jquery.fileupload.js

/*
 * jQuery File Upload Plugin 5.16.4
 * https://github.com/blueimp/jQuery-File-Upload
 *
 * Copyright 2010, Sebastian Tschan
 * https://blueimp.net
 *
 * Licensed under the MIT license:
 * http://www.opensource.org/licenses/MIT
 */

/*jslint nomen: true, unparam: true, regexp: true */
/*global define, window, document, Blob, FormData, location */

(function (factory) {
    'use strict';
    if (typeof define === 'function' && define.amd) {
        // Register as an anonymous AMD module:
        define([
            'jquery',
            'jquery/ui',
            'jquery/fileUploader/jquery.iframe-transport'
        ], factory);
    } else {
        // Browser globals:
        factory(window.jQuery);
    }
}(function ($) {
    'use strict';

    // The FileReader API is not actually used, but works as feature detection,
    // as e.g. Safari supports XHR file uploads via the FormData API,
    // but not non-multipart XHR file uploads:
    $.support.xhrFileUpload = !!(window.XMLHttpRequestUpload && window.FileReader);
    $.support.xhrFormDataFileUpload = !!window.FormData;

    // The fileupload widget listens for change events on file input fields defined
    // via fileInput setting and paste or drop events of the given dropZone.
    // In addition to the default jQuery Widget methods, the fileupload widget
    // exposes the "add" and "send" methods, to add or directly send files using
    // the fileupload API.
    // By default, files added via file input selection, paste, drag & drop or
    // "add" method are uploaded immediately, but it is possible to override
    // the "add" callback option to queue file uploads.
    $.widget('blueimp.fileupload', {

        options: {
            // The namespace used for event handler binding on the dropZone and
            // fileInput collections.
            // If not set, the name of the widget ("fileupload") is used.
            namespace: undefined,
            // The drop target collection, by the default the complete document.
            // Set to null or an empty collection to disable drag & drop support:
            dropZone: $(document),
            // The file input field collection, that is listened for change events.
            // If undefined, it is set to the file input fields inside
            // of the widget element on plugin initialization.
            // Set to null or an empty collection to disable the change listener.
            fileInput: undefined,
            // By default, the file input field is replaced with a clone after
            // each input field change event. This is required for iframe transport
            // queues and allows change events to be fired for the same file
            // selection, but can be disabled by setting the following option to false:
            replaceFileInput: true,
            // The parameter name for the file form data (the request argument name).
            // If undefined or empty, the name property of the file input field is
            // used, or "files[]" if the file input name property is also empty,
            // can be a string or an array of strings:
            paramName: undefined,
            // By default, each file of a selection is uploaded using an individual
            // request for XHR type uploads. Set to false to upload file
            // selections in one request each:
            singleFileUploads: true,
            // To limit the number of files uploaded with one XHR request,
            // set the following option to an integer greater than 0:
            limitMultiFileUploads: undefined,
            // Set the following option to true to issue all file upload requests
            // in a sequential order:
            sequentialUploads: false,
            // To limit the number of concurrent uploads,
            // set the following option to an integer greater than 0:
            limitConcurrentUploads: undefined,
            // Set the following option to true to force iframe transport uploads:
            forceIframeTransport: false,
            // Set the following option to the location of a redirect url on the
            // origin server, for cross-domain iframe transport uploads:
            redirect: undefined,
            // The parameter name for the redirect url, sent as part of the form
            // data and set to 'redirect' if this option is empty:
            redirectParamName: undefined,
            // Set the following option to the location of a postMessage window,
            // to enable postMessage transport uploads:
            postMessage: undefined,
            // By default, XHR file uploads are sent as multipart/form-data.
            // The iframe transport is always using multipart/form-data.
            // Set to false to enable non-multipart XHR uploads:
            multipart: true,
            // To upload large files in smaller chunks, set the following option
            // to a preferred maximum chunk size. If set to 0, null or undefined,
            // or the browser does not support the required Blob API, files will
            // be uploaded as a whole.
            maxChunkSize: undefined,
            // When a non-multipart upload or a chunked multipart upload has been
            // aborted, this option can be used to resume the upload by setting
            // it to the size of the already uploaded bytes. This option is most
            // useful when modifying the options object inside of the "add" or
            // "send" callbacks, as the options are cloned for each file upload.
            uploadedBytes: undefined,
            // By default, failed (abort or error) file uploads are removed from the
            // global progress calculation. Set the following option to false to
            // prevent recalculating the global progress data:
            recalculateProgress: true,
            // Interval in milliseconds to calculate and trigger progress events:
            progressInterval: 100,
            // Interval in milliseconds to calculate progress bitrate:
            bitrateInterval: 500,

