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

THREE.DRACOLoader = function ( manager ) {

	THREE.Loader.call( this, manager );

	this.decoderPath = '';
	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,

	setDecoderPath: function ( path ) {

		this.decoderPath = path;

		return this;

	},

	setDecoderConfig: function ( config ) {

		this.decoderConfig = config;

		return this;

	},

	setWorkerLimit: function ( workerLimit ) {

		this.workerLimit = workerLimit;

		return this;

	},

	/** @deprecated */
	setVerbosity: function () {

		console.warn( 'THREE.DRACOLoader: The .setVerbosity() method has been removed.' );

	},

	/** @deprecated */
	setDrawMode: function () {

		console.warn( 'THREE.DRACOLoader: The .setDrawMode() method has been removed.' );

	},

	/** @deprecated */
	setSkipDequantization: function () {

		console.warn( 'THREE.DRACOLoader: The .setSkipDequantization() method has been removed.' );

	},

	load: function ( url, onLoad, onProgress, onError ) {

		var loader = new THREE.FileLoader( this.manager );

		loader.setPath( this.path );
		loader.setResponseType( 'arraybuffer' );

		if ( this.crossOrigin === 'use-credentials' ) {

			loader.setWithCredentials( true );

		}

		loader.load( url, ( buffer ) => {

			var taskConfig = {
				attributeIDs: this.defaultAttributeIDs,
				attributeTypes: this.defaultAttributeTypes,
				useUniqueIDs: false
			};

			this.decodeGeometry( buffer, taskConfig )
				.then( onLoad )
				.catch( onError );

		}, onProgress, onError );

	},

	/** @deprecated Kept for backward-compatibility with previous DRACOLoader versions. */
	decodeDracoFile: function ( buffer, callback, attributeIDs, attributeTypes ) {

		var taskConfig = {
			attributeIDs: attributeIDs || this.defaultAttributeIDs,
			attributeTypes: attributeTypes || this.defaultAttributeTypes,
			useUniqueIDs: !! attributeIDs
		};

		this.decodeGeometry( buffer, taskConfig ).then( callback );

	},

	decodeGeometry: function ( buffer, taskConfig ) {

		// TODO: For backward-compatibility, support 'attributeTypes' objects containing
		// references (rather than names) to typed array constructors. These must be
		// serialized before sending them to the worker.
		for ( var attribute in taskConfig.attributeTypes ) {

			var type = taskConfig.attributeTypes[ attribute ];

			if ( type.BYTES_PER_ELEMENT !== undefined ) {

				taskConfig.attributeTypes[ attribute ] = type.name;

			}

		}

		//

		var taskKey = JSON.stringify( taskConfig );

		// Check for an existing task using this buffer. A transferred buffer cannot be transferred
		// again from this thread.
		if ( THREE.DRACOLoader.taskCache.has( buffer ) ) {

			var cachedTask = THREE.DRACOLoader.taskCache.get( buffer );

			if ( cachedTask.key === taskKey ) {

				return cachedTask.promise;

			} else if ( buffer.byteLength === 0 ) {

				// Technically, it would be possible to wait for the previous task to complete,
				// transfer the buffer back, and decode again with the second configuration. That
				// is complex, and I don't know of any reason to decode a Draco buffer twice in
				// different ways, so this is left unimplemented.
				throw new Error(

					'THREE.DRACOLoader: Unable to re-decode a buffer with different ' +
					'settings. Buffer has already been transferred.'

				);

			}

		}

		//

		var worker;
		var taskID = this.workerNextTaskID ++;
		var taskCost = buffer.byteLength;

		// Obtain a worker and assign a task, and construct a geometry instance
		// when the task completes.
		var geometryPending = this._getWorker( taskID, taskCost )
			.then( ( _worker ) => {

				worker = _worker;

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

					worker._callbacks[ taskID ] = { resolve, reject };

					worker.postMessage( { type: 'decode', id: taskID, taskConfig, buffer }, [ buffer ] );

					// this.debug();

				} );

			} )
			.then( ( message ) => this._createGeometry( message.geometry ) );

		// Remove task from the task list.
		geometryPending
			.finally( () => {

				if ( worker && taskID ) {

					this._releaseTask( worker, taskID );

					// this.debug();

				}

			} );

		// Cache the task result.
		THREE.DRACOLoader.taskCache.set( buffer, {

			key: taskKey,
			promise: geometryPending

		} );

		return geometryPending;

	},

	_createGeometry: function ( geometryData ) {

		var geometry = new THREE.BufferGeometry();

		if ( geometryData.index ) {

			geometry.setIndex( new THREE.BufferAttribute( geometryData.index.array, 1 ) );

		}

		for ( var i = 0; i < geometryData.attributes.length; i ++ ) {

			var attribute = geometryData.attributes[ i ];
			var name = attribute.name;
			var array = attribute.array;
			var itemSize = attribute.itemSize;

			geometry.setAttribute( name, new THREE.BufferAttribute( array, itemSize ) );

		}

		return geometry;

