/**
* This module provides a UI for file selection and multiple file upload capability using
* HTML5 XMLHTTPRequest Level 2 as a transport engine.
* The supported features include: automatic upload queue management, upload progress
* tracking, drag-and-drop support, server response retrieval and error reporting.
*
* @module uploader-html5
*/

// Shorthands for the external modules
var  substitute  = Y.Lang.sub,
     UploaderQueue = Y.Uploader.Queue;

/**
* This module provides a UI for file selection and multiple file upload capability using
* HTML5 XMLHTTPRequest Level 2 as a transport engine.
* @class UploaderHTML5
* @extends Widget
* @constructor
*/
function UploaderHTML5() {
    UploaderHTML5.superclass.constructor.apply ( this, arguments );
}



Y.UploaderHTML5 = Y.extend( UploaderHTML5, Y.Widget, {

    /**
    * Stored reference to the instance of the file input field used to
    * initiate the file selection dialog.
    *
    * @property _fileInputField
    * @type {Node}
    * @protected
    */
    _fileInputField: null,

    /**
    * Stored reference to the click event binding of the `Select Files`
    * button.
    *
    * @property _buttonBinding
    * @type {EventHandle}
    * @protected
    */
    _buttonBinding: null,

    /**
    * Stored reference to the instance of Uploader.Queue used to manage
    * the upload process. This is a read-only property that only exists
    * during an active upload process. Only one queue can be active at
    * a time; if an upload start is attempted while a queue is active,
    * it will be ignored.
    *
    * @property queue
    * @type {Y.Uploader.Queue}
    */
    queue: null,

    // Y.UploaderHTML5 prototype

    /**
    * Construction logic executed during UploaderHTML5 instantiation.
    *
    * @method initializer
    * @protected
    */
    initializer : function () {

        this._fileInputField = null;
        this.queue = null;
        this._buttonBinding = null;
        this._fileList = [];

        // Publish available events

        /**
        * Signals that files have been selected.
        *
        * @event fileselect
        * @param event {Event} The event object for the `fileselect` with the
        *                      following payload:
        *  <dl>
        *      <dt>fileList</dt>
        *          <dd>An `Array` of files selected by the user, encapsulated
        *              in Y.FileHTML5 objects.</dd>
        *  </dl>
        */
        this.publish("fileselect");

        /**
        * Signals that an upload of multiple files has been started.
        *
        * @event uploadstart
        * @param event {Event} The event object for the `uploadstart`.
        */
        this.publish("uploadstart");

        /**
        * Signals that an upload of a specific file has started.
        *
        * @event fileuploadstart
        * @param event {Event} The event object for the `fileuploadstart` with the
        *                      following payload:
        *  <dl>
        *      <dt>file</dt>
        *          <dd>A reference to the Y.File that dispatched the event.</dd>
        *      <dt>originEvent</dt>
        *          <dd>The original event dispatched by Y.File.</dd>
        *  </dl>
        */
        this.publish("fileuploadstart");

        /**
        * Reports on upload progress of a specific file.
        *
        * @event uploadprogress
        * @param event {Event} The event object for the `uploadprogress` with the
        *                      following payload:
        *  <dl>
        *      <dt>file</dt>
        *          <dd>The pointer to the instance of `Y.File` that dispatched the event.</dd>
        *      <dt>bytesLoaded</dt>
        *          <dd>The number of bytes of the file that has been uploaded</dd>
        *      <dt>bytesTotal</dt>
        *          <dd>The total number of bytes in the file</dd>
        *      <dt>percentLoaded</dt>
        *          <dd>The fraction of the file that has been uploaded, out of 100</dd>
        *      <dt>originEvent</dt>
        *          <dd>The original event dispatched by the HTML5 uploader</dd>
        *  </dl>
        */
        this.publish("uploadprogress");

