PrivateBin / PrivateBin

js/privatebin.js

/**
 * PrivateBin
 *
 * a zero-knowledge paste bin
 *
 * @see       {@link https://github.com/PrivateBin/PrivateBin}
 * @copyright 2012 Sébastien SAUVAGE ({@link http://sebsauvage.net})
 * @license   {@link https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License}
 * @version   1.1.1
 * @name      PrivateBin
 * @namespace
 */

/** global: Base64 */
/** global: DOMPurify */
/** global: FileReader */
/** global: RawDeflate */
/** global: history */
/** global: navigator */
/** global: prettyPrint */
/** global: prettyPrintOne */
/** global: showdown */
/** global: sjcl */
/** global: kjua */

// Immediately start random number generator collector.
sjcl.random.startCollectors();

// main application start, called when DOM is fully loaded
jQuery(document).ready(function() {
    'use strict';
    // run main controller
    $.PrivateBin.Controller.init();
});

jQuery.PrivateBin = (function($, sjcl, Base64, RawDeflate) {
    'use strict';

    /**
     * static Helper methods
     *
     * @name Helper
     * @class
     */
    var Helper = (function () {
        var me = {};

        /**
         * cache for script location
         *
         * @name Helper.baseUri
         * @private
         * @enum   {string|null}
         */
        var baseUri = null;

        /**
         * converts a duration (in seconds) into human friendly approximation
         *
         * @name Helper.secondsToHuman
         * @function
         * @param  {number} seconds
         * @return {Array}
         */
        me.secondsToHuman = function(seconds)
        {
            var v;
            if (seconds < 60)
            {
                v = Math.floor(seconds);
                return [v, 'second'];
            }
            if (seconds < 60 * 60)
            {
                v = Math.floor(seconds / 60);
                return [v, 'minute'];
            }
            if (seconds < 60 * 60 * 24)
            {
                v = Math.floor(seconds / (60 * 60));
                return [v, 'hour'];
            }
            // If less than 2 months, display in days:
            if (seconds < 60 * 60 * 24 * 60)
            {
                v = Math.floor(seconds / (60 * 60 * 24));
                return [v, 'day'];
            }
            v = Math.floor(seconds / (60 * 60 * 24 * 30));
            return [v, 'month'];
        };

        /**
         * text range selection
         *
         * @see    {@link https://stackoverflow.com/questions/985272/jquery-selecting-text-in-an-element-akin-to-highlighting-with-your-mouse}
         * @name   Helper.selectText
         * @function
         * @param  {HTMLElement} element
         */
        me.selectText = function(element)
        {
            var range, selection;

            // MS
            if (document.body.createTextRange) {
                range = document.body.createTextRange();
                range.moveToElementText(element);
                range.select();
            } else if (window.getSelection) {
                selection = window.getSelection();
                range = document.createRange();
                range.selectNodeContents(element);
                selection.removeAllRanges();
                selection.addRange(range);
            }
        };

        /**
         * convert URLs to clickable links.
         * URLs to handle:
         * <pre>
         *     magnet:?xt.1=urn:sha1:YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C&xt.2=urn:sha1:TXGCZQTH26NL6OUQAJJPFALHG2LTGBC7
         *     http://example.com:8800/zero/?6f09182b8ea51997#WtLEUO5Epj9UHAV9JFs+6pUQZp13TuspAUjnF+iM+dM=
         *     http://user:example.com@localhost:8800/zero/?6f09182b8ea51997#WtLEUO5Epj9UHAV9JFs+6pUQZp13TuspAUjnF+iM+dM=
         * </pre>
         *
         * @name   Helper.urls2links
         * @function
         * @param  {string} html
         * @return {string}
         */
        me.urls2links = function(html)
        {
            return html.replace(
                /(((http|https|ftp):\/\/[\w?=&.\/-;#@~%+*-]+(?![\w\s?&.\/;#~%"=-]*>))|((magnet):[\w?=&.\/-;#@~%+*-]+))/ig,
                '<a href="$1" rel="nofollow">$1</a>'
            );
        };

        /**
         * minimal sprintf emulation for %s and %d formats
         *
         * Note that this function needs the parameters in the same order as the
         * format strings appear in the string, contrary to the original.
         *
         * @see    {@link https://stackoverflow.com/questions/610406/javascript-equivalent-to-printf-string-format#4795914}
         * @name   Helper.sprintf
         * @function
         * @param  {string} format
         * @param  {...*} args - one or multiple parameters injected into format string
         * @return {string}
         */
        me.sprintf = function()
        {
            var args = Array.prototype.slice.call(arguments);
            var format = args[0],
                i = 1;
            return format.replace(/%(s|d)/g, function (m) {
                // m is the matched format, e.g. %s, %d
                var val = args[i];
                // A switch statement so that the formatter can be extended.
                switch (m)
                {
                    case '%d':
                        val = parseFloat(val);
                        if (isNaN(val)) {
                            val = 0;
                        }
                        break;
                    default:
                        // Default is %s
                }
                ++i;
                return val;
            });
        };

        /**
         * get value of cookie, if it was set, empty string otherwise
         *
         * @see    {@link http://www.w3schools.com/js/js_cookies.asp}
         * @name   Helper.getCookie
         * @function
         * @param  {string} cname - may not be empty
         * @return {string}
         */
        me.getCookie = function(cname) {
            var name = cname + '=',
                ca = document.cookie.split(';');
            for (var i = 0; i < ca.length; ++i) {
                var c = ca[i];
                while (c.charAt(0) === ' ')
                {
                    c = c.substring(1);
                }
                if (c.indexOf(name) === 0)
                {
                    return c.substring(name.length, c.length);
                }
            }
            return '';
        };

        /**
         * get the current location (without search or hash part of the URL),
         * eg. http://example.com/path/?aaaa#bbbb --> http://example.com/path/
         *
         * @name   Helper.baseUri
         * @function
         * @return {string}
         */
        me.baseUri = function()
        {
            // check for cached version
            if (baseUri !== null) {
                return baseUri;
            }

            baseUri = window.location.origin + window.location.pathname;
            return baseUri;
        };

        /**
         * resets state, used for unit testing
         *
         * @name   Helper.reset
         * @function
         */
        me.reset = function()
        {
            baseUri = null;
        };

        return me;
    })();

    /**
     * internationalization module
     *
     * @name I18n
     * @class
     */
    var I18n = (function () {
        var me = {};

        /**
         * const for string of loaded language
         *
         * @name I18n.languageLoadedEvent
         * @private
         * @prop   {string}
         * @readonly
         */
        var languageLoadedEvent = 'languageLoaded';

        /**
         * supported languages, minus the built in 'en'
         *
         * @name I18n.supportedLanguages
         * @private
         * @prop   {string[]}
         * @readonly
         */
        var supportedLanguages = ['de', 'es', 'fr', 'it', 'no', 'pl', 'pt', 'oc', 'ru', 'sl', 'zh'];

        /**
         * built in language
         *
         * @name I18n.language
         * @private
         * @prop   {string|null}
         */
        var language = null;

        /**
         * translation cache
         *
         * @name I18n.translations
         * @private
         * @enum   {Object}
         */
        var translations = {};

        /**
         * translate a string, alias for I18n.translate
         *
         * @name   I18n._
         * @function
         * @param  {jQuery} $element - optional
         * @param  {string} messageId
         * @param  {...*} args - one or multiple parameters injected into placeholders
         * @return {string}
         */
        me._ = function()
        {
            return me.translate.apply(this, arguments);
        };

        /**
         * translate a string
         *
         * Optionally pass a jQuery element as the first parameter, to automatically
         * let the text of this element be replaced. In case the (asynchronously
         * loaded) language is not downloadet yet, this will make sure the string
         * is replaced when it is actually loaded.
         * So for easy translations passing the jQuery object to apply it to is
         * more save, especially when they are loaded in the beginning.
         *
         * @name   I18n.translate
         * @function
         * @param  {jQuery} $element - optional
         * @param  {string} messageId
         * @param  {...*} args - one or multiple parameters injected into placeholders
         * @return {string}
         */
        me.translate = function()
        {
            // convert parameters to array
            var args = Array.prototype.slice.call(arguments),
                messageId,
                $element = null;

            // parse arguments
            if (args[0] instanceof jQuery) {
                // optional jQuery element as first parameter
                $element = args[0];
                args.shift();
            }

            // extract messageId from arguments
            var usesPlurals = $.isArray(args[0]);
            if (usesPlurals) {
                // use the first plural form as messageId, otherwise the singular
                messageId = args[0].length > 1 ? args[0][1] : args[0][0];
            } else {
                messageId = args[0];
            }

            if (messageId.length === 0) {
                return messageId;
            }

            // if no translation string cannot be found (in translations object)
            if (!translations.hasOwnProperty(messageId) || language === null) {
                // if language is still loading and we have an elemt assigned
                if (language === null && $element !== null) {
                    // handle the error by attaching the language loaded event
                    var orgArguments = arguments;
                    $(document).on(languageLoadedEvent, function () {
                        // log to show that the previous error could be mitigated
                        console.warn('Fix missing translation of \'' + messageId + '\' with now loaded language ' + language);
                        // re-execute this function
                        me.translate.apply(this, orgArguments);
                    });

                    // and fall back to English for now until the real language
                    // file is loaded
                }

                // for all other langauges than English for which this behaviour
                // is expected as it is built-in, log error
                if (language !== null && language !== 'en') {
                    console.error('Missing translation for: \'' + messageId + '\' in language ' + language);
                    // fallback to English
                }

                // save English translation (should be the same on both sides)
                translations[messageId] = args[0];
            }

            // lookup plural translation
            if (usesPlurals && $.isArray(translations[messageId])) {
                var n = parseInt(args[1] || 1, 10),
                    key = me.getPluralForm(n),
                    maxKey = translations[messageId].length - 1;
                if (key > maxKey) {
                    key = maxKey;
                }
                args[0] = translations[messageId][key];
                args[1] = n;
            } else {
                // lookup singular translation
                args[0] = translations[messageId];
            }

            // format string
            var output = Helper.sprintf.apply(this, args);

            // if $element is given, apply text to element
            if ($element !== null) {
                // get last text node of element
                var content = $element.contents();
                if (content.length > 1) {
                    content[content.length - 1].nodeValue = ' ' + output;
                } else {
                    $element.text(output);
                }
            }

            return output;
        };

        /**
         * per language functions to use to determine the plural form
         *
         * @see    {@link http://localization-guide.readthedocs.org/en/latest/l10n/pluralforms.html}
         * @name   I18n.getPluralForm
         * @function
         * @param  {int} n
         * @return {int} array key
         */
        me.getPluralForm = function(n) {
            switch (language)
            {
                case 'fr':
                case 'oc':
                case 'zh':
                    return n > 1 ? 1 : 0;
                case 'pl':
                    return n === 1 ? 0 : (n % 10 >= 2 && n %10 <=4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2);
                case 'ru':
                    return n % 10 === 1 && n % 100 !== 11 ? 0 : (n % 10 >= 2 && n % 10 <= 4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2);
                case 'sl':
                    return n % 100 === 1 ? 1 : (n % 100 === 2 ? 2 : (n % 100 === 3 || n % 100 === 4 ? 3 : 0));
                // de, en, es, it, no, pt
                default:
                    return n !== 1 ? 1 : 0;
            }
        };

        /**
         * load translations into cache
         *
         * @name   I18n.loadTranslations
         * @function
         */
        me.loadTranslations = function()
        {
            var newLanguage = Helper.getCookie('lang');

            // auto-select language based on browser settings
            if (newLanguage.length === 0) {
                newLanguage = (navigator.language || navigator.userLanguage || 'en').substring(0, 2);
            }

            // if language is already used skip update
            if (newLanguage === language) {
                return;
            }

