/*

 Javascript library for reading EXIF image meta data
 https://github.com/exif-js/exif-js
 
 The MIT License (MIT)

 Copyright (c) 2008 Jacob Seidelin

 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

(function() {

	var debug = false;

	var root = this;

	var EXIF = function(obj) {
		if (obj instanceof EXIF) return obj;
		if (!(this instanceof EXIF)) return new EXIF(obj);
		this.EXIFwrapped = obj;
	};

	if (typeof exports !== 'undefined') {
		if (typeof module !== 'undefined' && module.exports) {
			exports = module.exports = EXIF;
		}
		exports.EXIF = EXIF;
	} else {
		root.EXIF = EXIF;
	}

	var ExifTags = EXIF.Tags = {

		// version tags
		0x9000 : "ExifVersion",             // EXIF version
		0xA000 : "FlashpixVersion",         // Flashpix format version

		// colorspace tags
		0xA001 : "ColorSpace",              // Color space information tag

		// image configuration
		0xA002 : "PixelXDimension",         // Valid width of meaningful image
		0xA003 : "PixelYDimension",         // Valid height of meaningful image
		0x9101 : "ComponentsConfiguration", // Information about channels
		0x9102 : "CompressedBitsPerPixel",  // Compressed bits per pixel

		// user information
		0x927C : "MakerNote",               // Any desired information written by the manufacturer
		0x9286 : "UserComment",             // Comments by user

		// related file
		0xA004 : "RelatedSoundFile",        // Name of related sound file

		// date and time
		0x9003 : "DateTimeOriginal",        // Date and time when the original image was generated
		0x9004 : "DateTimeDigitized",       // Date and time when the image was stored digitally
		0x9290 : "SubsecTime",              // Fractions of seconds for DateTime
		0x9291 : "SubsecTimeOriginal",      // Fractions of seconds for DateTimeOriginal
		0x9292 : "SubsecTimeDigitized",     // Fractions of seconds for DateTimeDigitized

		// picture-taking conditions
		0x829A : "ExposureTime",            // Exposure time (in seconds)
		0x829D : "FNumber",                 // F number
		0x8822 : "ExposureProgram",         // Exposure program
		0x8824 : "SpectralSensitivity",     // Spectral sensitivity
		0x8827 : "ISOSpeedRatings",         // ISO speed rating
		0x8828 : "OECF",                    // Optoelectric conversion factor
		0x9201 : "ShutterSpeedValue",       // Shutter speed
		0x9202 : "ApertureValue",           // Lens aperture
		0x9203 : "BrightnessValue",         // Value of brightness
		0x9204 : "ExposureBias",            // Exposure bias
		0x9205 : "MaxApertureValue",        // Smallest F number of lens
		0x9206 : "SubjectDistance",         // Distance to subject in meters
		0x9207 : "MeteringMode",            // Metering mode
		0x9208 : "LightSource",             // Kind of light source
		0x9209 : "Flash",                   // Flash status
		0x9214 : "SubjectArea",             // Location and area of main subject
		0x920A : "FocalLength",             // Focal length of the lens in mm
		0xA20B : "FlashEnergy",             // Strobe energy in BCPS
		0xA20C : "SpatialFrequencyResponse",    //
		0xA20E : "FocalPlaneXResolution",   // Number of pixels in width direction per FocalPlaneResolutionUnit
		0xA20F : "FocalPlaneYResolution",   // Number of pixels in height direction per FocalPlaneResolutionUnit
		0xA210 : "FocalPlaneResolutionUnit",    // Unit for measuring FocalPlaneXResolution and FocalPlaneYResolution
		0xA214 : "SubjectLocation",         // Location of subject in image
		0xA215 : "ExposureIndex",           // Exposure index selected on camera
		0xA217 : "SensingMethod",           // Image sensor type
		0xA300 : "FileSource",              // Image source (3 == DSC)
		0xA301 : "SceneType",               // Scene type (1 == directly photographed)
		0xA302 : "CFAPattern",              // Color filter array geometric pattern
		0xA401 : "CustomRendered",          // Special processing
		0xA402 : "ExposureMode",            // Exposure mode
		0xA403 : "WhiteBalance",            // 1 = auto white balance, 2 = manual
		0xA404 : "DigitalZoomRation",       // Digital zoom ratio
		0xA405 : "FocalLengthIn35mmFilm",   // Equivalent foacl length assuming 35mm film camera (in mm)
		0xA406 : "SceneCaptureType",        // Type of scene
		0xA407 : "GainControl",             // Degree of overall image gain adjustment
		0xA408 : "Contrast",                // Direction of contrast processing applied by camera
		0xA409 : "Saturation",              // Direction of saturation processing applied by camera
		0xA40A : "Sharpness",               // Direction of sharpness processing applied by camera
		0xA40B : "DeviceSettingDescription",    //
		0xA40C : "SubjectDistanceRange",    // Distance to subject