        /**
        * Reports on the total upload progress of the file list.
        *
        * @event totaluploadprogress
        * @param event {Event} The event object for the `totaluploadprogress` with the
        *                      following payload:
        *  <dl>
        *      <dt>bytesLoaded</dt>
        *          <dd>The number of bytes of the file list that has been uploaded</dd>
        *      <dt>bytesTotal</dt>
        *          <dd>The total number of bytes in the file list</dd>
        *      <dt>percentLoaded</dt>
        *          <dd>The fraction of the file list that has been uploaded, out of 100</dd>
        *  </dl>
        */
        this.publish("totaluploadprogress");

        /**
        * Signals that a single file upload has been completed.
        *
        * @event uploadcomplete
        * @param event {Event} The event object for the `uploadcomplete` with the
        *                      following payload:
        *  <dl>
        *      <dt>file</dt>
        *          <dd>The pointer to the instance of `Y.File` whose upload has been completed.</dd>
        *      <dt>originEvent</dt>
        *          <dd>The original event fired by the SWF Uploader</dd>
        *      <dt>data</dt>
        *          <dd>Data returned by the server.</dd>
        *  </dl>
        */
        this.publish("uploadcomplete");

        /**
        * Signals that the upload process of the entire file list has been completed.
        *
        * @event alluploadscomplete
        * @param event {Event} The event object for the `alluploadscomplete`.
        */
        this.publish("alluploadscomplete");

        /**
        * Signals that a error has occurred in a specific file's upload process.
        *
        * @event uploaderror
        * @param event {Event} The event object for the `uploaderror` with the
        *                      following payload:
        *  <dl>
        *      <dt>originEvent</dt>
        *          <dd>The original error event fired by the HTML5 Uploader. </dd>
        *      <dt>file</dt>
        *          <dd>The pointer at the instance of Y.File that returned the error.</dd>
        *      <dt>status</dt>
        *          <dd>The status reported by the XMLHttpRequest object.</dd>
        *      <dt>statusText</dt>
        *          <dd>The statusText reported by the XMLHttpRequest object.</dd>
        *  </dl>
        */
        this.publish("uploaderror");

        /**
        * Signals that a dragged object has entered into the uploader's associated drag-and-drop area.
        *
        * @event dragenter
        * @param event {Event} The event object for the `dragenter`.
        */
        this.publish("dragenter");

        /**
        * Signals that an object has been dragged over the uploader's associated drag-and-drop area.
        *
        * @event dragover
        * @param event {Event} The event object for the `dragover`.
        */
        this.publish("dragover");

        /**
        * Signals that an object has been dragged off of the uploader's associated drag-and-drop area.
        *
        * @event dragleave
        * @param event {Event} The event object for the `dragleave`.
        */
        this.publish("dragleave");

        /**
        * Signals that an object has been dropped over the uploader's associated drag-and-drop area.
        *
        * @event drop
        * @param event {Event} The event object for the `drop`.
        */
        this.publish("drop");

    },

    /**
    * Create the DOM structure for the UploaderHTML5.
    * UploaderHTML5's DOM structure consists of a "Select Files" button that can
    * be replaced by the developer's widget of choice; and a hidden file input field
    * that is used to instantiate the File Select dialog.
    *
    * @method renderUI
    * @protected
    */
    renderUI : function () {
        var contentBox = this.get('contentBox'),
            selButton = this.get("selectFilesButton");

        selButton.setStyles({width:"100%", height:"100%"});
        contentBox.append(selButton);
        this._fileInputField = Y.Node.create(UploaderHTML5.HTML5FILEFIELD_TEMPLATE);
        contentBox.append(this._fileInputField);
    },

    /**
    * Binds to the UploaderHTML5 UI and subscribes to the necessary events.
    *
    * @method bindUI
    * @protected
    */
    bindUI : function () {

        this._bindSelectButton();
        this._setMultipleFiles();
        this._setFileFilters();
        this._bindDropArea();
        this._triggerEnabled();

        this.after("multipleFilesChange", this._setMultipleFiles, this);
        this.after("fileFiltersChange", this._setFileFilters, this);
        this.after("enabledChange", this._triggerEnabled, this);
        this.after("selectFilesButtonChange", this._bindSelectButton, this);
        this.after("dragAndDropAreaChange", this._bindDropArea, this);
        this.after("tabIndexChange", function () {
            this.get("selectFilesButton").set("tabIndex", this.get("tabIndex"));
        }, this);
        this._fileInputField.on("change", this._updateFileList, this);

