// (C) Copyright 2015 Moodle Pty Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {
    Directive,
    ElementRef,
    Input,
    Output,
    EventEmitter,
    OnChanges,
    SimpleChange,
    Optional,
    ViewContainerRef,
} from '@angular/core';
import { IonContent } from '@ionic/angular';

import { CoreEventLoadingChangedData, CoreEventObserver, CoreEvents } from '@singletons/events';
import { CoreSites } from '@services/sites';
import { CoreDomUtils } from '@services/utils/dom';
import { CoreIframeUtils, CoreIframeUtilsProvider } from '@services/utils/iframe';
import { CoreTextUtils } from '@services/utils/text';
import { CoreUtils } from '@services/utils/utils';
import { CoreSite } from '@classes/site';
import { Translate } from '@singletons';
import { CoreExternalContentDirective } from './external-content';
import { CoreLinkDirective } from './link';
import { CoreFilter, CoreFilterFilter, CoreFilterFormatTextOptions } from '@features/filter/services/filter';
import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
import { CoreFilterHelper } from '@features/filter/services/filter-helper';
import { CoreSubscriptions } from '@singletons/subscriptions';

/**
 * Directive to format text rendered. It renders the HTML and treats all links and media, using CoreLinkDirective
 * and CoreExternalContentDirective. It also applies filters if needed.
 *
 * Please use this directive if your text needs to be filtered or it can contain links or media (images, audio, video).
 *
 * Example usage:
 * <core-format-text [text]="myText" [component]="component" [componentId]="componentId"></core-format-text>
 */
@Directive({
    selector: 'core-format-text',
})
export class CoreFormatTextDirective implements OnChanges {

    @Input() text?: string; // The text to format.
    @Input() siteId?: string; // Site ID to use.
    @Input() component?: string; // Component for CoreExternalContentDirective.
    @Input() componentId?: string | number; // Component ID to use in conjunction with the component.
    @Input() adaptImg?: boolean | string = true; // Whether to adapt images to screen width.
    @Input() clean?: boolean | string; // Whether all the HTML tags should be removed.
    @Input() singleLine?: boolean | string; // Whether new lines should be removed (all text in single line). Only if clean=true.
    @Input() fullOnClick?: boolean | string; // Whether it should open a new page with the full contents on click.
    @Input() fullTitle?: string; // Title to use in full view. Defaults to "Description".
    @Input() highlight?: string; // Text to highlight.
    @Input() filter?: boolean | string; // Whether to filter the text. If not defined, true if contextLevel and instanceId are set.
    @Input() contextLevel?: string; // The context level of the text.
    @Input() contextInstanceId?: number; // The instance ID related to the context.
    @Input() courseId?: number; // Course ID the text belongs to. It can be used to improve performance with filters.
    @Input() wsNotFiltered?: boolean | string; // If true it means the WS didn't filter the text for some reason.
    @Input() captureLinks?: boolean; // Whether links should tried to be opened inside the app. Defaults to true.
    @Input() openLinksInApp?: boolean; // Whether links should be opened in InAppBrowser.

    /**
     * Max height in pixels to render the content box. It should be 50 at least to make sense.
     * Using this parameter will force display: block to calculate height better.
     * If you want to avoid this use class="inline" at the same time to use display: inline-block.
     */
    @Input() maxHeight?: number;

    @Output() afterRender: EventEmitter<void>; // Called when the data is rendered.

    protected element: HTMLElement;
    protected showMoreDisplayed = false;
    protected loadingChangedListener?: CoreEventObserver;

    constructor(
        element: ElementRef,
        @Optional() protected content: IonContent,
        protected viewContainerRef: ViewContainerRef,
    ) {

        this.element = element.nativeElement;
        this.element.classList.add('opacity-hide'); // Hide contents until they're treated.
        this.afterRender = new EventEmitter<void>();

        this.element.addEventListener('click', this.elementClicked.bind(this));
    }

    /**
     * Detect changes on input properties.
     */
    ngOnChanges(changes: { [name: string]: SimpleChange }): void {
        if (changes.text || changes.filter || changes.contextLevel || changes.contextInstanceId) {
            this.hideShowMore();
            this.formatAndRenderContents();
        }
    }

