File: //var/www/aspa/three/addons/animation/MMDAnimationHelper.js
import {
	AnimationMixer,
	Object3D,
	Quaternion,
	Vector3
} from 'three';
import { CCDIKSolver } from './CCDIKSolver.js';
import { MMDPhysics } from './MMDPhysics.js';
/**
 * MMDAnimationHelper handles animation of MMD assets loaded by MMDLoader
 * with MMD special features as IK, Grant, and Physics.
 *
 * Dependencies
 *  - ammo.js https://github.com/kripken/ammo.js
 *  - MMDPhysics
 *  - CCDIKSolver
 *
 * TODO
 *  - more precise grant skinning support.
 */
class MMDAnimationHelper {
	/**
	 * @param {Object} params - (optional)
	 * @param {boolean} params.sync - Whether animation durations of added objects are synched. Default is true.
	 * @param {Number} params.afterglow - Default is 0.0.
	 * @param {boolean} params.resetPhysicsOnLoop - Default is true.
	 */
	constructor( params = {} ) {
		this.meshes = [];
		this.camera = null;
		this.cameraTarget = new Object3D();
		this.cameraTarget.name = 'target';
		this.audio = null;
		this.audioManager = null;
		this.objects = new WeakMap();
		this.configuration = {
			sync: params.sync !== undefined ? params.sync : true,
			afterglow: params.afterglow !== undefined ? params.afterglow : 0.0,
			resetPhysicsOnLoop: params.resetPhysicsOnLoop !== undefined ? params.resetPhysicsOnLoop : true,
			pmxAnimation: params.pmxAnimation !== undefined ? params.pmxAnimation : false
		};
		this.enabled = {
			animation: true,
			ik: true,
			grant: true,
			physics: true,
			cameraAnimation: true
		};
		this.onBeforePhysics = function ( /* mesh */ ) {};
		// experimental
		this.sharedPhysics = false;
		this.masterPhysics = null;
	}
	/**
	 * Adds an Three.js Object to helper and setups animation.
	 * The anmation durations of added objects are synched
	 * if this.configuration.sync is true.
	 *
	 * @param {THREE.SkinnedMesh|THREE.Camera|THREE.Audio} object
	 * @param {Object} params - (optional)
	 * @param {THREE.AnimationClip|Array<THREE.AnimationClip>} params.animation - Only for THREE.SkinnedMesh and THREE.Camera. Default is undefined.
	 * @param {boolean} params.physics - Only for THREE.SkinnedMesh. Default is true.
	 * @param {Integer} params.warmup - Only for THREE.SkinnedMesh and physics is true. Default is 60.
	 * @param {Number} params.unitStep - Only for THREE.SkinnedMesh and physics is true. Default is 1 / 65.
	 * @param {Integer} params.maxStepNum - Only for THREE.SkinnedMesh and physics is true. Default is 3.
	 * @param {Vector3} params.gravity - Only for THREE.SkinnedMesh and physics is true. Default ( 0, - 9.8 * 10, 0 ).
	 * @param {Number} params.delayTime - Only for THREE.Audio. Default is 0.0.
	 * @return {MMDAnimationHelper}
	 */
	add( object, params = {} ) {
		if ( object.isSkinnedMesh ) {
			this._addMesh( object, params );
		} else if ( object.isCamera ) {
			this._setupCamera( object, params );
		} else if ( object.type === 'Audio' ) {
			this._setupAudio( object, params );
		} else {
			throw new Error( 'THREE.MMDAnimationHelper.add: '
				+ 'accepts only '
				+ 'THREE.SkinnedMesh or '
				+ 'THREE.Camera or '
				+ 'THREE.Audio instance.' );
		}
		if ( this.configuration.sync ) this._syncDuration();
		return this;
	}
	/**
	 * Removes an Three.js Object from helper.
