import {
	Bone,
	BoxGeometry,
	Color,
	CylinderGeometry,
	Euler,
	Matrix4,
	Mesh,
	MeshBasicMaterial,
	Object3D,
	Quaternion,
	SphereGeometry,
	Vector3
} from '../../../build/three.module.js';

/**
 * Dependencies
 *  - Ammo.js https://github.com/kripken/ammo.js
 *
 * MMDPhysics calculates physics with Ammo(Bullet based JavaScript Physics engine)
 * for MMD model loaded by MMDLoader.
 *
 * TODO
 *  - Physics in Worker
 */

/* global Ammo */

class MMDPhysics {

	/**
	 * @param {THREE.SkinnedMesh} mesh
	 * @param {Array<Object>} rigidBodyParams
	 * @param {Array<Object>} (optional) constraintParams
	 * @param {Object} params - (optional)
	 * @param {Number} params.unitStep - Default is 1 / 65.
	 * @param {Integer} params.maxStepNum - Default is 3.
	 * @param {Vector3} params.gravity - Default is ( 0, - 9.8 * 10, 0 )
	 */
	constructor( mesh, rigidBodyParams, constraintParams = [], params = {} ) {

		if ( typeof Ammo === 'undefined' ) {

			throw new Error( 'THREE.MMDPhysics: Import ammo.js https://github.com/kripken/ammo.js' );

		}

		this.manager = new ResourceManager();

		this.mesh = mesh;

		/*
		 * I don't know why but 1/60 unitStep easily breaks models
		 * so I set it 1/65 so far.
		 * Don't set too small unitStep because
		 * the smaller unitStep can make the performance worse.
		 */
		this.unitStep = ( params.unitStep !== undefined ) ? params.unitStep : 1 / 65;
		this.maxStepNum = ( params.maxStepNum !== undefined ) ? params.maxStepNum : 3;
		this.gravity = new Vector3( 0, - 9.8 * 10, 0 );

		if ( params.gravity !== undefined ) this.gravity.copy( params.gravity );

		this.world = params.world !== undefined ? params.world : null; // experimental

		this.bodies = [];
		this.constraints = [];

		this._init( mesh, rigidBodyParams, constraintParams );

	}

	/**
	 * Advances Physics calculation and updates bones.
	 *
	 * @param {Number} delta - time in second
	 * @return {MMDPhysics}
	 */
	update( delta ) {

		const manager = this.manager;
		const mesh = this.mesh;

		// rigid bodies and constrains are for
		// mesh's world scale (1, 1, 1).
		// Convert to (1, 1, 1) if it isn't.

		let isNonDefaultScale = false;

		const position = manager.allocThreeVector3();
		const quaternion = manager.allocThreeQuaternion();
		const scale = manager.allocThreeVector3();

		mesh.matrixWorld.decompose( position, quaternion, scale );

		if ( scale.x !== 1 || scale.y !== 1 || scale.z !== 1 ) {

			isNonDefaultScale = true;

		}

		let parent;

		if ( isNonDefaultScale ) {

			parent = mesh.parent;

			if ( parent !== null ) mesh.parent = null;

			scale.copy( this.mesh.scale );

			mesh.scale.set( 1, 1, 1 );
			mesh.updateMatrixWorld( true );

		}

		// calculate physics and update bones

		this._updateRigidBodies();
		this._stepSimulation( delta );
		this._updateBones();

		// restore mesh if converted above

		if ( isNonDefaultScale ) {

			if ( parent !== null ) mesh.parent = parent;

			mesh.scale.copy( scale );

		}

		manager.freeThreeVector3( scale );
		manager.freeThreeQuaternion( quaternion );
		manager.freeThreeVector3( position );

		return this;

	}

	/**
	 * Resets rigid bodies transorm to current bone's.
	 *
	 * @return {MMDPhysics}
	 */
	reset() {

		for ( let i = 0, il = this.bodies.length; i < il; i ++ ) {

			this.bodies[ i ].reset();

		}

		return this;

	}

	/**
	 * Warm ups Rigid bodies. Calculates cycles steps.
	 *
	 * @param {Integer} cycles
	 * @return {MMDPhysics}
	 */
	warmup( cycles ) {

		for ( let i = 0; i < cycles; i ++ ) {

			this.update( 1 / 60 );

		}

		return this;

	}

	/**
	 * Sets gravity.
	 *
	 * @param {Vector3} gravity
	 * @return {MMDPhysicsHelper}
	 */
	setGravity( gravity ) {

		this.world.setGravity( new Ammo.btVector3( gravity.x, gravity.y, gravity.z ) );
		this.gravity.copy( gravity );

		return this;