		// other tags
		0xA005 : "InteroperabilityIFDPointer",
		0xA420 : "ImageUniqueID"            // Identifier assigned uniquely to each image
	};

	var TiffTags = EXIF.TiffTags = {
		0x0100 : "ImageWidth",
		0x0101 : "ImageHeight",
		0x8769 : "ExifIFDPointer",
		0x8825 : "GPSInfoIFDPointer",
		0xA005 : "InteroperabilityIFDPointer",
		0x0102 : "BitsPerSample",
		0x0103 : "Compression",
		0x0106 : "PhotometricInterpretation",
		0x0112 : "Orientation",
		0x0115 : "SamplesPerPixel",
		0x011C : "PlanarConfiguration",
		0x0212 : "YCbCrSubSampling",
		0x0213 : "YCbCrPositioning",
		0x011A : "XResolution",
		0x011B : "YResolution",
		0x0128 : "ResolutionUnit",
		0x0111 : "StripOffsets",
		0x0116 : "RowsPerStrip",
		0x0117 : "StripByteCounts",
		0x0201 : "JPEGInterchangeFormat",
		0x0202 : "JPEGInterchangeFormatLength",
		0x012D : "TransferFunction",
		0x013E : "WhitePoint",
		0x013F : "PrimaryChromaticities",
		0x0211 : "YCbCrCoefficients",
		0x0214 : "ReferenceBlackWhite",
		0x0132 : "DateTime",
		0x010E : "ImageDescription",
		0x010F : "Make",
		0x0110 : "Model",
		0x0131 : "Software",
		0x013B : "Artist",
		0x8298 : "Copyright"
	};

	var GPSTags = EXIF.GPSTags = {
		0x0000 : "GPSVersionID",
		0x0001 : "GPSLatitudeRef",
		0x0002 : "GPSLatitude",
		0x0003 : "GPSLongitudeRef",
		0x0004 : "GPSLongitude",
		0x0005 : "GPSAltitudeRef",
		0x0006 : "GPSAltitude",
		0x0007 : "GPSTimeStamp",
		0x0008 : "GPSSatellites",
		0x0009 : "GPSStatus",
		0x000A : "GPSMeasureMode",
		0x000B : "GPSDOP",
		0x000C : "GPSSpeedRef",
		0x000D : "GPSSpeed",
		0x000E : "GPSTrackRef",
		0x000F : "GPSTrack",
		0x0010 : "GPSImgDirectionRef",
		0x0011 : "GPSImgDirection",
		0x0012 : "GPSMapDatum",
		0x0013 : "GPSDestLatitudeRef",
		0x0014 : "GPSDestLatitude",
		0x0015 : "GPSDestLongitudeRef",
		0x0016 : "GPSDestLongitude",
		0x0017 : "GPSDestBearingRef",
		0x0018 : "GPSDestBearing",
		0x0019 : "GPSDestDistanceRef",
		0x001A : "GPSDestDistance",
		0x001B : "GPSProcessingMethod",
		0x001C : "GPSAreaInformation",
		0x001D : "GPSDateStamp",
		0x001E : "GPSDifferential"
	};

	// EXIF 2.3 Spec
	var IFD1Tags = EXIF.IFD1Tags = {
		0x0100: "ImageWidth",
		0x0101: "ImageHeight",
		0x0102: "BitsPerSample",
		0x0103: "Compression",
		0x0106: "PhotometricInterpretation",
		0x0111: "StripOffsets",
		0x0112: "Orientation",
		0x0115: "SamplesPerPixel",
		0x0116: "RowsPerStrip",
		0x0117: "StripByteCounts",
		0x011A: "XResolution",
		0x011B: "YResolution",
		0x011C: "PlanarConfiguration",
		0x0128: "ResolutionUnit",
		0x0201: "JpegIFOffset",    // When image format is JPEG, this value show offset to JPEG data stored.(aka "ThumbnailOffset" or "JPEGInterchangeFormat")
		0x0202: "JpegIFByteCount", // When image format is JPEG, this value shows data size of JPEG image (aka "ThumbnailLength" or "JPEGInterchangeFormatLength")
		0x0211: "YCbCrCoefficients",
		0x0212: "YCbCrSubSampling",
		0x0213: "YCbCrPositioning",
		0x0214: "ReferenceBlackWhite"
	};