	},

	_loadLibrary: function ( url, responseType ) {

		var loader = new THREE.FileLoader( this.manager );
		loader.setPath( this.decoderPath );
		loader.setResponseType( responseType );

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

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

		} );

	},

	preload: function () {

		this._initDecoder();

		return this;

	},

	_initDecoder: function () {

		if ( this.decoderPending ) return this.decoderPending;

		var useJS = typeof WebAssembly !== 'object' || this.decoderConfig.type === 'js';
		var 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 ) => {

				var jsContent = libraries[ 0 ];

				if ( ! useJS ) {

					this.decoderConfig.wasmBinary = libraries[ 1 ];

				}

				var fn = THREE.DRACOLoader.DRACOWorker.toString();

				var body = [
					'/* draco decoder */',
					jsContent,
					'',
					'/* worker */',
					fn.substring( fn.indexOf( '{' ) + 1, fn.lastIndexOf( '}' ) )
				].join( '\n' );

				this.workerSourceURL = URL.createObjectURL( new Blob( [ body ] ) );

			} );

		return this.decoderPending;

	},

	_getWorker: function ( taskID, taskCost ) {

		return this._initDecoder().then( () => {

			if ( this.workerPool.length < this.workerLimit ) {

				var worker = new Worker( this.workerSourceURL );

				worker._callbacks = {};
				worker._taskCosts = {};
				worker._taskLoad = 0;

				worker.postMessage( { type: 'init', decoderConfig: this.decoderConfig } );

				worker.onmessage = function ( e ) {

					var message = e.data;

					switch ( message.type ) {

						case 'decode':
							worker._callbacks[ message.id ].resolve( message );
							break;

						case 'error':
							worker._callbacks[ message.id ].reject( message );
							break;

						default:
							console.error( 'THREE.DRACOLoader: Unexpected message, "' + message.type + '"' );

					}

				};

				this.workerPool.push( worker );

			} else {

				this.workerPool.sort( function ( a, b ) {

					return a._taskLoad > b._taskLoad ? - 1 : 1;

				} );

			}

			var worker = this.workerPool[ this.workerPool.length - 1 ];
			worker._taskCosts[ taskID ] = taskCost;
			worker._taskLoad += taskCost;
			return worker;

		} );

	},

	_releaseTask: function ( worker, taskID ) {

		worker._taskLoad -= worker._taskCosts[ taskID ];
		delete worker._callbacks[ taskID ];
		delete worker._taskCosts[ taskID ];

	},

	debug: function () {

		console.log( 'Task load: ', this.workerPool.map( ( worker ) => worker._taskLoad ) );

	},

	dispose: function () {

		for ( var i = 0; i < this.workerPool.length; ++ i ) {

			this.workerPool[ i ].terminate();

		}

		this.workerPool.length = 0;

		return this;

	}

} );

/* WEB WORKER */

THREE.DRACOLoader.DRACOWorker = function () {

	var decoderConfig;
	var decoderPending;

	onmessage = function ( e ) {

		var message = e.data;

		switch ( message.type ) {

			case 'init':
				decoderConfig = message.decoderConfig;
				decoderPending = new Promise( function ( resolve/*, reject*/ ) {

					decoderConfig.onModuleLoaded = function ( draco ) {

						// Module is Promise-like. Wrap before resolving to avoid loop.
						resolve( { draco: draco } );

					};

					DracoDecoderModule( decoderConfig );

				} );
				break;

			case 'decode':
				var buffer = message.buffer;
				var taskConfig = message.taskConfig;
				decoderPending.then( ( module ) => {

					var draco = module.draco;
					var decoder = new draco.Decoder();
					var decoderBuffer = new draco.DecoderBuffer();
					decoderBuffer.Init( new Int8Array( buffer ), buffer.byteLength );

					try {

						var geometry = decodeGeometry( draco, decoder, decoderBuffer, taskConfig );

						var buffers = geometry.attributes.map( ( attr ) => attr.array.buffer );

						if ( geometry.index ) buffers.push( geometry.index.array.buffer );

						self.postMessage( { type: 'decode', id: message.id, geometry }, buffers );

					} catch ( error ) {

						console.error( error );

						self.postMessage( { type: 'error', id: message.id, error: error.message } );

					} finally {

						draco.destroy( decoderBuffer );
						draco.destroy( decoder );

					}

				} );
				break;

		}

	};

	function decodeGeometry( draco, decoder, decoderBuffer, taskConfig ) {

		var attributeIDs = taskConfig.attributeIDs;
		var attributeTypes = taskConfig.attributeTypes;

		var dracoGeometry;
		var decodingStatus;

		var geometryType = decoder.GetEncodedGeometryType( decoderBuffer );

		if ( geometryType === draco.TRIANGULAR_MESH ) {

			dracoGeometry = new draco.Mesh();
			decodingStatus = decoder.DecodeBufferToMesh( decoderBuffer, dracoGeometry );

		} else if ( geometryType === draco.POINT_CLOUD ) {

			dracoGeometry = new draco.PointCloud();
			decodingStatus = decoder.DecodeBufferToPointCloud( decoderBuffer, dracoGeometry );