    /**
     * Apply CoreExternalContentDirective to a certain element.
     *
     * @param element Element to add the attributes to.
     * @return External content instance.
     */
    protected addExternalContent(element: Element): CoreExternalContentDirective {
        // Angular doesn't let adding directives dynamically. Create the CoreExternalContentDirective manually.
        const extContent = new CoreExternalContentDirective(new ElementRef(element));

        extContent.component = this.component;
        extContent.componentId = this.componentId;
        extContent.siteId = this.siteId;
        extContent.src = element.getAttribute('src') || undefined;
        extContent.href = element.getAttribute('href') || element.getAttribute('xlink:href') || undefined;
        extContent.targetSrc = element.getAttribute('target-src') || undefined;
        extContent.poster = element.getAttribute('poster') || undefined;

        extContent.ngAfterViewInit();

        return extContent;
    }

    /**
     * Add class to adapt media to a certain element.
     *
     * @param element Element to add the class to.
     */
    protected addMediaAdaptClass(element: HTMLElement): void {
        element.classList.add('core-media-adapt-width');
    }

    /**
     * Wrap an image with a container to adapt its width.
     *
     * @param img Image to adapt.
     */
    protected adaptImage(img: HTMLElement): void {
        // Element to wrap the image.
        const container = document.createElement('span');
        const originalWidth = img.attributes.getNamedItem('width');

        const forcedWidth = Number(originalWidth?.value);
        if (!isNaN(forcedWidth)) {
            if (originalWidth!.value.indexOf('%') < 0) {
                img.style.width = forcedWidth  + 'px';
            } else {
                img.style.width = forcedWidth  + '%';
            }
        }

        container.classList.add('core-adapted-img-container');
        container.style.cssFloat = img.style.cssFloat; // Copy the float to correctly position the search icon.
        if (img.classList.contains('atto_image_button_right')) {
            container.classList.add('atto_image_button_right');
        } else if (img.classList.contains('atto_image_button_left')) {
            container.classList.add('atto_image_button_left');
        } else if (img.classList.contains('atto_image_button_text-top')) {
            container.classList.add('atto_image_button_text-top');
        } else if (img.classList.contains('atto_image_button_middle')) {
            container.classList.add('atto_image_button_middle');
        } else if (img.classList.contains('atto_image_button_text-bottom')) {
            container.classList.add('atto_image_button_text-bottom');
        }

        CoreDomUtils.wrapElement(img, container);
    }

    /**
     * Add magnifying glass icons to view adapted images at full size.
     */
    addMagnifyingGlasses(): void {
        const imgs = Array.from(this.element.querySelectorAll('.core-adapted-img-container > img'));
        if (!imgs.length) {
            return;
        }

        // If cannot calculate element's width, use viewport width to avoid false adapt image icons appearing.
        const elWidth = this.getElementWidth(this.element) || window.innerWidth;

        imgs.forEach((img: HTMLImageElement) => {
            // Skip image if it's inside a link.
            if (img.closest('a')) {
                return;
            }

            let imgWidth = Number(img.getAttribute('width'));
            if (!imgWidth) {
                // No width attribute, use real size.
                imgWidth = img.naturalWidth;
            }

            if (imgWidth <= elWidth) {
                return;
            }

            const imgSrc = CoreTextUtils.escapeHTML(img.getAttribute('data-original-src') || img.getAttribute('src'));
            const label = Translate.instant('core.openfullimage');
            const anchor = document.createElement('a');

            anchor.classList.add('core-image-viewer-icon');
            anchor.setAttribute('aria-label', label);
            // Add an ion-icon item to apply the right styles, but the ion-icon component won't be executed.
            anchor.innerHTML = '<ion-icon name="fas-search" src="assets/fonts/font-awesome/solid/search.svg"></ion-icon>';

            anchor.addEventListener('click', (e: Event) => {
                e.preventDefault();
                e.stopPropagation();
                CoreDomUtils.viewImage(imgSrc, img.getAttribute('alt'), this.component, this.componentId, true);
            });

            img.parentNode?.appendChild(anchor);
        });
    }

    /**
     * Calculate the height and check if we need to display show more or not.
     */
    protected calculateHeight(): void {
        // @todo: Work on calculate this height better.
        if (!this.maxHeight) {
            return;
        }

        // Remove max-height (if any) to calculate the real height.
        const initialMaxHeight = this.element.style.maxHeight;
        this.element.style.maxHeight = '';

        const height = this.getElementHeight(this.element);