        this.get("selectFilesButton").set("tabIndex", this.get("tabIndex"));
    },


    /**
    * Recreates the file field to null out the previous list of files and
    * thus allow for an identical file list selection.
    *
    * @method _rebindFileField
    * @protected
    */
    _rebindFileField : function () {
        this._fileInputField.remove(true);
        this._fileInputField = Y.Node.create(UploaderHTML5.HTML5FILEFIELD_TEMPLATE);
        this.get("contentBox").append(this._fileInputField);
        this._fileInputField.on("change", this._updateFileList, this);
        this._setMultipleFiles();
        this._setFileFilters();
    },


    /**
    * Binds the specified drop area's drag and drop events to the
    * uploader's custom handler.
    *
    * @method _bindDropArea
    * @protected
    */
    _bindDropArea : function (event) {
        var ev = event || {prevVal: null},
            ddArea = this.get("dragAndDropArea");

        if (ev.prevVal !== null) {
            ev.prevVal.detach('drop', this._ddEventHandler);
            ev.prevVal.detach('dragenter', this._ddEventHandler);
            ev.prevVal.detach('dragover', this._ddEventHandler);
            ev.prevVal.detach('dragleave', this._ddEventHandler);
        }

        if (ddArea !== null) {
            ddArea.on('drop', this._ddEventHandler, this);
            ddArea.on('dragenter', this._ddEventHandler, this);
            ddArea.on('dragover', this._ddEventHandler, this);
            ddArea.on('dragleave', this._ddEventHandler, this);
        }
    },

    /**
    * Binds the instantiation of the file select dialog to the current file select
    * control.
    *
    * @method _bindSelectButton
    * @protected
    */
    _bindSelectButton : function () {
       this._buttonBinding = this.get("selectFilesButton").on("click", this.openFileSelectDialog, this);
    },

    /**
    * Handles the drag and drop events from the uploader's specified drop
    * area.
    *
    * @method _ddEventHandler
    * @protected
    */
    _ddEventHandler : function (event) {


        event.stopPropagation();
        event.preventDefault();

        if (Y.Array.indexOf(event._event.dataTransfer.types, 'Files') > -1) {
            switch (event.type) {
                case "dragenter":
                    this.fire("dragenter");
                    break;
                case "dragover":
                    this.fire("dragover");
                    break;
                case "dragleave":
                    this.fire("dragleave");
                    break;
                case "drop":

                    var newfiles = event._event.dataTransfer.files,
                        parsedFiles = [],
                        filterFunc = this.get("fileFilterFunction"),
                        oldfiles;

                    if (filterFunc) {
                        Y.each(newfiles, function (value) {
                            var newfile = new Y.FileHTML5(value);
                            if (filterFunc(newfile)) {
                                parsedFiles.push(newfile);
                            }
                        });
                    }
                    else {
                        Y.each(newfiles, function (value) {
                            parsedFiles.push(new Y.FileHTML5(value));
                        });
                    }

                    if (parsedFiles.length > 0) {
                        oldfiles = this.get("fileList");
                        this.set("fileList",
                        this.get("appendNewFiles") ? oldfiles.concat(parsedFiles) : parsedFiles);
                        this.fire("fileselect", {fileList: parsedFiles});
                    }

                    this.fire("drop");
                    break;
            }
        }
    },

    /**
    * Adds or removes a specified state CSS class to the underlying uploader button.
    *
    * @method _setButtonClass
    * @protected
    * @param state {String} The name of the state enumerated in `buttonClassNames` attribute
    * from which to derive the needed class name.
    * @param add {Boolean} A Boolean indicating whether to add or remove the class.
    */
    _setButtonClass : function (state, add) {
        if (add) {
            this.get("selectFilesButton").addClass(this.get("buttonClassNames")[state]);
        }
        else {
            this.get("selectFilesButton").removeClass(this.get("buttonClassNames")[state]);
        }
    },