	 *
	 * @param {THREE.SkinnedMesh|THREE.Camera|THREE.Audio} object
	 * @return {MMDAnimationHelper}
	 */
	remove( object ) {
		if ( object.isSkinnedMesh ) {
			this._removeMesh( object );
		} else if ( object.isCamera ) {
			this._clearCamera( object );
		} else if ( object.type === 'Audio' ) {
			this._clearAudio( object );
		} else {
			throw new Error( 'THREE.MMDAnimationHelper.remove: '
				+ 'accepts only '
				+ 'THREE.SkinnedMesh or '
				+ 'THREE.Camera or '
				+ 'THREE.Audio instance.' );
		}
		if ( this.configuration.sync ) this._syncDuration();
		return this;
	}
	/**
	 * Updates the animation.
	 *
	 * @param {Number} delta
	 * @return {MMDAnimationHelper}
	 */
	update( delta ) {
		if ( this.audioManager !== null ) this.audioManager.control( delta );
		for ( let i = 0; i < this.meshes.length; i ++ ) {
			this._animateMesh( this.meshes[ i ], delta );
		}
		if ( this.sharedPhysics ) this._updateSharedPhysics( delta );
		if ( this.camera !== null ) this._animateCamera( this.camera, delta );
		return this;
	}
	/**
	 * Changes the pose of SkinnedMesh as VPD specifies.
	 *
	 * @param {THREE.SkinnedMesh} mesh
	 * @param {Object} vpd - VPD content parsed MMDParser
	 * @param {Object} params - (optional)
	 * @param {boolean} params.resetPose - Default is true.
	 * @param {boolean} params.ik - Default is true.
	 * @param {boolean} params.grant - Default is true.
	 * @return {MMDAnimationHelper}
	 */
	pose( mesh, vpd, params = {} ) {
		if ( params.resetPose !== false ) mesh.pose();
		const bones = mesh.skeleton.bones;
		const boneParams = vpd.bones;
		const boneNameDictionary = {};
		for ( let i = 0, il = bones.length; i < il; i ++ ) {
			boneNameDictionary[ bones[ i ].name ] = i;
		}
		const vector = new Vector3();
		const quaternion = new Quaternion();
		for ( let i = 0, il = boneParams.length; i < il; i ++ ) {
			const boneParam = boneParams[ i ];
			const boneIndex = boneNameDictionary[ boneParam.name ];
			if ( boneIndex === undefined ) continue;
			const bone = bones[ boneIndex ];
			bone.position.add( vector.fromArray( boneParam.translation ) );
			bone.quaternion.multiply( quaternion.fromArray( boneParam.quaternion ) );
		}
		mesh.updateMatrixWorld( true );
		// PMX animation system special path
		if ( this.configuration.pmxAnimation &&
			mesh.geometry.userData.MMD && mesh.geometry.userData.MMD.format === 'pmx' ) {
			const sortedBonesData = this._sortBoneDataArray( mesh.geometry.userData.MMD.bones.slice() );
			const ikSolver = params.ik !== false ? this._createCCDIKSolver( mesh ) : null;
			const grantSolver = params.grant !== false ? this.createGrantSolver( mesh ) : null;
			this._animatePMXMesh( mesh, sortedBonesData, ikSolver, grantSolver );
		} else {
			if ( params.ik !== false ) {
				this._createCCDIKSolver( mesh ).update();
			}
			if ( params.grant !== false ) {
				this.createGrantSolver( mesh ).update();
			}
		}
		return this;
	}
	/**
	 * Enabes/Disables an animation feature.
	 *
	 * @param {string} key
	 * @param {boolean} enabled
	 * @return {MMDAnimationHelper}
	 */
	enable( key, enabled ) {
		if ( this.enabled[ key ] === undefined ) {
			throw new Error( 'THREE.MMDAnimationHelper.enable: '
				+ 'unknown key ' + key );
		}
		this.enabled[ key ] = enabled;
		if ( key === 'physics' ) {
			for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
				this._optimizeIK( this.meshes[ i ], enabled );
			}
		}
		return this;
	}
	/**
	 * Creates an GrantSolver instance.