        // Restore the max height now.
        this.element.style.maxHeight = initialMaxHeight;

        // If cannot calculate height, shorten always.
        if (!height || height > this.maxHeight) {
            if (!this.showMoreDisplayed) {
                this.displayShowMore();
            }
        } else if (this.showMoreDisplayed) {
            this.hideShowMore();
        }
    }

    /**
     * Display the "Show more" in the element.
     */
    protected displayShowMore(): void {
        const expandInFullview = CoreUtils.isTrueOrOne(this.fullOnClick) || false;
        const showMoreDiv = document.createElement('div');

        showMoreDiv.classList.add('core-show-more');
        showMoreDiv.innerHTML = Translate.instant('core.showmore');
        this.element.appendChild(showMoreDiv);

        if (expandInFullview) {
            this.element.classList.add('core-expand-in-fullview');
        }
        this.element.classList.add('core-text-formatted');
        this.element.classList.add('core-shortened');
        this.element.style.maxHeight = this.maxHeight + 'px';

        this.showMoreDisplayed = true;
    }

    /**
     * Listener to call when the element is clicked.
     *
     * @param e Click event.
     */
    protected elementClicked(e: MouseEvent): void {
        if (e.defaultPrevented) {
            // Ignore it if the event was prevented by some other listener.
            return;
        }
        if (!this.text) {
            return;
        }

        const expandInFullview = CoreUtils.isTrueOrOne(this.fullOnClick) || false;

        if (!expandInFullview && !this.showMoreDisplayed) {
            // Nothing to do on click, just stop.
            return;
        }

        e.preventDefault();
        e.stopPropagation();

        if (!expandInFullview) {
            // Change class.
            this.element.classList.toggle('core-shortened');

            return;
        } else {
            // Open a new state with the contents.
            const filter = typeof this.filter != 'undefined' ? CoreUtils.isTrueOrOne(this.filter) : undefined;

            CoreTextUtils.viewText(
                this.fullTitle || Translate.instant('core.description'),
                this.text,
                {
                    component: this.component,
                    componentId: this.componentId,
                    filter: filter,
                    contextLevel: this.contextLevel,
                    instanceId: this.contextInstanceId,
                    courseId: this.courseId,
                },
            );
        }
    }

    /**
     * Finish the rendering, displaying the element again and calling afterRender.
     */
    protected finishRender(): void {
        // Show the element again.
        this.element.classList.remove('opacity-hide');
        // Emit the afterRender output.
        this.afterRender.emit();
    }

    /**
     * Format contents and render.
     */
    protected async formatAndRenderContents(): Promise<void> {
        if (!this.text) {
            this.element.innerHTML = ''; // Remove current contents.
            this.finishRender();

            return;
        }

        // In AOT the inputs and ng-reflect aren't in the DOM sometimes. Add them so styles are applied.
        if (this.maxHeight && !this.element.getAttribute('maxHeight')) {
            this.element.setAttribute('maxHeight', String(this.maxHeight));
        }
        if (!this.element.getAttribute('singleLine')) {
            this.element.setAttribute('singleLine', String(CoreUtils.isTrueOrOne(this.singleLine)));
        }

        this.text = this.text ? this.text.trim() : '';

        const result = await this.formatContents();

        // Disable media adapt to correctly calculate the height.
        this.element.classList.add('core-disable-media-adapt');

        this.element.innerHTML = ''; // Remove current contents.
        if (this.maxHeight && result.div.innerHTML != '' &&
                (this.fullOnClick || (window.innerWidth < 576 || window.innerHeight < 576))) { // Don't collapse in big screens.

            // Move the children to the current element to be able to calculate the height.
            CoreDomUtils.moveChildren(result.div, this.element);

            // Calculate the height now.
            this.calculateHeight();

            // Add magnifying glasses to images.
            this.addMagnifyingGlasses();

            if (!this.loadingChangedListener) {
                // Recalculate the height if a parent core-loading displays the content.
                this.loadingChangedListener =
                    CoreEvents.on(CoreEvents.CORE_LOADING_CHANGED, (data: CoreEventLoadingChangedData) => {
                        if (data.loaded && CoreDomUtils.closest(this.element.parentElement, '#' + data.uniqueId)) {
                            // The format-text is inside the loading, re-calculate the height.
                            this.calculateHeight();
                        }
                    });
            }
        } else {
            CoreDomUtils.moveChildren(result.div, this.element);