	}

	/**
	 * Creates MMDPhysicsHelper
	 *
	 * @return {MMDPhysicsHelper}
	 */
	createHelper() {

		return new MMDPhysicsHelper( this.mesh, this );

	}

	// private methods

	_init( mesh, rigidBodyParams, constraintParams ) {

		const manager = this.manager;

		// rigid body/constraint parameters are for
		// mesh's default world transform as position(0, 0, 0),
		// quaternion(0, 0, 0, 1) and scale(0, 0, 0)

		let parent = mesh.parent;

		if ( parent !== null ) parent = null;

		const currentPosition = manager.allocThreeVector3();
		const currentQuaternion = manager.allocThreeQuaternion();
		const currentScale = manager.allocThreeVector3();

		currentPosition.copy( mesh.position );
		currentQuaternion.copy( mesh.quaternion );
		currentScale.copy( mesh.scale );

		mesh.position.set( 0, 0, 0 );
		mesh.quaternion.set( 0, 0, 0, 1 );
		mesh.scale.set( 1, 1, 1 );

		mesh.updateMatrixWorld( true );

		if ( this.world === null ) {

			this.world = this._createWorld();
			this.setGravity( this.gravity );

		}

		this._initRigidBodies( rigidBodyParams );
		this._initConstraints( constraintParams );

		if ( parent !== null ) mesh.parent = parent;

		mesh.position.copy( currentPosition );
		mesh.quaternion.copy( currentQuaternion );
		mesh.scale.copy( currentScale );

		mesh.updateMatrixWorld( true );

		this.reset();

		manager.freeThreeVector3( currentPosition );
		manager.freeThreeQuaternion( currentQuaternion );
		manager.freeThreeVector3( currentScale );

	}

	_createWorld() {

		const config = new Ammo.btDefaultCollisionConfiguration();
		const dispatcher = new Ammo.btCollisionDispatcher( config );
		const cache = new Ammo.btDbvtBroadphase();
		const solver = new Ammo.btSequentialImpulseConstraintSolver();
		const world = new Ammo.btDiscreteDynamicsWorld( dispatcher, cache, solver, config );
		return world;

	}

	_initRigidBodies( rigidBodies ) {

		for ( let i = 0, il = rigidBodies.length; i < il; i ++ ) {

			this.bodies.push( new RigidBody(
				this.mesh, this.world, rigidBodies[ i ], this.manager ) );

		}

	}

	_initConstraints( constraints ) {

		for ( let i = 0, il = constraints.length; i < il; i ++ ) {

			const params = constraints[ i ];
			const bodyA = this.bodies[ params.rigidBodyIndex1 ];
			const bodyB = this.bodies[ params.rigidBodyIndex2 ];
			this.constraints.push( new Constraint( this.mesh, this.world, bodyA, bodyB, params, this.manager ) );

		}

	}

	_stepSimulation( delta ) {

		const unitStep = this.unitStep;
		let stepTime = delta;
		let maxStepNum = ( ( delta / unitStep ) | 0 ) + 1;

		if ( stepTime < unitStep ) {

			stepTime = unitStep;
			maxStepNum = 1;

		}

		if ( maxStepNum > this.maxStepNum ) {

			maxStepNum = this.maxStepNum;

		}

		this.world.stepSimulation( stepTime, maxStepNum, unitStep );

	}

	_updateRigidBodies() {

		for ( let i = 0, il = this.bodies.length; i < il; i ++ ) {

			this.bodies[ i ].updateFromBone();

		}

	}

	_updateBones() {

		for ( let i = 0, il = this.bodies.length; i < il; i ++ ) {

			this.bodies[ i ].updateBone();

		}

	}

}

/**
 * This manager's responsibilies are
 *
 * 1. manage Ammo.js and Three.js object resources and
 *    improve the performance and the memory consumption by
 *    reusing objects.
 *
 * 2. provide simple Ammo object operations.
 */
class ResourceManager {

	constructor() {

		// for Three.js
		this.threeVector3s = [];
		this.threeMatrix4s = [];
		this.threeQuaternions = [];
		this.threeEulers = [];

		// for Ammo.js
		this.transforms = [];
		this.quaternions = [];
		this.vector3s = [];

	}

	allocThreeVector3() {

		return ( this.threeVector3s.length > 0 )
			? this.threeVector3s.pop()
			: new Vector3();

