/**
 * images.js : Functions for the processing of images
 *
 * Copyright 2013-2023 Jaifroid and contributors
 * License GPL v3:
 *
 * This file is part of Kiwix.
 *
 * Kiwix is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Kiwix is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Kiwix (file LICENSE-GPLv3.txt).  If not, see <http://www.gnu.org/licenses/>
 */

/* global params, appstate, Windows, articleContainer */

'use strict';

import uiUtil from './uiUtil.js';

/**
 * The Window on which to operate
 */
var container;

/**
 * A variable to keep track of how many images are being extracted by the extractor
 */
var extractorBusy = 0;

/**
 * A variable to signal that the current image processing queue should be abandoned (e.g. because user scrolled)
 */
var abandon = false;

/**
 * A regular expression to find or transform image URLs in an article
 * DEV: make sure list of file types here is the same as the list in Service Worker code
 */
var imageURLRegexp = /(^|\/).+\.(jpe?g|png|svg|gif|webp)($|[?#])/i;

/**
 * A regular expression to find MathTex in an image
 */
var transformMathTextRegexp = /<img\s+(?=[^>]+?math-fallback-image)[^>]*?alt\s*=\s*(['"])((?:[^"']|(?!\1)[\s\S])+)[^>]+>/ig;

/**
 * Iterates over an array or collection of image nodes, extracting the image data from the ZIM
 * and inserting a BLOB URL to each image in the image's src attribute
 *
 * @param {Object} images An array or collection of DOM image nodes
 * @param {Function} callback An optional function to call when all requested images have been loaded
 */
function extractImages (images, callback) {
    var remaining = images.length;
    if (!remaining && callback) callback();
    var checkBatch = function () {
        extractorBusy--;
        remaining--;
        if (!remaining && callback) callback();
        if (!remaining) queueImages();
    };
    Array.prototype.slice.call(images).forEach(function (image) {
        if (image.tagName !== 'IMG') {
            insertMediaBlobsJQuery(image);
            return;
        }
        var imageUrl = image.getAttribute('data-kiwixurl');
        if (!imageUrl) {
            remaining--; return;
        // Create data-kiwixsrc needed for stylesheets
        } else { image.setAttribute('data-kiwixsrc', imageUrl); }
        image.removeAttribute('data-kiwixurl');
        var title = decodeURIComponent(imageUrl);
        extractorBusy++;
        if (/^data:image\/webp/i.test(imageUrl)) {
            image.style.transition = 'opacity 0.3s ease-in';
            image.style.opacity = '1';
            uiUtil.feedNodeWithBlob(image, 'src', imageUrl, 'image/webp', params.manipulateImages || params.allowHTMLExtraction, function () {
                checkBatch();
            });
            return;
        }
        if (params.contentInjectionMode === 'serviceworker' && !(params.manipulateImages || params.allowHTMLExtraction)) {
            var transition = function () {
                image.style.transition = 'opacity 0.3s ease-in';
                image.style.opacity = '1';
                removeEventListener('load', transition);
            }
            image.addEventListener('load', transition);
            // Let's remove kiwix-display from the end of the url so that the SW will ask for the image
            image.src = imageUrl.replace(/\?kiwix-display/, '');
            // Timeout allows the loop to complete so we get an accurate busy count
            setTimeout(function () {
                checkBatch();
            });
            return;
        }
        // Zimit files (at least) will sometimes have a ZIM prefix, but we are extracting raw here
        title = title.replace(appstate.selectedArchive._file.name + '/', '');
        // Zimit files store URLs encoded!
        if (params.zimType === 'zimit') title = encodeURI(title);
        appstate.selectedArchive.getDirEntryByPath(title).then(function (dirEntry) {
            return appstate.selectedArchive.readBinaryFile(dirEntry, function (fileDirEntry, content) {
                image.style.background = '';
                var mimetype = dirEntry.getMimetype();
                uiUtil.feedNodeWithBlob(image, 'src', content, mimetype, params.manipulateImages || params.allowHTMLExtraction, function () {
                    checkBatch();
                });
                image.style.transition = 'opacity 0.3s ease-in';
                image.style.opacity = '1';
            });
        }).catch(function (e) {
            console.error('Could not find DirEntry for image: ' + title, e);
            checkBatch();
        });
    });
}