	var StringValues = EXIF.StringValues = {
		ExposureProgram : {
			0 : "Not defined",
			1 : "Manual",
			2 : "Normal program",
			3 : "Aperture priority",
			4 : "Shutter priority",
			5 : "Creative program",
			6 : "Action program",
			7 : "Portrait mode",
			8 : "Landscape mode"
		},
		MeteringMode : {
			0 : "Unknown",
			1 : "Average",
			2 : "CenterWeightedAverage",
			3 : "Spot",
			4 : "MultiSpot",
			5 : "Pattern",
			6 : "Partial",
			255 : "Other"
		},
		LightSource : {
			0 : "Unknown",
			1 : "Daylight",
			2 : "Fluorescent",
			3 : "Tungsten (incandescent light)",
			4 : "Flash",
			9 : "Fine weather",
			10 : "Cloudy weather",
			11 : "Shade",
			12 : "Daylight fluorescent (D 5700 - 7100K)",
			13 : "Day white fluorescent (N 4600 - 5400K)",
			14 : "Cool white fluorescent (W 3900 - 4500K)",
			15 : "White fluorescent (WW 3200 - 3700K)",
			17 : "Standard light A",
			18 : "Standard light B",
			19 : "Standard light C",
			20 : "D55",
			21 : "D65",
			22 : "D75",
			23 : "D50",
			24 : "ISO studio tungsten",
			255 : "Other"
		},
		Flash : {
			0x0000 : "Flash did not fire",
			0x0001 : "Flash fired",
			0x0005 : "Strobe return light not detected",
			0x0007 : "Strobe return light detected",
			0x0009 : "Flash fired, compulsory flash mode",
			0x000D : "Flash fired, compulsory flash mode, return light not detected",
			0x000F : "Flash fired, compulsory flash mode, return light detected",
			0x0010 : "Flash did not fire, compulsory flash mode",
			0x0018 : "Flash did not fire, auto mode",
			0x0019 : "Flash fired, auto mode",
			0x001D : "Flash fired, auto mode, return light not detected",
			0x001F : "Flash fired, auto mode, return light detected",
			0x0020 : "No flash function",
			0x0041 : "Flash fired, red-eye reduction mode",
			0x0045 : "Flash fired, red-eye reduction mode, return light not detected",
			0x0047 : "Flash fired, red-eye reduction mode, return light detected",
			0x0049 : "Flash fired, compulsory flash mode, red-eye reduction mode",
			0x004D : "Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected",
			0x004F : "Flash fired, compulsory flash mode, red-eye reduction mode, return light detected",
			0x0059 : "Flash fired, auto mode, red-eye reduction mode",
			0x005D : "Flash fired, auto mode, return light not detected, red-eye reduction mode",
			0x005F : "Flash fired, auto mode, return light detected, red-eye reduction mode"
		},
		SensingMethod : {
			1 : "Not defined",
			2 : "One-chip color area sensor",
			3 : "Two-chip color area sensor",
			4 : "Three-chip color area sensor",
			5 : "Color sequential area sensor",
			7 : "Trilinear sensor",
			8 : "Color sequential linear sensor"
		},
		SceneCaptureType : {
			0 : "Standard",
			1 : "Landscape",
			2 : "Portrait",
			3 : "Night scene"
		},
		SceneType : {
			1 : "Directly photographed"
		},
		CustomRendered : {
			0 : "Normal process",
			1 : "Custom process"
		},
		WhiteBalance : {
			0 : "Auto white balance",
			1 : "Manual white balance"
		},
		GainControl : {
			0 : "None",
			1 : "Low gain up",
			2 : "High gain up",
			3 : "Low gain down",
			4 : "High gain down"
		},
		Contrast : {
			0 : "Normal",
			1 : "Soft",
			2 : "Hard"
		},
		Saturation : {
			0 : "Normal",
			1 : "Low saturation",
			2 : "High saturation"
		},
		Sharpness : {
			0 : "Normal",
			1 : "Soft",
			2 : "Hard"
		},
		SubjectDistanceRange : {
			0 : "Unknown",
			1 : "Macro",
			2 : "Close view",
			3 : "Distant view"
		},
		FileSource : {
			3 : "DSC"
		},