	}

	freeThreeVector3( v ) {

		this.threeVector3s.push( v );

	}

	allocThreeMatrix4() {

		return ( this.threeMatrix4s.length > 0 )
			? this.threeMatrix4s.pop()
			: new Matrix4();

	}

	freeThreeMatrix4( m ) {

		this.threeMatrix4s.push( m );

	}

	allocThreeQuaternion() {

		return ( this.threeQuaternions.length > 0 )
			? this.threeQuaternions.pop()
			: new Quaternion();

	}

	freeThreeQuaternion( q ) {

		this.threeQuaternions.push( q );

	}

	allocThreeEuler() {

		return ( this.threeEulers.length > 0 )
			? this.threeEulers.pop()
			: new Euler();

	}

	freeThreeEuler( e ) {

		this.threeEulers.push( e );

	}

	allocTransform() {

		return ( this.transforms.length > 0 )
			? this.transforms.pop()
			: new Ammo.btTransform();

	}

	freeTransform( t ) {

		this.transforms.push( t );

	}

	allocQuaternion() {

		return ( this.quaternions.length > 0 )
			? this.quaternions.pop()
			: new Ammo.btQuaternion();

	}

	freeQuaternion( q ) {

		this.quaternions.push( q );

	}

	allocVector3() {

		return ( this.vector3s.length > 0 )
			? this.vector3s.pop()
			: new Ammo.btVector3();

	}

	freeVector3( v ) {

		this.vector3s.push( v );

	}

	setIdentity( t ) {

		t.setIdentity();

	}

	getBasis( t ) {

		var q = this.allocQuaternion();
		t.getBasis().getRotation( q );
		return q;

	}

	getBasisAsMatrix3( t ) {

		var q = this.getBasis( t );
		var m = this.quaternionToMatrix3( q );
		this.freeQuaternion( q );
		return m;

	}

	getOrigin( t ) {

		return t.getOrigin();

	}

	setOrigin( t, v ) {

		t.getOrigin().setValue( v.x(), v.y(), v.z() );

	}

	copyOrigin( t1, t2 ) {

		var o = t2.getOrigin();
		this.setOrigin( t1, o );

	}

	setBasis( t, q ) {

		t.setRotation( q );

	}

	setBasisFromMatrix3( t, m ) {

		var q = this.matrix3ToQuaternion( m );
		this.setBasis( t, q );
		this.freeQuaternion( q );

	}

	setOriginFromArray3( t, a ) {

		t.getOrigin().setValue( a[ 0 ], a[ 1 ], a[ 2 ] );

	}

	setOriginFromThreeVector3( t, v ) {

		t.getOrigin().setValue( v.x, v.y, v.z );

	}

	setBasisFromArray3( t, a ) {

		var thQ = this.allocThreeQuaternion();
		var thE = this.allocThreeEuler();
		thE.set( a[ 0 ], a[ 1 ], a[ 2 ] );
		this.setBasisFromThreeQuaternion( t, thQ.setFromEuler( thE ) );

		this.freeThreeEuler( thE );
		this.freeThreeQuaternion( thQ );

	}

	setBasisFromThreeQuaternion( t, a ) {

		var q = this.allocQuaternion();

		q.setX( a.x );
		q.setY( a.y );
		q.setZ( a.z );
		q.setW( a.w );
		this.setBasis( t, q );

		this.freeQuaternion( q );

	}

	multiplyTransforms( t1, t2 ) {

		var t = this.allocTransform();
		this.setIdentity( t );

		var m1 = this.getBasisAsMatrix3( t1 );
		var m2 = this.getBasisAsMatrix3( t2 );

		var o1 = this.getOrigin( t1 );
		var o2 = this.getOrigin( t2 );

		var v1 = this.multiplyMatrix3ByVector3( m1, o2 );
		var v2 = this.addVector3( v1, o1 );
		this.setOrigin( t, v2 );

		var m3 = this.multiplyMatrices3( m1, m2 );
		this.setBasisFromMatrix3( t, m3 );

		this.freeVector3( v1 );
		this.freeVector3( v2 );

		return t;

	}

	inverseTransform( t ) {

		var t2 = this.allocTransform();

		var m1 = this.getBasisAsMatrix3( t );
		var o = this.getOrigin( t );

		var m2 = this.transposeMatrix3( m1 );
		var v1 = this.negativeVector3( o );
		var v2 = this.multiplyMatrix3ByVector3( m2, v1 );

		this.setOrigin( t2, v2 );
		this.setBasisFromMatrix3( t2, m2 );

		this.freeVector3( v1 );
		this.freeVector3( v2 );

		return t2;

