import * as THREE from 'three';
import { TransformControls } from 'three/addons/controls/TransformControls.js';

/**
 * Posing. Each bone is driven as a rotation *relative to its rest pose*, so
 * every bone reads 0/0/0 in the original stance and a saved pose stays valid
 * even if the model is re-exported with different bone orientations.
 *
 * `bone.quaternion = rest * delta` and `delta = rest⁻¹ * quaternion`, with the
 * delta expressed as XYZ Euler angles in degrees for the UI.
 */

const RAD = Math.PI / 180;
const DEG = 180 / Math.PI;

/** three sanitises node names, so `armsupport.l` arrives as `armsupportl`. */
const normalizeName = (name) => (name ?? '').replace(/[.\s]/g, '').toLowerCase();

export class Rig {
  constructor({ bones, scene, camera, domElement, orbit, pickTargets, onChange = null }) {
    this.bones = bones;
    this.byName = new Map();
    for (const entry of bones) {
      this.byName.set(entry.name, entry);
      const alias = normalizeName(entry.name);
      if (!this.byName.has(alias)) this.byName.set(alias, entry);
    }
    this.scene = scene;
    this.domElement = domElement;
    this.orbit = orbit;
    this.pickTargets = pickTargets;
    this.onChange = onChange;
    this.selected = null;

    this.controls = new TransformControls(camera, domElement);
    this.controls.setMode('rotate');
    this.controls.setSpace('local');
    this.controls.setSize(0.8);
    this.helper = this.controls.getHelper();
    this.helper.visible = false;
    // Whether the user wants the gizmo at all. It starts OFF: the model is the
    // point, and the rings sat on top of it until you went looking for them.
    // Selecting a bone must not switch it back on by itself, so `select()`
    // consults this instead of always showing the helper.
    this.gizmoWanted = false;
    scene.add(this.helper);

    this.controls.addEventListener('dragging-changed', (event) => {
      this.orbit.enabled = !event.value;
    });
    this.controls.addEventListener('objectChange', () => {
      if (this.selected) this.onChange?.(this.selected);
    });

    this.raycaster = new THREE.Raycaster();
    this.pointer = new THREE.Vector2();
    this.pressAt = null;
    this.onPointerDown = this.handlePointerDown.bind(this);
    this.onPointerUp = this.handlePointerUp.bind(this);
    domElement.addEventListener('pointerdown', this.onPointerDown);
    domElement.addEventListener('pointerup', this.onPointerUp);
  }

  /* ------------------------------------------------------------ selection */

  select(name, { silent = false } = {}) {
    if (name && !this.byName.has(name)) return;
    this.selected = name ?? null;
    if (name) {
      this.controls.attach(this.byName.get(name).bone);
      this.helper.visible = this.gizmoWanted;
    } else {
      this.controls.detach();
      this.helper.visible = false;
    }
    if (!silent) this.onChange?.(this.selected);
  }

  selectAt(event) {
    const rect = this.domElement.getBoundingClientRect();
    this.pointer.set(
      ((event.clientX - rect.left) / rect.width) * 2 - 1,
      -((event.clientY - rect.top) / rect.height) * 2 + 1,
    );
    this.raycaster.setFromCamera(this.pointer, this.controls.camera);

    const targets = this.pickTargets().filter((mesh) => mesh.visible);
    const hits = this.raycaster.intersectObjects(targets, false);
    if (!hits.length) return null;

    const point = hits[0].point;
    let best = null;
    let bestDistance = Infinity;
    const world = new THREE.Vector3();
    for (const entry of this.bones) {
      entry.bone.getWorldPosition(world);
      const distance = world.distanceToSquared(point);
      if (distance < bestDistance) {
        bestDistance = distance;
        best = entry.name;
      }
    }
    if (best) this.select(best);
    return best;
  }

  handlePointerDown(event) {
    // Remember where the press started so a drag never changes the selection.
    this.pressAt = { x: event.clientX, y: event.clientY, axis: this.controls.axis };
  }

  handlePointerUp(event) {
    const press = this.pressAt;
    this.pressAt = null;
    if (!press || press.axis) return; // pressed on the gizmo, not the model
    if (Math.hypot(event.clientX - press.x, event.clientY - press.y) > 4) return;
    this.selectAt(event);
  }

  /* ----------------------------------------------------------------- pose */

  getDelta(name) {
    const entry = this.byName.get(name);
    if (!entry) return { x: 0, y: 0, z: 0 };
    const delta = entry.rest.clone().invert().multiply(entry.bone.quaternion);
    const euler = new THREE.Euler().setFromQuaternion(delta, 'XYZ');
    return { x: euler.x * DEG, y: euler.y * DEG, z: euler.z * DEG };
  }

  setDelta(name, { x = 0, y = 0, z = 0 }) {
    const entry = this.byName.get(name);
    if (!entry) return;
    const delta = new THREE.Quaternion().setFromEuler(
      new THREE.Euler(x * RAD, y * RAD, z * RAD, 'XYZ'),
    );
    entry.bone.quaternion.copy(entry.rest).multiply(delta);
  }

  /** `pose.bones` maps a bone name to `[x, y, z]` degrees; `pose.root` is a translation. */
  applyPose(pose = {}) {
    // Presets and saved files use the glTF bone names (`armsupport.l`) while
    // three sanitises them to `armsupportl`, so compare on the normalised form -
    // otherwise every preset that touches an arm or leg is silently ignored.
    const rotations = new Map();
    for (const [key, value] of Object.entries(pose.bones ?? {})) {
      rotations.set(normalizeName(key), value);
    }
    for (const entry of this.bones) {
      const value = rotations.get(normalizeName(entry.name));
      if (Array.isArray(value)) this.setDelta(entry.name, { x: value[0], y: value[1], z: value[2] });
      else this.setDelta(entry.name, { x: 0, y: 0, z: 0 });
    }
  }

  getPose({ onlyMoved = true } = {}) {
    const rotations = {};
    for (const entry of this.bones) {
      const { x, y, z } = this.getDelta(entry.name);
      const rounded = [round1(x), round1(y), round1(z)];
      if (onlyMoved && rounded.every((value) => value === 0)) continue;
      rotations[entry.name] = rounded;
    }
    return { bones: rotations };
  }

  reset(name) {
    if (name) {
      this.setDelta(name, { x: 0, y: 0, z: 0 });
      return;
    }
    for (const entry of this.bones) this.setDelta(entry.name, { x: 0, y: 0, z: 0 });
  }

  /** True when every bone sits at its rest rotation. */
  isRestPose() {
    return this.bones.every((entry) => {
      const { x, y, z } = this.getDelta(entry.name);
      return Math.abs(x) < 0.01 && Math.abs(y) < 0.01 && Math.abs(z) < 0.01;
    });
  }

  setGizmoVisible(visible) {
    this.gizmoWanted = visible !== false;
    this.helper.visible = this.gizmoWanted && this.selected != null;
  }

  dispose() {
    this.domElement.removeEventListener('pointerdown', this.onPointerDown);
    this.domElement.removeEventListener('pointerup', this.onPointerUp);
    this.controls.detach();
    this.controls.dispose();
    this.helper.removeFromParent();
  }
}

const round1 = (value) => Math.round(value * 10) / 10;