            // if language is built-in (English) skip update
            if (newLanguage === 'en') {
                language = 'en';
                return;
            }

            // if language is not supported, show error
            if (supportedLanguages.indexOf(newLanguage) === -1) {
                console.error('Language \'%s\' is not supported. Translation failed, fallback to English.', newLanguage);
                language = 'en';
                return;
            }

            // load strings from JSON
            $.getJSON('i18n/' + newLanguage + '.json', function(data) {
                language = newLanguage;
                translations = data;
                $(document).triggerHandler(languageLoadedEvent);
            }).fail(function (data, textStatus, errorMsg) {
                console.error('Language \'%s\' could not be loaded (%s: %s). Translation failed, fallback to English.', newLanguage, textStatus, errorMsg);
                language = 'en';
            });
        };

        /**
         * resets state, used for unit testing
         *
         * @name   I18n.reset
         * @function
         */
        me.reset = function(mockLanguage, mockTranslations)
        {
            language = mockLanguage || null;
            translations = mockTranslations || {};
        };

        return me;
    })();

    /**
     * handles everything related to en/decryption
     *
     * @name CryptTool
     * @class
     */
    var CryptTool = (function () {
        var me = {};

        /**
         * compress a message (deflate compression), returns base64 encoded data
         *
         * @name   CryptTool.compress
         * @function
         * @private
         * @param  {string} message
         * @return {string} base64 data
         */
        function compress(message)
        {
            return Base64.toBase64( RawDeflate.deflate( Base64.utob(message) ) );
        }

        /**
         * decompress a message compressed with cryptToolcompress()
         *
         * @name   CryptTool.decompress
         * @function
         * @private
         * @param  {string} data - base64 data
         * @return {string} message
         */
        function decompress(data)
        {
            return Base64.btou( RawDeflate.inflate( Base64.fromBase64(data) ) );
        }

        /**
         * compress, then encrypt message with given key and password
         *
         * @name   CryptTool.cipher
         * @function
         * @param  {string} key
         * @param  {string} password
         * @param  {string} message
         * @return {string} data - JSON with encrypted data
         */
        me.cipher = function(key, password, message)
        {
            // Galois Counter Mode, keysize 256 bit, authentication tag 128 bit
            var options = {
                mode: 'gcm',
                ks: 256,
                ts: 128
            };

            if ((password || '').trim().length === 0) {
                return sjcl.encrypt(key, compress(message), options);
            }
            return sjcl.encrypt(key + sjcl.codec.hex.fromBits(sjcl.hash.sha256.hash(password)), compress(message), options);
        };

        /**
         * decrypt message with key, then decompress
         *
         * @name   CryptTool.decipher
         * @function
         * @param  {string} key
         * @param  {string} password
         * @param  {string} data - JSON with encrypted data
         * @return {string} decrypted message, empty if decryption failed
         */
        me.decipher = function(key, password, data)
        {
            if (data !== undefined) {
                try {
                    return decompress(sjcl.decrypt(key, data));
                } catch(err) {
                    try {
                        return decompress(sjcl.decrypt(key + sjcl.codec.hex.fromBits(sjcl.hash.sha256.hash(password)), data));
                    } catch(e) {
                        return '';
                    }
                }
            }
        };

        /**
         * checks whether the crypt tool has collected enough entropy
         *
         * @name   CryptTool.isEntropyReady
         * @function
         * @return {bool}
         */
        me.isEntropyReady = function()
        {
            return sjcl.random.isReady();
        };

        /**
         * add a listener function, triggered when enough entropy is available
         *
         * @name   CryptTool.addEntropySeedListener
         * @function
         * @param {function} func
         */
        me.addEntropySeedListener = function(func)
        {
            sjcl.random.addEventListener('seeded', func);
        };

        /**
         * returns a random symmetric key
         *
         * @name   CryptTool.getSymmetricKey
         * @function
         * @return {string} func
         */
        me.getSymmetricKey = function()
        {
            return sjcl.codec.base64.fromBits(sjcl.random.randomWords(8, 0), 0);
        };

        return me;
    })();

    /**
     * (Model) Data source (aka MVC)
     *
     * @name   Model
     * @class
     */
    var Model = (function () {
        var me = {};

        var $cipherData,
            $templates;

        var id = null, symmetricKey = null;

        /**
         * returns the expiration set in the HTML
         *
         * @name   Model.getExpirationDefault
         * @function
         * @return string
         */
        me.getExpirationDefault = function()
        {
            return $('#pasteExpiration').val();
        };

        /**
         * returns the format set in the HTML
         *
         * @name   Model.getFormatDefault
         * @function
         * @return string
         */
        me.getFormatDefault = function()
        {
            return $('#pasteFormatter').val();
        };

        /**
         * check if cipher data was supplied
         *
         * @name   Model.getCipherData
         * @function
         * @return boolean
         */
        me.hasCipherData = function()
        {
            return me.getCipherData().length > 0;
        };

        /**
         * returns the cipher data
         *
         * @name   Model.getCipherData
         * @function
         * @return string
         */
        me.getCipherData = function()
        {
            return $cipherData.text();
        };

        /**
         * get the pastes unique identifier from the URL,
         * eg. http://example.com/path/?c05354954c49a487#dfdsdgdgdfgdf returns c05354954c49a487
         *
         * @name   Model.getPasteId
         * @function
         * @return {string} unique identifier
         * @throws {string}
         */
        me.getPasteId = function()
        {
            if (id === null) {
                id = window.location.search.substring(1);

                if (id === '') {
                    throw 'no paste id given';
                }
            }

            return id;
        };

        /**
         * return the deciphering key stored in anchor part of the URL
         *
         * @name   Model.getPasteKey
         * @function
         * @return {string|null} key
         * @throws {string}
         */
        me.getPasteKey = function()
        {
            if (symmetricKey === null) {
                symmetricKey = window.location.hash.substring(1);

                if (symmetricKey === '') {
                    throw 'no encryption key given';
                }

                // Some web 2.0 services and redirectors add data AFTER the anchor
                // (such as &utm_source=...). We will strip any additional data.
                var ampersandPos = symmetricKey.indexOf('&');
                if (ampersandPos > -1)
                {
                    symmetricKey = symmetricKey.substring(0, ampersandPos);
                }
            }

            return symmetricKey;
        };

        /**
         * returns a jQuery copy of the HTML template
         *
         * @name Model.getTemplate
         * @function
         * @param  {string} name - the name of the template
         * @return {jQuery}
         */
        me.getTemplate = function(name)
        {
            // find template
            var $element = $templates.find('#' + name + 'template').clone(true);
            // change ID to avoid collisions (one ID should really be unique)
            return $element.prop('id', name);
        };

        /**
         * resets state, used for unit testing
         *
         * @name   Model.reset
         * @function
         */
        me.reset = function()
        {
            $cipherData = $templates = id = symmetricKey = null;
        };

        /**
         * init navigation manager
         *
         * preloads jQuery elements
         *
         * @name   Model.init
         * @function
         */
        me.init = function()
        {
            $cipherData = $('#cipherdata');
            $templates = $('#templates');
        };

        return me;
    })();

    /**
     * Helper functions for user interface
     *
     * everything directly UI-related, which fits nowhere else
     *
     * @name   UiHelper
     * @class
     */
    var UiHelper = (function () {
        var me = {};

        /**
         * handle history (pop) state changes
         *
         * currently this does only handle redirects to the home page.
         *
         * @name   UiHelper.historyChange
         * @private
         * @function
         * @param  {Event} event
         */
        function historyChange(event)
        {
            var currentLocation = Helper.baseUri();
            if (event.originalEvent.state === null && // no state object passed
                event.target.location.href === currentLocation && // target location is home page
                window.location.href === currentLocation // and we are not already on the home page
            ) {
                // redirect to home page
                window.location.href = currentLocation;
            }
        }

        /**
         * reload the page
         *
         * This takes the user to the PrivateBin homepage.
         *
         * @name   UiHelper.reloadHome
         * @function
         */
        me.reloadHome = function()
        {
            window.location.href = Helper.baseUri();
        };

        /**
         * checks whether the element is currently visible in the viewport (so
         * the user can actually see it)
         *
         * @see    {@link https://stackoverflow.com/a/40658647}
         * @name   UiHelper.isVisible
         * @function
         * @param  {jQuery} $element The link hash to move to.
         */
        me.isVisible = function($element)
        {
            var elementTop = $element.offset().top;
            var viewportTop = $(window).scrollTop();
            var viewportBottom = viewportTop + $(window).height();

            return elementTop > viewportTop && elementTop < viewportBottom;
        };

        /**
         * scrolls to a specific element
         *
         * @see    {@link https://stackoverflow.com/questions/4198041/jquery-smooth-scroll-to-an-anchor#answer-12714767}
         * @name   UiHelper.scrollTo
         * @function
         * @param  {jQuery}           $element        The link hash to move to.
         * @param  {(number|string)}  animationDuration passed to jQuery .animate, when set to 0 the animation is skipped
         * @param  {string}           animationEffect   passed to jQuery .animate
         * @param  {function}         finishedCallback  function to call after animation finished
         */
        me.scrollTo = function($element, animationDuration, animationEffect, finishedCallback)
        {
            var $body = $('html, body'),
                margin = 50,
                callbackCalled = false;

            //calculate destination place
            var dest = 0;
            // if it would scroll out of the screen at the bottom only scroll it as
            // far as the screen can go
            if ($element.offset().top > $(document).height() - $(window).height()) {
                dest = $(document).height() - $(window).height();
            } else {
                dest = $element.offset().top - margin;
            }
            // skip animation if duration is set to 0
            if (animationDuration === 0) {
                window.scrollTo(0, dest);
            } else {
                // stop previous animation
                $body.stop();
                // scroll to destination
                $body.animate({
                    scrollTop: dest
                }, animationDuration, animationEffect);
            }

            // as we have finished we can enable scrolling again
            $body.queue(function (next) {
                if (!callbackCalled) {
                    // call user function if needed
                    if (typeof finishedCallback !== 'undefined') {
                        finishedCallback();
                    }

                    // prevent calling this function twice
                    callbackCalled = true;
                }
                next();
            });
        };

        /**
         * trigger a history (pop) state change
         *
         * used to test the UiHelper.historyChange private function
         *
         * @name   UiHelper.mockHistoryChange
         * @function
         * @param  {string} state   (optional) state to mock
         */
        me.mockHistoryChange = function(state)
        {
            if (typeof state === 'undefined') {
                state = null;
            }
            historyChange($.Event('popstate', {originalEvent: new PopStateEvent('popstate', {state: state}), target: window}));
        };

        /**
         * initialize
         *
         * @name   UiHelper.init
         * @function
         */
        me.init = function()
        {
            // update link to home page
            $('.reloadlink').prop('href', Helper.baseUri());

            $(window).on('popstate', historyChange);
        };

        return me;
    })();

    /**
     * Alert/error manager
     *
     * @name   Alert
     * @class
     */
    var Alert = (function () {
        var me = {};

        var $errorMessage,
            $loadingIndicator,
            $statusMessage,
            $remainingTime;

        var currentIcon;

        var alertType = [
            'loading', // not in bootstrap, but using a good value here
            'info', // status icon
            'warning', // not used yet
            'danger' // error icon
        ];

        var customHandler;

        /**
         * forwards a request to the i18n module and shows the element
         *
         * @name   Alert.handleNotification
         * @private
         * @function
         * @param  {int} id - id of notification
         * @param  {jQuery} $element - jQuery object
         * @param  {string|array} args
         * @param  {string|null} icon - optional, icon
         */
        function handleNotification(id, $element, args, icon)
        {
            // basic parsing/conversion of parameters
            if (typeof icon === 'undefined') {
                icon = null;
            }
            if (typeof args === 'undefined') {
                args = null;
            } else if (typeof args === 'string') {
                // convert string to array if needed
                args = [args];
            }