	}

	multiplyMatrices3( m1, m2 ) {

		var m3 = [];

		var v10 = this.rowOfMatrix3( m1, 0 );
		var v11 = this.rowOfMatrix3( m1, 1 );
		var v12 = this.rowOfMatrix3( m1, 2 );

		var v20 = this.columnOfMatrix3( m2, 0 );
		var v21 = this.columnOfMatrix3( m2, 1 );
		var v22 = this.columnOfMatrix3( m2, 2 );

		m3[ 0 ] = this.dotVectors3( v10, v20 );
		m3[ 1 ] = this.dotVectors3( v10, v21 );
		m3[ 2 ] = this.dotVectors3( v10, v22 );
		m3[ 3 ] = this.dotVectors3( v11, v20 );
		m3[ 4 ] = this.dotVectors3( v11, v21 );
		m3[ 5 ] = this.dotVectors3( v11, v22 );
		m3[ 6 ] = this.dotVectors3( v12, v20 );
		m3[ 7 ] = this.dotVectors3( v12, v21 );
		m3[ 8 ] = this.dotVectors3( v12, v22 );

		this.freeVector3( v10 );
		this.freeVector3( v11 );
		this.freeVector3( v12 );
		this.freeVector3( v20 );
		this.freeVector3( v21 );
		this.freeVector3( v22 );

		return m3;

	}

	addVector3( v1, v2 ) {

		var v = this.allocVector3();
		v.setValue( v1.x() + v2.x(), v1.y() + v2.y(), v1.z() + v2.z() );
		return v;

	}

	dotVectors3( v1, v2 ) {

		return v1.x() * v2.x() + v1.y() * v2.y() + v1.z() * v2.z();

	}

	rowOfMatrix3( m, i ) {

		var v = this.allocVector3();
		v.setValue( m[ i * 3 + 0 ], m[ i * 3 + 1 ], m[ i * 3 + 2 ] );
		return v;

	}

	columnOfMatrix3( m, i ) {

		var v = this.allocVector3();
		v.setValue( m[ i + 0 ], m[ i + 3 ], m[ i + 6 ] );
		return v;

	}

	negativeVector3( v ) {

		var v2 = this.allocVector3();
		v2.setValue( - v.x(), - v.y(), - v.z() );
		return v2;

	}

	multiplyMatrix3ByVector3( m, v ) {

		var v4 = this.allocVector3();

		var v0 = this.rowOfMatrix3( m, 0 );
		var v1 = this.rowOfMatrix3( m, 1 );
		var v2 = this.rowOfMatrix3( m, 2 );
		var x = this.dotVectors3( v0, v );
		var y = this.dotVectors3( v1, v );
		var z = this.dotVectors3( v2, v );

		v4.setValue( x, y, z );

		this.freeVector3( v0 );
		this.freeVector3( v1 );
		this.freeVector3( v2 );

		return v4;

	}

	transposeMatrix3( m ) {

		var m2 = [];
		m2[ 0 ] = m[ 0 ];
		m2[ 1 ] = m[ 3 ];
		m2[ 2 ] = m[ 6 ];
		m2[ 3 ] = m[ 1 ];
		m2[ 4 ] = m[ 4 ];
		m2[ 5 ] = m[ 7 ];
		m2[ 6 ] = m[ 2 ];
		m2[ 7 ] = m[ 5 ];
		m2[ 8 ] = m[ 8 ];
		return m2;

	}

	quaternionToMatrix3( q ) {

		var m = [];

		var x = q.x();
		var y = q.y();
		var z = q.z();
		var w = q.w();

		var xx = x * x;
		var yy = y * y;
		var zz = z * z;

		var xy = x * y;
		var yz = y * z;
		var zx = z * x;

		var xw = x * w;
		var yw = y * w;
		var zw = z * w;

		m[ 0 ] = 1 - 2 * ( yy + zz );
		m[ 1 ] = 2 * ( xy - zw );
		m[ 2 ] = 2 * ( zx + yw );
		m[ 3 ] = 2 * ( xy + zw );
		m[ 4 ] = 1 - 2 * ( zz + xx );
		m[ 5 ] = 2 * ( yz - xw );
		m[ 6 ] = 2 * ( zx - yw );
		m[ 7 ] = 2 * ( yz + xw );
		m[ 8 ] = 1 - 2 * ( xx + yy );

		return m;