            // Additional form data to be sent along with the file uploads can be set
            // using this option, which accepts an array of objects with name and
            // value properties, a function returning such an array, a FormData
            // object (for XHR file uploads), or a simple object.
            // The form of the first fileInput is given as parameter to the function:
            formData: function (form) {
                return form.serializeArray();
            },

            // The add callback is invoked as soon as files are added to the fileupload
            // widget (via file input selection, drag & drop, paste or add API call).
            // If the singleFileUploads option is enabled, this callback will be
            // called once for each file in the selection for XHR file uplaods, else
            // once for each file selection.
            // The upload starts when the submit method is invoked on the data parameter.
            // The data object contains a files property holding the added files
            // and allows to override plugin options as well as define ajax settings.
            // Listeners for this callback can also be bound the following way:
            // .bind('fileuploadadd', func);
            // data.submit() returns a Promise object and allows to attach additional
            // handlers using jQuery's Deferred callbacks:
            // data.submit().done(func).fail(func).always(func);
            add: function (e, data) {
                data.submit();
            },

            // Other callbacks:
            // Callback for the submit event of each file upload:
            // submit: function (e, data) {}, // .bind('fileuploadsubmit', func);
            // Callback for the start of each file upload request:
            // send: function (e, data) {}, // .bind('fileuploadsend', func);
            // Callback for successful uploads:
            // done: function (e, data) {}, // .bind('fileuploaddone', func);
            // Callback for failed (abort or error) uploads:
            // fail: function (e, data) {}, // .bind('fileuploadfail', func);
            // Callback for completed (success, abort or error) requests:
            // always: function (e, data) {}, // .bind('fileuploadalways', func);
            // Callback for upload progress events:
            // progress: function (e, data) {}, // .bind('fileuploadprogress', func);
            // Callback for global upload progress events:
            // progressall: function (e, data) {}, // .bind('fileuploadprogressall', func);
            // Callback for uploads start, equivalent to the global ajaxStart event:
            // start: function (e) {}, // .bind('fileuploadstart', func);
            // Callback for uploads stop, equivalent to the global ajaxStop event:
            // stop: function (e) {}, // .bind('fileuploadstop', func);
            // Callback for change events of the fileInput collection:
            // change: function (e, data) {}, // .bind('fileuploadchange', func);
            // Callback for paste events to the dropZone collection:
            // paste: function (e, data) {}, // .bind('fileuploadpaste', func);
            // Callback for drop events of the dropZone collection:
            // drop: function (e, data) {}, // .bind('fileuploaddrop', func);
            // Callback for dragover events of the dropZone collection:
            // dragover: function (e) {}, // .bind('fileuploaddragover', func);

            // The plugin options are used as settings object for the ajax calls.
            // The following are jQuery ajax settings required for the file uploads:
            processData: false,
            contentType: false,
            cache: false
        },

        // A list of options that require a refresh after assigning a new value:
        _refreshOptionsList: [
            'namespace',
            'dropZone',
            'fileInput',
            'multipart',
            'forceIframeTransport'
        ],

        _BitrateTimer: function () {
            this.timestamp = +(new Date());
            this.loaded = 0;
            this.bitrate = 0;
            this.getBitrate = function (now, loaded, interval) {
                var timeDiff = now - this.timestamp;
                if (!this.bitrate || !interval || timeDiff > interval) {
                    this.bitrate = (loaded - this.loaded) * (1000 / timeDiff) * 8;
                    this.loaded = loaded;
                    this.timestamp = now;
                }
                return this.bitrate;
            };
        },

        _isXHRUpload: function (options) {
            return !options.forceIframeTransport &&
                ((!options.multipart && $.support.xhrFileUpload) ||
                $.support.xhrFormDataFileUpload);
        },

        _getFormData: function (options) {
            var formData;
            if (typeof options.formData === 'function') {
                return options.formData(options.form);
            }
			if ($.isArray(options.formData)) {
                return options.formData;
            }
			if (options.formData) {
                formData = [];
                $.each(options.formData, function (name, value) {
                    formData.push({name: name, value: value});
                });
                return formData;
            }
            return [];
        },