            // pass to custom handler if defined
            if (typeof customHandler === 'function') {
                var handlerResult = customHandler(alertType[id], $element, args, icon);
                if (handlerResult === true) {
                    // if it returns true, skip own handler
                    return;
                }
                if (handlerResult instanceof jQuery) {
                    // continue processing with new element
                    $element = handlerResult;
                    icon = null; // icons not supported in this case
                }
            }

            // handle icon
            if (icon !== null && // icon was passed
                icon !== currentIcon[id] // and it differs from current icon
            ) {
                var $glyphIcon = $element.find(':first');

                // remove (previous) icon
                $glyphIcon.removeClass(currentIcon[id]);

                // any other thing as a string (e.g. 'null') (only) removes the icon
                if (typeof icon === 'string') {
                    // set new icon
                    currentIcon[id] = 'glyphicon-' + icon;
                    $glyphIcon.addClass(currentIcon[id]);
                }
            }

            // show text
            if (args !== null) {
                // add jQuery object to it as first parameter
                args.unshift($element);
                // pass it to I18n
                I18n._.apply(this, args);
            }

            // show notification
            $element.removeClass('hidden');
        }

        /**
         * display a status message
         *
         * This automatically passes the text to I18n for translation.
         *
         * @name   Alert.showStatus
         * @function
         * @param  {string|array} message     string, use an array for %s/%d options
         * @param  {string|null}  icon        optional, the icon to show,
         *                                    default: leave previous icon
         */
        me.showStatus = function(message, icon)
        {
            console.info('status shown: ', message);
            handleNotification(1, $statusMessage, message, icon);
        };

        /**
         * display an error message
         *
         * This automatically passes the text to I18n for translation.
         *
         * @name   Alert.showError
         * @function
         * @param  {string|array} message     string, use an array for %s/%d options
         * @param  {string|null}  icon        optional, the icon to show, default:
         *                                    leave previous icon
         */
        me.showError = function(message, icon)
        {
            console.error('error message shown: ', message);
            handleNotification(3, $errorMessage, message, icon);
        };

        /**
         * display remaining message
         *
         * This automatically passes the text to I18n for translation.
         *
         * @name   Alert.showRemaining
         * @function
         * @param  {string|array} message     string, use an array for %s/%d options
         */
        me.showRemaining = function(message)
        {
            console.info('remaining message shown: ', message);
            handleNotification(1, $remainingTime, message);
        };

        /**
         * shows a loading message, optionally with a percentage
         *
         * This automatically passes all texts to the i10s module.
         *
         * @name   Alert.showLoading
         * @function
         * @param  {string|array|null} message      optional, use an array for %s/%d options, default: 'Loading…'
         * @param  {string|null}       icon         optional, the icon to show, default: leave previous icon
         */
        me.showLoading = function(message, icon)
        {
            if (typeof message !== 'undefined' && message !== null) {
                console.info('status changed: ', message);
            }

            // default message text
            if (typeof message === 'undefined') {
                message = 'Loading…';
            }

            handleNotification(0, $loadingIndicator, message, icon);

            // show loading status (cursor)
            $('body').addClass('loading');
        };

        /**
         * hides the loading message
         *
         * @name   Alert.hideLoading
         * @function
         */
        me.hideLoading = function()
        {
            $loadingIndicator.addClass('hidden');

            // hide loading cursor
            $('body').removeClass('loading');
        };

        /**
         * hides any status/error messages
         *
         * This does not include the loading message.
         *
         * @name   Alert.hideMessages
         * @function
         */
        me.hideMessages = function()
        {
            // also possible: $('.statusmessage').addClass('hidden');
            $statusMessage.addClass('hidden');
            $errorMessage.addClass('hidden');
        };

        /**
         * set a custom handler, which gets all notifications.
         *
         * This handler gets the following arguments:
         * alertType (see array), $element, args, icon
         * If it returns true, the own processing will be stopped so the message
         * will not be displayed. Otherwise it will continue.
         * As an aditional feature it can return q jQuery element, which will
         * then be used to add the message there. Icons are not supported in
         * that case and will be ignored.
         * Pass 'null' to reset/delete the custom handler.
         * Note that there is no notification when a message is supposed to get
         * hidden.
         *
         * @name   Alert.setCustomHandler
         * @function
         * @param {function|null} newHandler
         */
        me.setCustomHandler = function(newHandler)
        {
            customHandler = newHandler;
        };

        /**
         * init status manager
         *
         * preloads jQuery elements
         *
         * @name   Alert.init
         * @function
         */
        me.init = function()
        {
            // hide "no javascript" error message
            $('#noscript').hide();

            // not a reset, but first set of the elements
            $errorMessage = $('#errormessage');
            $loadingIndicator = $('#loadingindicator');
            $statusMessage = $('#status');
            $remainingTime = $('#remainingtime');

            currentIcon = [
                'glyphicon-time', // loading icon
                'glyphicon-info-sign', // status icon
                '', // reserved for warning, not used yet
                'glyphicon-alert' // error icon
            ];
        };

        return me;
    })();

    /**
     * handles paste status/result
     *
     * @name   PasteStatus
     * @class
     */
    var PasteStatus = (function () {
        var me = {};

        var $pasteSuccess,
            $pasteUrl,
            $remainingTime,
            $shortenButton;

        /**
         * forward to URL shortener
         *
         * @name   PasteStatus.sendToShortener
         * @private
         * @function
         */
        function sendToShortener()
        {
            window.location.href = $shortenButton.data('shortener') +
                                   encodeURIComponent($pasteUrl.attr('href'));
        }

        /**
         * Forces opening the paste if the link does not do this automatically.
         *
         * This is necessary as browsers will not reload the page when it is
         * already loaded (which is fake as it is set via history.pushState()).
         *
         * @name   PasteStatus.pasteLinkClick
         * @function
         */
        function pasteLinkClick()
        {
            // check if location is (already) shown in URL bar
            if (window.location.href === $pasteUrl.attr('href')) {
                // if so we need to load link by reloading the current site
                window.location.reload(true);
            }
        }

        /**
         * creates a notification after a successfull paste upload
         *
         * @name   PasteStatus.createPasteNotification
         * @function
         * @param  {string} url
         * @param  {string} deleteUrl
         */
        me.createPasteNotification = function(url, deleteUrl)
        {
            $('#pastelink').html(
                I18n._(
                    'Your paste is <a id="pasteurl" href="%s">%s</a> <span id="copyhint">(Hit [Ctrl]+[c] to copy)</span>',
                    url, url
                )
            );
            // save newly created element
            $pasteUrl = $('#pasteurl');
            // and add click event
            $pasteUrl.click(pasteLinkClick);

            // shorten button
            $('#deletelink').html('<a href="' + deleteUrl + '">' + I18n._('Delete data') + '</a>');

            // show result
            $pasteSuccess.removeClass('hidden');
            // we pre-select the link so that the user only has to [Ctrl]+[c] the link
            Helper.selectText($pasteUrl[0]);
        };

        /**
         * shows the remaining time
         *
         * @name PasteStatus.showRemainingTime
         * @function
         * @param {object} pasteMetaData
         */
        me.showRemainingTime = function(pasteMetaData)
        {
            if (pasteMetaData.burnafterreading) {
                // display paste "for your eyes only" if it is deleted

                // actually remove paste, before we claim it is deleted
                Controller.removePaste(Model.getPasteId(), 'burnafterreading');

                Alert.showRemaining("FOR YOUR EYES ONLY. Don't close this window, this message can't be displayed again.");
                $remainingTime.addClass('foryoureyesonly');

                // discourage cloning (it cannot really be prevented)
                TopNav.hideCloneButton();

            } else if (pasteMetaData.expire_date) {
                // display paste expiration
                var expiration = Helper.secondsToHuman(pasteMetaData.remaining_time),
                    expirationLabel = [
                        'This document will expire in %d ' + expiration[1] + '.',
                        'This document will expire in %d ' + expiration[1] + 's.'
                    ];

                Alert.showRemaining([expirationLabel, expiration[0]]);
                $remainingTime.removeClass('foryoureyesonly');
            } else {
                // never expires
                return;
            }

            // in the end, display notification
            $remainingTime.removeClass('hidden');
        };

        /**
         * hides the remaining time and successful upload notification
         *
         * @name PasteStatus.hideMessages
         * @function
         */
        me.hideMessages = function()
        {
            $remainingTime.addClass('hidden');
            $pasteSuccess.addClass('hidden');
        };

        /**
         * init status manager
         *
         * preloads jQuery elements
         *
         * @name   PasteStatus.init
         * @function
         */
        me.init = function()
        {
            $pasteSuccess = $('#pastesuccess');
            // $pasteUrl is saved in me.createPasteNotification() after creation
            $remainingTime = $('#remainingtime');
            $shortenButton = $('#shortenbutton');

            // bind elements
            $shortenButton.click(sendToShortener);
        };

        return me;
    })();

    /**
     * password prompt
     *
     * @name Prompt
     * @class
     */
    var Prompt = (function () {
        var me = {};

        var $passwordDecrypt,
            $passwordForm,
            $passwordModal;

        var password = '';

        /**
         * submit a password in the modal dialog
         *
         * @name Prompt.submitPasswordModal
         * @private
         * @function
         * @param  {Event} event
         */
        function submitPasswordModal(event)
        {
            event.preventDefault();

            // get input
            password = $passwordDecrypt.val();

            // hide modal
            $passwordModal.modal('hide');

            PasteDecrypter.run();
        }

        /**
         * ask the user for the password and set it
         *
         * @name Prompt.requestPassword
         * @function
         */
        me.requestPassword = function()
        {
            // show new bootstrap method (if available)
            if ($passwordModal.length !== 0) {
                $passwordModal.modal({
                    backdrop: 'static',
                    keyboard: false
                });
                return;
            }

            // fallback to old method for page template
            var newPassword = prompt(I18n._('Please enter the password for this paste:'), '');
            if (newPassword === null) {
                throw 'password prompt canceled';
            }
            if (password.length === 0) {
                // recurse…
                return me.requestPassword();
            }

            password = newPassword;
        };

        /**
         * get the cached password
         *
         * If you do not get a password with this function
         * (returns an empty string), use requestPassword.
         *
         * @name   Prompt.getPassword
         * @function
         * @return {string}
         */
        me.getPassword = function()
        {
            return password;
        };

        /**
         * init status manager
         *
         * preloads jQuery elements
         *
         * @name   Prompt.init
         * @function
         */
        me.init = function()
        {
            $passwordDecrypt = $('#passworddecrypt');
            $passwordForm = $('#passwordform');
            $passwordModal = $('#passwordmodal');

            // bind events

            // focus password input when it is shown
            $passwordModal.on('shown.bs.Model', function () {
                $passwordDecrypt.focus();
            });
            // handle Model password submission
            $passwordForm.submit(submitPasswordModal);
        };

        return me;
    })();

    /**
     * Manage paste/message input, and preview tab
     *
     * Note that the actual preview is handled by PasteViewer.
     *
     * @name   Editor
     * @class
     */
    var Editor = (function () {
        var me = {};

        var $editorTabs,
            $messageEdit,
            $messagePreview,
            $message;

        var isPreview = false;

        /**
         * support input of tab character
         *
         * @name   Editor.supportTabs
         * @function
         * @param  {Event} event
         * @this $message (but not used, so it is jQuery-free, possibly faster)
         */
        function supportTabs(event)
        {
            var keyCode = event.keyCode || event.which;
            // tab was pressed
            if (keyCode === 9) {
                // get caret position & selection
                var val   = this.value,
                    start = this.selectionStart,
                    end   = this.selectionEnd;
                // set textarea value to: text before caret + tab + text after caret
                this.value = val.substring(0, start) + '\t' + val.substring(end);
                // put caret at right position again
                this.selectionStart = this.selectionEnd = start + 1;
                // prevent the textarea to lose focus
                event.preventDefault();
            }
        }