	}

	matrix3ToQuaternion( m ) {

		var t = m[ 0 ] + m[ 4 ] + m[ 8 ];
		var s, x, y, z, w;

		if ( t > 0 ) {

			s = Math.sqrt( t + 1.0 ) * 2;
			w = 0.25 * s;
			x = ( m[ 7 ] - m[ 5 ] ) / s;
			y = ( m[ 2 ] - m[ 6 ] ) / s;
			z = ( m[ 3 ] - m[ 1 ] ) / s;

		} else if ( ( m[ 0 ] > m[ 4 ] ) && ( m[ 0 ] > m[ 8 ] ) ) {

			s = Math.sqrt( 1.0 + m[ 0 ] - m[ 4 ] - m[ 8 ] ) * 2;
			w = ( m[ 7 ] - m[ 5 ] ) / s;
			x = 0.25 * s;
			y = ( m[ 1 ] + m[ 3 ] ) / s;
			z = ( m[ 2 ] + m[ 6 ] ) / s;

		} else if ( m[ 4 ] > m[ 8 ] ) {

			s = Math.sqrt( 1.0 + m[ 4 ] - m[ 0 ] - m[ 8 ] ) * 2;
			w = ( m[ 2 ] - m[ 6 ] ) / s;
			x = ( m[ 1 ] + m[ 3 ] ) / s;
			y = 0.25 * s;
			z = ( m[ 5 ] + m[ 7 ] ) / s;

		} else {

			s = Math.sqrt( 1.0 + m[ 8 ] - m[ 0 ] - m[ 4 ] ) * 2;
			w = ( m[ 3 ] - m[ 1 ] ) / s;
			x = ( m[ 2 ] + m[ 6 ] ) / s;
			y = ( m[ 5 ] + m[ 7 ] ) / s;
			z = 0.25 * s;

		}

		var q = this.allocQuaternion();
		q.setX( x );
		q.setY( y );
		q.setZ( z );
		q.setW( w );
		return q;

	}

}

/**
 * @param {THREE.SkinnedMesh} mesh
 * @param {Ammo.btDiscreteDynamicsWorld} world
 * @param {Object} params
 * @param {ResourceManager} manager
 */
class RigidBody {

	constructor( mesh, world, params, manager ) {

		this.mesh = mesh;
		this.world = world;
		this.params = params;
		this.manager = manager;

		this.body = null;
		this.bone = null;
		this.boneOffsetForm = null;
		this.boneOffsetFormInverse = null;

		this._init();

	}

	/**
	 * Resets rigid body transform to the current bone's.
	 *
	 * @return {RigidBody}
	 */
	reset() {

		this._setTransformFromBone();
		return this;

	}

	/**
	 * Updates rigid body's transform from the current bone.
	 *
	 * @return {RidigBody}
	 */
	updateFromBone() {

		if ( this.params.boneIndex !== - 1 && this.params.type === 0 ) {

			this._setTransformFromBone();

		}

		return this;

	}

	/**
	 * Updates bone from the current ridid body's transform.
	 *
	 * @return {RidigBody}
	 */
	updateBone() {

		if ( this.params.type === 0 || this.params.boneIndex === - 1 ) {

			return this;

		}

		this._updateBoneRotation();

		if ( this.params.type === 1 ) {

			this._updateBonePosition();

		}

		this.bone.updateMatrixWorld( true );

		if ( this.params.type === 2 ) {

			this._setPositionFromBone();

		}

		return this;

	}

	// private methods

	_init() {

		function generateShape( p ) {

			switch ( p.shapeType ) {

				case 0:
					return new Ammo.btSphereShape( p.width );

				case 1:
					return new Ammo.btBoxShape( new Ammo.btVector3( p.width, p.height, p.depth ) );

				case 2:
					return new Ammo.btCapsuleShape( p.width, p.height );

				default:
					throw 'unknown shape type ' + p.shapeType;

			}

		}

		const manager = this.manager;
		const params = this.params;
		const bones = this.mesh.skeleton.bones;
		const bone = ( params.boneIndex === - 1 )
			? new Bone()
			: bones[ params.boneIndex ];

		const shape = generateShape( params );
		const weight = ( params.type === 0 ) ? 0 : params.weight;
		const localInertia = manager.allocVector3();
		localInertia.setValue( 0, 0, 0 );

		if ( weight !== 0 ) {

			shape.calculateLocalInertia( weight, localInertia );