        _getTotal: function (files) {
            var total = 0;
            $.each(files, function (index, file) {
                total += file.size || 1;
            });
            return total;
        },

        _onProgress: function (e, data) {
            if (e.lengthComputable) {
                var now = +(new Date()),
                    total,
                    loaded;
                if (data._time && data.progressInterval &&
                        (now - data._time < data.progressInterval) &&
                        e.loaded !== e.total) {
                    return;
                }
                data._time = now;
                total = data.total || this._getTotal(data.files);
                loaded = parseInt(
                    e.loaded / e.total * (data.chunkSize || total),
                    10
                ) + (data.uploadedBytes || 0);
                this._loaded += loaded - (data.loaded || data.uploadedBytes || 0);
                data.lengthComputable = true;
                data.loaded = loaded;
                data.total = total;
                data.bitrate = data._bitrateTimer.getBitrate(
                    now,
                    loaded,
                    data.bitrateInterval
                );
                // Trigger a custom progress event with a total data property set
                // to the file size(s) of the current upload and a loaded data
                // property calculated accordingly:
                this._trigger('progress', e, data);
                // Trigger a global progress event for all current file uploads,
                // including ajax calls queued for sequential file uploads:
                this._trigger('progressall', e, {
                    lengthComputable: true,
                    loaded: this._loaded,
                    total: this._total,
                    bitrate: this._bitrateTimer.getBitrate(
                        now,
                        this._loaded,
                        data.bitrateInterval
                    )
                });
            }
        },

        _initProgressListener: function (options) {
            var that = this,
                xhr = options.xhr ? options.xhr() : $.ajaxSettings.xhr();
            // Accesss to the native XHR object is required to add event listeners
            // for the upload progress event:
            if (xhr.upload) {
                $(xhr.upload).bind('progress', function (e) {
                    var oe = e.originalEvent;
                    // Make sure the progress event properties get copied over:
                    e.lengthComputable = oe.lengthComputable;
                    e.loaded = oe.loaded;
                    e.total = oe.total;
                    that._onProgress(e, options);
                });
                options.xhr = function () {
                    return xhr;
                };
            }
        },

        _initXHRData: function (options) {
            var formData,
                file = options.files[0],
                // Ignore non-multipart setting if not supported:
                multipart = options.multipart || !$.support.xhrFileUpload,
                paramName = options.paramName[0];
            if (!multipart || options.blob) {
                // For non-multipart uploads and chunked uploads,
                // file meta data is not part of the request body,
                // so we transmit this data as part of the HTTP headers.
                // For cross domain requests, these headers must be allowed
                // via Access-Control-Allow-Headers or removed using
                // the beforeSend callback:
                options.headers = $.extend(options.headers, {
                    'X-File-Name': file.name,
                    'X-File-Type': file.type,
                    'X-File-Size': file.size
                });
                if (!options.blob) {
                    // Non-chunked non-multipart upload:
                    options.contentType = file.type;
                    options.data = file;
                } else if (!multipart) {
                    // Chunked non-multipart upload:
                    options.contentType = 'application/octet-stream';
                    options.data = options.blob;
                }
            }
            if (multipart && $.support.xhrFormDataFileUpload) {
                if (options.postMessage) {
                    // window.postMessage does not allow sending FormData
                    // objects, so we just add the File/Blob objects to
                    // the formData array and let the postMessage window
                    // create the FormData object out of this array:
                    formData = this._getFormData(options);
                    if (options.blob) {
                        formData.push({
                            name: paramName,
                            value: options.blob
                        });
                    } else {
                        $.each(options.files, function (index, file) {
                            formData.push({
                                name: options.paramName[index] || paramName,
                                value: file
                            });
                        });
                    }
                } else {
                    if (options.formData instanceof FormData) {
                        formData = options.formData;
                    } else {
                        formData = new FormData();
                        $.each(this._getFormData(options), function (index, field) {
                            formData.append(field.name, field.value);
                        });
                    }
                    if (options.blob) {
                        formData.append(paramName, options.blob, file.name);
                    } else {
                        $.each(options.files, function (index, file) {
                            // File objects are also Blob instances.
                            // This check allows the tests to run with
                            // dummy objects:
                            if (file instanceof Blob) {
                                formData.append(
                                    options.paramName[index] || paramName,
                                    file,
                                    file.name
                                );
                            }
                        });
                    }
                }
                options.data = formData;
            }
            // Blob reference is not needed anymore, free memory:
            options.blob = null;
        },