	 *
	 * @param {THREE.SkinnedMesh} mesh
	 * @return {GrantSolver}
	 */
	createGrantSolver( mesh ) {
		return new GrantSolver( mesh, mesh.geometry.userData.MMD.grants );
	}
	// private methods
	_addMesh( mesh, params ) {
		if ( this.meshes.indexOf( mesh ) >= 0 ) {
			throw new Error( 'THREE.MMDAnimationHelper._addMesh: '
				+ 'SkinnedMesh \'' + mesh.name + '\' has already been added.' );
		}
		this.meshes.push( mesh );
		this.objects.set( mesh, { looped: false } );
		this._setupMeshAnimation( mesh, params.animation );
		if ( params.physics !== false ) {
			this._setupMeshPhysics( mesh, params );
		}
		return this;
	}
	_setupCamera( camera, params ) {
		if ( this.camera === camera ) {
			throw new Error( 'THREE.MMDAnimationHelper._setupCamera: '
				+ 'Camera \'' + camera.name + '\' has already been set.' );
		}
		if ( this.camera ) this.clearCamera( this.camera );
		this.camera = camera;
		camera.add( this.cameraTarget );
		this.objects.set( camera, {} );
		if ( params.animation !== undefined ) {
			this._setupCameraAnimation( camera, params.animation );
		}
		return this;
	}
	_setupAudio( audio, params ) {
		if ( this.audio === audio ) {
			throw new Error( 'THREE.MMDAnimationHelper._setupAudio: '
				+ 'Audio \'' + audio.name + '\' has already been set.' );
		}
		if ( this.audio ) this.clearAudio( this.audio );
		this.audio = audio;
		this.audioManager = new AudioManager( audio, params );
		this.objects.set( this.audioManager, {
			duration: this.audioManager.duration
		} );
		return this;
	}
	_removeMesh( mesh ) {
		let found = false;
		let writeIndex = 0;
		for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
			if ( this.meshes[ i ] === mesh ) {
				this.objects.delete( mesh );
				found = true;
				continue;
			}
			this.meshes[ writeIndex ++ ] = this.meshes[ i ];
		}
		if ( ! found ) {
			throw new Error( 'THREE.MMDAnimationHelper._removeMesh: '
				+ 'SkinnedMesh \'' + mesh.name + '\' has not been added yet.' );
		}
		this.meshes.length = writeIndex;
		return this;
	}
	_clearCamera( camera ) {
		if ( camera !== this.camera ) {
			throw new Error( 'THREE.MMDAnimationHelper._clearCamera: '
				+ 'Camera \'' + camera.name + '\' has not been set yet.' );
		}
		this.camera.remove( this.cameraTarget );
		this.objects.delete( this.camera );
		this.camera = null;
		return this;
	}
	_clearAudio( audio ) {
		if ( audio !== this.audio ) {
			throw new Error( 'THREE.MMDAnimationHelper._clearAudio: '
				+ 'Audio \'' + audio.name + '\' has not been set yet.' );
		}
		this.objects.delete( this.audioManager );
		this.audio = null;
		this.audioManager = null;
		return this;
	}
	_setupMeshAnimation( mesh, animation ) {
		const objects = this.objects.get( mesh );
		if ( animation !== undefined ) {
			const animations = Array.isArray( animation )
				? animation : [ animation ];
			objects.mixer = new AnimationMixer( mesh );
			for ( let i = 0, il = animations.length; i < il; i ++ ) {
				objects.mixer.clipAction( animations[ i ] ).play();
			}
			// TODO: find a workaround not to access ._clip looking like a private property
			objects.mixer.addEventListener( 'loop', function ( event ) {
				const tracks = event.action._clip.tracks;
				if ( tracks.length > 0 && tracks[ 0 ].name.slice( 0, 6 ) !== '.bones' ) return;
				objects.looped = true;
			} );
		}
		objects.ikSolver = this._createCCDIKSolver( mesh );
		objects.grantSolver = this.createGrantSolver( mesh );
		return this;
	}
	_setupCameraAnimation( camera, animation ) {
		const animations = Array.isArray( animation )
			? animation : [ animation ];
		const objects = this.objects.get( camera );
		objects.mixer = new AnimationMixer( camera );
		for ( let i = 0, il = animations.length; i < il; i ++ ) {
			objects.mixer.clipAction( animations[ i ] ).play();
		}
	}
	_setupMeshPhysics( mesh, params ) {
		const objects = this.objects.get( mesh );
		// shared physics is experimental
		if ( params.world === undefined && this.sharedPhysics ) {
			const masterPhysics = this._getMasterPhysics();
			if ( masterPhysics !== null ) world = masterPhysics.world; // eslint-disable-line no-undef
		}
		objects.physics = this._createMMDPhysics( mesh, params );
		if ( objects.mixer && params.animationWarmup !== false ) {
			this._animateMesh( mesh, 0 );
			objects.physics.reset();
		}
		objects.physics.warmup( params.warmup !== undefined ? params.warmup : 60 );
		this._optimizeIK( mesh, true );
	}
	_animateMesh( mesh, delta ) {
		const objects = this.objects.get( mesh );
		const mixer = objects.mixer;
		const ikSolver = objects.ikSolver;
		const grantSolver = objects.grantSolver;
		const physics = objects.physics;
		const looped = objects.looped;
		if ( mixer && this.enabled.animation ) {
			// alternate solution to save/restore bones but less performant?
