/**
 * @author Nikos M. / https://github.com/foo123/
 */

// https://github.com/mrdoob/three.js/issues/5552
// http://en.wikipedia.org/wiki/RGBE_image_format

THREE.RGBELoader = function ( manager ) {

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

};

// extend THREE.DataTextureLoader
THREE.RGBELoader.prototype = Object.create( THREE.DataTextureLoader.prototype );

// adapted from http://www.graphics.cornell.edu/~bjw/rgbe.html
THREE.RGBELoader.prototype._parser = function ( buffer ) {

	var
		/* return codes for rgbe routines */
		//RGBE_RETURN_SUCCESS = 0,
		RGBE_RETURN_FAILURE = - 1,

		/* default error routine.  change this to change error handling */
		rgbe_read_error = 1,
		rgbe_write_error = 2,
		rgbe_format_error = 3,
		rgbe_memory_error = 4,
		rgbe_error = function ( rgbe_error_code, msg ) {

			switch ( rgbe_error_code ) {

				case rgbe_read_error: console.error( "THREE.RGBELoader Read Error: " + ( msg || '' ) );
					break;
				case rgbe_write_error: console.error( "THREE.RGBELoader Write Error: " + ( msg || '' ) );
					break;
				case rgbe_format_error: console.error( "THREE.RGBELoader Bad File Format: " + ( msg || '' ) );
					break;
				default:
				case rgbe_memory_error: console.error( "THREE.RGBELoader: Error: " + ( msg || '' ) );

			}
			return RGBE_RETURN_FAILURE;

		},

		/* offsets to red, green, and blue components in a data (float) pixel */
		//RGBE_DATA_RED = 0,
		//RGBE_DATA_GREEN = 1,
		//RGBE_DATA_BLUE = 2,

		/* number of floats per pixel, use 4 since stored in rgba image format */
		//RGBE_DATA_SIZE = 4,

		/* flags indicating which fields in an rgbe_header_info are valid */
		RGBE_VALID_PROGRAMTYPE = 1,
		RGBE_VALID_FORMAT = 2,
		RGBE_VALID_DIMENSIONS = 4,

		NEWLINE = "\n",

		fgets = function ( buffer, lineLimit, consume ) {

			lineLimit = ! lineLimit ? 1024 : lineLimit;
			var p = buffer.pos,
				i = - 1, len = 0, s = '', chunkSize = 128,
				chunk = String.fromCharCode.apply( null, new Uint16Array( buffer.subarray( p, p + chunkSize ) ) )
			;
			while ( ( 0 > ( i = chunk.indexOf( NEWLINE ) ) ) && ( len < lineLimit ) && ( p < buffer.byteLength ) ) {

				s += chunk; len += chunk.length;
				p += chunkSize;
				chunk += String.fromCharCode.apply( null, new Uint16Array( buffer.subarray( p, p + chunkSize ) ) );

			}

			if ( - 1 < i ) {

				/*for (i=l-1; i>=0; i--) {
					byteCode = m.charCodeAt(i);
					if (byteCode > 0x7f && byteCode <= 0x7ff) byteLen++;
					else if (byteCode > 0x7ff && byteCode <= 0xffff) byteLen += 2;
					if (byteCode >= 0xDC00 && byteCode <= 0xDFFF) i--; //trail surrogate
				}*/
				if ( false !== consume ) buffer.pos += len + i + 1;
				return s + chunk.slice( 0, i );

			}
			return false;

		},

		/* minimal header reading.  modify if you want to parse more information */
		RGBE_ReadHeader = function ( buffer ) {

			var line, match,

				// regexes to parse header info fields
				magic_token_re = /^#\?(\S+)$/,
				gamma_re = /^\s*GAMMA\s*=\s*(\d+(\.\d+)?)\s*$/,
				exposure_re = /^\s*EXPOSURE\s*=\s*(\d+(\.\d+)?)\s*$/,
				format_re = /^\s*FORMAT=(\S+)\s*$/,
				dimensions_re = /^\s*\-Y\s+(\d+)\s+\+X\s+(\d+)\s*$/,