/**
 * Iterates over an array or collection of image nodes, preparing each node for manual image
 * extraction when user taps the indicated area
 *
 */
function prepareManualExtraction (win) {
    container = win;
    var doc = container.document;
    var documentImages = doc.querySelectorAll('img');
    for (var i = 0, l = documentImages.length; i < l; i++) {
        var originalHeight = documentImages[i].getAttribute('height') || '';
        // Ensure 36px clickable image height so user can request images by tapping
        documentImages[i].height = '36';
        documentImages[i].style.background = 'lightblue';
        documentImages[i].style.opacity = '1';
        documentImages[i].dataset.kiwixheight = originalHeight;
        documentImages[i].dataset.kiwixhidden = 'true';
        documentImages[i].addEventListener('click', function (e) {
            // Line below ensures documentImages remains in scope
            var thisImage = e.currentTarget;
            // Exit function if image was already extracted
            if (!thisImage.dataset.kiwixurl) return;
            // Cancel event bubbling, so that we don't navigate away from the article if the image is hyperlinked
            e.preventDefault();
            e.stopPropagation();
            // DEV: Algorithm below doesn't queue webp images correctly, so for now we will extract images
            // only one-by-one on image click
            // var visibleImages = queueImages('poll', 0, function() { extractImages(visibleImages); }).visible;
            // visibleImages.forEach(function (image) {
            //    image.style.opacity = '0';
            //    if (image.dataset.kiwixheight) image.height = image.dataset.kiwixheight;
            //    else image.removeAttribute('height');
            // });
            thisImage.style.opacity = '0';
            if (thisImage.dataset.kiwixheight) thisImage.height = thisImage.dataset.kiwixheight;
            else thisImage.removeAttribute('height');
            delete thisImage.dataset.kiwixhidden;
            extractImages([thisImage]);
        });
    }
}

// Image store is a buffer for images that are waiting for the extractor to finish
var imageStore = [];
var maxImageBatch = 1;

/**
 * Sorts an array or collection of image nodes, returning a list of those that are inside the visible viewport
 *
 * @param {Array} docImgs The array of images to process
 * @param {String} action If null, imageStore only will be processed; if 'extract', documentImages in viewport will be
 *     extracted; if 'poll', will just return the visible and remaining image arrays
 * @param {Number} margin An extra margin to add to the top (-) or bottom (+) of windows.innerHeight
 * @param {Function} callback Function to call when last image has been extracted (only called if <extract> is true)
 * @returns {Object} An object with two arrays of images, visible and remaining
 */
function queueImages (docImgs, action, margin, callback) {
    if (abandon) {
        for (var q = imageStore.length; q--;) {
            imageStore[q].queued = false;
        }
        // console.log('User scrolled: abandoning image queue...')
        imageStore = [];
    }
    if (imageStore.length && !extractorBusy) {
        extractImages(imageStore.splice(0, imageStore.length < maxImageBatch ? imageStore.length : maxImageBatch));
    }
    if (!action || !docImgs.length) { if (callback) setTimeout(callback); return; }
    margin = margin || 0;
    var visible = [];
    var remaining = [];
    var batchCount = 0;
    // console.log('Images requested...');
    for (var i = 0, l = docImgs.length; i < l; i++) {
        if (docImgs[i].queued || docImgs[i].tagName === 'IMG' && !docImgs[i].dataset.kiwixurl) continue;
        if (uiUtil.isElementInView(container, docImgs[i], null, margin)) {
            visible.push(docImgs[i]);
            if (action !== 'extract') continue;
            docImgs[i].queued = true;
            if (extractorBusy < maxImageBatch) {
                batchCount++;
                console.debug('Extracting image #' + i);
                extractImages([docImgs[i]], function () {
                    batchCount--;
                    if (callback && !batchCount) callback();
                });
            } else {
                console.log('Queueing image #' + i);
                imageStore.push(docImgs[i]);
            }
        } else {
            remaining.push(docImgs[i]);
        }
    }
    // Callback has to be run inside a timeout because receiving function will expect the visible and remaining arrays to
    // have been returned before running callback code; NB if images have been scheduled for extraction, callback will be
    // called above instead of here, but we still need this in case there are no immediately visible images
    if (callback && !batchCount) setTimeout(callback);
    return { visible: visible, remaining: remaining };
}

