/**
 * @author Don McCurdy / https://www.donmccurdy.com
 */

THREE.DRACOLoader = function ( manager ) {

	THREE.Loader.call( this, manager );

	this.decoderType = typeof WebAssembly !== 'object' || this.workerLimit === 0 ? 'js' : 'wasm';
	this.decoderConfig = {};
	this.decoderBinary = null;
	this.decoderPending = null;

	this.workerLimit = 4;
	this.workerPool = [];
	this.workerNextTaskID = 1;
	this.workerSourceURL = '';

	this.defaultAttributeIDs = {
		position: 'POSITION',
		normal: 'NORMAL',
		color: 'COLOR',
		uv: 'TEX_COORD'
	};
	this.defaultAttributeTypes = {
		position: 'Float32Array',
		normal: 'Float32Array',
		color: 'Float32Array',
		uv: 'Float32Array'
	};

};

THREE.DRACOLoader.prototype = Object.assign( Object.create( THREE.Loader.prototype ), {

	constructor: THREE.DRACOLoader,

	setDecoderType: function ( type ) {

		this.decoderType = type;
		return this;

	},

	setWorkerLimit: function ( workerLimit ) {

		this.workerLimit = workerLimit;
		return this;

	},

	setVerbosity: function ( level ) {

		this.verbosity = level;
		return this;

	},

	setDecoderConfig: function ( config ) {

		this.decoderConfig = config;
		return this;

	},

	setDecoderPath: function ( path ) {

		this.decoderPath = path;
		return this;

	},

	preload: function () {

		this._initDecoder();
		return this;

	},

	_initDecoder: function () {

		if ( this.decoderPending ) return this.decoderPending;

		const useJS = this.decoderType === 'js';
		const librariesPending = [];

		if ( useJS ) {

			librariesPending.push( this._loadLibrary( 'draco_decoder.js', 'text' ) );

		} else {

			librariesPending.push( this._loadLibrary( 'draco_wasm_wrapper.js', 'text' ) );
			librariesPending.push( this._loadLibrary( 'draco_decoder.wasm', 'arraybuffer' ) );

		}

		this.decoderPending = Promise.all( librariesPending )
			.then( ( libraries ) => {

				const jsContent = libraries[ 0 ];

				if ( useJS ) {

					this.decoderSourceURL = URL.createObjectURL( new Blob( [ jsContent ], { type: 'application/javascript' } ) );

				} else {

					this.decoderSourceURL = URL.createObjectURL( new Blob( [ jsContent ], { type: 'application/javascript' } ) );
					this.decoderConfig.wasmBinary = libraries[ 1 ];

				}

			} );

		return this.decoderPending;

	},

	_loadLibrary: function ( url, responseType ) {

		const loader = new THREE.FileLoader( this.manager );
		loader.setPath( this.decoderPath );
		loader.setResponseType( responseType );
		loader.setWithCredentials( this.withCredentials );

		return new Promise( ( resolve, reject ) => {

			loader.load( url, resolve, undefined, reject );

		} );

	},

	dispose: function () {

		this.workerPool.length = 0;

		if ( this.decoderSourceURL !== '' ) {

			URL.revokeObjectURL( this.decoderSourceURL );

		}

		return this;

	}

} );