/**
 * player.js — the small person: rig, clips, camera-relative control.  (Lane D)
 *
 * The deterministic half lives in player.sim.js; this file is the view. It follows the 90sDJsim
 * DEVMANUAL "Rigged animated characters" rules, which are law here:
 *   · SkeletonUtils.clone() for instances — a plain .clone() breaks skinned meshes
 *   · height-normalise off the HEAD BONE and plant the feet — Mixamo scale is unreliable, so the
 *     scale factor is always MEASURED, never a blind setScalar of a guessed constant
 *   · canonicalise the bone namespace so any clip binds to any character
 *
 * Assets (see models/MODELS.md): player_01.glb is an untouched ped (metre-scale, head bone 1.75 m);
 * player_anims.glb is an anim-only carrier built by tools/character/build_player_anims.py. The clips
 * are retargeted onto the ped at load — see _rotOnly for why that is safe at any carrier scale.
 */
import * as THREE from '../vendor/three.module.js';
import { clone as skeletonClone } from '../vendor/addons/utils/SkeletonUtils.js';
import { GLTFLoader } from '../vendor/addons/loaders/GLTFLoader.js';
import { PlayerSim, STATES, TUNE } from './player.sim.js';

export { PlayerSim, STATES, TUNE };

export const CHAR_URL = './models/player_01.glb';
export const ANIM_URL = './models/player_anims.glb';

/**
 * Canonicalise the Mixamo skeleton namespace (mixamorig4: vs mixamorig12:) so any clip binds to any
 * character. Every Mixamo auto-rig upload gets its own numbered namespace and three.js binds tracks
 * BY NODE NAME — a mismatched clip binds to nothing and plays a silent T-pose, with no error.
 * (Straight from 90sDJsim index.html. The \d+ is deliberate: a bare "mixamorig:" is already canonical.)
 */
const _canon = (s) => s.replace(/mixamorig\d+/g, 'mixamorig');

const canonRig = (r) => {
  if (!r) return r;
  if (r.scene) r.scene.traverse((o) => { o.name = _canon(o.name); });
  if (r.anims) r.anims.forEach((a) => a.tracks.forEach((t) => { t.name = _canon(t.name); }));
  return r;
};

/**
 * Shared-clip filter: keep limb/spine rotations only. Drop ALL position tracks (a different-scale
 * source inflates or crumples the target) AND Hips.quaternion (a different-orientation source lays
 * the target flat). Quaternions are scale-invariant, which is the whole reason a clip carrier at any
 * scale retargets cleanly onto the metre-scale ped.
 *
 * The cost is that a clip can no longer lie the body down — so the knockdown does NOT come from the
 * Falling clip's root. player.sim.js pitches the root itself, which is also how the fall gets to go
 * DOWNWIND of the gust that caused it. The clip only supplies the flail.
 */
const _rotOnly = (c) => new THREE.AnimationClip(c.name, c.duration,
  c.tracks.filter((t) => t.name.endsWith('.quaternion') && !/Hips\.quaternion$/i.test(t.name)));

const _loadGLTF = (loader, url) => new Promise((res, rej) =>
  loader.load(url, (g) => res({ scene: g.scene, anims: g.animations }), undefined,
    () => rej(new Error(`player: failed to load ${url}`))));

const UP = new THREE.Vector3(0, 1, 0);

export class PlayerView {
  /**
   * @param {object} rig    {scene, anims} — the character
   * @param {Array}  clips  retargeted AnimationClips
   * @param {number} height metres to the top of the head
   */
  constructor(rig, clips, height = 1.72) {
    // root: world position + facing + knockdown pitch.  fig: the rig, lifted so its feet sit at y=0.
    this.root = new THREE.Group();
    this.root.name = 'player';

    const fig = skeletonClone(rig.scene);
    this.fig = fig;
    fig.traverse((o) => { if (o.isMesh) { o.frustumCulled = false; o.castShadow = true; } });
    this.root.add(fig);
    this.root.updateWorldMatrix(true, true);