/**
 * Prepares the article container in order to process the image nodes that have been disabled in Service Worker
 *
 * @param {Window} win The Window of the iframe tab that contains the document
 * @param {Boolean} forPrinting If true, extracts all images
 */
function prepareImagesServiceWorker (win, forPrinting) {
    container = win;
    var doc = container.document;
    var documentImages = doc.querySelectorAll('img:not([src^="data:"])');
    // Schedule loadMathJax here in case next line aborts this function
    setTimeout(function () {
        loadMathJax();
    }, 1000);
    if (!forPrinting && !documentImages.length) return;
    var imageHtml;
    var indexRoot = window.location.pathname.replace(/[^/]+$/, '') + encodeURI(appstate.selectedArchive._file.name) + '/';
    for (var i = 0, l = documentImages.length; i < l; i++) {
        // Process Wikimedia MathML, but not if we'll be using the jQuery routine later
        if (!(params.manipulateImages || params.allowHTMLExtraction)) {
            imageHtml = documentImages[i].outerHTML;
            if (params.useMathJax && /\bmath\/tex\b/i.test(imageHtml)) {
                params.containsMathTex = true;
                documentImages[i].outerHTML = imageHtml.replace(transformMathTextRegexp, function (p0, p1, math) {
                    // Remove any rogue ampersands in MathJax due to double escaping (by Wikipedia)
                    math = math.replace(/&amp;/g, '&');
                    return '<script type="math/tex">' + math + '</script>';
                });
            }
        }
        // Remove unneeded proprietary lazyload
        documentImages[i].removeAttribute('loading');
        // We exempt images that are from the file system
        var src = documentImages[i].getAttribute('src');
        if (!~src.indexOf(window.location.protocol) && !/data:image/i.test(src)) {
            documentImages[i].dataset.kiwixurl = documentImages[i].getAttribute('src');
            if (params.imageDisplayMode === 'progressive') {
                documentImages[i].style.opacity = '0';
            }
            if (params.manipulateImages || params.allowHTMLExtraction) {
                documentImages[i].outerHTML = documentImages[i].outerHTML.replace(params.regexpTagsWithZimUrl, function (match, blockStart, equals, quote, relAssetUrl, blockEnd) {
                    var parameters = relAssetUrl.replace(/^[^?]+/, '');
                    var assetZIMUrlEnc;
                    if (params.zimType === 'zimit' && !relAssetUrl.indexOf(indexRoot)) {
                        assetZIMUrlEnc = relAssetUrl.replace(indexRoot, '');
                    } else {
                        // DEV: Note that deriveZimUrlFromRelativeUrl produces a *decoded* URL (and incidentally would remove any URI component
                        // if we had captured it). We therefore re-encode the URI with encodeURI (which does not encode forward slashes) instead
                        // of encodeURIComponent.
                        assetZIMUrlEnc = encodeURI(uiUtil.deriveZimUrlFromRelativeUrl(relAssetUrl, params.baseURL)) + parameters;
                    }
                    return blockStart + 'data-kiwixurl' + equals + assetZIMUrlEnc + blockEnd;
                });
            }
        }
    }
    if (params.manipulateImages || params.allowHTMLExtraction) {
        prepareImagesJQuery(win, forPrinting);
        return;
    }

    if (forPrinting) {
        if (params.preloadAllImages) uiUtil.pollSpinner();
        extractImages(documentImages, params.preloadingAllImages ? params.preloadAllImages : params.printImagesLoaded);
    } else {
        if (params.imageDisplayMode === 'manual') {
            prepareManualExtraction(container);
        } else {
            // We need to start detecting images after the hidden articleContent has been displayed (otherwise they are not detected)
            setTimeout(function () {
                lazyLoad(documentImages);
            }, 400);
        }
    }
}