		} else {

			throw new Error( 'THREE.DRACOLoader: Unexpected geometry type.' );

		}

		if ( ! decodingStatus.ok() || dracoGeometry.ptr === 0 ) {

			throw new Error( 'THREE.DRACOLoader: Decoding failed: ' + decodingStatus.error_msg() );

		}

		var geometry = { index: null, attributes: [] };

		// Gather all vertex attributes.
		for ( var attributeName in attributeIDs ) {

			var attributeType = self[ attributeTypes[ attributeName ] ];

			var attribute;
			var attributeID;

			// A Draco file may be created with default vertex attributes, whose attribute IDs
			// are mapped 1:1 from their semantic name (POSITION, NORMAL, ...). Alternatively,
			// a Draco file may contain a custom set of attributes, identified by known unique
			// IDs. glTF files always do the latter, and `.drc` files typically do the former.
			if ( taskConfig.useUniqueIDs ) {

				attributeID = attributeIDs[ attributeName ];
				attribute = decoder.GetAttributeByUniqueId( dracoGeometry, attributeID );

			} else {

				attributeID = decoder.GetAttributeId( dracoGeometry, draco[ attributeIDs[ attributeName ] ] );

				if ( attributeID === - 1 ) continue;

				attribute = decoder.GetAttribute( dracoGeometry, attributeID );

			}

			geometry.attributes.push( decodeAttribute( draco, decoder, dracoGeometry, attributeName, attributeType, attribute ) );

		}

		// Add index.
		if ( geometryType === draco.TRIANGULAR_MESH ) {

			// Generate mesh faces.
			var numFaces = dracoGeometry.num_faces();
			var numIndices = numFaces * 3;
			var index = new Uint32Array( numIndices );
			var indexArray = new draco.DracoInt32Array();

			for ( var i = 0; i < numFaces; ++ i ) {

				decoder.GetFaceFromMesh( dracoGeometry, i, indexArray );

				for ( var j = 0; j < 3; ++ j ) {

					index[ i * 3 + j ] = indexArray.GetValue( j );

				}

			}

			geometry.index = { array: index, itemSize: 1 };

			draco.destroy( indexArray );

		}

		draco.destroy( dracoGeometry );

		return geometry;

	}

	function decodeAttribute( draco, decoder, dracoGeometry, attributeName, attributeType, attribute ) {

		var numComponents = attribute.num_components();
		var numPoints = dracoGeometry.num_points();
		var numValues = numPoints * numComponents;
		var dracoArray;

		var array;

		switch ( attributeType ) {

			case Float32Array:
				dracoArray = new draco.DracoFloat32Array();
				decoder.GetAttributeFloatForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Float32Array( numValues );
				break;

			case Int8Array:
				dracoArray = new draco.DracoInt8Array();
				decoder.GetAttributeInt8ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Int8Array( numValues );
				break;

			case Int16Array:
				dracoArray = new draco.DracoInt16Array();
				decoder.GetAttributeInt16ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Int16Array( numValues );
				break;

			case Int32Array:
				dracoArray = new draco.DracoInt32Array();
				decoder.GetAttributeInt32ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Int32Array( numValues );
				break;

			case Uint8Array:
				dracoArray = new draco.DracoUInt8Array();
				decoder.GetAttributeUInt8ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Uint8Array( numValues );
				break;

			case Uint16Array:
				dracoArray = new draco.DracoUInt16Array();
				decoder.GetAttributeUInt16ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Uint16Array( numValues );
				break;

			case Uint32Array:
				dracoArray = new draco.DracoUInt32Array();
				decoder.GetAttributeUInt32ForAllPoints( dracoGeometry, attribute, dracoArray );
				array = new Uint32Array( numValues );
				break;

			default:
				throw new Error( 'THREE.DRACOLoader: Unexpected attribute type.' );

		}

		for ( var i = 0; i < numValues; i ++ ) {

			array[ i ] = dracoArray.GetValue( i );

		}

		draco.destroy( dracoArray );

		return {
			name: attributeName,
			array: array,
			itemSize: numComponents
		};

	}

};

THREE.DRACOLoader.taskCache = new WeakMap();

/** Deprecated static methods */

/** @deprecated */
THREE.DRACOLoader.setDecoderPath = function () {

	console.warn( 'THREE.DRACOLoader: The .setDecoderPath() method has been removed. Use instance methods.' );

};

/** @deprecated */
THREE.DRACOLoader.setDecoderConfig = function () {

	console.warn( 'THREE.DRACOLoader: The .setDecoderConfig() method has been removed. Use instance methods.' );

};

/** @deprecated */
THREE.DRACOLoader.releaseDecoderModule = function () {

	console.warn( 'THREE.DRACOLoader: The .releaseDecoderModule() method has been removed. Use instance methods.' );

};

/** @deprecated */
THREE.DRACOLoader.getDecoderModule = function () {

	console.warn( 'THREE.DRACOLoader: The .getDecoderModule() method has been removed. Use instance methods.' );

};