			//mesh.pose();
			//this._updatePropertyMixersBuffer( mesh );
			this._restoreBones( mesh );
			mixer.update( delta );
			this._saveBones( mesh );
			// PMX animation system special path
			if ( this.configuration.pmxAnimation &&
				mesh.geometry.userData.MMD && mesh.geometry.userData.MMD.format === 'pmx' ) {
				if ( ! objects.sortedBonesData ) objects.sortedBonesData = this._sortBoneDataArray( mesh.geometry.userData.MMD.bones.slice() );
				this._animatePMXMesh(
					mesh,
					objects.sortedBonesData,
					ikSolver && this.enabled.ik ? ikSolver : null,
					grantSolver && this.enabled.grant ? grantSolver : null
				);
			} else {
				if ( ikSolver && this.enabled.ik ) {
					mesh.updateMatrixWorld( true );
					ikSolver.update();
				}
				if ( grantSolver && this.enabled.grant ) {
					grantSolver.update();
				}
			}
		}
		if ( looped === true && this.enabled.physics ) {
			if ( physics && this.configuration.resetPhysicsOnLoop ) physics.reset();
			objects.looped = false;
		}
		if ( physics && this.enabled.physics && ! this.sharedPhysics ) {
			this.onBeforePhysics( mesh );
			physics.update( delta );
		}
	}
	// Sort bones in order by 1. transformationClass and 2. bone index.
	// In PMX animation system, bone transformations should be processed
	// in this order.
	_sortBoneDataArray( boneDataArray ) {
		return boneDataArray.sort( function ( a, b ) {
			if ( a.transformationClass !== b.transformationClass ) {
				return a.transformationClass - b.transformationClass;
			} else {
				return a.index - b.index;
			}
		} );
	}
	// PMX Animation system is a bit too complex and doesn't great match to
	// Three.js Animation system. This method attempts to simulate it as much as
	// possible but doesn't perfectly simulate.
	// This method is more costly than the regular one so
	// you are recommended to set constructor parameter "pmxAnimation: true"
	// only if your PMX model animation doesn't work well.
	// If you need better method you would be required to write your own.