/**
 * Prepares the article container in order to process the image nodes that have been disabled in the DOM
 *
 * @param {Window} win The Window of the iframe or tab that contains the document
 * @param {Boolean} forPrinting If true, extracts all images
 */
function prepareImagesJQuery (win, forPrinting) {
    container = win;
    var doc = container.document;
    var documentImages = doc.querySelectorAll('img[data-kiwixurl], video, audio');
    var indexRoot = window.location.pathname.replace(/[^/]+$/, '') + encodeURI(appstate.selectedArchive._file.name) + '/';
    indexRoot = indexRoot.replace(/^\//, '');
    // Zimit ZIMs work better if all images are extracted
    if (params.zimType === 'zimit') forPrinting = true;
    // In case there are no images in the doc, we need to schedule the loadMathJax function here
    setTimeout(function () {
        loadMathJax();
    }, 1000);
    if (!forPrinting && !documentImages.length) return;
    // Firefox squashes empty images, but we don't want to alter the vertical heights constantly as we scroll
    // so substitute empty images with a plain svg
    var image;
    for (var i = documentImages.length; i--;) {
        image = documentImages[i];
        if (image.tagName === 'IMG') {
            image.src = "data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg'/%3E";
            image.style.opacity = '0';
            // Set a minimum width to avoid some images not rendering in squashed hidden tables
            if (params.displayHiddenBlockElements && image.width && !image.style.minWidth &&
                /wiki|wiktionary/i.test(appstate.selectedArchive._file.name)) {
                var imgX = image.width + '';
                imgX = imgX.replace(/(\d+)$/, '$1px');
                image.style.minWidth = imgX;
            }
            if (params.zimType === 'zimit' && !(image.dataset.kiwixurl).indexOf(indexRoot)) {
                image.dataset.kiwixurl = image.dataset.kiwixurl.replace(indexRoot, '');
            }
        }
    }

    if (forPrinting) {
        extractImages(documentImages, params.preloadingAllImages ? params.preloadAllImages : params.printImagesLoaded);
    } else if (params.imageDisplayMode === 'progressive') {
        // We need to start detecting images after the hidden articleContent has been displayed (otherwise they are not detected)
        setTimeout(function () {
            lazyLoad(documentImages);
        }, 400);
    } else {
        // User wishes to extract images manually
        prepareManualExtraction(container);
    }
}