    /**
    * Syncs the state of the `multipleFiles` attribute between this class
    * and the file input field.
    *
    * @method _setMultipleFiles
    * @protected
    */
    _setMultipleFiles : function () {
        if (this.get("multipleFiles") === true) {
            this._fileInputField.set("multiple", "multiple");
        }
        else {
            this._fileInputField.set("multiple", "");
        }
    },

    /**
    * Syncs the state of the `fileFilters` attribute between this class
    * and the file input field.
    *
    * @method _setFileFilters
    * @protected
    */
    _setFileFilters : function () {
        if (this.get("fileFilters").length > 0) {
            this._fileInputField.set("accept", this.get("fileFilters").join(","));
        }
        else {
            this._fileInputField.set("accept", "");
        }
    },


    /**
    * Syncs the state of the `enabled` attribute between this class
    * and the underlying button.
    *
    * @method _triggerEnabled
    * @private
    */
    _triggerEnabled : function () {
        if (this.get("enabled") && this._buttonBinding === null) {
            this._bindSelectButton();
            this._setButtonClass("disabled", false);
            this.get("selectFilesButton").setAttribute("aria-disabled", "false");
        }
        else if (!this.get("enabled") && this._buttonBinding) {
            this._buttonBinding.detach();
            this._buttonBinding = null;
            this._setButtonClass("disabled", true);
            this.get("selectFilesButton").setAttribute("aria-disabled", "true");
        }
    },

    /**
    * Getter for the `fileList` attribute
    *
    * @method _getFileList
    * @private
    */
    _getFileList : function () {
        return this._fileList.concat();
    },

    /**
    * Setter for the `fileList` attribute
    *
    * @method _setFileList
    * @private
    */
    _setFileList : function (val) {
        this._fileList = val.concat();
        return this._fileList.concat();
    },

    /**
    * Adjusts the content of the `fileList` based on the results of file selection
    * and the `appendNewFiles` attribute. If the `appendNewFiles` attribute is true,
    * then selected files are appended to the existing list; otherwise, the list is
    * cleared and populated with the newly selected files.
    *
    * @method _updateFileList
    * @param ev {Event} The file selection event received from the uploader.
    * @protected
    */
    _updateFileList : function (ev) {
        var newfiles = ev.target.getDOMNode().files,
            parsedFiles = [],
            filterFunc = this.get("fileFilterFunction"),
            oldfiles;

        if (filterFunc) {
            Y.each(newfiles, function (value) {
                var newfile = new Y.FileHTML5(value);
                if (filterFunc(newfile)) {
                    parsedFiles.push(newfile);
                }
            });
        }
        else {
            Y.each(newfiles, function (value) {
                parsedFiles.push(new Y.FileHTML5(value));
            });
        }

        if (parsedFiles.length > 0) {
            oldfiles = this.get("fileList");

            this.set("fileList",
                    this.get("appendNewFiles") ? oldfiles.concat(parsedFiles) : parsedFiles );

            this.fire("fileselect", {fileList: parsedFiles});
        }

        this._rebindFileField();
    },


    /**
    * Handles and retransmits events fired by `Y.File` and `Y.Uploader.Queue`.
    *
    * @method _uploadEventHandler
    * @param event The event dispatched during the upload process.
    * @protected
    */
    _uploadEventHandler : function (event) {

        switch (event.type) {
            case "file:uploadstart":
                this.fire("fileuploadstart", event);
                break;
            case "file:uploadprogress":
                this.fire("uploadprogress", event);
                break;
            case "uploaderqueue:totaluploadprogress":
                this.fire("totaluploadprogress", event);
                break;
            case "file:uploadcomplete":
                this.fire("uploadcomplete", event);
                break;
            case "uploaderqueue:alluploadscomplete":
                this.queue = null;
                this.fire("alluploadscomplete", event);
                break;
            case "file:uploaderror": // overflow intentional
            case "uploaderqueue:uploaderror":
                this.fire("uploaderror", event);
                break;
            case "file:uploadcancel": // overflow intentional
            case "uploaderqueue:uploadcancel":
                this.fire("uploadcancel", event);
                break;
        }