    // measure, then scale — never a blind setScalar (DEVMANUAL). /head/i matches both Head and
    // HeadTop_End; max() takes the crown, which is what "height" means.
    const wp = new THREE.Vector3();
    let headY = 0;
    fig.traverse((o) => {
      if (!o.isBone) return;
      o.getWorldPosition(wp);
      if (/head/i.test(o.name)) headY = Math.max(headY, wp.y);
    });
    if (headY > 1e-4) { fig.scale.setScalar(height / headY); fig.updateWorldMatrix(true, true); }
    this.height = height;

    // plant the feet: lift the rig so its lowest bone sits on the root's origin
    let minY = Infinity;
    fig.traverse((o) => { if (o.isBone) { o.getWorldPosition(wp); minY = Math.min(minY, wp.y); } });
    if (minY < Infinity) fig.position.y = -minY;

    this.mixer = new THREE.AnimationMixer(fig);
    this.actions = {};
    // some characters lack bones a shared clip animates (thumb joints, say) — bind only what exists,
    // else three.js spams "No target node found" for every missing bone
    const nodes = new Set();
    fig.traverse((o) => { if (o.name) nodes.add(o.name); });
    for (const clip of clips) {
      const bindable = clip.tracks.filter((t) => nodes.has(t.name.split('.')[0]));
      if (!bindable.length) continue;
      const use = bindable.length === clip.tracks.length
        ? clip : new THREE.AnimationClip(clip.name, clip.duration, bindable);
      this.actions[clip.name] = this.mixer.clipAction(use);
    }
    this.current = null;
    this._axis = new THREE.Vector3();
    this._qYaw = new THREE.Quaternion();
    this._qPitch = new THREE.Quaternion();
  }

  /** @returns {string[]} clip names that bound to at least one bone */
  get clipNames() { return Object.keys(this.actions); }

  play(name, loop = true, fade = 0.18) {
    const next = this.actions[name];
    if (!next || next === this.current) return;
    next.reset();
    next.setEffectiveWeight(1);
    next.setLoop(loop ? THREE.LoopRepeat : THREE.LoopOnce, loop ? Infinity : 1);
    next.clampWhenFinished = !loop;
    if (this.current) next.crossFadeFrom(this.current, fade, false);
    next.play();
    this.current = next;
  }

  /** Push one sim frame onto the rig. dt drives the mixer only — the sim already stepped. */
  sync(sim, dt) {
    const st = STATES[sim.state];
    this.play(st.clip, st.loop !== false);

    this.root.position.set(sim.pos.x, sim.pos.y, sim.pos.z);

    // yaw, then tip over about a world-horizontal axis square to the fall direction, pivoting at the
    // feet. At pitch 0 this is exactly the yaw, so upright play is untouched.
    this._qYaw.setFromAxisAngle(UP, sim.facing);
    if (sim.pitch > 1e-4) {
      this._axis.set(sim.knockDir.z, 0, -sim.knockDir.x);
      if (this._axis.lengthSq() < 1e-8) this._axis.set(1, 0, 0);
      this._qPitch.setFromAxisAngle(this._axis.normalize(), sim.pitch * Math.PI * 0.5);
      this.root.quaternion.copy(this._qPitch).multiply(this._qYaw);
    } else {
      this.root.quaternion.copy(this._qYaw);
    }

    this.mixer.update(dt);
  }

  dispose() {
    this.mixer.stopAllAction();
    this.root.removeFromParent();
  }
}