				// RGBE format header struct
				header = {

					valid: 0, /* indicate which fields are valid */

					string: '', /* the actual header string */

					comments: '', /* comments found in header */

					programtype: 'RGBE', /* listed at beginning of file to identify it after "#?". defaults to "RGBE" */

					format: '', /* RGBE format, default 32-bit_rle_rgbe */

					gamma: 1.0, /* image has already been gamma corrected with given gamma. defaults to 1.0 (no correction) */

					exposure: 1.0, /* a value of 1.0 in an image corresponds to <exposure> watts/steradian/m^2. defaults to 1.0 */

					width: 0, height: 0 /* image dimensions, width/height */

				};

			if ( buffer.pos >= buffer.byteLength || ! ( line = fgets( buffer ) ) ) {

				return rgbe_error( rgbe_read_error, "no header found" );

			}
			/* if you want to require the magic token then uncomment the next line */
			if ( ! ( match = line.match( magic_token_re ) ) ) {

				return rgbe_error( rgbe_format_error, "bad initial token" );

			}
			header.valid |= RGBE_VALID_PROGRAMTYPE;
			header.programtype = match[ 1 ];
			header.string += line + "\n";

			while ( true ) {

				line = fgets( buffer );
				if ( false === line ) break;
				header.string += line + "\n";

				if ( '#' === line.charAt( 0 ) ) {

					header.comments += line + "\n";
					continue; // comment line

				}

				if ( match = line.match( gamma_re ) ) {

					header.gamma = parseFloat( match[ 1 ], 10 );

				}
				if ( match = line.match( exposure_re ) ) {

					header.exposure = parseFloat( match[ 1 ], 10 );

				}
				if ( match = line.match( format_re ) ) {

					header.valid |= RGBE_VALID_FORMAT;
					header.format = match[ 1 ];//'32-bit_rle_rgbe';

				}
				if ( match = line.match( dimensions_re ) ) {

					header.valid |= RGBE_VALID_DIMENSIONS;
					header.height = parseInt( match[ 1 ], 10 );
					header.width = parseInt( match[ 2 ], 10 );

				}

				if ( ( header.valid & RGBE_VALID_FORMAT ) && ( header.valid & RGBE_VALID_DIMENSIONS ) ) break;

			}

			if ( ! ( header.valid & RGBE_VALID_FORMAT ) ) {

				return rgbe_error( rgbe_format_error, "missing format specifier" );

			}
			if ( ! ( header.valid & RGBE_VALID_DIMENSIONS ) ) {

				return rgbe_error( rgbe_format_error, "missing image size specifier" );

			}

			return header;

		},

		RGBE_ReadPixels_RLE = function ( buffer, w, h ) {

			var data_rgba, offset, pos, count, byteValue,
				scanline_buffer, ptr, ptr_end, i, l, off, isEncodedRun,
				scanline_width = w, num_scanlines = h, rgbeStart
			;

			if (
				// run length encoding is not allowed so read flat
				( ( scanline_width < 8 ) || ( scanline_width > 0x7fff ) ) ||
				// this file is not run length encoded
				( ( 2 !== buffer[ 0 ] ) || ( 2 !== buffer[ 1 ] ) || ( buffer[ 2 ] & 0x80 ) )
			) {

				// return the flat buffer
				return new Uint8Array( buffer );

			}

			if ( scanline_width !== ( ( buffer[ 2 ] << 8 ) | buffer[ 3 ] ) ) {

				return rgbe_error( rgbe_format_error, "wrong scanline width" );

			}

			data_rgba = new Uint8Array( 4 * w * h );

			if ( ! data_rgba || ! data_rgba.length ) {

				return rgbe_error( rgbe_memory_error, "unable to allocate buffer space" );

			}

			offset = 0; pos = 0; ptr_end = 4 * scanline_width;
			rgbeStart = new Uint8Array( 4 );
			scanline_buffer = new Uint8Array( ptr_end );

			// read in each successive scanline
			while ( ( num_scanlines > 0 ) && ( pos < buffer.byteLength ) ) {

				if ( pos + 4 > buffer.byteLength ) {

					return rgbe_error( rgbe_read_error );