        _initIframeSettings: function (options) {
            // Setting the dataType to iframe enables the iframe transport:
            options.dataType = 'iframe ' + (options.dataType || '');
            // The iframe transport accepts a serialized array as form data:
            options.formData = this._getFormData(options);
            // Add redirect url to form data on cross-domain uploads:
            if (options.redirect && $('<a></a>').prop('href', options.url)
                    .prop('host') !== location.host) {
                options.formData.push({
                    name: options.redirectParamName || 'redirect',
                    value: options.redirect
                });
            }
        },

        _initDataSettings: function (options) {
            if (this._isXHRUpload(options)) {
                if (!this._chunkedUpload(options, true)) {
                    if (!options.data) {
                        this._initXHRData(options);
                    }
                    this._initProgressListener(options);
                }
                if (options.postMessage) {
                    // Setting the dataType to postmessage enables the
                    // postMessage transport:
                    options.dataType = 'postmessage ' + (options.dataType || '');
                }
            } else {
                this._initIframeSettings(options, 'iframe');
            }
        },

        _getParamName: function (options) {
            var fileInput = $(options.fileInput),
                paramName = options.paramName;
            if (!paramName) {
                paramName = [];
                fileInput.each(function () {
                    var input = $(this),
                        name = input.prop('name') || 'files[]',
                        i = (input.prop('files') || [1]).length;
                    while (i) {
                        paramName.push(name);
                        i -= 1;
                    }
                });
                if (!paramName.length) {
                    paramName = [fileInput.prop('name') || 'files[]'];
                }
            } else if (!$.isArray(paramName)) {
                paramName = [paramName];
            }
            return paramName;
        },

        _initFormSettings: function (options) {
            // Retrieve missing options from the input field and the
            // associated form, if available:
            if (!options.form || !options.form.length) {
                options.form = $(options.fileInput.prop('form'));
            }
            options.paramName = this._getParamName(options);
            if (!options.url) {
                options.url = options.form.prop('action') || location.href;
            }
            // The HTTP request method must be "POST" or "PUT":
            options.type = (options.type || options.form.prop('method') || '')
                .toUpperCase();
            if (options.type !== 'POST' && options.type !== 'PUT') {
                options.type = 'POST';
            }
            if (!options.formAcceptCharset) {
                options.formAcceptCharset = options.form.attr('accept-charset');
            }
        },

        _getAJAXSettings: function (data) {
            var options = $.extend({}, this.options, data);
            this._initFormSettings(options);
            this._initDataSettings(options);
            return options;
        },

        // Maps jqXHR callbacks to the equivalent
        // methods of the given Promise object:
        _enhancePromise: function (promise) {
            promise.success = promise.done;
            promise.error = promise.fail;
            promise.complete = promise.always;
            return promise;
        },

        // Creates and returns a Promise object enhanced with
        // the jqXHR methods abort, success, error and complete:
        _getXHRPromise: function (resolveOrReject, context, args) {
            var dfd = $.Deferred(),
                promise = dfd.promise();
            context = context || this.options.context || promise;
            if (resolveOrReject === true) {
                dfd.resolveWith(context, args);
            } else if (resolveOrReject === false) {
                dfd.rejectWith(context, args);
            }
            promise.abort = dfd.promise;
            return this._enhancePromise(promise);
        },