		}

		const boneOffsetForm = manager.allocTransform();
		manager.setIdentity( boneOffsetForm );
		manager.setOriginFromArray3( boneOffsetForm, params.position );
		manager.setBasisFromArray3( boneOffsetForm, params.rotation );

		const vector = manager.allocThreeVector3();
		const boneForm = manager.allocTransform();
		manager.setIdentity( boneForm );
		manager.setOriginFromThreeVector3( boneForm, bone.getWorldPosition( vector ) );

		const form = manager.multiplyTransforms( boneForm, boneOffsetForm );
		const state = new Ammo.btDefaultMotionState( form );

		const info = new Ammo.btRigidBodyConstructionInfo( weight, state, shape, localInertia );
		info.set_m_friction( params.friction );
		info.set_m_restitution( params.restitution );

		const body = new Ammo.btRigidBody( info );

		if ( params.type === 0 ) {

			body.setCollisionFlags( body.getCollisionFlags() | 2 );

			/*
			 * It'd be better to comment out this line though in general I should call this method
			 * because I'm not sure why but physics will be more like MMD's
			 * if I comment out.
			 */
			body.setActivationState( 4 );

		}

		body.setDamping( params.positionDamping, params.rotationDamping );
		body.setSleepingThresholds( 0, 0 );

		this.world.addRigidBody( body, 1 << params.groupIndex, params.groupTarget );

		this.body = body;
		this.bone = bone;
		this.boneOffsetForm = boneOffsetForm;
		this.boneOffsetFormInverse = manager.inverseTransform( boneOffsetForm );

		manager.freeVector3( localInertia );
		manager.freeTransform( form );
		manager.freeTransform( boneForm );
		manager.freeThreeVector3( vector );

	}

	_getBoneTransform() {

		const manager = this.manager;
		const p = manager.allocThreeVector3();
		const q = manager.allocThreeQuaternion();
		const s = manager.allocThreeVector3();

		this.bone.matrixWorld.decompose( p, q, s );

		const tr = manager.allocTransform();
		manager.setOriginFromThreeVector3( tr, p );
		manager.setBasisFromThreeQuaternion( tr, q );

		const form = manager.multiplyTransforms( tr, this.boneOffsetForm );

		manager.freeTransform( tr );
		manager.freeThreeVector3( s );
		manager.freeThreeQuaternion( q );
		manager.freeThreeVector3( p );

		return form;

	}

	_getWorldTransformForBone() {

		const manager = this.manager;
		const tr = this.body.getCenterOfMassTransform();
		return manager.multiplyTransforms( tr, this.boneOffsetFormInverse );

	}

	_setTransformFromBone() {

		const manager = this.manager;
		const form = this._getBoneTransform();

		// TODO: check the most appropriate way to set
		//this.body.setWorldTransform( form );
		this.body.setCenterOfMassTransform( form );
		this.body.getMotionState().setWorldTransform( form );

		manager.freeTransform( form );

	}

	_setPositionFromBone() {

		const manager = this.manager;
		const form = this._getBoneTransform();

		const tr = manager.allocTransform();
		this.body.getMotionState().getWorldTransform( tr );
		manager.copyOrigin( tr, form );

		// TODO: check the most appropriate way to set
		//this.body.setWorldTransform( tr );
		this.body.setCenterOfMassTransform( tr );
		this.body.getMotionState().setWorldTransform( tr );

		manager.freeTransform( tr );
		manager.freeTransform( form );

	}

	_updateBoneRotation() {

		const manager = this.manager;

		const tr = this._getWorldTransformForBone();
		const q = manager.getBasis( tr );

		const thQ = manager.allocThreeQuaternion();
		const thQ2 = manager.allocThreeQuaternion();
		const thQ3 = manager.allocThreeQuaternion();

		thQ.set( q.x(), q.y(), q.z(), q.w() );
		thQ2.setFromRotationMatrix( this.bone.matrixWorld );
		thQ2.conjugate();
		thQ2.multiply( thQ );

		//this.bone.quaternion.multiply( thQ2 );

		thQ3.setFromRotationMatrix( this.bone.matrix );

		// Renormalizing quaternion here because repeatedly transforming
		// quaternion continuously accumulates floating point error and
		// can end up being overflow. See #15335
		this.bone.quaternion.copy( thQ2.multiply( thQ3 ).normalize() );

		manager.freeThreeQuaternion( thQ );
		manager.freeThreeQuaternion( thQ2 );
		manager.freeThreeQuaternion( thQ3 );

		manager.freeQuaternion( q );
		manager.freeTransform( tr );