	_animatePMXMesh( mesh, sortedBonesData, ikSolver, grantSolver ) {
		_quaternionIndex = 0;
		_grantResultMap.clear();
		for ( let i = 0, il = sortedBonesData.length; i < il; i ++ ) {
			updateOne( mesh, sortedBonesData[ i ].index, ikSolver, grantSolver );
		}
		mesh.updateMatrixWorld( true );
		return this;
	}
	_animateCamera( camera, delta ) {
		const mixer = this.objects.get( camera ).mixer;
		if ( mixer && this.enabled.cameraAnimation ) {
			mixer.update( delta );
			camera.updateProjectionMatrix();
			camera.up.set( 0, 1, 0 );
			camera.up.applyQuaternion( camera.quaternion );
			camera.lookAt( this.cameraTarget.position );
		}
	}
	_optimizeIK( mesh, physicsEnabled ) {
		const iks = mesh.geometry.userData.MMD.iks;
		const bones = mesh.geometry.userData.MMD.bones;
		for ( let i = 0, il = iks.length; i < il; i ++ ) {
			const ik = iks[ i ];
			const links = ik.links;
			for ( let j = 0, jl = links.length; j < jl; j ++ ) {
				const link = links[ j ];
				if ( physicsEnabled === true ) {
					// disable IK of the bone the corresponding rigidBody type of which is 1 or 2
					// because its rotation will be overriden by physics
					link.enabled = bones[ link.index ].rigidBodyType > 0 ? false : true;
				} else {
					link.enabled = true;
				}
			}
		}
	}
	_createCCDIKSolver( mesh ) {
		if ( CCDIKSolver === undefined ) {
			throw new Error( 'THREE.MMDAnimationHelper: Import CCDIKSolver.' );
		}
		return new CCDIKSolver( mesh, mesh.geometry.userData.MMD.iks );
	}
	_createMMDPhysics( mesh, params ) {
		if ( MMDPhysics === undefined ) {
			throw new Error( 'THREE.MMDPhysics: Import MMDPhysics.' );
		}
		return new MMDPhysics(
			mesh,
			mesh.geometry.userData.MMD.rigidBodies,
			mesh.geometry.userData.MMD.constraints,
			params );
	}
	/*
	 * Detects the longest duration and then sets it to them to sync.
	 * TODO: Not to access private properties ( ._actions and ._clip )
	 */
	_syncDuration() {
		let max = 0.0;
		const objects = this.objects;
		const meshes = this.meshes;
		const camera = this.camera;
		const audioManager = this.audioManager;
		// get the longest duration
		for ( let i = 0, il = meshes.length; i < il; i ++ ) {
			const mixer = this.objects.get( meshes[ i ] ).mixer;
			if ( mixer === undefined ) continue;
			for ( let j = 0; j < mixer._actions.length; j ++ ) {
				const clip = mixer._actions[ j ]._clip;
				if ( ! objects.has( clip ) ) {
					objects.set( clip, {
						duration: clip.duration
					} );
				}
				max = Math.max( max, objects.get( clip ).duration );
			}
		}
		if ( camera !== null ) {
			const mixer = this.objects.get( camera ).mixer;
			if ( mixer !== undefined ) {
				for ( let i = 0, il = mixer._actions.length; i < il; i ++ ) {
					const clip = mixer._actions[ i ]._clip;
					if ( ! objects.has( clip ) ) {
						objects.set( clip, {
							duration: clip.duration
						} );
					}
					max = Math.max( max, objects.get( clip ).duration );
				}
			}
		}
		if ( audioManager !== null ) {
			max = Math.max( max, objects.get( audioManager ).duration );
		}
		max += this.configuration.afterglow;
		// update the duration
		for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
			const mixer = this.objects.get( this.meshes[ i ] ).mixer;
			if ( mixer === undefined ) continue;
			for ( let j = 0, jl = mixer._actions.length; j < jl; j ++ ) {
				mixer._actions[ j ]._clip.duration = max;
			}
		}
		if ( camera !== null ) {
			const mixer = this.objects.get( camera ).mixer;
			if ( mixer !== undefined ) {
				for ( let i = 0, il = mixer._actions.length; i < il; i ++ ) {
					mixer._actions[ i ]._clip.duration = max;
				}
			}
		}
		if ( audioManager !== null ) {
			audioManager.duration = max;
		}
	}
	// workaround
	_updatePropertyMixersBuffer( mesh ) {
		const mixer = this.objects.get( mesh ).mixer;
		const propertyMixers = mixer._bindings;
		const accuIndex = mixer._accuIndex;
		for ( let i = 0, il = propertyMixers.length; i < il; i ++ ) {
			const propertyMixer = propertyMixers[ i ];
			const buffer = propertyMixer.buffer;
			const stride = propertyMixer.valueSize;
			const offset = ( accuIndex + 1 ) * stride;
			propertyMixer.binding.getValue( buffer, offset );
		}
	}
	/*
	 * Avoiding these two issues by restore/save bones before/after mixer animation.