    },

    /**
    * Opens the File Selection dialog by simulating a click on the file input field.
    *
    * @method openFileSelectDialog
    */
    openFileSelectDialog : function () {
        var fileDomNode = this._fileInputField.getDOMNode();
        if (fileDomNode.click) {
            fileDomNode.click();
        }
    },

    /**
    * Starts the upload of a specific file.
    *
    * @method upload
    * @param file {Y.File} Reference to the instance of the file to be uploaded.
    * @param url {String} The URL to upload the file to.
    * @param postVars {Object} (optional) A set of key-value pairs to send as variables along with the file upload HTTP request.
    *                          If not specified, the values from the attribute `postVarsPerFile` are used instead.
    */
    upload : function (file, url, postvars) {

        var uploadURL = url || this.get("uploadURL"),
            postVars = postvars || this.get("postVarsPerFile"),
            fileId = file.get("id");

        postVars = postVars.hasOwnProperty(fileId) ? postVars[fileId] : postVars;

        if (file instanceof Y.FileHTML5) {

            file.on("uploadstart", this._uploadEventHandler, this);
            file.on("uploadprogress", this._uploadEventHandler, this);
            file.on("uploadcomplete", this._uploadEventHandler, this);
            file.on("uploaderror", this._uploadEventHandler, this);
            file.on("uploadcancel", this._uploadEventHandler, this);

            file.startUpload(uploadURL, postVars, this.get("fileFieldName"));
        }
    },

   /**
    * Starts the upload of all files on the file list, using an automated queue.
    *
    * @method uploadAll
    * @param url {String} The URL to upload the files to.
    * @param [postVars] {Object} A set of key-value pairs to send as variables along with the file upload HTTP request.
    *                          If not specified, the values from the attribute `postVarsPerFile` are used instead.
    */
    uploadAll : function (url, postvars) {
        this.uploadThese(this.get("fileList"), url, postvars);
    },

    /**
    * Starts the upload of the files specified in the first argument, using an automated queue.
    *
    * @method uploadThese
    * @param files {Array} The list of files to upload.
    * @param url {String} The URL to upload the files to.
    * @param [postVars] {Object} A set of key-value pairs to send as variables along with the file upload HTTP request.
    *                          If not specified, the values from the attribute `postVarsPerFile` are used instead.
    */
    uploadThese : function (files, url, postvars) {
        if (!this.queue) {
            var uploadURL = url || this.get("uploadURL"),
                postVars = postvars || this.get("postVarsPerFile");

            this.queue = new UploaderQueue({
                simUploads: this.get("simLimit"),
                errorAction: this.get("errorAction"),
                fileFieldName: this.get("fileFieldName"),
                fileList: files,
                uploadURL: uploadURL,
                perFileParameters: postVars,
                retryCount: this.get("retryCount"),
                uploadHeaders: this.get("uploadHeaders"),
                withCredentials: this.get("withCredentials")
            });

            this.queue.on("uploadstart", this._uploadEventHandler, this);
            this.queue.on("uploadprogress", this._uploadEventHandler, this);
            this.queue.on("totaluploadprogress", this._uploadEventHandler, this);
            this.queue.on("uploadcomplete", this._uploadEventHandler, this);
            this.queue.on("alluploadscomplete", this._uploadEventHandler, this);
            this.queue.on("uploadcancel", this._uploadEventHandler, this);
            this.queue.on("uploaderror", this._uploadEventHandler, this);
            this.queue.startUpload();

            this.fire("uploadstart");
       }
       else if (this.queue._currentState === UploaderQueue.UPLOADING) {
            this.queue.set("perFileParameters", this.get("postVarsPerFile"));
            Y.each(files, function (file) {
                this.queue.addToQueueBottom(file);
            }, this);
       }
    }
}, {

    /**
    * The template for the hidden file input field container. The file input field will only
    * accept clicks if its visibility is set to hidden (and will not if it's `display` value
    * is set to `none`)
    *
    * @property HTML5FILEFIELD_TEMPLATE
    * @type {String}
    * @static
    */
    HTML5FILEFIELD_TEMPLATE: "<input type='file' style='visibility:hidden; width:0px; height: 0px;'>",