		Components : {
			0 : "",
			1 : "Y",
			2 : "Cb",
			3 : "Cr",
			4 : "R",
			5 : "G",
			6 : "B"
		}
	};

	function addEvent(element, event, handler) {
		if (element.addEventListener) {
			element.addEventListener(event, handler, false);
		} else if (element.attachEvent) {
			element.attachEvent("on" + event, handler);
		}
	}

	function imageHasData(img) {
		return !!(img.exifdata);
	}


	function base64ToArrayBuffer(base64, contentType) {
		contentType = contentType || base64.match(/^data\:([^\;]+)\;base64,/mi)[1] || ''; // e.g. 'data:image/jpeg;base64,...' => 'image/jpeg'
		base64 = base64.replace(/^data\:([^\;]+)\;base64,/gmi, '');
		var binary = atob(base64);
		var len = binary.length;
		var buffer = new ArrayBuffer(len);
		var view = new Uint8Array(buffer);
		for (var i = 0; i < len; i++) {
			view[i] = binary.charCodeAt(i);
		}
		return buffer;
	}

	function objectURLToBlob(url, callback) {
		var http = new XMLHttpRequest();
		http.open("GET", url, true);
		http.responseType = "blob";
		http.onload = function(e) {
			if (this.status == 200 || this.status === 0) {
				callback(this.response);
			}
		};
		http.send();
	}

	function getImageData(img, callback) {
		function handleBinaryFile(binFile) {
			var data = findEXIFinJPEG(binFile);
			var iptcdata = findIPTCinJPEG(binFile);
			var xmpdata= findXMPinJPEG(binFile);
			img.exifdata = data || {};
			img.iptcdata = iptcdata || {};
			img.xmpdata = xmpdata || {};
			if (callback) {
				callback.call(img);
			}
		}

		if (img.src) {
			if (/^data\:/i.test(img.src)) { // Data URI
				var arrayBuffer = base64ToArrayBuffer(img.src);
				handleBinaryFile(arrayBuffer);

			} else if (/^blob\:/i.test(img.src)) { // Object URL
				var fileReader = new FileReader();
				fileReader.onload = function(e) {
					handleBinaryFile(e.target.result);
				};
				objectURLToBlob(img.src, function (blob) {
					fileReader.readAsArrayBuffer(blob);
				});
			} else {
				var http = new XMLHttpRequest();
				http.onload = function() {
					if (this.status == 200 || this.status === 0) {
						handleBinaryFile(http.response);
					} else {
						throw "Could not load image";
					}
					http = null;
				};
				http.open("GET", img.src, true);
				http.responseType = "arraybuffer";
				http.send(null);
			}
		} else if (self.FileReader && (img instanceof self.Blob || img instanceof self.File)) {
			var fileReader = new FileReader();
			fileReader.onload = function(e) {
				if (debug) console.log("Got file of length " + e.target.result.byteLength);
				handleBinaryFile(e.target.result);
			};

			fileReader.readAsArrayBuffer(img);
		}
	}

	function findEXIFinJPEG(file) {
		var dataView = new DataView(file);

		if (debug) console.log("Got file of length " + file.byteLength);
		if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
			if (debug) console.log("Not a valid JPEG");
			return false; // not a valid jpeg
		}

		var offset = 2,
			length = file.byteLength,
			marker;

		while (offset < length) {
			if (dataView.getUint8(offset) != 0xFF) {
				if (debug) console.log("Not a valid marker at offset " + offset + ", found: " + dataView.getUint8(offset));
				return false; // not a valid marker, something is wrong
			}

			marker = dataView.getUint8(offset + 1);
			if (debug) console.log(marker);

			// we could implement handling for other markers here,
			// but we're only looking for 0xFFE1 for EXIF data

			if (marker == 225) {
				if (debug) console.log("Found 0xFFE1 marker");

				return readEXIFData(dataView, offset + 4, dataView.getUint16(offset + 2) - 2);

				// offset += 2 + file.getShortAt(offset+2, true);

			} else {
				offset += 2 + dataView.getUint16(offset+2);
			}

		}

	}

	function findIPTCinJPEG(file) {
		var dataView = new DataView(file);

		if (debug) console.log("Got file of length " + file.byteLength);
		if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
			if (debug) console.log("Not a valid JPEG");
			return false; // not a valid jpeg
		}

		var offset = 2,
			length = file.byteLength;


		var isFieldSegmentStart = function(dataView, offset){
			return (
				dataView.getUint8(offset) === 0x38 &&
				dataView.getUint8(offset+1) === 0x42 &&
				dataView.getUint8(offset+2) === 0x49 &&
				dataView.getUint8(offset+3) === 0x4D &&
				dataView.getUint8(offset+4) === 0x04 &&
				dataView.getUint8(offset+5) === 0x04
			);
		};

		while (offset < length) {

			if ( isFieldSegmentStart(dataView, offset )){

				// Get the length of the name header (which is padded to an even number of bytes)
				var nameHeaderLength = dataView.getUint8(offset+7);
				if(nameHeaderLength % 2 !== 0) nameHeaderLength += 1;
				// Check for pre photoshop 6 format
				if(nameHeaderLength === 0) {
					// Always 4
					nameHeaderLength = 4;
				}

				var startOffset = offset + 8 + nameHeaderLength;
				var sectionLength = dataView.getUint16(offset + 6 + nameHeaderLength);

				return readIPTCData(file, startOffset, sectionLength);

				break;