        // Uploads a file in multiple, sequential requests
        // by splitting the file up in multiple blob chunks.
        // If the second parameter is true, only tests if the file
        // should be uploaded in chunks, but does not invoke any
        // upload requests:
        _chunkedUpload: function (options, testOnly) {
            var that = this,
                file = options.files[0],
                fs = file.size,
                ub = options.uploadedBytes = options.uploadedBytes || 0,
                mcs = options.maxChunkSize || fs,
                // Use the Blob methods with the slice implementation
                // according to the W3C Blob API specification:
                slice = file.webkitSlice || file.mozSlice || file.slice,
                upload,
                n,
                jqXHR,
                pipe;
            if (!(this._isXHRUpload(options) && slice && (ub || mcs < fs)) ||
                    options.data) {
                return false;
            }
            if (testOnly) {
                return true;
            }
            if (ub >= fs) {
                file.error = 'uploadedBytes';
                return this._getXHRPromise(
                    false,
                    options.context,
                    [null, 'error', file.error]
                );
            }
            // n is the number of blobs to upload,
            // calculated via filesize, uploaded bytes and max chunk size:
            n = Math.ceil((fs - ub) / mcs);
            // The chunk upload method accepting the chunk number as parameter:
            upload = function (i) {
                if (!i) {
                    return that._getXHRPromise(true, options.context);
                }
                // Upload the blobs in sequential order:
                return upload(i -= 1).pipe(function () {
                    // Clone the options object for each chunk upload:
                    var o = $.extend({}, options);
                    o.blob = slice.call(
                        file,
                        ub + i * mcs,
                        ub + (i + 1) * mcs
                    );
                    // Expose the chunk index:
                    o.chunkIndex = i;
                    // Expose the number of chunks:
                    o.chunksNumber = n;
                    // Store the current chunk size, as the blob itself
                    // will be dereferenced after data processing:
                    o.chunkSize = o.blob.size;
                    // Process the upload data (the blob and potential form data):
                    that._initXHRData(o);
                    // Add progress listeners for this chunk upload:
                    that._initProgressListener(o);
                    jqXHR = ($.ajax(o) || that._getXHRPromise(false, o.context))
                        .done(function () {
                            // Create a progress event if upload is done and
                            // no progress event has been invoked for this chunk:
                            if (!o.loaded) {
                                that._onProgress($.Event('progress', {
                                    lengthComputable: true,
                                    loaded: o.chunkSize,
                                    total: o.chunkSize
                                }), o);
                            }
                            options.uploadedBytes = o.uploadedBytes +=
                                o.chunkSize;
                        });
                    return jqXHR;
                });
            };
            // Return the piped Promise object, enhanced with an abort method,
            // which is delegated to the jqXHR object of the current upload,
            // and jqXHR callbacks mapped to the equivalent Promise methods:
            pipe = upload(n);
            pipe.abort = function () {
                return jqXHR.abort();
            };
            return this._enhancePromise(pipe);
        },

        _beforeSend: function (e, data) {
            if (this._active === 0) {
                // the start callback is triggered when an upload starts
                // and no other uploads are currently running,
                // equivalent to the global ajaxStart event:
                this._trigger('start');
                // Set timer for global bitrate progress calculation:
                this._bitrateTimer = new this._BitrateTimer();
            }
            this._active += 1;
            // Initialize the global progress values:
            this._loaded += data.uploadedBytes || 0;
            this._total += this._getTotal(data.files);
        },

        _onDone: function (result, textStatus, jqXHR, options) {
            if (!this._isXHRUpload(options)) {
                // Create a progress event for each iframe load:
                this._onProgress($.Event('progress', {
                    lengthComputable: true,
                    loaded: 1,
                    total: 1
                }), options);
            }
            options.result = result;
            options.textStatus = textStatus;
            options.jqXHR = jqXHR;
            this._trigger('done', null, options);
        },

        _onFail: function (jqXHR, textStatus, errorThrown, options) {
            options.jqXHR = jqXHR;
            options.textStatus = textStatus;
            options.errorThrown = errorThrown;
            this._trigger('fail', null, options);
            if (options.recalculateProgress) {
                // Remove the failed (error or abort) file upload from
                // the global progress calculation:
                this._loaded -= options.loaded || options.uploadedBytes || 0;
                this._total -= options.total || this._getTotal(options.files);
            }
        },

        _onAlways: function (jqXHRorResult, textStatus, jqXHRorError, options) {
            this._active -= 1;
            options.textStatus = textStatus;
            if (jqXHRorError && jqXHRorError.always) {
                options.jqXHR = jqXHRorError;
                options.result = jqXHRorResult;
            } else {
                options.jqXHR = jqXHRorResult;
                options.errorThrown = jqXHRorError;
            }
            this._trigger('always', null, options);
            if (this._active === 0) {
                // The stop callback is triggered when all uploads have
                // been completed, equivalent to the global ajaxStop event:
                this._trigger('stop');
                // Reset the global progress values:
                this._loaded = this._total = 0;
                this._bitrateTimer = null;
            }
        },