        /**
         * view the Editor tab
         *
         * @name   Editor.viewEditor
         * @function
         * @param  {Event} event - optional
         */
        function viewEditor(event)
        {
            // toggle buttons
            $messageEdit.addClass('active');
            $messagePreview.removeClass('active');

            PasteViewer.hide();

            // reshow input
            $message.removeClass('hidden');

            me.focusInput();

            // finish
            isPreview = false;

            // prevent jumping of page to top
            if (typeof event !== 'undefined') {
                event.preventDefault();
            }
        }

        /**
         * view the preview tab
         *
         * @name   Editor.viewPreview
         * @function
         * @param  {Event} event
         */
        function viewPreview(event)
        {
            // toggle buttons
            $messageEdit.removeClass('active');
            $messagePreview.addClass('active');

            // hide input as now preview is shown
            $message.addClass('hidden');

            // show preview
            PasteViewer.setText($message.val());
            PasteViewer.run();

            // finish
            isPreview = true;

            // prevent jumping of page to top
            if (typeof event !== 'undefined') {
                event.preventDefault();
            }
        }

        /**
         * get the state of the preview
         *
         * @name   Editor.isPreview
         * @function
         */
        me.isPreview = function()
        {
            return isPreview;
        };

        /**
         * reset the Editor view
         *
         * @name   Editor.resetInput
         * @function
         */
        me.resetInput = function()
        {
            // go back to input
            if (isPreview) {
                viewEditor();
            }

            // clear content
            $message.val('');
        };

        /**
         * shows the Editor
         *
         * @name   Editor.show
         * @function
         */
        me.show = function()
        {
            $message.removeClass('hidden');
            $editorTabs.removeClass('hidden');
        };

        /**
         * hides the Editor
         *
         * @name   Editor.reset
         * @function
         */
        me.hide = function()
        {
            $message.addClass('hidden');
            $editorTabs.addClass('hidden');
        };

        /**
         * focuses the message input
         *
         * @name   Editor.focusInput
         * @function
         */
        me.focusInput = function()
        {
            $message.focus();
        };

        /**
         * sets a new text
         *
         * @name   Editor.setText
         * @function
         * @param {string} newText
         */
        me.setText = function(newText)
        {
            $message.val(newText);
        };

        /**
         * returns the current text
         *
         * @name   Editor.getText
         * @function
         * @return {string}
         */
        me.getText = function()
        {
            return $message.val();
        };

        /**
         * init status manager
         *
         * preloads jQuery elements
         *
         * @name   Editor.init
         * @function
         */
        me.init = function()
        {
            $editorTabs = $('#editorTabs');
            $message = $('#message');

            // bind events
            $message.keydown(supportTabs);

            // bind click events to tab switchers (a), but save parent of them
            // (li)
            $messageEdit = $('#messageedit').click(viewEditor).parent();
            $messagePreview = $('#messagepreview').click(viewPreview).parent();
        };

        return me;
    })();

    /**
     * (view) Parse and show paste.
     *
     * @name   PasteViewer
     * @class
     */
    var PasteViewer = (function () {
        var me = {};

        var $placeholder,
            $prettyMessage,
            $prettyPrint,
            $plainText;

        var text,
            format = 'plaintext',
            isDisplayed = false,
            isChanged = true; // by default true as nothing was parsed yet

        /**
         * apply the set format on paste and displays it
         *
         * @name   PasteViewer.parsePaste
         * @private
         * @function
         */
        function parsePaste()
        {
            // skip parsing if no text is given
            if (text === '') {
                return;
            }

            // escape HTML entities, link URLs, sanitize
            var escapedLinkedText = Helper.urls2links(
                    $('<div />').text(text).html()
                ),
                sanitizedLinkedText = DOMPurify.sanitize(escapedLinkedText);
            $plainText.html(sanitizedLinkedText);
            $prettyPrint.html(sanitizedLinkedText);

            switch (format) {
                case 'markdown':
                    var converter = new showdown.Converter({
                        strikethrough: true,
                        tables: true,
                        tablesHeaderId: true
                    });
                    // let showdown convert the HTML and sanitize HTML *afterwards*!
                    $plainText.html(
                        DOMPurify.sanitize(converter.makeHtml(text))
                    );
                    // add table classes from bootstrap css
                    $plainText.find('table').addClass('table-condensed table-bordered');
                    break;
                case 'syntaxhighlighting':
                    // yes, this is really needed to initialize the environment
                    if (typeof prettyPrint === 'function')
                    {
                        prettyPrint();
                    }

                    $prettyPrint.html(
                        DOMPurify.sanitize(
                            prettyPrintOne(escapedLinkedText, null, true)
                        )
                    );
                    // fall through, as the rest is the same
                default: // = 'plaintext'
                    $prettyPrint.css('white-space', 'pre-wrap');
                    $prettyPrint.css('word-break', 'normal');
                    $prettyPrint.removeClass('prettyprint');
            }
        }

        /**
         * displays the paste
         *
         * @name   PasteViewer.showPaste
         * @private
         * @function
         */
        function showPaste()
        {
            // instead of "nothing" better display a placeholder
            if (text === '') {
                $placeholder.removeClass('hidden');
                return;
            }
            // otherwise hide the placeholder
            $placeholder.addClass('hidden');

            switch (format) {
                case 'markdown':
                    $plainText.removeClass('hidden');
                    $prettyMessage.addClass('hidden');
                    break;
                default:
                    $plainText.addClass('hidden');
                    $prettyMessage.removeClass('hidden');
                    break;
            }
        }

        /**
         * sets the format in which the text is shown
         *
         * @name   PasteViewer.setFormat
         * @function
         * @param {string} newFormat the new format
         */
        me.setFormat = function(newFormat)
        {
            // skip if there is no update
            if (format === newFormat) {
                return;
            }

            // needs to update display too, if we switch from or to Markdown
            if (format === 'markdown' || newFormat === 'markdown') {
                isDisplayed = false;
            }

            format = newFormat;
            isChanged = true;
        };

        /**
         * returns the current format
         *
         * @name   PasteViewer.getFormat
         * @function
         * @return {string}
         */
        me.getFormat = function()
        {
            return format;
        };

        /**
         * returns whether the current view is pretty printed
         *
         * @name   PasteViewer.isPrettyPrinted
         * @function
         * @return {bool}
         */
        me.isPrettyPrinted = function()
        {
            return $prettyPrint.hasClass('prettyprinted');
        };

        /**
         * sets the text to show
         *
         * @name   PasteViewer.setText
         * @function
         * @param {string} newText the text to show
         */
        me.setText = function(newText)
        {
            if (text !== newText) {
                text = newText;
                isChanged = true;
            }
        };

        /**
         * gets the current cached text
         *
         * @name   PasteViewer.getText
         * @function
         * @return {string}
         */
        me.getText = function()
        {
            return text;
        };

        /**
         * show/update the parsed text (preview)
         *
         * @name   PasteViewer.run
         * @function
         */
        me.run = function()
        {
            if (isChanged) {
                parsePaste();
                isChanged = false;
            }

            if (!isDisplayed) {
                showPaste();
                isDisplayed = true;
            }
        };

        /**
         * hide parsed text (preview)
         *
         * @name   PasteViewer.hide
         * @function
         */
        me.hide = function()
        {
            if (!isDisplayed) {
                console.warn('PasteViewer was called to hide the parsed view, but it is already hidden.');
            }

            $plainText.addClass('hidden');
            $prettyMessage.addClass('hidden');
            $placeholder.addClass('hidden');

            isDisplayed = false;
        };

        /**
         * init status manager
         *
         * preloads jQuery elements
         *
         * @name   PasteViewer.init
         * @function
         */
        me.init = function()
        {
            $placeholder = $('#placeholder');
            $plainText = $('#plaintext');
            $prettyMessage = $('#prettymessage');
            $prettyPrint = $('#prettyprint');

            // check requirements
            if (typeof prettyPrintOne !== 'function') {
                Alert.showError([
                    'The library %s is not available. This may cause display errors.',
                    'pretty print'
                ]);
            }
            if (typeof showdown !== 'object') {
                Alert.showError([
                    'The library %s is not available. This may cause display errors.',
                    'showdown'
                ]);
            }

            // get default option from template/HTML or fall back to set value
            format = Model.getFormatDefault() || format;
            text = '';
            isDisplayed = false;
            isChanged = true;
        };

        return me;
    })();

    /**
     * (view) Show attachment and preview if possible
     *
     * @name   AttachmentViewer
     * @class
     */
    var AttachmentViewer = (function () {
        var me = {};

        var $attachmentLink,
            $attachmentPreview,
            $attachment;

        var attachmentHasPreview = false;

        /**
         * sets the attachment but does not yet show it
         *
         * @name   AttachmentViewer.setAttachment
         * @function
         * @param {string} attachmentData - base64-encoded data of file
         * @param {string} fileName - optional, file name
         */
        me.setAttachment = function(attachmentData, fileName)
        {
            var imagePrefix = 'data:image/';

            // IE does not support setting a data URI on an a element
            // Convert dataURI to a Blob and use msSaveBlob to download
            if (window.Blob && navigator.msSaveBlob) {
                $attachmentLink.off('click').on('click', function () {
                    // data URI format: data:[<mediaType>][;base64],<data>

                    // position in data URI string of where data begins
                    var base64Start = attachmentData.indexOf(',') + 1;
                    // position in data URI string of where mediaType ends
                    var mediaTypeEnd = attachmentData.indexOf(';');

                    // extract mediaType
                    var mediaType = attachmentData.substring(5, mediaTypeEnd);
                    // extract data and convert to binary
                    var decodedData = Base64.atob(attachmentData.substring(base64Start));

                    // Transform into a Blob
                    var decodedDataLength = decodedData.length;
                    var buf = new Uint8Array(decodedDataLength);

                    for (var i = 0; i < decodedDataLength; i++) {
                        buf[i] = decodedData.charCodeAt(i);
                    }

                    var blob = new window.Blob([ buf ], { type: mediaType });
                    navigator.msSaveBlob(blob, fileName);
                });
            } else {
                $attachmentLink.attr('href', attachmentData);
            }

            if (typeof fileName !== 'undefined') {
                $attachmentLink.attr('download', fileName);
            }

            // if the attachment is an image, display it
            if (attachmentData.substring(0, imagePrefix.length) === imagePrefix) {
                $attachmentPreview.html(
                    $(document.createElement('img'))
                        .attr('src', attachmentData)
                        .attr('class', 'img-thumbnail')
                );
                attachmentHasPreview = true;
            }
        };

        /**
         * displays the attachment
         *
         * @name AttachmentViewer.showAttachment
         * @function
         */
        me.showAttachment = function()
        {
            $attachment.removeClass('hidden');

            if (attachmentHasPreview) {
                $attachmentPreview.removeClass('hidden');
            }
        };

        /**
         * removes the attachment
         *
         * This automatically hides the attachment containers to, to
         * prevent an inconsistent display.
         *
         * @name AttachmentViewer.removeAttachment
         * @function
         */
        me.removeAttachment = function()
        {
            me.hideAttachment();
            me.hideAttachmentPreview();
            $attachmentLink.prop('href', '');
            $attachmentLink.prop('download', '');
            $attachmentLink.off('click');
            $attachmentPreview.html('');
        };

        /**
         * hides the attachment
         *
         * This will not hide the preview (see AttachmentViewer.hideAttachmentPreview
         * for that) nor will it hide the attachment link if it was moved somewhere
         * else (see AttachmentViewer.moveAttachmentTo).
         *
         * @name AttachmentViewer.hideAttachment
         * @function
         */
        me.hideAttachment = function()
        {
            $attachment.addClass('hidden');
        };