			}


			// Not the marker, continue searching
			offset++;

		}

	}
	var IptcFieldMap = {
		0x78 : 'caption',
		0x6E : 'credit',
		0x19 : 'keywords',
		0x37 : 'dateCreated',
		0x50 : 'byline',
		0x55 : 'bylineTitle',
		0x7A : 'captionWriter',
		0x69 : 'headline',
		0x74 : 'copyright',
		0x0F : 'category'
	};
	function readIPTCData(file, startOffset, sectionLength){
		var dataView = new DataView(file);
		var data = {};
		var fieldValue, fieldName, dataSize, segmentType, segmentSize;
		var segmentStartPos = startOffset;
		while(segmentStartPos < startOffset+sectionLength) {
			if(dataView.getUint8(segmentStartPos) === 0x1C && dataView.getUint8(segmentStartPos+1) === 0x02){
				segmentType = dataView.getUint8(segmentStartPos+2);
				if(segmentType in IptcFieldMap) {
					dataSize = dataView.getInt16(segmentStartPos+3);
					segmentSize = dataSize + 5;
					fieldName = IptcFieldMap[segmentType];
					fieldValue = getStringFromDB(dataView, segmentStartPos+5, dataSize);
					// Check if we already stored a value with this name
					if(data.hasOwnProperty(fieldName)) {
						// Value already stored with this name, create multivalue field
						if(data[fieldName] instanceof Array) {
							data[fieldName].push(fieldValue);
						}
						else {
							data[fieldName] = [data[fieldName], fieldValue];
						}
					}
					else {
						data[fieldName] = fieldValue;
					}
				}

			}
			segmentStartPos++;
		}
		return data;
	}



	function readTags(file, tiffStart, dirStart, strings, bigEnd) {
		var entries = file.getUint16(dirStart, !bigEnd),
			tags = {},
			entryOffset, tag,
			i;

		for (i=0;i<entries;i++) {
			entryOffset = dirStart + i*12 + 2;
			tag = strings[file.getUint16(entryOffset, !bigEnd)];
			if (!tag && debug) console.log("Unknown tag: " + file.getUint16(entryOffset, !bigEnd));
			tags[tag] = readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd);
		}
		return tags;
	}


	function readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd) {
		var type = file.getUint16(entryOffset+2, !bigEnd),
			numValues = file.getUint32(entryOffset+4, !bigEnd),
			valueOffset = file.getUint32(entryOffset+8, !bigEnd) + tiffStart,
			offset,
			vals, val, n,
			numerator, denominator;

		switch (type) {
			case 1: // byte, 8-bit unsigned int
			case 7: // undefined, 8-bit byte, value depending on field
				if (numValues == 1) {
					return file.getUint8(entryOffset + 8, !bigEnd);
				} else {
					offset = numValues > 4 ? valueOffset : (entryOffset + 8);
					vals = [];
					for (n=0;n<numValues;n++) {
						vals[n] = file.getUint8(offset + n);
					}
					return vals;
				}

			case 2: // ascii, 8-bit byte
				offset = numValues > 4 ? valueOffset : (entryOffset + 8);
				return getStringFromDB(file, offset, numValues-1);

			case 3: // short, 16 bit int
				if (numValues == 1) {
					return file.getUint16(entryOffset + 8, !bigEnd);
				} else {
					offset = numValues > 2 ? valueOffset : (entryOffset + 8);
					vals = [];
					for (n=0;n<numValues;n++) {
						vals[n] = file.getUint16(offset + 2*n, !bigEnd);
					}
					return vals;
				}

			case 4: // long, 32 bit int
				if (numValues == 1) {
					return file.getUint32(entryOffset + 8, !bigEnd);
				} else {
					vals = [];
					for (n=0;n<numValues;n++) {
						vals[n] = file.getUint32(valueOffset + 4*n, !bigEnd);
					}
					return vals;
				}

			case 5:    // rational = two long values, first is numerator, second is denominator
				if (numValues == 1) {
					numerator = file.getUint32(valueOffset, !bigEnd);
					denominator = file.getUint32(valueOffset+4, !bigEnd);
					val = new Number(numerator / denominator);
					val.numerator = numerator;
					val.denominator = denominator;
					return val;
				} else {
					vals = [];
					for (n=0;n<numValues;n++) {
						numerator = file.getUint32(valueOffset + 8*n, !bigEnd);
						denominator = file.getUint32(valueOffset+4 + 8*n, !bigEnd);
						vals[n] = new Number(numerator / denominator);
						vals[n].numerator = numerator;
						vals[n].denominator = denominator;
					}
					return vals;
				}

