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

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

THREE.HDRLoader = THREE.RGBELoader = function ( manager ) {

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

};

// extend THREE.BinaryTextureLoader
THREE.RGBELoader.prototype = Object.create( THREE.BinaryTextureLoader.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 byteArray = new Uint8Array( buffer ),
		byteLength = byteArray.byteLength;
	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 ) {

			return {
				width: w, height: h,
				data: image_rgba_data,
				header: rgbe_header_info.string,
				gamma: rgbe_header_info.gamma,
				exposure: rgbe_header_info.exposure,
				format: THREE.RGBEFormat, // handled as THREE.RGBAFormat in shaders
				type: THREE.UnsignedByteType
			};

		}

	}
	return null;

};