        /**
         * hides the attachment preview
         *
         * @name AttachmentViewer.hideAttachmentPreview
         * @function
         */
        me.hideAttachmentPreview = function()
        {
            $attachmentPreview.addClass('hidden');
        };

        /**
         * checks if there is an attachment
         *
         * @name   AttachmentViewer.hasAttachment
         * @function
         */
        me.hasAttachment = function()
        {
            var link = $attachmentLink.prop('href');
            return typeof link !== 'undefined' && link !== '';
        };

        /**
         * return the attachment
         *
         * @name   AttachmentViewer.getAttachment
         * @function
         * @returns {array}
         */
        me.getAttachment = function()
        {
            return [
                $attachmentLink.prop('href'),
                $attachmentLink.prop('download')
            ];
        };

        /**
         * moves the attachment link to another element
         *
         * It is advisable to hide the attachment afterwards (AttachmentViewer.hideAttachment)
         *
         * @name   AttachmentViewer.moveAttachmentTo
         * @function
         * @param {jQuery} $element - the wrapper/container element where this should be moved to
         * @param {string} label - the text to show (%s will be replaced with the file name), will automatically be translated
         */
        me.moveAttachmentTo = function($element, label)
        {
            // move elemement to new place
            $attachmentLink.appendTo($element);

            // update text
            I18n._($attachmentLink, label, $attachmentLink.attr('download'));
        };

        /**
         * initiate
         *
         * preloads jQuery elements
         *
         * @name   AttachmentViewer.init
         * @function
         */
        me.init = function()
        {
            $attachment = $('#attachment');
            $attachmentLink = $('#attachment a');
            $attachmentPreview = $('#attachmentPreview');
            attachmentHasPreview = false;
        };

        return me;
    })();

    /**
     * (view) Shows discussion thread and handles replies
     *
     * @name   DiscussionViewer
     * @class
     */
    var DiscussionViewer = (function () {
        var me = {};

        var $commentTail,
            $discussion,
            $reply,
            $replyMessage,
            $replyNickname,
            $replyStatus,
            $commentContainer;

        var replyCommentId;

        /**
         * initializes the templates
         *
         * @name   DiscussionViewer.initTemplates
         * @private
         * @function
         */
        function initTemplates()
        {
            $reply = Model.getTemplate('reply');
            $replyMessage = $reply.find('#replymessage');
            $replyNickname = $reply.find('#nickname');
            $replyStatus = $reply.find('#replystatus');

            // cache jQuery elements
            $commentTail = Model.getTemplate('commenttail');
        }

        /**
         * open the comment entry when clicking the "Reply" button of a comment
         *
         * @name   DiscussionViewer.openReply
         * @private
         * @function
         * @param  {Event} event
         */
        function openReply(event)
        {
            var $source = $(event.target);

            // clear input
            $replyMessage.val('');
            $replyNickname.val('');

            // get comment id from source element
            replyCommentId = $source.parent().prop('id').split('_')[1];

            // move to correct position
            $source.after($reply);

            // show
            $reply.removeClass('hidden');
            $replyMessage.focus();

            event.preventDefault();
        }

        /**
         * custom handler for displaying notifications in own status message area
         *
         * @name   DiscussionViewer.handleNotification
         * @function
         * @param  {string} alertType
         * @return {bool|jQuery}
         */
        me.handleNotification = function(alertType)
        {
            // ignore loading messages
            if (alertType === 'loading') {
                return false;
            }

            if (alertType === 'danger') {
                $replyStatus.removeClass('alert-info');
                $replyStatus.addClass('alert-danger');
                $replyStatus.find(':first').removeClass('glyphicon-alert');
                $replyStatus.find(':first').addClass('glyphicon-info-sign');
            } else {
                $replyStatus.removeClass('alert-danger');
                $replyStatus.addClass('alert-info');
                $replyStatus.find(':first').removeClass('glyphicon-info-sign');
                $replyStatus.find(':first').addClass('glyphicon-alert');
            }

            return $replyStatus;
        };

        /**
         * adds another comment
         *
         * @name   DiscussionViewer.addComment
         * @function
         * @param {object} comment
         * @param {string} commentText
         * @param {string} nickname
         */
        me.addComment = function(comment, commentText, nickname)
        {
            if (commentText === '') {
                commentText = 'comment decryption failed';
            }

            // create new comment based on template
            var $commentEntry = Model.getTemplate('comment');
            $commentEntry.prop('id', 'comment_' + comment.id);
            var $commentEntryData = $commentEntry.find('div.commentdata');

            // set & parse text
            $commentEntryData.html(
                DOMPurify.sanitize(
                    Helper.urls2links(commentText)
                )
            );

            // set nickname
            if (nickname.length > 0) {
                $commentEntry.find('span.nickname').text(nickname);
            } else {
                $commentEntry.find('span.nickname').html('<i></i>');
                I18n._($commentEntry.find('span.nickname i'), 'Anonymous');
            }

            // set date
            $commentEntry.find('span.commentdate')
                      .text(' (' + (new Date(comment.meta.postdate * 1000).toLocaleString()) + ')')
                      .attr('title', 'CommentID: ' + comment.id);

            // if an avatar is available, display it
            if (comment.meta.vizhash) {
                $commentEntry.find('span.nickname')
                             .before(
                                '<img src="' + comment.meta.vizhash + '" class="vizhash" /> '
                             );
                $(document).on('languageLoaded', function () {
                    $commentEntry.find('img.vizhash')
                                 .prop('title', I18n._('Avatar generated from IP address'));
                });
            }

            // starting point (default value/fallback)
            var $place = $commentContainer;

            // if parent comment exists
            var $parentComment = $('#comment_' + comment.parentid);
            if ($parentComment.length) {
                // use parent as position for new comment, so it is shifted
                // to the right
                $place = $parentComment;
            }

            // finally append comment
            $place.append($commentEntry);
        };

        /**
         * finishes the discussion area after last comment
         *
         * @name   DiscussionViewer.finishDiscussion
         * @function
         */
        me.finishDiscussion = function()
        {
            // add 'add new comment' area
            $commentContainer.append($commentTail);

            // show discussions
            $discussion.removeClass('hidden');
        };

        /**
         * removes the old discussion and prepares everything for creating a new
         * one.
         *
         * @name   DiscussionViewer.prepareNewDiscussion
         * @function
         */
        me.prepareNewDiscussion = function()
        {
            $commentContainer.html('');
            $discussion.addClass('hidden');

            // (re-)init templates
            initTemplates();
        };

        /**
         * returns the users message from the reply form
         *
         * @name   DiscussionViewer.getReplyMessage
         * @function
         * @return {String}
         */
        me.getReplyMessage = function()
        {
            return $replyMessage.val();
        };

        /**
         * returns the users nickname (if any) from the reply form
         *
         * @name   DiscussionViewer.getReplyNickname
         * @function
         * @return {String}
         */
        me.getReplyNickname = function()
        {
            return $replyNickname.val();
        };

        /**
         * returns the id of the parent comment the user is replying to
         *
         * @name   DiscussionViewer.getReplyCommentId
         * @function
         * @return {int|undefined}
         */
        me.getReplyCommentId = function()
        {
            return replyCommentId;
        };

        /**
         * highlights a specific comment and scrolls to it if necessary
         *
         * @name   DiscussionViewer.highlightComment
         * @function
         * @param {string} commentId
         * @param {bool} fadeOut - whether to fade out the comment
         */
        me.highlightComment = function(commentId, fadeOut)
        {
            var $comment = $('#comment_' + commentId);
            // in case comment does not exist, cancel
            if ($comment.length === 0) {
                return;
            }

            var highlightComment = function () {
                $comment.addClass('highlight');
                if (fadeOut === true) {
                    setTimeout(function () {
                        $comment.removeClass('highlight');
                    }, 300);
                }
            };

            if (UiHelper.isVisible($comment)) {
                return highlightComment();
            }

            UiHelper.scrollTo($comment, 100, 'swing', highlightComment);
        };

        /**
         * initiate
         *
         * preloads jQuery elements
         *
         * @name   DiscussionViewer.init
         * @function
         */
        me.init = function()
        {
            // bind events to templates (so they are later cloned)
            $('#commenttailtemplate, #commenttemplate').find('button').on('click', openReply);
            $('#replytemplate').find('button').on('click', PasteEncrypter.sendComment);

            $commentContainer = $('#commentcontainer');
            $discussion = $('#discussion');
        };

        return me;
    })();

    /**
     * Manage top (navigation) bar
     *
     * @name   TopNav
     * @param  {object} window
     * @param  {object} document
     * @class
     */
    var TopNav = (function (window, document) {
        var me = {};

        var createButtonsDisplayed = false;
        var viewButtonsDisplayed = false;

        var $attach,
            $burnAfterReading,
            $burnAfterReadingOption,
            $cloneButton,
            $customAttachment,
            $expiration,
            $fileRemoveButton,
            $fileWrap,
            $formatter,
            $newButton,
            $openDiscussion,
            $openDiscussionOption,
            $password,
            $passwordInput,
            $rawTextButton,
            $qrCodeLink,
            $sendButton;

        var pasteExpiration = '1week';

        /**
         * set the expiration on bootstrap templates in dropdown
         *
         * @name   TopNav.updateExpiration
         * @private
         * @function
         * @param  {Event} event
         */
        function updateExpiration(event)
        {
            // get selected option
            var target = $(event.target);

            // update dropdown display and save new expiration time
            $('#pasteExpirationDisplay').text(target.text());
            pasteExpiration = target.data('expiration');

            event.preventDefault();
        }

        /**
         * set the format on bootstrap templates in dropdown
         *
         * @name   TopNav.updateFormat
         * @private
         * @function
         * @param  {Event} event
         */
        function updateFormat(event)
        {
            // get selected option
            var $target = $(event.target);

            // update dropdown display and save new format
            var newFormat = $target.data('format');
            $('#pasteFormatterDisplay').text($target.text());
            PasteViewer.setFormat(newFormat);

            // update preview
            if (Editor.isPreview()) {
                PasteViewer.run();
            }

            event.preventDefault();
        }

        /**
         * when "burn after reading" is checked, disable discussion
         *
         * @name   TopNav.changeBurnAfterReading
         * @private
         * @function
         */
        function changeBurnAfterReading()
        {
            if ($burnAfterReading.is(':checked')) {
                $openDiscussionOption.addClass('buttondisabled');
                $openDiscussion.prop('checked', false);

                // if button is actually disabled, force-enable it and uncheck other button
                $burnAfterReadingOption.removeClass('buttondisabled');
            } else {
                $openDiscussionOption.removeClass('buttondisabled');
            }
        }

        /**
         * when discussion is checked, disable "burn after reading"
         *
         * @name   TopNav.changeOpenDiscussion
         * @private
         * @function
         */
        function changeOpenDiscussion()
        {
            if ($openDiscussion.is(':checked')) {
                $burnAfterReadingOption.addClass('buttondisabled');
                $burnAfterReading.prop('checked', false);

                // if button is actually disabled, force-enable it and uncheck other button
                $openDiscussionOption.removeClass('buttondisabled');
            } else {
                $burnAfterReadingOption.removeClass('buttondisabled');
            }
        }

        /**
         * return raw text
         *
         * @name   TopNav.rawText
         * @private
         * @function
         */
        function rawText()
        {
            TopNav.hideAllButtons();
            Alert.showLoading('Showing raw text…', 'time');
            var paste = PasteViewer.getText();

            // push a new state to allow back navigation with browser back button
            history.pushState(
                {type: 'raw'},
                document.title,
                // recreate paste URL
                Helper.baseUri() + '?' + Model.getPasteId() + '#' +
                Model.getPasteKey()
            );