				}

				rgbeStart[ 0 ] = buffer[ pos ++ ];
				rgbeStart[ 1 ] = buffer[ pos ++ ];
				rgbeStart[ 2 ] = buffer[ pos ++ ];
				rgbeStart[ 3 ] = buffer[ pos ++ ];

				if ( ( 2 != rgbeStart[ 0 ] ) || ( 2 != rgbeStart[ 1 ] ) || ( ( ( rgbeStart[ 2 ] << 8 ) | rgbeStart[ 3 ] ) != scanline_width ) ) {

					return rgbe_error( rgbe_format_error, "bad rgbe scanline format" );

				}

				// read each of the four channels for the scanline into the buffer
				// first red, then green, then blue, then exponent
				ptr = 0;
				while ( ( ptr < ptr_end ) && ( pos < buffer.byteLength ) ) {

					count = buffer[ pos ++ ];
					isEncodedRun = count > 128;
					if ( isEncodedRun ) count -= 128;

					if ( ( 0 === count ) || ( ptr + count > ptr_end ) ) {

						return rgbe_error( rgbe_format_error, "bad scanline data" );

					}

					if ( isEncodedRun ) {

						// a (encoded) run of the same value
						byteValue = buffer[ pos ++ ];
						for ( i = 0; i < count; i ++ ) {

							scanline_buffer[ ptr ++ ] = byteValue;

						}
						//ptr += count;

					} else {

						// a literal-run
						scanline_buffer.set( buffer.subarray( pos, pos + count ), ptr );
						ptr += count; pos += count;

					}

				}


				// now convert data from buffer into rgba
				// first red, then green, then blue, then exponent (alpha)
				l = scanline_width; //scanline_buffer.byteLength;
				for ( i = 0; i < l; i ++ ) {

					off = 0;
					data_rgba[ offset ] = scanline_buffer[ i + off ];
					off += scanline_width; //1;
					data_rgba[ offset + 1 ] = scanline_buffer[ i + off ];
					off += scanline_width; //1;
					data_rgba[ offset + 2 ] = scanline_buffer[ i + off ];
					off += scanline_width; //1;
					data_rgba[ offset + 3 ] = scanline_buffer[ i + off ];
					offset += 4;

				}

				num_scanlines --;

			}

			return data_rgba;

		};

	var RGBEByteToRGBFloat = function ( sourceArray, sourceOffset, destArray, destOffset ) {

		var e = sourceArray[ sourceOffset + 3 ];
		var scale = Math.pow( 2.0, e - 128.0 ) / 255.0;

		destArray[ destOffset + 0 ] = sourceArray[ sourceOffset + 0 ] * scale;
		destArray[ destOffset + 1 ] = sourceArray[ sourceOffset + 1 ] * scale;
		destArray[ destOffset + 2 ] = sourceArray[ sourceOffset + 2 ] * scale;

	};

	var RGBEByteToRGBHalf = ( function () {

		// Source: http://gamedev.stackexchange.com/questions/17326/conversion-of-a-number-from-single-precision-floating-point-representation-to-a/17410#17410

		var floatView = new Float32Array( 1 );
		var int32View = new Int32Array( floatView.buffer );

		/* This method is faster than the OpenEXR implementation (very often
		 * used, eg. in Ogre), with the additional benefit of rounding, inspired
		 * by James Tursa?s half-precision code. */
		function toHalf( val ) {

			floatView[ 0 ] = val;
			var x = int32View[ 0 ];

			var bits = ( x >> 16 ) & 0x8000; /* Get the sign */
			var m = ( x >> 12 ) & 0x07ff; /* Keep one extra bit for rounding */
			var e = ( x >> 23 ) & 0xff; /* Using int is faster here */

			/* If zero, or denormal, or exponent underflows too much for a denormal
			 * half, return signed zero. */
			if ( e < 103 ) return bits;

			/* If NaN, return NaN. If Inf or exponent overflow, return Inf. */
			if ( e > 142 ) {

				bits |= 0x7c00;
				/* If exponent was 0xff and one mantissa bit was set, it means NaN,
						 * not Inf, so make sure we set one mantissa bit too. */
				bits |= ( ( e == 255 ) ? 0 : 1 ) && ( x & 0x007fffff );
				return bits;