			case 9: // slong, 32 bit signed int
				if (numValues == 1) {
					return file.getInt32(entryOffset + 8, !bigEnd);
				} else {
					vals = [];
					for (n=0;n<numValues;n++) {
						vals[n] = file.getInt32(valueOffset + 4*n, !bigEnd);
					}
					return vals;
				}

			case 10: // signed rational, two slongs, first is numerator, second is denominator
				if (numValues == 1) {
					return file.getInt32(valueOffset, !bigEnd) / file.getInt32(valueOffset+4, !bigEnd);
				} else {
					vals = [];
					for (n=0;n<numValues;n++) {
						vals[n] = file.getInt32(valueOffset + 8*n, !bigEnd) / file.getInt32(valueOffset+4 + 8*n, !bigEnd);
					}
					return vals;
				}
		}
	}

	/**
	 * Given an IFD (Image File Directory) start offset
	 * returns an offset to next IFD or 0 if it's the last IFD.
	 */
	function getNextIFDOffset(dataView, dirStart, bigEnd){
		//the first 2bytes means the number of directory entries contains in this IFD
		var entries = dataView.getUint16(dirStart, !bigEnd);

		// After last directory entry, there is a 4bytes of data,
		// it means an offset to next IFD.
		// If its value is '0x00000000', it means this is the last IFD and there is no linked IFD.

		return dataView.getUint32(dirStart + 2 + entries * 12, !bigEnd); // each entry is 12 bytes long
	}

	function readThumbnailImage(dataView, tiffStart, firstIFDOffset, bigEnd){
		// get the IFD1 offset
		var IFD1OffsetPointer = getNextIFDOffset(dataView, tiffStart+firstIFDOffset, bigEnd);

		if (!IFD1OffsetPointer) {
			// console.log('******** IFD1Offset is empty, image thumb not found ********');
			return {};
		}
		else if (IFD1OffsetPointer > dataView.byteLength) { // this should not happen
			// console.log('******** IFD1Offset is outside the bounds of the DataView ********');
			return {};
		}
		// console.log('*******  thumbnail IFD offset (IFD1) is: %s', IFD1OffsetPointer);

		var thumbTags = readTags(dataView, tiffStart, tiffStart + IFD1OffsetPointer, IFD1Tags, bigEnd)

		// EXIF 2.3 specification for JPEG format thumbnail

		// If the value of Compression(0x0103) Tag in IFD1 is '6', thumbnail image format is JPEG.
		// Most of Exif image uses JPEG format for thumbnail. In that case, you can get offset of thumbnail
		// by JpegIFOffset(0x0201) Tag in IFD1, size of thumbnail by JpegIFByteCount(0x0202) Tag.
		// Data format is ordinary JPEG format, starts from 0xFFD8 and ends by 0xFFD9. It seems that
		// JPEG format and 160x120pixels of size are recommended thumbnail format for Exif2.1 or later.

		if (thumbTags['Compression']) {
			// console.log('Thumbnail image found!');

			switch (thumbTags['Compression']) {
				case 6:
					// console.log('Thumbnail image format is JPEG');
					if (thumbTags.JpegIFOffset && thumbTags.JpegIFByteCount) {
						// extract the thumbnail
						var tOffset = tiffStart + thumbTags.JpegIFOffset;
						var tLength = thumbTags.JpegIFByteCount;
						thumbTags['blob'] = new Blob([new Uint8Array(dataView.buffer, tOffset, tLength)], {
							type: 'image/jpeg'
						});
					}
					break;

				case 1:
					console.log("Thumbnail image format is TIFF, which is not implemented.");
					break;
				default:
					console.log("Unknown thumbnail image format '%s'", thumbTags['Compression']);
			}
		}
		else if (thumbTags['PhotometricInterpretation'] == 2) {
			console.log("Thumbnail image format is RGB, which is not implemented.");
		}
		return thumbTags;
	}

	function getStringFromDB(buffer, start, length) {
		var outstr = "";
		for (n = start; n < start+length; n++) {
			outstr += String.fromCharCode(buffer.getUint8(n));
		}
		return outstr;
	}

	function readEXIFData(file, start) {
		if (getStringFromDB(file, start, 4) != "Exif") {
			if (debug) console.log("Not valid EXIF data! " + getStringFromDB(file, start, 4));
			return false;
		}

		var bigEnd,
			tags, tag,
			exifData, gpsData,
			tiffOffset = start + 6;