/**
 * Extracts media blobs in jQuery mode and offers to download them
 * @param {Node} medium A DOM node representing a medium
 */
function insertMediaBlobsJQuery (medium) {
    var trackBlob;
    var media = [medium];
    // Ensure we have a source or sources
    if (!medium.getAttribute('src')) {
        media = medium.querySelectorAll('source');
    }
    Array.prototype.slice.call(media).forEach(function (mediaSource) {
        var source = mediaSource.getAttribute('src');
        source = source ? uiUtil.deriveZimUrlFromRelativeUrl(source, params.baseURL) : null;
        if (!source || !params.regexpZIMUrlWithNamespace.test(source)) {
            if (source) console.error('No usable media source was found for: ' + source);
            return;
        }
        var mediaElement = /audio|video/i.test(mediaSource.tagName) ? mediaSource : mediaSource.parentElement;
        // If the "controls" property is missing, we need to add it to ensure jQuery-only users can operate the video. See kiwix-js #760.
        if (/audio|video/i.test(mediaElement.tagName) && !mediaElement.hasAttribute('controls')) mediaElement.setAttribute('controls', '');
        // Create custom subtitle / cc load menu if it doesn't already exist
        if (!container.document.getElementById('kiwixCCMenu')) {
            buildCustomCCMenu(container.document, mediaElement, function (ccBlob) {
                trackBlob = ccBlob;
            });
        }
        // Load media file
        appstate.selectedArchive.getDirEntryByPath(decodeURIComponent(source)).then(function (dirEntry) {
            return appstate.selectedArchive.readBinaryFile(dirEntry, function (fileDirEntry, mediaArray) {
                var mimeType = mediaSource.type ? mediaSource.type : dirEntry.getMimetype();
                var blob = new Blob([mediaArray], {
                    type: mimeType
                });
                mediaSource.src = URL.createObjectURL(blob);
                // In Firefox and Chromium it is necessary to re-register the inserted media source
                // but do not reload for text tracks (closed captions / subtitles)
                if (/track/i.test(mediaSource.tagName)) return;
                mediaElement.load();
                // Add a download link in case media source not supported
                if (container.kiwixType === 'iframe') {
                    var iframe = container.document;
                    document.getElementById('alertBoxFooter').innerHTML =
                        '<div id="downloadAlert" class="alert alert-info alert-dismissible">\n' +
                        '    <a href="#" class="close" data-dismiss="alert" aria-label="close">&times;</a>\n' +
                        '    <span id="alertMessage"></span>\n' +
                        '</div>\n';
                    var alertMessage = document.getElementById('alertMessage');
                    var filename = iframe.title + '_' + dirEntry.url.replace(/^.*\/([^/]+)$/, '$1');
                    // Make filename safe
                    filename = filename.replace(/[/\\:*?"<>|]/g, '_');
                    alertMessage.innerHTML = '<a href="#" class="alert-link" id="downloadMedia">Download this file</a> (and any selected subtitles) to play with another app';
                    document.getElementById('downloadMedia').addEventListener('click', function () {
                        var downloadFiles = [];
                        downloadFiles.push({
                            blob: blob,
                            filename: filename,
                            src: mediaSource.src
                        });
                        // Add any selected subtitle file to the download package
                        var selTextTrack = iframe.getElementById('kiwixSelCC');
                        if (selTextTrack) {
                            var selTextExt = selTextTrack.dataset.kiwixurl.replace(/^.*\.([^.]+)$/, '$1');
                            // Subtitle files should have same name as video + .es.vtt (for example)
                            downloadFiles.push({
                                blob: trackBlob,
                                filename: filename.replace(/^(.*)\.[^.]+$/, '$1.' + selTextTrack.srclang + '.' + selTextExt),
                                src: selTextTrack.src
                            });
                        }
                        for (var j = downloadFiles.length; j--;) {
                            if (typeof Windows !== 'undefined' && typeof Windows.Storage !== 'undefined') {
                                uiUtil.downloadBlobUWP(downloadFiles[j].blob, downloadFiles[j].filename, alertMessage);
                            } else {
                                var mimeType = downloadFiles[j].blob.type ? downloadFiles[j].blob.type : 'application/octet-stream';
                                var a = document.createElement('a');
                                a.href = downloadFiles[j].src;
                                a.target = '_blank';
                                a.type = mimeType;
                                a.download = downloadFiles[j].filename;
                                alertMessage.appendChild(a); // NB we have to add the anchor to the document for Firefox to be able to click it
                                try {
                                    a.click();
                                } catch (err) {
                                    // If the click fails, use an alternative download method
                                    if (window.navigator && window.navigator.msSaveBlob) {
                                        // This works for IE11
                                        window.navigator.msSaveBlob(downloadFiles[j].blob, downloadFiles[j].filename);
                                    }
                                }
                            }
                        }
                        articleContainer.addEventListener('unload', function (e) {
                            alertMessage.remove();
                        });
                    });
                }
            });
        });
    });
    // For TED ZIMs, the initial video div height is set incorectly, so we correct it
    var videoWrapper = container.document.getElementById('video-wrapper');
    if (videoWrapper) videoWrapper.style.height = 'auto';
}