        _onSend: function (e, data) {
            var that = this,
                jqXHR,
                slot,
                pipe,
                options = that._getAJAXSettings(data),
                send = function (resolve, args) {
                    that._sending += 1;
                    // Set timer for bitrate progress calculation:
                    options._bitrateTimer = new that._BitrateTimer();
                    jqXHR = jqXHR || (
                        (resolve !== false &&
                        that._trigger('send', e, options) !== false &&
                        (that._chunkedUpload(options) || $.ajax(options))) ||
                        that._getXHRPromise(false, options.context, args)
                    ).done(function (result, textStatus, jqXHR) {
                        that._onDone(result, textStatus, jqXHR, options);
                    }).fail(function (jqXHR, textStatus, errorThrown) {
                        that._onFail(jqXHR, textStatus, errorThrown, options);
                    }).always(function (jqXHRorResult, textStatus, jqXHRorError) {
                        that._sending -= 1;
                        that._onAlways(
                            jqXHRorResult,
                            textStatus,
                            jqXHRorError,
                            options
                        );
                        if (options.limitConcurrentUploads &&
                                options.limitConcurrentUploads > that._sending) {
                            // Start the next queued upload,
                            // that has not been aborted:
                            var nextSlot = that._slots.shift(),
                                isPending;
                            while (nextSlot) {
                                // jQuery 1.6 doesn't provide .state(),
                                // while jQuery 1.8+ removed .isRejected():
                                isPending = nextSlot.state ?
                                        nextSlot.state() === 'pending' :
                                        !nextSlot.isRejected();
                                if (isPending) {
                                    nextSlot.resolve();
                                    break;
                                }
                                nextSlot = that._slots.shift();
                            }
                        }
                    });
                    return jqXHR;
                };
            this._beforeSend(e, options);
            if (this.options.sequentialUploads ||
                    (this.options.limitConcurrentUploads &&
                    this.options.limitConcurrentUploads <= this._sending)) {
                if (this.options.limitConcurrentUploads > 1) {
                    slot = $.Deferred();
                    this._slots.push(slot);
                    pipe = slot.pipe(send);
                } else {
                    pipe = (this._sequence = this._sequence.pipe(send, send));
                }
                // Return the piped Promise object, enhanced with an abort method,
                // which is delegated to the jqXHR object of the current upload,
                // and jqXHR callbacks mapped to the equivalent Promise methods:
                pipe.abort = function () {
                    var args = [undefined, 'abort', 'abort'];
                    if (!jqXHR) {
                        if (slot) {
                            slot.rejectWith(pipe, args);
                        }
                        return send(false, args);
                    }
                    return jqXHR.abort();
                };
                return this._enhancePromise(pipe);
            }
            return send();
        },

        _onAdd: function (e, data) {
            var that = this,
                result = true,
                options = $.extend({}, this.options, data),
                limit = options.limitMultiFileUploads,
                paramName = this._getParamName(options),
                paramNameSet,
                paramNameSlice,
                fileSet,
                i;
            if (!(options.singleFileUploads || limit) ||
                    !this._isXHRUpload(options)) {
                fileSet = [data.files];
                paramNameSet = [paramName];
            } else if (!options.singleFileUploads && limit) {
                fileSet = [];
                paramNameSet = [];
                for (i = 0; i < data.files.length; i += limit) {
                    fileSet.push(data.files.slice(i, i + limit));
                    paramNameSlice = paramName.slice(i, i + limit);
                    if (!paramNameSlice.length) {
                        paramNameSlice = paramName;
                    }
                    paramNameSet.push(paramNameSlice);
                }
            } else {
                paramNameSet = paramName;
            }
            data.originalFiles = data.files;
            $.each(fileSet || data.files, function (index, element) {
                var newData = $.extend({}, data);
                newData.files = fileSet ? element : [element];
                newData.paramName = paramNameSet[index];
                newData.submit = function () {
                    newData.jqXHR = this.jqXHR =
                        (that._trigger('submit', e, this) !== false) &&
                        that._onSend(e, this);
                    return this.jqXHR;
                };
                return (result = that._trigger('add', e, newData));
            });
            return result;
        },

        _replaceFileInput: function (input) {
            var inputClone = input.clone(true);
            $('<form></form>').append(inputClone)[0].reset();
            // Detaching allows to insert the fileInput on another form
            // without loosing the file input value:
            input.after(inputClone).detach();
            // Avoid memory leaks with the detached file input:
            $.cleanData(input.unbind('remove'));
            // Replace the original file input element in the fileInput
            // collection with the clone, which has been copied including
            // event handlers:
            this.options.fileInput = this.options.fileInput.map(function (i, el) {
                if (el === input[0]) {
                    return inputClone[0];
                }
                return el;
            });
            // If the widget has been initialized on the file input itself,
            // override this.element with the file input clone:
            if (input[0] === this.element[0]) {
                this.element = inputClone;
            }
        },