	}

	_updateBonePosition() {

		const manager = this.manager;

		const tr = this._getWorldTransformForBone();

		const thV = manager.allocThreeVector3();

		const o = manager.getOrigin( tr );
		thV.set( o.x(), o.y(), o.z() );

		if ( this.bone.parent ) {

			this.bone.parent.worldToLocal( thV );

		}

		this.bone.position.copy( thV );

		manager.freeThreeVector3( thV );

		manager.freeTransform( tr );

	}

}

//

class Constraint {

	/**
	 * @param {THREE.SkinnedMesh} mesh
	 * @param {Ammo.btDiscreteDynamicsWorld} world
	 * @param {RigidBody} bodyA
	 * @param {RigidBody} bodyB
	 * @param {Object} params
	 * @param {ResourceManager} manager
	 */
	constructor( mesh, world, bodyA, bodyB, params, manager ) {

		this.mesh = mesh;
		this.world = world;
		this.bodyA = bodyA;
		this.bodyB = bodyB;
		this.params = params;
		this.manager = manager;

		this.constraint = null;

		this._init();

	}

	// private method

	_init() {

		const manager = this.manager;
		const params = this.params;
		const bodyA = this.bodyA;
		const bodyB = this.bodyB;

		const form = manager.allocTransform();
		manager.setIdentity( form );
		manager.setOriginFromArray3( form, params.position );
		manager.setBasisFromArray3( form, params.rotation );

		const formA = manager.allocTransform();
		const formB = manager.allocTransform();

		bodyA.body.getMotionState().getWorldTransform( formA );
		bodyB.body.getMotionState().getWorldTransform( formB );

		const formInverseA = manager.inverseTransform( formA );
		const formInverseB = manager.inverseTransform( formB );

		const formA2 = manager.multiplyTransforms( formInverseA, form );
		const formB2 = manager.multiplyTransforms( formInverseB, form );

		const constraint = new Ammo.btGeneric6DofSpringConstraint( bodyA.body, bodyB.body, formA2, formB2, true );

		const lll = manager.allocVector3();
		const lul = manager.allocVector3();
		const all = manager.allocVector3();
		const aul = manager.allocVector3();

		lll.setValue( params.translationLimitation1[ 0 ],
		              params.translationLimitation1[ 1 ],
		              params.translationLimitation1[ 2 ] );
		lul.setValue( params.translationLimitation2[ 0 ],
		              params.translationLimitation2[ 1 ],
		              params.translationLimitation2[ 2 ] );
		all.setValue( params.rotationLimitation1[ 0 ],
		              params.rotationLimitation1[ 1 ],
		              params.rotationLimitation1[ 2 ] );
		aul.setValue( params.rotationLimitation2[ 0 ],
		              params.rotationLimitation2[ 1 ],
		              params.rotationLimitation2[ 2 ] );

		constraint.setLinearLowerLimit( lll );
		constraint.setLinearUpperLimit( lul );
		constraint.setAngularLowerLimit( all );
		constraint.setAngularUpperLimit( aul );

		for ( let i = 0; i < 3; i ++ ) {

			if ( params.springPosition[ i ] !== 0 ) {

				constraint.enableSpring( i, true );
				constraint.setStiffness( i, params.springPosition[ i ] );

			}

		}

		for ( let i = 0; i < 3; i ++ ) {

			if ( params.springRotation[ i ] !== 0 ) {

				constraint.enableSpring( i + 3, true );
				constraint.setStiffness( i + 3, params.springRotation[ i ] );

			}

		}

		/*
		 * Currently(10/31/2016) official ammo.js doesn't support
		 * btGeneric6DofSpringConstraint.setParam method.
		 * You need custom ammo.js (add the method into idl) if you wanna use.
		 * By setting this parameter, physics will be more like MMD's
		 */
		if ( constraint.setParam !== undefined ) {

			for ( let i = 0; i < 6; i ++ ) {

				// this parameter is from http://www20.atpages.jp/katwat/three.js_r58/examples/mytest37/mmd.three.js
				constraint.setParam( 2, 0.475, i );

			}

		}

		this.world.addConstraint( constraint, true );
		this.constraint = constraint;

		manager.freeTransform( form );
		manager.freeTransform( formA );
		manager.freeTransform( formB );
		manager.freeTransform( formInverseA );
		manager.freeTransform( formInverseB );
		manager.freeTransform( formA2 );
		manager.freeTransform( formB2 );
		manager.freeVector3( lll );
		manager.freeVector3( lul );
		manager.freeVector3( all );
		manager.freeVector3( aul );