            // Add magnifying glasses to images.
            this.addMagnifyingGlasses();
        }

        if (result.options.filter) {
            // Let filters handle HTML. We do it here because we don't want them to block the render of the text.
            CoreFilterDelegate.handleHtml(
                this.element,
                result.filters,
                this.viewContainerRef,
                result.options,
                [],
                this.component,
                this.componentId,
                result.siteId,
            );
        }

        this.element.classList.remove('core-disable-media-adapt');
        this.finishRender();
    }

    /**
     * Apply formatText and set sub-directives.
     *
     * @return Promise resolved with a div element containing the code.
     */
    protected async formatContents(): Promise<FormatContentsResult> {
        // Retrieve the site since it might be needed later.
        const site = await CoreUtils.ignoreErrors(CoreSites.getSite(this.siteId));

        const siteId = site?.getId();

        if (site && this.contextLevel == 'course' && this.contextInstanceId !== undefined && this.contextInstanceId <= 0) {
            this.contextInstanceId = site.getSiteHomeId();
        }

        const filter = typeof this.filter == 'undefined' ?
            !!(this.contextLevel && typeof this.contextInstanceId != 'undefined') : CoreUtils.isTrueOrOne(this.filter);

        const options: CoreFilterFormatTextOptions = {
            clean: CoreUtils.isTrueOrOne(this.clean),
            singleLine: CoreUtils.isTrueOrOne(this.singleLine),
            highlight: this.highlight,
            courseId: this.courseId,
            wsNotFiltered: CoreUtils.isTrueOrOne(this.wsNotFiltered),
        };

        let formatted: string;
        let filters: CoreFilterFilter[] = [];

        if (filter) {
            const filterResult = await CoreFilterHelper.getFiltersAndFormatText(
                this.text || '',
                this.contextLevel || '',
                this.contextInstanceId ?? -1,
                options,
                siteId,
            );

            filters = filterResult.filters;
            formatted = filterResult.text;
        } else {
            formatted = await CoreFilter.formatText(this.text || '', options, [], siteId);
        }

        formatted = this.treatWindowOpen(formatted);

        const div = document.createElement('div');

        div.innerHTML = formatted;

        this.treatHTMLElements(div, site);

        return {
            div,
            filters,
            options,
            siteId,
        };
    }

    /**
     * Treat HTML elements when formatting contents.
     *
     * @param div Div element.
     * @param site Site instance.
     * @return Promise resolved when done.
     */
    protected async treatHTMLElements(div: HTMLElement, site?: CoreSite): Promise<void> {
        const canTreatVimeo = site?.isVersionGreaterEqualThan(['3.3.4', '3.4']) || false;

        const images = Array.from(div.querySelectorAll('img'));
        const anchors = Array.from(div.querySelectorAll('a'));
        const audios = Array.from(div.querySelectorAll('audio'));
        const videos = Array.from(div.querySelectorAll('video'));
        const iframes = Array.from(div.querySelectorAll('iframe'));
        const buttons = Array.from(div.querySelectorAll('.button'));
        const elementsWithInlineStyles = Array.from(div.querySelectorAll('*[style]'));
        const stopClicksElements = Array.from(div.querySelectorAll('button,input,select,textarea'));
        const frames = Array.from(div.querySelectorAll(CoreIframeUtilsProvider.FRAME_TAGS.join(',').replace(/iframe,?/, '')));
        const svgImages = Array.from(div.querySelectorAll('image'));
        const promises: Promise<void>[] = [];

        // Walk through the content to find the links and add our directive to it.
        // Important: We need to look for links first because in 'img' we add new links without core-link.
        anchors.forEach((anchor) => {
            // Angular 2 doesn't let adding directives dynamically. Create the CoreLinkDirective manually.
            const linkDir = new CoreLinkDirective(new ElementRef(anchor), this.content);
            linkDir.capture = this.captureLinks ?? true;
            linkDir.inApp = this.openLinksInApp;
            linkDir.ngOnInit();

            this.addExternalContent(anchor);
        });

        const externalImages: CoreExternalContentDirective[] = [];
        if (images && images.length > 0) {
            // Walk through the content to find images, and add our directive.
            images.forEach((img: HTMLElement) => {
                this.addMediaAdaptClass(img);