        _handleFileTreeEntry: function (entry, path) {
            var that = this,
                dfd = $.Deferred(),
                errorHandler = function () {
                    dfd.reject();
                },
                dirReader;
            path = path || '';
            if (entry.isFile) {
                entry.file(function (file) {
                    file.relativePath = path;
                    dfd.resolve(file);
                }, errorHandler);
            } else if (entry.isDirectory) {
                dirReader = entry.createReader();
                dirReader.readEntries(function (entries) {
                    that._handleFileTreeEntries(
                        entries,
                        path + entry.name + '/'
                    ).done(function (files) {
                        dfd.resolve(files);
                    }).fail(errorHandler);
                }, errorHandler);
            } else {
                errorHandler();
            }
            return dfd.promise();
        },

        _handleFileTreeEntries: function (entries, path) {
            var that = this;
            return $.when.apply(
                $,
                $.map(entries, function (entry) {
                    return that._handleFileTreeEntry(entry, path);
                })
            ).pipe(function () {
                return Array.prototype.concat.apply(
                    [],
                    arguments
                );
            });
        },

        _getDroppedFiles: function (dataTransfer) {
            dataTransfer = dataTransfer || {};
            var items = dataTransfer.items;
            if (items && items.length && (items[0].webkitGetAsEntry ||
                    items[0].getAsEntry)) {
                return this._handleFileTreeEntries(
                    $.map(items, function (item) {
                        if (item.webkitGetAsEntry) {
                            return item.webkitGetAsEntry();
                        }
                        return item.getAsEntry();
                    })
                );
            }
            return $.Deferred().resolve(
                $.makeArray(dataTransfer.files)
            ).promise();
        },

        _getFileInputFiles: function (fileInput) {
            fileInput = $(fileInput);
            var entries = fileInput.prop('webkitEntries') ||
                    fileInput.prop('entries'),
                files,
                value;
            if (entries && entries.length) {
                return this._handleFileTreeEntries(entries);
            }
            files = $.makeArray(fileInput.prop('files'));
            if (!files.length) {
                value = fileInput.prop('value');
                if (!value) {
                    return $.Deferred().reject([]).promise();
                }
                // If the files property is not available, the browser does not
                // support the File API and we add a pseudo File object with
                // the input value as name with path information removed:
                files = [{name: value.replace(/^.*\\/, '')}];
            }
            return $.Deferred().resolve(files).promise();
        },

        _onChange: function (e) {
            var that = e.data.fileupload,
                data = {
                    fileInput: $(e.target),
                    form: $(e.target.form)
                };
            that._getFileInputFiles(data.fileInput).always(function (files) {
                data.files = files;
                if (that.options.replaceFileInput) {
                    that._replaceFileInput(data.fileInput);
                }
                if (that._trigger('change', e, data) !== false) {
                    that._onAdd(e, data);
                }
            });
        },

        _onPaste: function (e) {
            var that = e.data.fileupload,
                cbd = e.originalEvent.clipboardData,
                items = (cbd && cbd.items) || [],
                data = {files: []};
            $.each(items, function (index, item) {
                var file = item.getAsFile && item.getAsFile();
                if (file) {
                    data.files.push(file);
                }
            });
            if (that._trigger('paste', e, data) === false ||
                    that._onAdd(e, data) === false) {
                return false;
            }
        },

        _onDrop: function (e) {
            e.preventDefault();
            var that = e.data.fileupload,
                dataTransfer = e.dataTransfer = e.originalEvent.dataTransfer,
                data = {};
            that._getDroppedFiles(dataTransfer).always(function (files) {
                data.files = files;
                if (that._trigger('drop', e, data) !== false) {
                    that._onAdd(e, data);
                }
            });
        },

        _onDragOver: function (e) {
            var that = e.data.fileupload,
                dataTransfer = e.dataTransfer = e.originalEvent.dataTransfer;
            if (that._trigger('dragover', e) === false) {
                return false;
            }
            if (dataTransfer) {
                dataTransfer.dropEffect = 'copy';
            }
            e.preventDefault();
        },