            // we use text/html instead of text/plain to avoid a bug when
            // reloading the raw text view (it reverts to type text/html)
            var $head = $('head').children().not('noscript, script, link[type="text/css"]');
            var newDoc = document.open('text/html', 'replace');
            newDoc.write('<!DOCTYPE html><html><head>');
            for (var i = 0; i < $head.length; i++) {
                newDoc.write($head[i].outerHTML);
            }
            newDoc.write('</head><body><pre>' + DOMPurify.sanitize(paste) + '</pre></body></html>');
            newDoc.close();
        }

        /**
         * saves the language in a cookie and reloads the page
         *
         * @name   TopNav.setLanguage
         * @private
         * @function
         * @param  {Event} event
         */
        function setLanguage(event)
        {
            document.cookie = 'lang=' + $(event.target).data('lang');
            UiHelper.reloadHome();
        }

        /**
         * hides all messages and creates a new paste
         *
         * @name   TopNav.clickNewPaste
         * @private
         * @function
         */
        function clickNewPaste()
        {
            Controller.hideStatusMessages();
            Controller.newPaste();
        }

        /**
         * removes the existing attachment
         *
         * @name   TopNav.removeAttachment
         * @private
         * @function
         * @param  {Event} event
         */
        function removeAttachment(event)
        {
            // if custom attachment is used, remove it first
            if (!$customAttachment.hasClass('hidden')) {
                AttachmentViewer.removeAttachment();
                $customAttachment.addClass('hidden');
                $fileWrap.removeClass('hidden');
            }

            // our up-to-date jQuery can handle it :)
            $fileWrap.find('input').val('');

            // pevent '#' from appearing in the URL
            event.preventDefault();
        }

        /**
         * Shows the QR code of the current paste (URL).
         *
         * @name   TopNav.displayQrCode
         * @private
         * @function
         */
        function displayQrCode()
        {
            var qrCanvas = kjua({
                render: 'canvas',
                text: window.location.href
            });
            $('#qrcode-display').html(qrCanvas);
        }

        /**
         * Shows all navigation elements for viewing an existing paste
         *
         * @name   TopNav.showViewButtons
         * @function
         */
        me.showViewButtons = function()
        {
            if (viewButtonsDisplayed) {
                console.warn('showViewButtons: view buttons are already displayed');
                return;
            }

            $newButton.removeClass('hidden');
            $cloneButton.removeClass('hidden');
            $rawTextButton.removeClass('hidden');
            $qrCodeLink.removeClass('hidden');

            viewButtonsDisplayed = true;
        };

        /**
         * Hides all navigation elements for viewing an existing paste
         *
         * @name   TopNav.hideViewButtons
         * @function
         */
        me.hideViewButtons = function()
        {
            if (!viewButtonsDisplayed) {
                console.warn('hideViewButtons: view buttons are already hidden');
                return;
            }

            $newButton.addClass('hidden');
            $cloneButton.addClass('hidden');
            $rawTextButton.addClass('hidden');
            $qrCodeLink.addClass('hidden');

            viewButtonsDisplayed = false;
        };

        /**
         * Hides all elements belonging to existing pastes
         *
         * @name   TopNav.hideAllButtons
         * @function
         */
        me.hideAllButtons = function()
        {
            me.hideViewButtons();
            me.hideCreateButtons();
        };

        /**
         * shows all elements needed when creating a new paste
         *
         * @name   TopNav.showCreateButtons
         * @function
         */
        me.showCreateButtons = function()
        {
            if (createButtonsDisplayed) {
                console.warn('showCreateButtons: create buttons are already displayed');
                return;
            }

            $sendButton.removeClass('hidden');
            $expiration.removeClass('hidden');
            $formatter.removeClass('hidden');
            $burnAfterReadingOption.removeClass('hidden');
            $openDiscussionOption.removeClass('hidden');
            $newButton.removeClass('hidden');
            $password.removeClass('hidden');
            $attach.removeClass('hidden');

            createButtonsDisplayed = true;
        };

        /**
         * shows all elements needed when creating a new paste
         *
         * @name   TopNav.hideCreateButtons
         * @function
         */
        me.hideCreateButtons = function()
        {
            if (!createButtonsDisplayed) {
                console.warn('hideCreateButtons: create buttons are already hidden');
                return;
            }

            $newButton.addClass('hidden');
            $sendButton.addClass('hidden');
            $expiration.addClass('hidden');
            $formatter.addClass('hidden');
            $burnAfterReadingOption.addClass('hidden');
            $openDiscussionOption.addClass('hidden');
            $password.addClass('hidden');
            $attach.addClass('hidden');

            createButtonsDisplayed = false;
        };

        /**
         * only shows the "new paste" button
         *
         * @name   TopNav.showNewPasteButton
         * @function
         */
        me.showNewPasteButton = function()
        {
            $newButton.removeClass('hidden');
        };

        /**
         * only hides the clone button
         *
         * @name   TopNav.hideCloneButton
         * @function
         */
        me.hideCloneButton = function()
        {
            $cloneButton.addClass('hidden');
        };

        /**
         * only hides the raw text button
         *
         * @name   TopNav.hideRawButton
         * @function
         */
        me.hideRawButton = function()
        {
            $rawTextButton.addClass('hidden');
        };

        /**
         * hides the file selector in attachment
         *
         * @name   TopNav.hideFileSelector
         * @function
         */
        me.hideFileSelector = function()
        {
            $fileWrap.addClass('hidden');
        };


        /**
         * shows the custom attachment
         *
         * @name   TopNav.showCustomAttachment
         * @function
         */
        me.showCustomAttachment = function()
        {
            $customAttachment.removeClass('hidden');
        };

        /**
         * collapses the navigation bar, only if expanded
         *
         * @name   TopNav.collapseBar
         * @function
         */
        me.collapseBar = function()
        {
            if ($('#navbar').attr('aria-expanded') === 'true') {
                $('.navbar-toggle').click();
            }
        };

        /**
         * returns the currently set expiration time
         *
         * @name   TopNav.getExpiration
         * @function
         * @return {int}
         */
        me.getExpiration = function()
        {
            return pasteExpiration;
        };

        /**
         * returns the currently selected file(s)
         *
         * @name   TopNav.getFileList
         * @function
         * @return {FileList|null}
         */
        me.getFileList = function()
        {
            var $file = $('#file');

            // if no file given, return null
            if (!$file.length || !$file[0].files.length) {
                return null;
            }

            // ensure the selected file is still accessible
            if (!($file[0].files && $file[0].files[0])) {
                return null;
            }

            return $file[0].files;
        };

        /**
         * returns the state of the burn after reading checkbox
         *
         * @name   TopNav.getExpiration
         * @function
         * @return {bool}
         */
        me.getBurnAfterReading = function()
        {
            return $burnAfterReading.is(':checked');
        };

        /**
         * returns the state of the discussion checkbox
         *
         * @name   TopNav.getOpenDiscussion
         * @function
         * @return {bool}
         */
        me.getOpenDiscussion = function()
        {
            return $openDiscussion.is(':checked');
        };

        /**
         * returns the entered password
         *
         * @name   TopNav.getPassword
         * @function
         * @return {string}
         */
        me.getPassword = function()
        {
            return $passwordInput.val();
        };

        /**
         * returns the element where custom attachments can be placed
         *
         * Used by AttachmentViewer when an attachment is cloned here.
         *
         * @name   TopNav.getCustomAttachment
         * @function
         * @return {jQuery}
         */
        me.getCustomAttachment = function()
        {
            return $customAttachment;
        };

        /**
         * init navigation manager
         *
         * preloads jQuery elements
         *
         * @name   TopNav.init
         * @function
         */
        me.init = function()
        {
            $attach = $('#attach');
            $burnAfterReading = $('#burnafterreading');
            $burnAfterReadingOption = $('#burnafterreadingoption');
            $cloneButton = $('#clonebutton');
            $customAttachment = $('#customattachment');
            $expiration = $('#expiration');
            $fileRemoveButton = $('#fileremovebutton');
            $fileWrap = $('#filewrap');
            $formatter = $('#formatter');
            $newButton = $('#newbutton');
            $openDiscussion = $('#opendiscussion');
            $openDiscussionOption = $('#opendiscussionoption');
            $password = $('#password');
            $passwordInput = $('#passwordinput');
            $rawTextButton = $('#rawtextbutton');
            $sendButton = $('#sendbutton');
            $qrCodeLink = $('#qrcodelink');

            // bootstrap template drop down
            $('#language ul.dropdown-menu li a').click(setLanguage);
            // page template drop down
            $('#language select option').click(setLanguage);

            // bind events
            $burnAfterReading.change(changeBurnAfterReading);
            $openDiscussionOption.change(changeOpenDiscussion);
            $newButton.click(clickNewPaste);
            $sendButton.click(PasteEncrypter.sendPaste);
            $cloneButton.click(Controller.clonePaste);
            $rawTextButton.click(rawText);
            $fileRemoveButton.click(removeAttachment);
            $qrCodeLink.click(displayQrCode);

            // bootstrap template drop downs
            $('ul.dropdown-menu li a', $('#expiration').parent()).click(updateExpiration);
            $('ul.dropdown-menu li a', $('#formatter').parent()).click(updateFormat);

            // initiate default state of checkboxes
            changeBurnAfterReading();
            changeOpenDiscussion();

            // get default value from template or fall back to set value
            pasteExpiration = Model.getExpirationDefault() || pasteExpiration;

            createButtonsDisplayed = false;
            viewButtonsDisplayed = false;
        };

        return me;
    })(window, document);

    /**
     * Responsible for AJAX requests, transparently handles encryption…
     *
     * @name   Uploader
     * @class
     */
    var Uploader = (function () {
        var me = {};

        var successFunc = null,
            failureFunc = null,
            url,
            data,
            symmetricKey,
            password;

        /**
         * public variable ('constant') for errors to prevent magic numbers
         *
         * @name   Uploader.error
         * @readonly
         * @enum   {Object}
         */
        me.error = {
            okay: 0,
            custom: 1,
            unknown: 2,
            serverError: 3
        };

        /**
         * ajaxHeaders to send in AJAX requests
         *
         * @name   Uploader.ajaxHeaders
         * @private
         * @readonly
         * @enum   {Object}
         */
        var ajaxHeaders = {'X-Requested-With': 'JSONHttpRequest'};

        /**
         * called after successful upload
         *
         * @name   Uploader.checkCryptParameters
         * @private
         * @function
         * @throws {string}
         */
        function checkCryptParameters()
        {
            // workaround for this nasty 'bug' in ECMAScript
            // see https://stackoverflow.com/questions/18808226/why-is-typeof-null-object
            var typeOfKey = typeof symmetricKey;
            if (symmetricKey === null) {
                typeOfKey = 'null';
            }

            // in case of missing preparation, throw error
            switch (typeOfKey) {
                case 'string':
                    // already set, all right
                    return;
                case 'null':
                    // needs to be generated auto-generate
                    symmetricKey = CryptTool.getSymmetricKey();
                    break;
                default:
                    console.error('current invalid symmetricKey:', symmetricKey);
                    throw 'symmetricKey is invalid, probably the module was not prepared';
            }
            // password is optional
        }

        /**
         * called after successful upload
         *
         * @name   Uploader.success
         * @private
         * @function
         * @param {int} status
         * @param {int} result - optional
         */
        function success(status, result)
        {
            // add useful data to result
            result.encryptionKey = symmetricKey;
            result.requestData = data;

            if (successFunc !== null) {
                successFunc(status, result);
            }
        }

        /**
         * called after a upload failure
         *
         * @name   Uploader.fail
         * @private
         * @function
         * @param {int} status - internal code
         * @param {int} result - original error code
         */
        function fail(status, result)
        {
            if (failureFunc !== null) {
                failureFunc(status, result);
            }
        }