                const externalImage = this.addExternalContent(img);
                if (!externalImage.invalid) {
                    externalImages.push(externalImage);
                }

                if (CoreUtils.isTrueOrOne(this.adaptImg) && !img.classList.contains('icon')) {
                    this.adaptImage(img);
                }
            });
        }

        audios.forEach((audio) => {
            this.treatMedia(audio);
        });

        videos.forEach((video) => {
            this.treatMedia(video);
        });

        iframes.forEach((iframe) => {
            promises.push(this.treatIframe(iframe, site, canTreatVimeo));
        });

        svgImages.forEach((image) => {
            this.addExternalContent(image);
        });

        // Handle buttons with inner links.
        buttons.forEach((button: HTMLElement) => {
            // Check if it has a link inside.
            if (button.querySelector('a')) {
                button.classList.add('core-button-with-inner-link');
            }
        });

        // Handle inline styles.
        elementsWithInlineStyles.forEach((el: HTMLElement) => {
            // Only add external content for tags that haven't been treated already.
            if (el.tagName != 'A' && el.tagName != 'IMG' && el.tagName != 'AUDIO' && el.tagName != 'VIDEO'
                    && el.tagName != 'SOURCE' && el.tagName != 'TRACK') {
                this.addExternalContent(el);
            }
        });

        // Stop propagating click events.
        stopClicksElements.forEach((element: HTMLElement) => {
            element.addEventListener('click', (e) => {
                e.stopPropagation();
            });
        });

        // Handle all kind of frames.
        frames.forEach((frame: HTMLFrameElement | HTMLObjectElement | HTMLEmbedElement) => {
            CoreIframeUtils.treatFrame(frame, false);
        });

        CoreDomUtils.handleBootstrapTooltips(div);

        if (externalImages.length) {
            // Wait for images to load.
            const promise = CoreUtils.allPromises(externalImages.map((externalImage) => {
                if (externalImage.loaded) {
                    // Image has already been loaded, no need to wait.
                    return Promise.resolve();
                }

                return new Promise(resolve => CoreSubscriptions.once(externalImage.onLoad, resolve));
            }));

            // Automatically reject the promise after 5 seconds to prevent blocking the user forever.
            promises.push(CoreUtils.ignoreErrors(CoreUtils.timeoutPromise(promise, 5000)));
        }

        await Promise.all(promises);
    }

    /**
     * Returns the element width in pixels.
     *
     * @param element Element to get width from.
     * @return The width of the element in pixels. When 0 is returned it means the element is not visible.
     */
    protected getElementWidth(element: HTMLElement): number {
        let width = CoreDomUtils.getElementWidth(element);

        if (!width) {
            // All elements inside are floating or inline. Change display mode to allow calculate the width.
            const parentWidth = element.parentElement ?
                CoreDomUtils.getElementWidth(element.parentElement, true, false, false, true) : 0;
            const previousDisplay = getComputedStyle(element, null).display;

            element.style.display = 'inline-block';

            width = CoreDomUtils.getElementWidth(element);

            // If width is incorrectly calculated use parent width instead.
            if (parentWidth > 0 && (!width || width > parentWidth)) {
                width = parentWidth;
            }

            element.style.display = previousDisplay;
        }

        return width;
    }

    /**
     * Returns the element height in pixels.
     *
     * @param elementAng Element to get height from.
     * @return The height of the element in pixels. When 0 is returned it means the element is not visible.
     */
    protected getElementHeight(element: HTMLElement): number {
        return CoreDomUtils.getElementHeight(element) || 0;
    }

    /**
     * "Hide" the "Show more" in the element if it's shown.
     */
    protected hideShowMore(): void {
        const showMoreDiv = this.element.querySelector('div.core-show-more');

        if (showMoreDiv) {
            showMoreDiv.remove();
        }

        this.element.classList.remove('core-expand-in-fullview');
        this.element.classList.remove('core-text-formatted');
        this.element.classList.remove('core-shortened');
        this.element.style.maxHeight = '';
        this.showMoreDisplayed = false;
    }