        _initEventHandlers: function () {
            var ns = this.options.namespace;
            if (this._isXHRUpload(this.options)) {
                this.options.dropZone
                    .bind('dragover.' + ns, {fileupload: this}, this._onDragOver)
                    .bind('drop.' + ns, {fileupload: this}, this._onDrop)
                    .bind('paste.' + ns, {fileupload: this}, this._onPaste);
            }
            this.options.fileInput
                .bind('change.' + ns, {fileupload: this}, this._onChange);
        },

        _destroyEventHandlers: function () {
            var ns = this.options.namespace;
            this.options.dropZone
                .unbind('dragover.' + ns, this._onDragOver)
                .unbind('drop.' + ns, this._onDrop)
                .unbind('paste.' + ns, this._onPaste);
            this.options.fileInput
                .unbind('change.' + ns, this._onChange);
        },

        _setOption: function (key, value) {
            var refresh = $.inArray(key, this._refreshOptionsList) !== -1;
            if (refresh) {
                this._destroyEventHandlers();
            }
            $.Widget.prototype._setOption.call(this, key, value);
            if (refresh) {
                this._initSpecialOptions();
                this._initEventHandlers();
            }
        },

        _initSpecialOptions: function () {
            var options = this.options;
            if (options.fileInput === undefined) {
                options.fileInput = this.element.is('input[type="file"]') ?
                        this.element : this.element.find('input[type="file"]');
            } else if (!(options.fileInput instanceof $)) {
                options.fileInput = $(options.fileInput);
            }
            if (!(options.dropZone instanceof $)) {
                options.dropZone = $(options.dropZone);
            }
        },

        _create: function () {
            var options = this.options;
            // Initialize options set via HTML5 data-attributes:
            $.extend(options, $(this.element[0].cloneNode(false)).data());
            options.namespace = options.namespace || this.widgetName;
            this._initSpecialOptions();
            this._slots = [];
            this._sequence = this._getXHRPromise(true);
            this._sending = this._active = this._loaded = this._total = 0;
            this._initEventHandlers();
        },

        destroy: function () {
            this._destroyEventHandlers();
            $.Widget.prototype.destroy.call(this);
        },

        enable: function () {
            var wasDisabled = false;
            if (this.options.disabled) {
                wasDisabled = true;
            }
            $.Widget.prototype.enable.call(this);
            if (wasDisabled) {
                this._initEventHandlers();
            }
        },

        disable: function () {
            if (!this.options.disabled) {
                this._destroyEventHandlers();
            }
            $.Widget.prototype.disable.call(this);
        },

        // This method is exposed to the widget API and allows adding files
        // using the fileupload API. The data parameter accepts an object which
        // must have a files property and can contain additional options:
        // .fileupload('add', {files: filesList});
        add: function (data) {
            var that = this;
            if (!data || this.options.disabled) {
                return;
            }
            if (data.fileInput && !data.files) {
                this._getFileInputFiles(data.fileInput).always(function (files) {
                    data.files = files;
                    that._onAdd(null, data);
                });
            } else {
                data.files = $.makeArray(data.files);
                this._onAdd(null, data);
            }
        },

        // This method is exposed to the widget API and allows sending files
        // using the fileupload API. The data parameter accepts an object which
        // must have a files or fileInput property and can contain additional options:
        // .fileupload('send', {files: filesList});
        // The method returns a Promise object for the file upload call.
        send: function (data) {
            if (data && !this.options.disabled) {
                if (data.fileInput && !data.files) {
                    var that = this,
                        dfd = $.Deferred(),
                        promise = dfd.promise(),
                        jqXHR,
                        aborted;
                    promise.abort = function () {
                        aborted = true;
                        if (jqXHR) {
                            return jqXHR.abort();
                        }
                        dfd.reject(null, 'abort', 'abort');
                        return promise;
                    };
                    this._getFileInputFiles(data.fileInput).always(
                        function (files) {
                            if (aborted) {
                                return;
                            }
                            data.files = files;
                            jqXHR = that._onSend(null, data).then(
                                function (result, textStatus, jqXHR) {
                                    dfd.resolve(result, textStatus, jqXHR);
                                },
                                function (jqXHR, textStatus, errorThrown) {
                                    dfd.reject(jqXHR, textStatus, errorThrown);
                                }
                            );
                        }
                    );
                    return this._enhancePromise(promise);
                }
                data.files = $.makeArray(data.files);
                if (data.files.length) {
                    return this._onSend(null, data);
                }
            }
            return this._getXHRPromise(false, data && data.context);
        }

    });

}));