/**
 * Load the player and attach it to a scene.
 * @param {THREE.Scene|THREE.Object3D} scene
 * @param {object} [opts]  {start, facing, height, groundAt, tune, charUrl, animUrl}
 * @returns {Promise<{sim: PlayerSim, view: PlayerView, step: function}>}
 */
export async function loadPlayer(scene, opts = {}) {
  const loader = new GLTFLoader();
  const [rig, animPack] = await Promise.all([
    _loadGLTF(loader, opts.charUrl || CHAR_URL),
    _loadGLTF(loader, opts.animUrl || ANIM_URL),
  ]);
  canonRig(rig);
  canonRig(animPack);

  const clips = animPack.anims.map(_rotOnly).filter((c) => c.tracks.length);
  const view = new PlayerView(rig, clips, opts.height || 1.72);
  scene.add(view.root);

  const sim = new PlayerSim(opts);

  const missing = Object.values(STATES).map((s) => s.clip).filter((c, i, a) =>
    a.indexOf(c) === i && !view.actions[c]);
  if (missing.length) console.warn('player: state machine wants clips that did not bind:', missing);

  return {
    sim,
    view,
    /** Convenience: step the sim then push it to the rig. */
    step(dt, t, input, wind) {
      sim.step(dt, t, input, wind);
      view.sync(sim, dt);
      return sim.state;
    },
  };
}

/**
 * The `Player` contract factory (contracts.js) — this is the one main.js calls.
 * Drop-in for createPlaceholderPlayer(scene, world, cameraRig): same first three args, so boot()
 * only changes which function it calls. Everything the player needs per frame it pulls itself, so
 * `update(dt, t)` matches the contract's signature exactly.
 *
 * @param {THREE.Object3D} scene
 * @param {object} world      contracts World — `heightAt(x,z)` clamps the player to the ground
 * @param {object} cameraRig  contracts Camera — `yaw` is what WASD is relative to
 * @param {object} [opts]     {wind, interact, start, facing, height, tune, charUrl, animUrl}
 * @returns {Promise<object>} satisfies checkContract('player', …)
 */
export async function createPlayer(scene, world, cameraRig, opts = {}) {
  const p = await loadPlayer(scene, {
    ...opts,
    groundAt: world && world.heightAt ? (x, z) => world.heightAt(x, z) : undefined,
    start: opts.start || { x: 0, y: 0, z: 6 },
  });
  const keyboard = new KeyboardInput();
  const { sim, view } = p;

  return {
    get pos() { return sim.pos; },
    get carrying() { return sim.carrying; },
    set carrying(v) { sim.carrying = v; },
    get busy() { return sim.busy; },

    /** @param {number} dt @param {number} t — main.js's fixed-dt loop drives this */
    update(dt, t) {
      const input = keyboard.read(cameraRig ? cameraRig.yaw || 0 : 0);
      sim.step(dt, t, input, opts.wind);
      if (opts.interact) opts.interact.step(dt, t, sim, keyboard.holding);
      view.sync(sim, dt);
    },

    /** The Object3D to follow/frame. Lane A's camera wants this, not the raw rig. */
    get object() { return view.root; },
    sim,
    view,
    keyboard,
    dispose() { keyboard.dispose(); view.dispose(); },
  };
}

/**
 * Keyboard → the sim's input shape. Camera yaw comes from Lane A's camera each frame.
 * Kept out of PlayerSim so the sim stays headless.
 */
export class KeyboardInput {
  constructor(target = window) {
    this.keys = new Set();
    this._down = (e) => {
      this.keys.add(e.code);
      if (/^(Arrow|Space)/.test(e.code)) e.preventDefault();
    };
    this._up = (e) => this.keys.delete(e.code);
    target.addEventListener('keydown', this._down);
    target.addEventListener('keyup', this._up);
    this._target = target;
  }

  get holding() { return this.keys.has('KeyE'); }

  /** @param {number} camYaw radians */
  read(camYaw = 0) {
    const k = this.keys;
    const x = (k.has('KeyD') || k.has('ArrowRight') ? 1 : 0) - (k.has('KeyA') || k.has('ArrowLeft') ? 1 : 0);
    const z = (k.has('KeyW') || k.has('ArrowUp') ? 1 : 0) - (k.has('KeyS') || k.has('ArrowDown') ? 1 : 0);
    return { x, z, run: k.has('ShiftLeft') || k.has('ShiftRight'), camYaw };
  }

  dispose() {
    this._target.removeEventListener('keydown', this._down);
    this._target.removeEventListener('keyup', this._up);
  }
}