/**
 * Create a custom dropdown menu item beneath the given mediaElement (audio or video block) to allow the user to
 * select the language of text tracks (subtitles/CC) to extract from the ZIM (this is necessary because there is
 * no universal onchange event that fires for subtitle changes in the html5 video widget when the URL is invalid)
 *
 * @param {Document} doc The document in which the new menu will be placed (usually window.document or iframe)
 * @param {Element} mediaElement The media element (usually audio or video block) which contains the text tracks
 * @param {Function} callback The function to call wtih the blob
 */
function buildCustomCCMenu (doc, mediaElement, callback) {
    var optionList = [];
    var langs = '';
    var src = '';
    var currentTracks = mediaElement.getElementsByTagName('track');
    // Extract track data from current media element
    for (var i = currentTracks.length; i--;) {
        langs = currentTracks[i].label + ' [' + currentTracks[i].srclang + ']';
        src = currentTracks[i].getAttribute('src');
        src = src ? uiUtil.deriveZimUrlFromRelativeUrl(src, params.baseURL) : null;
        if (src && params.regexpZIMUrlWithNamespace.test(src)) {
            optionList.unshift('<option value="' + currentTracks[i].srclang + '" data-kiwixsrc="' +
                src + '" data-kiwixkind="' + currentTracks[i].kind + '">' + langs + '</option>');
        }
        currentTracks[i].parentNode.removeChild(currentTracks[i]);
    }
    optionList.unshift('<option value="" data-kiwixsrc="">None</option>');
    var newKiwixCCMenu = '<select id="kiwixCCMenuLangList">\n' + optionList.join('\n') + '\n</select>';
    // Create the new container and menu
    var d = doc.createElement('DIV');
    d.id = 'kiwixCCMenu';
    d.setAttribute('style', 'margin-top: 1em; text-align: left; position: relative;');
    d.innerHTML = 'Please select subtitle language: ' + newKiwixCCMenu;
    mediaElement.parentElement.insertBefore(d, mediaElement.nextSibling);
    // Add event listener to extract the text track from the ZIM and insert it into the media element when the user selects it
    newKiwixCCMenu = doc.getElementById('kiwixCCMenu').addEventListener('change', function (v) {
        var existingCC = doc.getElementById('kiwixSelCC');
        if (existingCC) existingCC.parentNode.removeChild(existingCC);
        var sel = v.target.options[v.target.selectedIndex];
        if (!sel.value) return; // User selected "none"
        appstate.selectedArchive.getDirEntryByPath(sel.dataset.kiwixsrc).then(function (dirEntry) {
            return appstate.selectedArchive.readBinaryFile(dirEntry, function (fileDirEntry, trackContents) {
                var blob = new Blob([trackContents], {
                    type: 'text/vtt'
                });
                var t = doc.createElement('track');
                t.id = 'kiwixSelCC';
                t.kind = sel.dataset.kiwixkind;
                t.label = sel.innerHTML;
                t.srclang = sel.value;
                t.default = true;
                t.src = URL.createObjectURL(blob);
                t.dataset.kiwixurl = sel.dataset.kiwixsrc;
                mediaElement.appendChild(t);
                callback(blob);
            });
        });
    });
}

/**
 * Processes an array or collection of image nodes so that they will be lazy loaded (progressive extraction)
 *
 * @param {Object} documentImages An array or collection of DOM image nodes which will be processed for
 *        progressive image extraction
 */
function lazyLoad (documentImages) {
    // The amount by which to offset the second reading of the viewport
    var offset = window.innerHeight * 2;
    // Perform an immediate extraction of visible images so as not to disconcert the user
    // We request images twice because frequently the position of all of them is not known at this stage in rendering
    queueImages(documentImages, 'extract', 0, function () {
        queueImages(documentImages, 'extract', offset);
    });
    if (!documentImages.length) return;
    // There are images remaining, so set up an event listener to load more images once user has stopped scrolling the iframe or window
    var scrollPos;
    // var rateLimiter = 0;
    var rate = 8; // DEV: Set the milliseconds to wait before allowing another iteration of the image stack
    var timeout;
    // NB we add the event listener this way so we can access it in app.js
    container.onscroll = function () {
        abandon = true;
        clearTimeout(timeout);
        var velo = container.pageYOffset - scrollPos;
        timeout = setTimeout(function () {
            // We have stopped scrolling
            // console.log("Stopped scrolling; velo=" + velo);
            queueImages(documentImages);
            abandon = false;
            queueImages(documentImages, 'extract', 0, function () {
                queueImages(documentImages, 'extract', velo >= 0 ? offset : -offset);
            });
        }, rate);
        scrollPos = container.pageYOffset;
    };
}