	 *
	 * 1. PropertyMixer used by AnimationMixer holds cache value in .buffer.
	 *    Calculating IK, Grant, and Physics after mixer animation can break
	 *    the cache coherency.
	 *
	 * 2. Applying Grant two or more times without reset the posing breaks model.
	 */
	_saveBones( mesh ) {
		const objects = this.objects.get( mesh );
		const bones = mesh.skeleton.bones;
		let backupBones = objects.backupBones;
		if ( backupBones === undefined ) {
			backupBones = new Float32Array( bones.length * 7 );
			objects.backupBones = backupBones;
		}
		for ( let i = 0, il = bones.length; i < il; i ++ ) {
			const bone = bones[ i ];
			bone.position.toArray( backupBones, i * 7 );
			bone.quaternion.toArray( backupBones, i * 7 + 3 );
		}
	}
	_restoreBones( mesh ) {
		const objects = this.objects.get( mesh );
		const backupBones = objects.backupBones;
		if ( backupBones === undefined ) return;
		const bones = mesh.skeleton.bones;
		for ( let i = 0, il = bones.length; i < il; i ++ ) {
			const bone = bones[ i ];
			bone.position.fromArray( backupBones, i * 7 );
			bone.quaternion.fromArray( backupBones, i * 7 + 3 );
		}
	}
	// experimental
	_getMasterPhysics() {
		if ( this.masterPhysics !== null ) return this.masterPhysics;
		for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
			const physics = this.meshes[ i ].physics;
			if ( physics !== undefined && physics !== null ) {
				this.masterPhysics = physics;
				return this.masterPhysics;
			}
		}
		return null;
	}
	_updateSharedPhysics( delta ) {
		if ( this.meshes.length === 0 || ! this.enabled.physics || ! this.sharedPhysics ) return;
		const physics = this._getMasterPhysics();
		if ( physics === null ) return;
		for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
			const p = this.meshes[ i ].physics;
			if ( p !== null && p !== undefined ) {
				p.updateRigidBodies();
			}
		}
		physics.stepSimulation( delta );
		for ( let i = 0, il = this.meshes.length; i < il; i ++ ) {
			const p = this.meshes[ i ].physics;
			if ( p !== null && p !== undefined ) {
				p.updateBones();
			}
		}
	}
}
// Keep working quaternions for less GC
const _quaternions = [];
let _quaternionIndex = 0;
function getQuaternion() {
	if ( _quaternionIndex >= _quaternions.length ) {
		_quaternions.push( new Quaternion() );
	}
	return _quaternions[ _quaternionIndex ++ ];
}
// Save rotation whose grant and IK are already applied
// used by grant children
const _grantResultMap = new Map();
function updateOne( mesh, boneIndex, ikSolver, grantSolver ) {
	const bones = mesh.skeleton.bones;
	const bonesData = mesh.geometry.userData.MMD.bones;
	const boneData = bonesData[ boneIndex ];
	const bone = bones[ boneIndex ];
	// Return if already updated by being referred as a grant parent.
	if ( _grantResultMap.has( boneIndex ) ) return;
	const quaternion = getQuaternion();
	// Initialize grant result here to prevent infinite loop.
	// If it's referred before updating with actual result later
	// result without applyting IK or grant is gotten
	// but better than composing of infinite loop.