	}

}

//

const _position = new Vector3();
const _quaternion = new Quaternion();
const _scale = new Vector3();
const _matrixWorldInv = new Matrix4();

class MMDPhysicsHelper extends Object3D {

	/**
	 * Visualize Rigid bodies
	 *
	 * @param {THREE.SkinnedMesh} mesh
	 * @param {Physics} physics
	 */
	constructor( mesh, physics ) {

		super();

		this.root = mesh;
		this.physics = physics;

		this.matrix.copy( mesh.matrixWorld );
		this.matrixAutoUpdate = false;

		this.materials = [];

		this.materials.push(
			new MeshBasicMaterial( {
				color: new Color( 0xff8888 ),
				wireframe: true,
				depthTest: false,
				depthWrite: false,
				opacity: 0.25,
				transparent: true
			} )
		);

		this.materials.push(
			new MeshBasicMaterial( {
				color: new Color( 0x88ff88 ),
				wireframe: true,
				depthTest: false,
				depthWrite: false,
				opacity: 0.25,
				transparent: true
			} )
		);

		this.materials.push(
			new MeshBasicMaterial( {
				color: new Color( 0x8888ff ),
				wireframe: true,
				depthTest: false,
				depthWrite: false,
				opacity: 0.25,
				transparent: true
			} )
		);

		this._init();

	}

	/**
	 * Updates Rigid Bodies visualization.
	 */
	updateMatrixWorld( force ) {

		var mesh = this.root;

		if ( this.visible ) {

			var bodies = this.physics.bodies;

			_matrixWorldInv
				.copy( mesh.matrixWorld )
				.decompose( _position, _quaternion, _scale )
				.compose( _position, _quaternion, _scale.set( 1, 1, 1 ) )
				.invert();

			for ( var i = 0, il = bodies.length; i < il; i ++ ) {

				var body = bodies[ i ].body;
				var child = this.children[ i ];

				var tr = body.getCenterOfMassTransform();
				var origin = tr.getOrigin();
				var rotation = tr.getRotation();

				child.position
					.set( origin.x(), origin.y(), origin.z() )
					.applyMatrix4( _matrixWorldInv );

				child.quaternion
					.setFromRotationMatrix( _matrixWorldInv )
					.multiply(
						_quaternion.set( rotation.x(), rotation.y(), rotation.z(), rotation.w() )
					);

			}

		}

		this.matrix
			.copy( mesh.matrixWorld )
			.decompose( _position, _quaternion, _scale )
			.compose( _position, _quaternion, _scale.set( 1, 1, 1 ) );

		super.updateMatrixWorld( force );

	}

	// private method

	_init() {

		var bodies = this.physics.bodies;

		function createGeometry( param ) {

			switch ( param.shapeType ) {

				case 0:
					return new SphereGeometry( param.width, 16, 8 );

				case 1:
					return new BoxGeometry( param.width * 2, param.height * 2, param.depth * 2, 8, 8, 8 );

				case 2:
					return new createCapsuleGeometry( param.width, param.height, 16, 8 );

				default:
					return null;

			}

		}

		// copy from http://www20.atpages.jp/katwat/three.js_r58/examples/mytest37/mytest37.js?ver=20160815
		function createCapsuleGeometry( radius, cylinderHeight, segmentsRadius, segmentsHeight ) {

			var geometry = new CylinderGeometry( radius, radius, cylinderHeight, segmentsRadius, segmentsHeight, true );
			var upperSphere = new Mesh( new SphereGeometry( radius, segmentsRadius, segmentsHeight, 0, Math.PI * 2, 0, Math.PI / 2 ) );
			var lowerSphere = new Mesh( new SphereGeometry( radius, segmentsRadius, segmentsHeight, 0, Math.PI * 2, Math.PI / 2, Math.PI / 2 ) );

			upperSphere.position.set( 0, cylinderHeight / 2, 0 );
			lowerSphere.position.set( 0, - cylinderHeight / 2, 0 );

			upperSphere.updateMatrix();
			lowerSphere.updateMatrix();

			geometry.merge( upperSphere.geometry, upperSphere.matrix );
			geometry.merge( lowerSphere.geometry, lowerSphere.matrix );

			return geometry;

		}

		for ( var i = 0, il = bodies.length; i < il; i ++ ) {

			var param = bodies[ i ].params;
			this.add( new Mesh( createGeometry( param ), this.materials[ param.type ] ) );

		}

	}

}

export { MMDPhysics };