		// test for TIFF validity and endianness
		if (file.getUint16(tiffOffset) == 0x4949) {
			bigEnd = false;
		} else if (file.getUint16(tiffOffset) == 0x4D4D) {
			bigEnd = true;
		} else {
			if (debug) console.log("Not valid TIFF data! (no 0x4949 or 0x4D4D)");
			return false;
		}

		if (file.getUint16(tiffOffset+2, !bigEnd) != 0x002A) {
			if (debug) console.log("Not valid TIFF data! (no 0x002A)");
			return false;
		}

		var firstIFDOffset = file.getUint32(tiffOffset+4, !bigEnd);

		if (firstIFDOffset < 0x00000008) {
			if (debug) console.log("Not valid TIFF data! (First offset less than 8)", file.getUint32(tiffOffset+4, !bigEnd));
			return false;
		}

		tags = readTags(file, tiffOffset, tiffOffset + firstIFDOffset, TiffTags, bigEnd);

		if (tags.ExifIFDPointer) {
			exifData = readTags(file, tiffOffset, tiffOffset + tags.ExifIFDPointer, ExifTags, bigEnd);
			for (tag in exifData) {
				switch (tag) {
					case "LightSource" :
					case "Flash" :
					case "MeteringMode" :
					case "ExposureProgram" :
					case "SensingMethod" :
					case "SceneCaptureType" :
					case "SceneType" :
					case "CustomRendered" :
					case "WhiteBalance" :
					case "GainControl" :
					case "Contrast" :
					case "Saturation" :
					case "Sharpness" :
					case "SubjectDistanceRange" :
					case "FileSource" :
						exifData[tag] = StringValues[tag][exifData[tag]];
						break;

					case "ExifVersion" :
					case "FlashpixVersion" :
						exifData[tag] = String.fromCharCode(exifData[tag][0], exifData[tag][1], exifData[tag][2], exifData[tag][3]);
						break;

					case "ComponentsConfiguration" :
						exifData[tag] =
							StringValues.Components[exifData[tag][0]] +
							StringValues.Components[exifData[tag][1]] +
							StringValues.Components[exifData[tag][2]] +
							StringValues.Components[exifData[tag][3]];
						break;
				}
				tags[tag] = exifData[tag];
			}
		}

		if (tags.GPSInfoIFDPointer) {
			gpsData = readTags(file, tiffOffset, tiffOffset + tags.GPSInfoIFDPointer, GPSTags, bigEnd);
			for (tag in gpsData) {
				switch (tag) {
					case "GPSVersionID" :
						gpsData[tag] = gpsData[tag][0] +
							"." + gpsData[tag][1] +
							"." + gpsData[tag][2] +
							"." + gpsData[tag][3];
						break;
				}
				tags[tag] = gpsData[tag];
			}
		}

		// extract thumbnail
		tags['thumbnail'] = readThumbnailImage(file, tiffOffset, firstIFDOffset, bigEnd);

		return tags;
	}

	function findXMPinJPEG(file) {

		if (!('DOMParser' in self)) {
			// console.warn('XML parsing not supported without DOMParser');
			return;
		}
		var dataView = new DataView(file);

		if (debug) console.log("Got file of length " + file.byteLength);
		if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
			if (debug) console.log("Not a valid JPEG");
			return false; // not a valid jpeg
		}

		var offset = 2,
			length = file.byteLength,
			dom = new DOMParser();

		while (offset < (length-4)) {
			if (getStringFromDB(dataView, offset, 4) == "http") {
				var startOffset = offset - 1;
				var sectionLength = dataView.getUint16(offset - 2) - 1;
				var xmpString = getStringFromDB(dataView, startOffset, sectionLength)
				var xmpEndIndex = xmpString.indexOf('xmpmeta>') + 8;
				xmpString = xmpString.substring( xmpString.indexOf( '<x:xmpmeta' ), xmpEndIndex );

				var indexOfXmp = xmpString.indexOf('x:xmpmeta') + 10
				//Many custom written programs embed xmp/xml without any namespace. Following are some of them.
				//Without these namespaces, XML is thought to be invalid by parsers
				xmpString = xmpString.slice(0, indexOfXmp)
					+ 'xmlns:Iptc4xmpCore="http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/" '
					+ 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
					+ 'xmlns:tiff="http://ns.adobe.com/tiff/1.0/" '
					+ 'xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus" '
					+ 'xmlns:ext="http://www.gettyimages.com/xsltExtension/1.0" '
					+ 'xmlns:exif="http://ns.adobe.com/exif/1.0/" '
					+ 'xmlns:stEvt="http://ns.adobe.com/xap/1.0/sType/ResourceEvent#" '
					+ 'xmlns:stRef="http://ns.adobe.com/xap/1.0/sType/ResourceRef#" '
					+ 'xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/" '
					+ 'xmlns:xapGImg="http://ns.adobe.com/xap/1.0/g/img/" '
					+ 'xmlns:Iptc4xmpExt="http://iptc.org/std/Iptc4xmpExt/2008-02-29/" '
					+ xmpString.slice(indexOfXmp)

