/**
 * @author aleeper / http://adamleeper.com/
 * @author mrdoob / http://mrdoob.com/
 * @author gero3 / https://github.com/gero3
 * @author Mugen87 / https://github.com/Mugen87
 *
 * Description: A THREE loader for STL ASCII files, as created by Solidworks and other CAD programs.
 *
 * Supports both binary and ASCII encoded files, with automatic detection of type.
 *
 * The loader returns a non-indexed buffer geometry.
 *
 * Limitations:
 *  Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
 *  There is perhaps some question as to how valid it is to always assume little-endian-ness.
 *  ASCII decoding assumes file is UTF-8.
 *
 * Usage:
 *  var loader = new THREE.STLLoader();
 *  loader.load( './models/stl/slotted_disk.stl', function ( geometry ) {
 *    scene.add( new THREE.Mesh( geometry ) );
 *  });
 *
 * For binary STLs geometry might contain colors for vertices. To use it:
 *  // use the same code to load STL as above
 *  if (geometry.hasColors) {
 *    material = new THREE.MeshPhongMaterial({ opacity: geometry.alpha, vertexColors: THREE.VertexColors });
 *  } else { .... }
 *  var mesh = new THREE.Mesh( geometry, material );
 */


THREE.STLLoader = function ( manager ) {

	this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager;

};

THREE.STLLoader.prototype = {

	constructor: THREE.STLLoader,

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

		var scope = this;

		var loader = new THREE.FileLoader( scope.manager );
		loader.setResponseType( 'arraybuffer' );
		loader.load( url, function ( text ) {

			onLoad( scope.parse( text ) );

		}, onProgress, onError );

	},

	parse: function ( data ) {

		var isBinary = function () {

			var expect, face_size, n_faces, reader;
			reader = new DataView( binData );
			face_size = ( 32 / 8 * 3 ) + ( ( 32 / 8 * 3 ) * 3 ) + ( 16 / 8 );
			n_faces = reader.getUint32( 80, true );
			expect = 80 + ( 32 / 8 ) + ( n_faces * face_size );

			if ( expect === reader.byteLength ) {

				return true;

			}

			// some binary files will have different size from expected,
			// checking characters higher than ASCII to confirm is binary
			var fileLength = reader.byteLength;
			for ( var index = 0; index < fileLength; index ++ ) {

				if ( reader.getUint8( index, false ) > 127 ) {

					return true;

				}

			}

			return false;

		};

		var binData = this.ensureBinary( data );

		return isBinary() ? this.parseBinary( binData ) : this.parseASCII( this.ensureString( data ) );

	},

	parseBinary: function ( data ) {

		var reader = new DataView( data );
		var faces = reader.getUint32( 80, true );

		var r, g, b, hasColors = false, colors;
		var defaultR, defaultG, defaultB, alpha;

		// process STL header
		// check for default color in header ("COLOR=rgba" sequence).

		for ( var index = 0; index < 80 - 10; index ++ ) {

			if ( ( reader.getUint32( index, false ) == 0x434F4C4F /*COLO*/ ) &&
				( reader.getUint8( index + 4 ) == 0x52 /*'R'*/ ) &&
				( reader.getUint8( index + 5 ) == 0x3D /*'='*/ ) ) {

				hasColors = true;
				colors = [];

				defaultR = reader.getUint8( index + 6 ) / 255;
				defaultG = reader.getUint8( index + 7 ) / 255;
				defaultB = reader.getUint8( index + 8 ) / 255;
				alpha = reader.getUint8( index + 9 ) / 255;

			}

		}

		var dataOffset = 84;
		var faceLength = 12 * 4 + 2;

		var geometry = new THREE.BufferGeometry();

		var vertices = [];
		var normals = [];

		for ( var face = 0; face < faces; face ++ ) {

			var start = dataOffset + face * faceLength;
			var normalX = reader.getFloat32( start, true );
			var normalY = reader.getFloat32( start + 4, true );
			var normalZ = reader.getFloat32( start + 8, true );

			if ( hasColors ) {

				var packedColor = reader.getUint16( start + 48, true );

				if ( ( packedColor & 0x8000 ) === 0 ) {

					// facet has its own unique color

					r = ( packedColor & 0x1F ) / 31;
					g = ( ( packedColor >> 5 ) & 0x1F ) / 31;
					b = ( ( packedColor >> 10 ) & 0x1F ) / 31;

				} else {

					r = defaultR;
					g = defaultG;
					b = defaultB;

				}

			}

			for ( var i = 1; i <= 3; i ++ ) {

				var vertexstart = start + i * 12;

				vertices.push( reader.getFloat32( vertexstart, true ) );
				vertices.push( reader.getFloat32( vertexstart + 4, true ) );
				vertices.push( reader.getFloat32( vertexstart + 8, true ) );

				normals.push( normalX, normalY, normalZ );

				if ( hasColors ) {

					colors.push( r, g, b );

				}

			}

		}

		geometry.addAttribute( 'position', new THREE.BufferAttribute( new Float32Array( vertices ), 3 ) );
		geometry.addAttribute( 'normal', new THREE.BufferAttribute( new Float32Array( normals ), 3 ) );

		if ( hasColors ) {

			geometry.addAttribute( 'color', new THREE.BufferAttribute( new Float32Array( colors ), 3 ) );
			geometry.hasColors = true;
			geometry.alpha = alpha;

		}

		return geometry;

	},

	parseASCII: function ( data ) {

		var geometry, length, patternFace, patternNormal, patternVertex, result, text;
		geometry = new THREE.BufferGeometry();
		patternFace = /facet([\s\S]*?)endfacet/g;

		var vertices = [];
		var normals = [];

		var normal = new THREE.Vector3();

		while ( ( result = patternFace.exec( data ) ) !== null ) {

			text = result[ 0 ];
			patternNormal = /normal[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;

			while ( ( result = patternNormal.exec( text ) ) !== null ) {

				normal.x = parseFloat( result[ 1 ] );
				normal.y = parseFloat( result[ 3 ] );
				normal.z = parseFloat( result[ 5 ] );

			}

			patternVertex = /vertex[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;

			while ( ( result = patternVertex.exec( text ) ) !== null ) {

				vertices.push( parseFloat( result[ 1 ] ), parseFloat( result[ 3 ] ), parseFloat( result[ 5 ] ) );
				normals.push( normal.x, normal.y, normal.z );

			}

		}

		geometry.addAttribute( 'position', new THREE.BufferAttribute( new Float32Array( vertices ), 3 ) );
		geometry.addAttribute( 'normal', new THREE.BufferAttribute( new Float32Array( normals ), 3 ) );

		return geometry;

	},

	ensureString: function ( buf ) {

		if ( typeof buf !== "string" ) {

			var array_buffer = new Uint8Array( buf );
			var strArray = [];
			for ( var i = 0; i < buf.byteLength; i ++ ) {

				strArray.push(String.fromCharCode( array_buffer[ i ] )); // implicitly assumes little-endian

			}
			return strArray.join('');

		} else {

			return buf;

		}

	},

	ensureBinary: function ( buf ) {

		if ( typeof buf === "string" ) {

			var array_buffer = new Uint8Array( buf.length );
			for ( var i = 0; i < buf.length; i ++ ) {

				array_buffer[ i ] = buf.charCodeAt( i ) & 0xff; // implicitly assumes little-endian

			}
			return array_buffer.buffer || array_buffer;

		} else {

			return buf;

		}

	}

};