        /**
         * actually uploads the data
         *
         * @name   Uploader.run
         * @function
         */
        me.run = function()
        {
            $.ajax({
                type: 'POST',
                url: url,
                data: data,
                dataType: 'json',
                headers: ajaxHeaders,
                success: function(result) {
                    if (result.status === 0) {
                        success(0, result);
                    } else if (result.status === 1) {
                        fail(1, result);
                    } else {
                        fail(2, result);
                    }
                }
            })
            .fail(function(jqXHR, textStatus, errorThrown) {
                console.error(textStatus, errorThrown);
                fail(3, jqXHR);
            });
        };

        /**
         * set success function
         *
         * @name   Uploader.setUrl
         * @function
         * @param {function} newUrl
         */
        me.setUrl = function(newUrl)
        {
            url = newUrl;
        };

        /**
         * sets the password to use (first value) and optionally also the
         * encryption key (not recommend, it is automatically generated).
         *
         * Note: Call this after prepare() as prepare() resets these values.
         *
         * @name   Uploader.setCryptValues
         * @function
         * @param {string} newPassword
         * @param {string} newKey       - optional
         */
        me.setCryptParameters = function(newPassword, newKey)
        {
            password = newPassword;

            if (typeof newKey !== 'undefined') {
                symmetricKey = newKey;
            }
        };

        /**
         * set success function
         *
         * @name   Uploader.setSuccess
         * @function
         * @param {function} func
         */
        me.setSuccess = function(func)
        {
            successFunc = func;
        };

        /**
         * set failure function
         *
         * @name   Uploader.setFailure
         * @function
         * @param {function} func
         */
        me.setFailure = function(func)
        {
            failureFunc = func;
        };

        /**
         * prepares a new upload
         *
         * Call this when doing a new upload to reset any data from potential
         * previous uploads. Must be called before any other method of this
         * module.
         *
         * @name   Uploader.prepare
         * @function
         * @return {object}
         */
        me.prepare = function()
        {
            // entropy should already be checked!

            // reset password
            password = '';

            // reset key, so it a new one is generated when it is used
            symmetricKey = null;

            // reset data
            successFunc = null;
            failureFunc = null;
            url = Helper.baseUri();
            data = {};
        };

        /**
         * encrypts and sets the data
         *
         * @name   Uploader.setData
         * @function
         * @param {string} index
         * @param {mixed} element
         */
        me.setData = function(index, element)
        {
            checkCryptParameters();
            data[index] = CryptTool.cipher(symmetricKey, password, element);
        };

        /**
         * set the additional metadata to send unencrypted
         *
         * @name   Uploader.setUnencryptedData
         * @function
         * @param {string} index
         * @param {mixed} element
         */
        me.setUnencryptedData = function(index, element)
        {
            data[index] = element;
        };

        /**
         * set the additional metadata to send unencrypted passed at once
         *
         * @name   Uploader.setUnencryptedData
         * @function
         * @param {object} newData
         */
        me.setUnencryptedBulkData = function(newData)
        {
            $.extend(data, newData);
        };

        /**
         * Helper, which parses shows a general error message based on the result of the Uploader
         *
         * @name    Uploader.parseUploadError
         * @function
         * @param {int} status
         * @param {object} data
         * @param {string} doThisThing - a human description of the action, which was tried
         * @return {array}
         */
        me.parseUploadError = function(status, data, doThisThing) {
            var errorArray;

            switch (status) {
                case me.error.custom:
                    errorArray = ['Could not ' + doThisThing + ': %s', data.message];
                    break;
                case me.error.unknown:
                    errorArray = ['Could not ' + doThisThing + ': %s', I18n._('unknown status')];
                    break;
                case me.error.serverError:
                    errorArray = ['Could not ' + doThisThing + ': %s', I18n._('server error or not responding')];
                    break;
                default:
                    errorArray = ['Could not ' + doThisThing + ': %s', I18n._('unknown error')];
                    break;
            }

            return errorArray;
        };

        /**
         * init Uploader
         *
         * @name   Uploader.init
         * @function
         */
        me.init = function()
        {
            // nothing yet
        };

        return me;
    })();

    /**
     * (controller) Responsible for encrypting paste and sending it to server.
     *
     * Does upload, encryption is done transparently by Uploader.
     *
     * @name PasteEncrypter
     * @class
     */
    var PasteEncrypter = (function () {
        var me = {};

        var requirementsChecked = false;

        /**
         * checks whether there is a suitable amount of entrophy
         *
         * @name PasteEncrypter.checkRequirements
         * @private
         * @function
         * @param {function} retryCallback - the callback to execute to retry the upload
         * @return {bool}
         */
        function checkRequirements(retryCallback) {
            // skip double requirement checks
            if (requirementsChecked === true) {
                return true;
            }

            if (!CryptTool.isEntropyReady()) {
                // display a message and wait
                Alert.showStatus('Please move your mouse for more entropy…');

                CryptTool.addEntropySeedListener(retryCallback);
                return false;
            }

            requirementsChecked = true;

            return true;
        }

        /**
         * called after successful paste upload
         *
         * @name PasteEncrypter.showCreatedPaste
         * @private
         * @function
         * @param {int} status
         * @param {object} data
         */
        function showCreatedPaste(status, data) {
            Alert.hideLoading();

            var url = Helper.baseUri() + '?' + data.id + '#' + data.encryptionKey,
                deleteUrl = Helper.baseUri() + '?pasteid=' + data.id + '&deletetoken=' + data.deletetoken;

            Alert.hideMessages();

            // show notification
            PasteStatus.createPasteNotification(url, deleteUrl);

            // show new URL in browser bar
            history.pushState({type: 'newpaste'}, document.title, url);

            TopNav.showViewButtons();
            TopNav.hideRawButton();
            Editor.hide();

            // parse and show text
            // (preparation already done in me.sendPaste())
            PasteViewer.run();
        }

        /**
         * called after successful comment upload
         *
         * @name PasteEncrypter.showUploadedComment
         * @private
         * @function
         * @param {int} status
         * @param {object} data
         */
        function showUploadedComment(status, data) {
            // show success message
            Alert.showStatus('Comment posted.');

            // reload paste
            Controller.refreshPaste(function () {
                // highlight sent comment
                DiscussionViewer.highlightComment(data.id, true);
                // reset error handler
                Alert.setCustomHandler(null);
            });
        }

        /**
         * adds attachments to the Uploader
         *
         * @name PasteEncrypter.encryptAttachments
         * @private
         * @function
         * @param {File|null|undefined} file - optional, falls back to cloned attachment
         * @param {function} callback - excuted when action is successful
         */
        function encryptAttachments(file, callback) {
            if (typeof file !== 'undefined' && file !== null) {
                // check file reader requirements for upload
                if (typeof FileReader === 'undefined') {
                    Alert.showError('Your browser does not support uploading encrypted files. Please use a newer browser.');
                    // cancels process as it does not execute callback
                    return;
                }

                var reader = new FileReader();

                // closure to capture the file information
                reader.onload = function(event) {
                    Uploader.setData('attachment', event.target.result);
                    Uploader.setData('attachmentname', file.name);

                    // run callback
                    return callback();
                };

                // actually read first file
                reader.readAsDataURL(file);

There is no return statement in this branch, but you do return something in other branches. Did you maybe miss it? If you do not want to return anything, consider adding return undefined; explicitly.

            } else if (AttachmentViewer.hasAttachment()) {
                // fall back to cloned part
                var attachment = AttachmentViewer.getAttachment();

                Uploader.setData('attachment', attachment[0]);
                Uploader.setData('attachmentname', attachment[1]);
                return callback();
            } else {
                // if there are no attachments, this is of course still successful
                return callback();
            }
        }

        /**
         * send a reply in a discussion
         *
         * @name   PasteEncrypter.sendComment
         * @function
         */
        me.sendComment = function()
        {
            Alert.hideMessages();
            Alert.setCustomHandler(DiscussionViewer.handleNotification);

            // UI loading state
            TopNav.hideAllButtons();
            Alert.showLoading('Sending comment…', 'cloud-upload');

            // get data
            var plainText = DiscussionViewer.getReplyMessage(),
                nickname = DiscussionViewer.getReplyNickname(),
                parentid = DiscussionViewer.getReplyCommentId();

            // do not send if there is no data
            if (plainText.length === 0) {
                // revert loading status…
                Alert.hideLoading();
                Alert.setCustomHandler(null);
                TopNav.showViewButtons();
                return;
            }

            // check entropy
            if (!checkRequirements(function () {
                me.sendComment();
            })) {
                return; // to prevent multiple executions
            }

            // prepare Uploader
            Uploader.prepare();
            Uploader.setCryptParameters(Prompt.getPassword(), Model.getPasteKey());

            // set success/fail functions
            Uploader.setSuccess(showUploadedComment);
            Uploader.setFailure(function (status, data) {
                // revert loading status…
                Alert.hideLoading();
                TopNav.showViewButtons();

                // show error message
                Alert.showError(
                    Uploader.parseUploadError(status, data, 'post comment')
                );

                // reset error handler
                Alert.setCustomHandler(null);
            });

            // fill it with unencrypted params
            Uploader.setUnencryptedData('pasteid', Model.getPasteId());
            if (typeof parentid === 'undefined') {
                // if parent id is not set, this is the top-most comment, so use
                // paste id as parent, as the root element of the discussion tree
                Uploader.setUnencryptedData('parentid', Model.getPasteId());
            } else {
                Uploader.setUnencryptedData('parentid', parentid);
            }

            // encrypt data
            Uploader.setData('data', plainText);

            if (nickname.length > 0) {
                Uploader.setData('nickname', nickname);
            }

            Uploader.run();
        };

        /**
         * sends a new paste to server
         *
         * @name   PasteEncrypter.sendPaste
         * @function
         */
        me.sendPaste = function()
        {
            // hide previous (error) messages
            Controller.hideStatusMessages();

            // UI loading state
            TopNav.hideAllButtons();
            Alert.showLoading('Sending paste…', 'cloud-upload');
            TopNav.collapseBar();

            // get data
            var plainText = Editor.getText(),
                format = PasteViewer.getFormat(),
                files = TopNav.getFileList();

            // do not send if there is no data
            if (plainText.length === 0 && files === null) {
                // revert loading status…
                Alert.hideLoading();
                TopNav.showCreateButtons();
                return;
            }

            // check entropy
            if (!checkRequirements(function () {
                me.sendPaste();
            })) {
                return; // to prevent multiple executions
            }

            // prepare Uploader
            Uploader.prepare();
            Uploader.setCryptParameters(TopNav.getPassword());

            // set success/fail functions
            Uploader.setSuccess(showCreatedPaste);
            Uploader.setFailure(function (status, data) {
                // revert loading status…
                Alert.hideLoading();
                TopNav.showCreateButtons();

                // show error message
                Alert.showError(
                    Uploader.parseUploadError(status, data, 'create paste')
                );
            });

            // fill it with unencrypted submitted options
            Uploader.setUnencryptedBulkData({
                expire:           TopNav.getExpiration(),
                formatter:        format,
                burnafterreading: TopNav.getBurnAfterReading() ? 1 : 0,
                opendiscussion:   TopNav.getOpenDiscussion() ? 1 : 0
            });

            // prepare PasteViewer for later preview
            PasteViewer.setText(plainText);
            PasteViewer.setFormat(format);

            // encrypt cipher data
            Uploader.setData('data', plainText);

            // encrypt attachments
            encryptAttachments(
                files === null ? null : files[0],
                function () {
                    // send data
                    Uploader.run();
                }
            );
        };

        /**
         * initialize
         *
         * @name   PasteEncrypter.init
         * @function
         */
        me.init = function()
        {
            // nothing yet
        };

        return me;
    })();