				var domDocument = dom.parseFromString( xmpString, 'text/xml' );
				return xml2Object(domDocument);
			} else{
				offset++;
			}
		}
	}

	function xml2Object(xml) {

		// https://github.com/exif-js/exif-js/issues/84
		function xml2json(xml) {
			var json = {};

			if (xml.nodeType == 1) { // element node
				if (xml.attributes.length > 0) {
					json['@attributes'] = {};
					for (var j = 0; j < xml.attributes.length; j++) {
						var attribute = xml.attributes.item(j);
						json['@attributes'][attribute.nodeName] = attribute.nodeValue;
					}
				}
			} else if (xml.nodeType == 3) { // text node
				return xml.nodeValue;
			}

			// deal with children
			if (xml.hasChildNodes()) {
				for(var i = 0; i < xml.childNodes.length; i++) {
					var child = xml.childNodes.item(i);
					var nodeName = child.nodeName;
					if (json[nodeName] == null) {
						json[nodeName] = xml2json(child);
					} else {
						if (json[nodeName].push == null) {
							var old = json[nodeName];
							json[nodeName] = [];
							json[nodeName].push(old);
						}
						json[nodeName].push(xml2json(child));
					}
				}
			}

			return json;
		}
		
		
		try {
			var obj = {};
			if (xml.children.length > 0) {
				for (var i = 0; i < xml.children.length; i++) {
					var item = xml.children.item(i);
					var attributes = item.attributes;
					for(var idx in attributes) {
						var itemAtt = attributes[idx];
						var dataKey = itemAtt.nodeName;
						var dataValue = itemAtt.nodeValue;

						if(dataKey !== undefined) {
							obj[dataKey] = dataValue;
						}
					}
					var nodeName = item.nodeName;

					if (typeof (obj[nodeName]) == "undefined") {
						obj[nodeName] = xml2json(item);
					} else {
						if (typeof (obj[nodeName].push) == "undefined") {
							var old = obj[nodeName];

							obj[nodeName] = [];
							obj[nodeName].push(old);
						}
						obj[nodeName].push(xml2json(item));
					}
				}
			} else {
				obj = xml.textContent;
			}
			return obj;
		} catch (e) {
			console.log(e.message);
		}
	}

	EXIF.getData = function(img, callback) {
		if (((self.Image && img instanceof self.Image)
			|| (self.HTMLImageElement && img instanceof self.HTMLImageElement))
			&& !img.complete)
			return false;
		/*	
		if ((self.Image && img instanceof self.Image)
			|| (self.HTMLImageElement && img instanceof self.HTMLImageElement)
			&& !img.complete)
			return false;
		*/

		if (!imageHasData(img)) {
			getImageData(img, callback);
		} else {
			if (callback) {
				callback.call(img);
			}
		}
		return true;
	}

	EXIF.getTag = function(img, tag) {
		if (!imageHasData(img)) return;
		return img.exifdata[tag];
	}

	EXIF.getIptcTag = function(img, tag) {
		if (!imageHasData(img)) return;
		return img.iptcdata[tag];
	}

	EXIF.getAllTags = function(img) {
		if (!imageHasData(img)) return {};
		var a,
			data = img.exifdata,
			tags = {};
		for (a in data) {
			if (data.hasOwnProperty(a)) {
				tags[a] = data[a];
			}
		}
		return tags;
	}

	EXIF.getAllIptcTags = function(img) {
		if (!imageHasData(img)) return {};
		var a,
			data = img.iptcdata,
			tags = {};
		for (a in data) {
			if (data.hasOwnProperty(a)) {
				tags[a] = data[a];
			}
		}
		return tags;
	}

	EXIF.pretty = function(img) {
		if (!imageHasData(img)) return "";
		var a,
			data = img.exifdata,
			strPretty = "";
		for (a in data) {
			if (data.hasOwnProperty(a)) {
				if (typeof data[a] == "object") {
					if (data[a] instanceof Number) {
						strPretty += a + " : " + data[a] + " [" + data[a].numerator + "/" + data[a].denominator + "]\r\n";
					} else {
						strPretty += a + " : [" + data[a].length + " values]\r\n";
					}
				} else {
					strPretty += a + " : " + data[a] + "\r\n";
				}
			}
		}
		return strPretty;
	}

	EXIF.readFromBinaryFile = function(file) {
		return findEXIFinJPEG(file);
	}

	if (typeof define === 'function' && define.amd) {
		define('exif-js', [], function() {
			return EXIF;
		});
	}
}.call(this));