntensity: opts.emissiveIntensity ?? 1,
      transparent: !!opts.transparent, opacity: opts.opacity ?? 1,
    });
    matCache.set(key, m);
  }
  return matCache.get(key);
}
export function basicMat(color, opacity = 1) {
  const key = `b|${color}|${opacity}`;
  if (!matCache.has(key)) {
    matCache.set(key, new THREE.MeshBasicMaterial({ color, transparent: opacity < 1, opacity }));
  }
  return matCache.get(key);
}

// ---------- geometry helpers ----------
export function roundedBox(w, h, d, r = 0.06, seg = 2) {
  // lightweight rounded box via BoxGeometry + bevel illusion (cheap): we just use box here
  // (RoundedBoxGeometry import kept out to save bundle; visual difference minor at this scale)
  return new THREE.BoxGeometry(w, h, d, 1, 1, 1);
}
export function cyl(rt, rb, h, seg = 12) { return new THREE.CylinderGeometry(rt, rb, h, seg); }
export function sph(r, seg = 14) { return new THREE.SphereGeometry(r, seg, Math.max(8, seg / 2)); }

export function disposeObject(obj) {
  obj.traverse(o => {
    if (o.geometry) o.geometry.dispose();
    // materials are cached/shared — don't dispose
  });
  obj.parent?.remove(obj);
}