/**
 * @author aleeper / http://adamleeper.com/
 * @author mrdoob / http://mrdoob.com/
 * @author gero3 / https://github.com/gero3
 *
 * 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.
 *
 * 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. Seems to work for the examples...
 *
 * 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.XHRLoader( 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 = new Float32Array( faces * 3 * 3 );

				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 offset = 0;

		var geometry = new THREE.BufferGeometry();

		var vertices = new Float32Array( faces * 3 * 3 );
		var normals = new Float32Array( faces * 3 * 3 );

		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[ offset ] = reader.getFloat32( vertexstart, true );
				vertices[ offset + 1 ] = reader.getFloat32( vertexstart + 4, true );
				vertices[ offset + 2 ] = reader.getFloat32( vertexstart + 8, true );

				normals[ offset ] = normalX;
				normals[ offset + 1 ] = normalY;
				normals[ offset + 2 ] = normalZ;

				if ( hasColors ) {

					colors[ offset ] = r;
					colors[ offset + 1 ] = g;
					colors[ offset + 2 ] = b;

				}

				offset += 3;

			}

		}

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

		if ( hasColors ) {

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

		}

		return geometry;

	},

	parseASCII: function ( data ) {

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

		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 = new THREE.Vector3( parseFloat( result[ 1 ] ), parseFloat( result[ 3 ] ), 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 ) {

				geometry.vertices.push( new THREE.Vector3( parseFloat( result[ 1 ] ), parseFloat( result[ 3 ] ), parseFloat( result[ 5 ] ) ) );

			}

			length = geometry.vertices.length;

			geometry.faces.push( new THREE.Face3( length - 3, length - 2, length - 1, normal ) );

		}

		geometry.computeBoundingBox();
		geometry.computeBoundingSphere();

		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;

		}

	}

};

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

	DataView = function( buffer, byteOffset, byteLength ) {

		this.buffer = buffer;
		this.byteOffset = byteOffset || 0;
		this.byteLength = byteLength || buffer.byteLength || buffer.length;
		this._isString = typeof buffer === "string";

	};

	DataView.prototype = {

		_getCharCodes: function( buffer, start, length ) {

			start = start || 0;
			length = length || buffer.length;
			var end = start + length;
			var codes = [];
			for ( var i = start; i < end; i ++ ) {

				codes.push( buffer.charCodeAt( i ) & 0xff );

			}
			return codes;

		},

		_getBytes: function ( length, byteOffset, littleEndian ) {

			var result;

			// Handle the lack of endianness
			if ( littleEndian === undefined ) {

				littleEndian = this._littleEndian;

			}

			// Handle the lack of byteOffset
			if ( byteOffset === undefined ) {

				byteOffset = this.byteOffset;

			} else {

				byteOffset = this.byteOffset + byteOffset;

			}

			if ( length === undefined ) {

				length = this.byteLength - byteOffset;

			}

			// Error Checking
			if ( typeof byteOffset !== 'number' ) {

				throw new TypeError( 'DataView byteOffset is not a number' );

			}

			if ( length < 0 || byteOffset + length > this.byteLength ) {

				throw new Error( 'DataView length or (byteOffset+length) value is out of bounds' );

			}

			if ( this.isString ) {

				result = this._getCharCodes( this.buffer, byteOffset, byteOffset + length );

			} else {

				result = this.buffer.slice( byteOffset, byteOffset + length );

			}

			if ( ! littleEndian && length > 1 ) {

				if ( Array.isArray( result ) === false ) {

					result = Array.prototype.slice.call( result );

				}

				result.reverse();

			}

			return result;

		},

		// Compatibility functions on a String Buffer

		getFloat64: function ( byteOffset, littleEndian ) {

			var b = this._getBytes( 8, byteOffset, littleEndian ),

				sign = 1 - ( 2 * ( b[ 7 ] >> 7 ) ),
				exponent = ( ( ( ( b[ 7 ] << 1 ) & 0xff ) << 3 ) | ( b[ 6 ] >> 4 ) ) - ( ( 1 << 10 ) - 1 ),

			// Binary operators such as | and << operate on 32 bit values, using + and Math.pow(2) instead
				mantissa = ( ( b[ 6 ] & 0x0f ) * Math.pow( 2, 48 ) ) + ( b[ 5 ] * Math.pow( 2, 40 ) ) + ( b[ 4 ] * Math.pow( 2, 32 ) ) +
							( b[ 3 ] * Math.pow( 2, 24 ) ) + ( b[ 2 ] * Math.pow( 2, 16 ) ) + ( b[ 1 ] * Math.pow( 2, 8 ) ) + b[ 0 ];

			if ( exponent === 1024 ) {

				if ( mantissa !== 0 ) {

					return NaN;

				} else {

					return sign * Infinity;

				}

			}

			if ( exponent === - 1023 ) {

				// Denormalized
				return sign * mantissa * Math.pow( 2, - 1022 - 52 );

			}

			return sign * ( 1 + mantissa * Math.pow( 2, - 52 ) ) * Math.pow( 2, exponent );

		},

		getFloat32: function ( byteOffset, littleEndian ) {

			var b = this._getBytes( 4, byteOffset, littleEndian ),

				sign = 1 - ( 2 * ( b[ 3 ] >> 7 ) ),
				exponent = ( ( ( b[ 3 ] << 1 ) & 0xff ) | ( b[ 2 ] >> 7 ) ) - 127,
				mantissa = ( ( b[ 2 ] & 0x7f ) << 16 ) | ( b[ 1 ] << 8 ) | b[ 0 ];

			if ( exponent === 128 ) {

				if ( mantissa !== 0 ) {

					return NaN;

				} else {

					return sign * Infinity;

				}

			}

			if ( exponent === - 127 ) {

				// Denormalized
				return sign * mantissa * Math.pow( 2, - 126 - 23 );

			}

			return sign * ( 1 + mantissa * Math.pow( 2, - 23 ) ) * Math.pow( 2, exponent );

		},

		getInt32: function ( byteOffset, littleEndian ) {

			var b = this._getBytes( 4, byteOffset, littleEndian );
			return ( b[ 3 ] << 24 ) | ( b[ 2 ] << 16 ) | ( b[ 1 ] << 8 ) | b[ 0 ];

		},

		getUint32: function ( byteOffset, littleEndian ) {

			return this.getInt32( byteOffset, littleEndian ) >>> 0;

		},

		getInt16: function ( byteOffset, littleEndian ) {

			return ( this.getUint16( byteOffset, littleEndian ) << 16 ) >> 16;

		},

		getUint16: function ( byteOffset, littleEndian ) {

			var b = this._getBytes( 2, byteOffset, littleEndian );
			return ( b[ 1 ] << 8 ) | b[ 0 ];

		},

		getInt8: function ( byteOffset ) {

			return ( this.getUint8( byteOffset ) << 24 ) >> 24;

		},

		getUint8: function ( byteOffset ) {

			return this._getBytes( 1, byteOffset )[ 0 ];

		}

	 };

}