			}

			/* If exponent underflows but not too much, return a denormal */
			if ( e < 113 ) {

				m |= 0x0800;
				/* Extra rounding may overflow and set mantissa to 0 and exponent
				 * to 1, which is OK. */
				bits |= ( m >> ( 114 - e ) ) + ( ( m >> ( 113 - e ) ) & 1 );
				return bits;

			}

			bits |= ( ( e - 112 ) << 10 ) | ( m >> 1 );
			/* Extra rounding. An overflow will set mantissa to 0 and increment
			 * the exponent, which is OK. */
			bits += m & 1;
			return bits;

		}

		return function ( sourceArray, sourceOffset, destArray, destOffset ) {

			var e = sourceArray[ sourceOffset + 3 ];
			var scale = Math.pow( 2.0, e - 128.0 ) / 255.0;

			destArray[ destOffset + 0 ] = toHalf( sourceArray[ sourceOffset + 0 ] * scale );
			destArray[ destOffset + 1 ] = toHalf( sourceArray[ sourceOffset + 1 ] * scale );
			destArray[ destOffset + 2 ] = toHalf( sourceArray[ sourceOffset + 2 ] * scale );

		};

	} )();

	var byteArray = new Uint8Array( buffer );
	byteArray.pos = 0;
	var rgbe_header_info = RGBE_ReadHeader( byteArray );

	if ( RGBE_RETURN_FAILURE !== rgbe_header_info ) {

		var w = rgbe_header_info.width,
			h = rgbe_header_info.height,
			image_rgba_data = RGBE_ReadPixels_RLE( byteArray.subarray( byteArray.pos ), w, h );

		if ( RGBE_RETURN_FAILURE !== image_rgba_data ) {

			switch ( this.type ) {

				case THREE.UnsignedByteType:

					var data = image_rgba_data;
					var format = THREE.RGBEFormat; // handled as THREE.RGBAFormat in shaders
					var type = THREE.UnsignedByteType;
					break;

				case THREE.FloatType:

					var numElements = ( image_rgba_data.length / 4 ) * 3;
					var floatArray = new Float32Array( numElements );

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

						RGBEByteToRGBFloat( image_rgba_data, j * 4, floatArray, j * 3 );

					}

					var data = floatArray;
					var format = THREE.RGBFormat;
					var type = THREE.FloatType;
					break;

				case THREE.HalfFloatType:

					var numElements = ( image_rgba_data.length / 4 ) * 3;
					var halfArray = new Uint16Array( numElements );

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

						RGBEByteToRGBHalf( image_rgba_data, j * 4, halfArray, j * 3 );

					}

					var data = halfArray;
					var format = THREE.RGBFormat;
					var type = THREE.HalfFloatType;
					break;

				default:

					console.error( 'THREE.RGBELoader: unsupported type: ', this.type );
					break;

			}

			return {
				width: w, height: h,
				data: data,
				header: rgbe_header_info.string,
				gamma: rgbe_header_info.gamma,
				exposure: rgbe_header_info.exposure,
				format: format,
				type: type
			};

		}

	}

	return null;

};

THREE.RGBELoader.prototype.setType = function ( value ) {

	this.type = value;
	return this;

};

THREE.RGBELoader.prototype.load = function ( url, onLoad, onProgress, onError ) {

	function onLoadCallback( texture, texData ) {

		switch ( texture.type ) {

			case THREE.UnsignedByteType:

				texture.encoding = THREE.RGBEEncoding;
				texture.minFilter = THREE.NearestFilter;
				texture.magFilter = THREE.NearestFilter;
				texture.generateMipmaps = false;
				texture.flipY = true;
				break;

			case THREE.FloatType:

				texture.encoding = THREE.LinearEncoding;
				texture.minFilter = THREE.LinearFilter;
				texture.magFilter = THREE.LinearFilter;
				texture.generateMipmaps = false;
				texture.flipY = true;
				break;

			case THREE.HalfFloatType:

				texture.encoding = THREE.LinearEncoding;
				texture.minFilter = THREE.LinearFilter;
				texture.magFilter = THREE.LinearFilter;
				texture.generateMipmaps = false;
				texture.flipY = true;
				break;

		}

		if ( onLoad ) onLoad( texture, texData );

	}

	return THREE.DataTextureLoader.prototype.load.call( this, url, onLoadCallback, onProgress, onError );

};