/**
 * Attaches KaTeX scripts to the window of the document, if there is MathML to process
 *
 * @param {Object} win The window that contains the document to be processed
 * @returns {Null} Returns null if the function was aborted
 */
function loadMathJax (win) {
    if (!params.useMathJax) return;
    container = container || win;
    var doc = container.document;
    var prefix = '';
    if (params.contentInjectionMode === 'serviceworker') {
        params.containsMathSVG = /<img\s+(?=[^>]+?math-fallback-image)[^>]*?alt\s*=\s*['"][^'"]+[^>]+>/i.test(doc.body.innerHTML);
        prefix = document.location.href.replace(/index\.html(?:$|[#?].*$)/, '');
    }
    if (params.containsMathTexRaw || params.containsMathTex || params.containsMathSVG) {
        var script1, script2, script3;
        var link = doc.createElement('link');
        link.rel = 'stylesheet';
        link.href = prefix + 'js/katex/katex.min.css';
        doc.head.appendChild(link);
        script1 = doc.createElement('script');
        script1.type = 'text/javascript';
        // script.src = "js/MathJax/MathJax.js?config=TeX-AMS_HTML-full";
        script1.src = prefix + 'js/katex/katex.min.js';
        if (params.containsMathTex) {
            script2 = doc.createElement('script');
            script2.type = 'text/javascript';
            script2.src = prefix + 'js/katex/contrib/mathtex-script-type.min.js';
        }
        if (params.containsMathTex || params.containsMathTexRaw) {
            script3 = doc.createElement('script');
            script3.type = 'text/javascript';
            script3.src = prefix + 'js/katex/contrib/auto-render.min.js';
            script3.onload = function () {
                container.renderMathInElement(doc.body, {
                    delimiters: [
                        { left: '$$', right: '$$', display: true },
                        { left: '$', right: '$', display: false },
                        { left: '\\(', right: '\\)', display: false },
                        // {left: "\\begin{equation}", right: "\\end{equation}", display: true},
                        // {left: "\\begin{align}", right: "\\end{align}", display: true},
                        // {left: "\\begin{alignat}", right: "\\end{alignat}", display: true},
                        // {left: "\\begin{gather}", right: "\\end{gather}", display: true},
                        // {left: "\\begin{CD}", right: "\\end{CD}", display: true},
                        { left: '\\[', right: '\\]', display: true }
                    ],
                    globalGroup: true,
                    throwOnError: false
                });
            };
        }
        script1.onload = function () {
            if (script2) doc.body.appendChild(script2);
            if (script3) doc.body.appendChild(script3);
        };
        doc.body.appendChild(script1);
        // if (params.containsMathTex || params.containsMathTexRaw) script.innerHTML = 'MathJax.Hub.Queue(["Typeset", MathJax.Hub]); \
        //     console.log("Typesetting maths with MathJax");';
        params.containsMathTexRaw = false; // Prevents doing a second Typeset run on the same document
        params.containsMathTex = false;
    }
}

export default {
    extractImages: extractImages,
    setupManualImageExtraction: prepareManualExtraction,
    prepareImagesServiceWorker: prepareImagesServiceWorker,
    prepareImagesJQuery: prepareImagesJQuery,
    lazyLoad: lazyLoad,
    loadMathJax: loadMathJax
};