    /**
     * (controller) Responsible for decrypting cipherdata and passing data to view.
     *
     * Only decryption, no download.
     *
     * @name PasteDecrypter
     * @class
     */
    var PasteDecrypter = (function () {
        var me = {};

        /**
         * decrypt data or prompts for password in cvase of failure
         *
         * @name   PasteDecrypter.decryptOrPromptPassword
         * @private
         * @function
         * @param  {string} key
         * @param  {string} password - optional, may be an empty string
         * @param  {string} cipherdata
         * @throws {string}
         * @return {false|string} false, when unsuccessful or string (decrypted data)
         */
        function decryptOrPromptPassword(key, password, cipherdata)
        {
            // try decryption without password
            var plaindata = CryptTool.decipher(key, password, cipherdata);

            // if it fails, request password
            if (plaindata.length === 0 && password.length === 0) {
                // try to get cached password first
                password = Prompt.getPassword();

                // if password is there, re-try
                if (password.length === 0) {
                    password = Prompt.requestPassword();
                }
                // recursive
                // note: an infinite loop is prevented as the previous if
                // clause checks whether a password is already set and ignores
                // errors when a password has been passed
                return decryptOrPromptPassword.apply(key, password, cipherdata);
            }

            // if all tries failed, we can only return an error
            if (plaindata.length === 0) {
                throw 'failed to decipher data';
            }

            return plaindata;
        }

        /**
         * decrypt the actual paste text
         *
         * @name   PasteDecrypter.decryptOrPromptPassword
         * @private
         * @function
         * @param  {object} paste - paste data in object form
         * @param  {string} key
         * @param  {string} password
         * @param  {bool} ignoreError - ignore decryption errors iof set to true
         * @return {bool} whether action was successful
         * @throws {string}
         */
        function decryptPaste(paste, key, password, ignoreError)
        {
            var plaintext;
            if (ignoreError === true) {
                plaintext = CryptTool.decipher(key, password, paste.data);
            } else {
                try {
                    plaintext = decryptOrPromptPassword(key, password, paste.data);
                } catch (err) {
                    throw 'failed to decipher paste text: ' + err;
                }
                if (plaintext === false) {
                    return false;
                }
            }

            // on success show paste
            PasteViewer.setFormat(paste.meta.formatter);
            PasteViewer.setText(plaintext);
            // trigger to show the text (attachment loaded afterwards)
            PasteViewer.run();

            return true;
        }

        /**
         * decrypts any attachment
         *
         * @name   PasteDecrypter.decryptAttachment
         * @private
         * @function
         * @param  {object} paste - paste data in object form
         * @param  {string} key
         * @param  {string} password
         * @return {bool} whether action was successful
         * @throws {string}
         */
        function decryptAttachment(paste, key, password)
        {
            var attachment, attachmentName;

            // decrypt attachment
            try {
                attachment = decryptOrPromptPassword(key, password, paste.attachment);
            } catch (err) {
                throw 'failed to decipher attachment: ' + err;
            }
            if (attachment === false) {
                return false;
            }

            // decrypt attachment name
            if (paste.attachmentname) {
                try {
                    attachmentName = decryptOrPromptPassword(key, password, paste.attachmentname);
                } catch (err) {
                    throw 'failed to decipher attachment name: ' + err;
                }
                if (attachmentName === false) {
                    return false;
                }
            }

            AttachmentViewer.setAttachment(attachment, attachmentName);
            AttachmentViewer.showAttachment();

            return true;
        }

        /**
         * decrypts all comments and shows them
         *
         * @name   PasteDecrypter.decryptComments
         * @private
         * @function
         * @param  {object} paste - paste data in object form
         * @param  {string} key
         * @param  {string} password
         * @return {bool} whether action was successful
         */
        function decryptComments(paste, key, password)
        {
            // remove potentially previous discussion
            DiscussionViewer.prepareNewDiscussion();

            // iterate over comments
            for (var i = 0; i < paste.comments.length; ++i) {
                var comment = paste.comments[i];

                DiscussionViewer.addComment(
                    comment,
                    CryptTool.decipher(key, password, comment.data),
                    CryptTool.decipher(key, password, comment.meta.nickname)
                );
            }

            DiscussionViewer.finishDiscussion();
            return true;
        }

        /**
         * show decrypted text in the display area, including discussion (if open)
         *
         * @name   PasteDecrypter.run
         * @function
         * @param  {Object} [paste] - (optional) object including comments to display (items = array with keys ('data','meta'))
         */
        me.run = function(paste)
        {
            Alert.hideMessages();
            Alert.showLoading('Decrypting paste…', 'cloud-download');

            if (typeof paste === 'undefined') {
                paste = $.parseJSON(Model.getCipherData());
            }

            var key = Model.getPasteKey(),
                password = Prompt.getPassword();

            if (PasteViewer.isPrettyPrinted()) {
                // don't decrypt twice
                return;
            }

            // try to decrypt the paste
            try {
                // decrypt attachments
                if (paste.attachment) {
                    // try to decrypt paste and if it fails (because the password is
                    // missing) return to let JS continue and wait for user
                    if (!decryptAttachment(paste, key, password)) {
                        return;
                    }
                    // ignore empty paste, as this is allowed when pasting attachments
                    decryptPaste(paste, key, password, true);
                } else {
                    decryptPaste(paste, key, password);
                }


                // shows the remaining time (until) deletion
                PasteStatus.showRemainingTime(paste.meta);

                // if the discussion is opened on this paste, display it
                if (paste.meta.opendiscussion) {
                    decryptComments(paste, key, password);
                }

                Alert.hideLoading();
                TopNav.showViewButtons();
            } catch(err) {
                Alert.hideLoading();

                // log and show error
                console.error(err);
                Alert.showError('Could not decrypt data (Wrong key?)');
            }
        };

        /**
         * initialize
         *
         * @name   PasteDecrypter.init
         * @function
         */
        me.init = function()
        {
            // nothing yet
        };

        return me;
    })();

    /**
     * (controller) main PrivateBin logic
     *
     * @name   Controller
     * @param  {object} window
     * @param  {object} document
     * @class
     */
    var Controller = (function (window, document) {
        var me = {};

        /**
         * hides all status messages no matter which module showed them
         *
         * @name   Controller.hideStatusMessages
         * @function
         */
        me.hideStatusMessages = function()
        {
            PasteStatus.hideMessages();
            Alert.hideMessages();
        };

        /**
         * creates a new paste
         *
         * @name   Controller.newPaste
         * @function
         */
        me.newPaste = function()
        {
            // Important: This *must not* run Alert.hideMessages() as previous
            // errors from viewing a paste should be shown.
            TopNav.hideAllButtons();
            Alert.showLoading('Preparing new paste…', 'time');

            PasteStatus.hideMessages();
            PasteViewer.hide();
            Editor.resetInput();
            Editor.show();
            Editor.focusInput();

            TopNav.showCreateButtons();
            Alert.hideLoading();
        };

        /**
         * shows the loaded paste
         *
         * @name   Controller.showPaste
         * @function
         */
        me.showPaste = function()
        {
            try {
                Model.getPasteId();
                Model.getPasteKey();
            } catch (err) {
                console.error(err);

                // missing decryption key (or paste ID) in URL?
                if (window.location.hash.length === 0) {
                    Alert.showError('Cannot decrypt paste: Decryption key missing in URL (Did you use a redirector or an URL shortener which strips part of the URL?)');
                    return;
                }
            }

            // show proper elements on screen
            PasteDecrypter.run();
        };

        /**
         * refreshes the loaded paste to show potential new data
         *
         * @name   Controller.refreshPaste
         * @function
         * @param  {function} callback
         */
        me.refreshPaste = function(callback)
        {
            // save window position to restore it later
            var orgPosition = $(window).scrollTop();

            Uploader.prepare();
            Uploader.setUrl(Helper.baseUri() + '?' + Model.getPasteId());

            Uploader.setFailure(function (status, data) {
                // revert loading status…
                Alert.hideLoading();
                TopNav.showViewButtons();

                // show error message
                Alert.showError(
                    Uploader.parseUploadError(status, data, 'refresh display')
                );
            });
            Uploader.setSuccess(function (status, data) {
                PasteDecrypter.run(data);

                // restore position
                window.scrollTo(0, orgPosition);

                callback();
            });
            Uploader.run();
        };

        /**
         * clone the current paste
         *
         * @name   Controller.clonePaste
         * @function
         */
        me.clonePaste = function()
        {
            TopNav.collapseBar();
            TopNav.hideAllButtons();
            Alert.showLoading('Cloning paste…', 'transfer');

            // hide messages from previous paste
            me.hideStatusMessages();

            // erase the id and the key in url
            history.pushState({type: 'clone'}, document.title, Helper.baseUri());

            if (AttachmentViewer.hasAttachment()) {
                AttachmentViewer.moveAttachmentTo(
                    TopNav.getCustomAttachment(),
                    'Cloned: \'%s\''
                );
                TopNav.hideFileSelector();
                AttachmentViewer.hideAttachment();
                // NOTE: it also looks nice without removing the attachment
                // but for a consistent display we remove it…
                AttachmentViewer.hideAttachmentPreview();
                TopNav.showCustomAttachment();

                // show another status message to make the user aware that the
                // file was cloned too!
                Alert.showStatus(
                    [
                        'The cloned file \'%s\' was attached to this paste.',
                        AttachmentViewer.getAttachment()[1]
                    ],
                    'copy'
                );
            }

            Editor.setText(PasteViewer.getText());
            PasteViewer.hide();
            Editor.show();

            Alert.hideLoading();
            TopNav.showCreateButtons();
        };

        /**
         * removes a saved paste
         *
         * @name   Controller.removePaste
         * @function
         * @param  {string} pasteId
         * @param  {string} deleteToken
         */
        me.removePaste = function(pasteId, deleteToken) {
            // unfortunately many web servers don't support DELETE (and PUT) out of the box
            // so we use a POST request
            Uploader.prepare();
            Uploader.setUrl(Helper.baseUri() + '?' + pasteId);
            Uploader.setUnencryptedData('deletetoken', deleteToken);

            Uploader.setFailure(function () {
                Alert.showError(
                    I18n._('Could not delete the paste, it was not stored in burn after reading mode.')
                );
            });
            Uploader.run();
        };

        /**
         * application start
         *
         * @name   Controller.init
         * @function
         */
        me.init = function()
        {
            // first load translations
            I18n.loadTranslations();

            DOMPurify.setConfig({SAFE_FOR_JQUERY: true});

            // initialize other modules/"classes"
            Alert.init();
            Model.init();
            AttachmentViewer.init();
            DiscussionViewer.init();
            Editor.init();
            PasteDecrypter.init();
            PasteEncrypter.init();
            PasteStatus.init();
            PasteViewer.init();
            Prompt.init();
            TopNav.init();
            UiHelper.init();
            Uploader.init();

            // display an existing paste
            if (Model.hasCipherData()) {
                return me.showPaste();
            }

            // otherwise create a new paste
            me.newPaste();
        };

        return me;
    })(window, document);

    return {
        Helper: Helper,
        I18n: I18n,
        CryptTool: CryptTool,
        Model: Model,
        UiHelper: UiHelper,
        Alert: Alert,
        PasteStatus: PasteStatus,
        Prompt: Prompt,
        Editor: Editor,
        PasteViewer: PasteViewer,
        AttachmentViewer: AttachmentViewer,
        DiscussionViewer: DiscussionViewer,
        TopNav: TopNav,
        Uploader: Uploader,
        PasteEncrypter: PasteEncrypter,
        PasteDecrypter: PasteDecrypter,
        Controller: Controller
    };
})(jQuery, sjcl, Base64, RawDeflate);