    /**
    * The template for the "Select Files" button.
    *
    * @property SELECT_FILES_BUTTON
    * @type {HTML}
    * @static
    * @default '<button type="button" class="yui3-button" role="button" aria-label="{selectButtonLabel}"
    *           tabindex="{tabIndex}">{selectButtonLabel}</button>'
    */
    SELECT_FILES_BUTTON: '<button type="button" class="yui3-button" role="button" aria-label="{selectButtonLabel}" ' +
                         'tabindex="{tabIndex}">{selectButtonLabel}</button>',

    /**
    * The static property reflecting the type of uploader that `Y.Uploader`
    * aliases. The UploaderHTML5 value is `"html5"`.
    *
    * @property TYPE
    * @type {String}
    * @static
    */
    TYPE: "html5",

    /**
    * The identity of the widget.
    *
    * @property NAME
    * @type String
    * @default 'uploader'
    * @readOnly
    * @protected
    * @static
    */
    NAME: "uploader",

    /**
    * Static property used to define the default attribute configuration of
    * the Widget.
    *
    * @property ATTRS
    * @type {Object}
    * @protected
    * @static
    */
    ATTRS: {

        /**
        * A Boolean indicating whether newly selected files should be appended
        * to the existing file list, or whether they should replace it.
        *
        * @attribute appendNewFiles
        * @type {Boolean}
        * @default true
        */
        appendNewFiles : {
            value: true
        },

        /**
        * The names of CSS classes that correspond to different button states
        * of the "Select Files" control. These classes are assigned to the
        * "Select Files" control based on the configuration of the uploader.
        * Currently, the only class name used is that corresponding to the
        * `disabled` state of the uploader. Other button states should be managed
        * directly via CSS selectors.
        * <ul>
        *   <li> <strong>`disabled`</strong>: the class corresponding to the disabled state
        *      of the "Select Files" button.</li>
        * </ul>
        * @attribute buttonClassNames
        * @type {Object}
        * @default {
        *            disabled: "yui3-button-disabled"
        *          }
        */
        buttonClassNames: {
            value: {
                "hover": "yui3-button-hover",
                "active": "yui3-button-active",
                "disabled": "yui3-button-disabled",
                "focus": "yui3-button-selected"
            }
        },

        /**
        * The node that serves as the drop target for files.
        *
        * @attribute dragAndDropArea
        * @type {Node}
        * @default null
        */
        dragAndDropArea: {
            value: null,
            setter: function (val) {
                return Y.one(val);
            }
        },

        /**
        * A Boolean indicating whether the uploader is enabled or disabled for user input.
        *
        * @attribute enabled
        * @type {Boolean}
        * @default true
        */
        enabled : {
            value: true
        },

        /**
        * The action  performed when an upload error occurs for a specific file being uploaded.
        * The possible values are:
        * <ul>
        *   <li> <strong>`UploaderQueue.CONTINUE`</strong>: the error is ignored and the upload process is continued.</li>
        *   <li> <strong>`UploaderQueue.STOP`</strong>: the upload process is stopped as soon as any other parallel file
        *     uploads are finished.</li>
        *   <li> <strong>`UploaderQueue.RESTART_ASAP`</strong>: the file is added back to the front of the queue.</li>
        *   <li> <strong>`UploaderQueue.RESTART_AFTER`</strong>: the file is added to the back of the queue.</li>
        * </ul>
        * @attribute errorAction
        * @type {String}
        * @default UploaderQueue.CONTINUE
        */
        errorAction: {
            value: "continue",
            validator: function (val) {
                return (
                    val === UploaderQueue.CONTINUE ||
                    val === UploaderQueue.STOP ||
                    val === UploaderQueue.RESTART_ASAP ||
                    val === UploaderQueue.RESTART_AFTER
                );
            }
        },

        /**
        * An array indicating what fileFilters should be applied to the file
        * selection dialog. Each element in the array should be a string
        * indicating the Media (MIME) type for the files that should be supported
        * for selection. The Media type strings should be properly formatted
        * or this parameter will be ignored. Examples of valid strings include:
        * "audio/*", "video/*", "application/pdf", etc. More information
        * on valid Media type strings is available here:
        * http://www.iana.org/assignments/media-types/index.html
        * @attribute fileFilters
        * @type {Array}
        * @default []
        */
        fileFilters: {
            value: []
        },