	_grantResultMap.set( boneIndex, quaternion.copy( bone.quaternion ) );
	// @TODO: Support global grant and grant position
	if ( grantSolver && boneData.grant &&
		! boneData.grant.isLocal && boneData.grant.affectRotation ) {
		const parentIndex = boneData.grant.parentIndex;
		const ratio = boneData.grant.ratio;
		if ( ! _grantResultMap.has( parentIndex ) ) {
			updateOne( mesh, parentIndex, ikSolver, grantSolver );
		}
		grantSolver.addGrantRotation( bone, _grantResultMap.get( parentIndex ), ratio );
	}
	if ( ikSolver && boneData.ik ) {
		// @TODO: Updating world matrices every time solving an IK bone is
		// costly. Optimize if possible.
		mesh.updateMatrixWorld( true );
		ikSolver.updateOne( boneData.ik );
		// No confident, but it seems the grant results with ik links should be updated?
		const links = boneData.ik.links;
		for ( let i = 0, il = links.length; i < il; i ++ ) {
			const link = links[ i ];
			if ( link.enabled === false ) continue;
			const linkIndex = link.index;
			if ( _grantResultMap.has( linkIndex ) ) {
				_grantResultMap.set( linkIndex, _grantResultMap.get( linkIndex ).copy( bones[ linkIndex ].quaternion ) );
			}
		}
	}
	// Update with the actual result here
	quaternion.copy( bone.quaternion );
}
//
class AudioManager {
	/**
	 * @param {THREE.Audio} audio
	 * @param {Object} params - (optional)
	 * @param {Nuumber} params.delayTime
	 */
	constructor( audio, params = {} ) {
		this.audio = audio;
		this.elapsedTime = 0.0;
		this.currentTime = 0.0;
		this.delayTime = params.delayTime !== undefined
			? params.delayTime : 0.0;
		this.audioDuration = this.audio.buffer.duration;
		this.duration = this.audioDuration + this.delayTime;
	}
	/**
	 * @param {Number} delta
	 * @return {AudioManager}
	 */
	control( delta ) {
		this.elapsed += delta;
		this.currentTime += delta;
		if ( this._shouldStopAudio() ) this.audio.stop();
		if ( this._shouldStartAudio() ) this.audio.play();
		return this;
	}
	// private methods
	_shouldStartAudio() {
		if ( this.audio.isPlaying ) return false;
		while ( this.currentTime >= this.duration ) {
			this.currentTime -= this.duration;
		}
		if ( this.currentTime < this.delayTime ) return false;
		// 'duration' can be bigger than 'audioDuration + delayTime' because of sync configuration
		if ( ( this.currentTime - this.delayTime ) > this.audioDuration ) return false;
		return true;
	}
	_shouldStopAudio() {
		return this.audio.isPlaying &&
			this.currentTime >= this.duration;
	}
}
const _q = new Quaternion();
/**
 * Solver for Grant (Fuyo in Japanese. I just google translated because
 * Fuyo may be MMD specific term and may not be common word in 3D CG terms.)
 * Grant propagates a bone's transform to other bones transforms even if
 * they are not children.
 * @param {THREE.SkinnedMesh} mesh
 * @param {Array<Object>} grants
 */
class GrantSolver {
	constructor( mesh, grants = [] ) {
		this.mesh = mesh;
		this.grants = grants;
	}
	/**
	 * Solve all the grant bones
	 * @return {GrantSolver}
	 */
	update() {
		const grants = this.grants;
		for ( let i = 0, il = grants.length; i < il; i ++ ) {
			this.updateOne( grants[ i ] );
		}
		return this;
	}
	/**
	 * Solve a grant bone
	 * @param {Object} grant - grant parameter
	 * @return {GrantSolver}
	 */
	updateOne( grant ) {
		const bones = this.mesh.skeleton.bones;
		const bone = bones[ grant.index ];
		const parentBone = bones[ grant.parentIndex ];
		if ( grant.isLocal ) {
			// TODO: implement
			if ( grant.affectPosition ) {
			}
			// TODO: implement
			if ( grant.affectRotation ) {
			}
		} else {
			// TODO: implement
			if ( grant.affectPosition ) {
			}
			if ( grant.affectRotation ) {
				this.addGrantRotation( bone, parentBone.quaternion, grant.ratio );
			}
		}
		return this;
	}
	addGrantRotation( bone, q, ratio ) {
		_q.set( 0, 0, 0, 1 );
		_q.slerp( q, ratio );
		bone.quaternion.multiply( _q );
		return this;
	}
}
export { MMDAnimationHelper };