        /**
        * A filtering function that is applied to every file selected by the user.
        * The function receives the `Y.File` object and must return a Boolean value.
        * If a `false` value is returned, the file in question is not added to the
        * list of files to be uploaded.
        * Use this function to put limits on file sizes or check the file names for
        * correct extension, but make sure that a server-side check is also performed,
        * since any client-side restrictions are only advisory and can be circumvented.
        *
        * @attribute fileFilterFunction
        * @type {Function}
        * @default null
        */
        fileFilterFunction: {
            value: null
        },

        /**
        * A String specifying what should be the POST field name for the file
        * content in the upload request.
        *
        * @attribute fileFieldName
        * @type {String}
        * @default Filedata
        */
        fileFieldName: {
            value: "Filedata"
        },

        /**
        * The array of files to be uploaded. All elements in the array
        * must be instances of `Y.File` and be instantiated with an instance
        * of native JavaScript File() class.
        *
        * @attribute fileList
        * @type {Array}
        * @default []
        */
        fileList: {
            value: [],
            getter: "_getFileList",
            setter: "_setFileList"
        },

        /**
        * A Boolean indicating whether multiple file selection is enabled.
        *
        * @attribute multipleFiles
        * @type {Boolean}
        * @default false
        */
        multipleFiles: {
            value: false
        },

        /**
        * An object, keyed by `fileId`, containing sets of key-value pairs
        * that should be passed as POST variables along with each corresponding
        * file. This attribute is only used if no POST variables are specifed
        * in the upload method call.
        *
        * @attribute postVarsPerFile
        * @type {Object}
        * @default {}
        */
        postVarsPerFile: {
            value: {}
        },

        /**
        * The label for the "Select Files" widget. This is the value that replaces the
        * `{selectButtonLabel}` token in the `SELECT_FILES_BUTTON` template.
        *
        * @attribute selectButtonLabel
        * @type {String}
        * @default "Select Files"
        */
        selectButtonLabel: {
            value: "Select Files"
        },

        /**
        * The widget that serves as the "Select Files control for the file uploader
        *
        *
        * @attribute selectFilesButton
        * @type {Node | Widget}
        * @default A standard HTML button with YUI CSS Button skin.
        */
        selectFilesButton : {
            valueFn: function () {
                return Y.Node.create(substitute(Y.UploaderHTML5.SELECT_FILES_BUTTON, {
                    selectButtonLabel: this.get("selectButtonLabel"),
                    tabIndex: this.get("tabIndex")
                }));
            }
        },

        /**
        * The number of files that can be uploaded
        * simultaneously if the automatic queue management
        * is used. This value can be in the range between 2
        * and 5.
        *
        * @attribute simLimit
        * @type {Number}
        * @default 2
        */
        simLimit: {
            value: 2,
            validator: function (val) {
                return (val >= 1 && val <= 5);
            }
        },

        /**
        * The URL to which file upload requested are POSTed. Only used if a different url is not passed to the upload method call.
        *
        * @attribute uploadURL
        * @type {String}
        * @default ""
        */
        uploadURL: {
            value: ""
        },

        /**
        * Additional HTTP headers that should be included
        * in the upload request.
        *
        *
        * @attribute uploadHeaders
        * @type {Object}
        * @default {}
        */
        uploadHeaders: {
            value: {}
        },

        /**
        * A Boolean that specifies whether the file should be
        * uploaded with the appropriate user credentials for the
        * domain.
        *
        * @attribute withCredentials
        * @type {Boolean}
        * @default true
        */
        withCredentials: {
            value: true
        },

        /**
        * The number of times to try re-uploading a file that failed to upload before
        * cancelling its upload.
        *
        * @attribute retryCount
        * @type {Number}
        * @default 3
        */
        retryCount: {
            value: 3
        }
    }
});

Y.UploaderHTML5.Queue = UploaderQueue;