    /**
     * Add media adapt class and apply CoreExternalContentDirective to the media element and its sources and tracks.
     *
     * @param element Video or audio to treat.
     */
    protected treatMedia(element: HTMLElement): void {
        this.addMediaAdaptClass(element);
        this.addExternalContent(element);

        const sources = Array.from(element.querySelectorAll('source'));
        const tracks = Array.from(element.querySelectorAll('track'));

        sources.forEach((source) => {
            source.setAttribute('target-src', source.getAttribute('src') || '');
            source.removeAttribute('src');
            this.addExternalContent(source);
        });

        tracks.forEach((track) => {
            this.addExternalContent(track);
        });

        // Stop propagating click events.
        element.addEventListener('click', (e) => {
            e.stopPropagation();
        });
    }

    /**
     * Add media adapt class and treat the iframe source.
     *
     * @param iframe Iframe to treat.
     * @param site Site instance.
     * @param canTreatVimeo Whether Vimeo videos can be treated in the site.
     */
    protected async treatIframe(
        iframe: HTMLIFrameElement,
        site: CoreSite | undefined,
        canTreatVimeo: boolean,
    ): Promise<void> {
        const src = iframe.src;
        const currentSite = CoreSites.getCurrentSite();

        this.addMediaAdaptClass(iframe);

        if (CoreIframeUtils.shouldDisplayHelpForUrl(src)) {
            this.addIframeHelp(iframe);
        }

        if (currentSite?.containsUrl(src)) {
            // URL points to current site, try to use auto-login.
            const finalUrl = await currentSite.getAutoLoginUrl(src, false);
            await CoreIframeUtils.fixIframeCookies(finalUrl);

            iframe.src = finalUrl;
            CoreIframeUtils.treatFrame(iframe, false);

            return;
        }

        await CoreIframeUtils.fixIframeCookies(src);

        if (site && src && canTreatVimeo) {
            // Check if it's a Vimeo video. If it is, use the wsplayer script instead to make restricted videos work.
            const matches = iframe.src.match(/https?:\/\/player\.vimeo\.com\/video\/([0-9]+)/);
            if (matches && matches[1]) {
                let newUrl = CoreTextUtils.concatenatePaths(site.getURL(), '/media/player/vimeo/wsplayer.php?video=') +
                    matches[1] + '&token=' + site.getToken();

                // Width and height are mandatory, we need to calculate them.
                let width: string | number;
                let height: string | number;

                if (iframe.width) {
                    width = iframe.width;
                } else {
                    width = this.getElementWidth(iframe);
                    if (!width) {
                        width = window.innerWidth;
                    }
                }

                if (iframe.height) {
                    height = iframe.height;
                } else {
                    height = this.getElementHeight(iframe);
                    if (!height) {
                        height = width;
                    }
                }

                // Width and height parameters are required in 3.6 and older sites.
                if (site && !site.isVersionGreaterEqualThan('3.7')) {
                    newUrl += '&width=' + width + '&height=' + height;
                }

                await CoreIframeUtils.fixIframeCookies(src);

                iframe.src = newUrl;

                if (!iframe.width) {
                    iframe.width = String(width);
                }
                if (!iframe.height) {
                    iframe.height = String(height);
                }

                // Do the iframe responsive.
                if (iframe.parentElement?.classList.contains('embed-responsive')) {
                    iframe.addEventListener('load', () => {
                        if (iframe.contentDocument) {
                            const css = document.createElement('style');
                            css.setAttribute('type', 'text/css');
                            css.innerHTML = 'iframe {width: 100%;height: 100%;}';
                            iframe.contentDocument.head.appendChild(css);
                        }
                    });
                }
            }
        }

        CoreIframeUtils.treatFrame(iframe, false);
    }

    /**
     * Add iframe help option.
     *
     * @param iframe Iframe.
     */
    protected addIframeHelp(iframe: HTMLIFrameElement): void {
        const helpDiv = document.createElement('div');

        helpDiv.classList.add('ion-text-center');
        helpDiv.classList.add('ion-text-wrap');
        helpDiv.classList.add('core-iframe-help');

        const button = document.createElement('ion-button');
        button.setAttribute('fill', 'clear');
        button.setAttribute('aria-haspopup', 'dialog');
        button.innerHTML = Translate.instant('core.iframehelp');

        button.addEventListener('click', () => {
            CoreIframeUtils.openIframeHelpModal();
        });

        helpDiv.appendChild(button);

        iframe.after(helpDiv);
    }

    /**
     * Convert window.open to window.openWindowSafely inside HTML tags.
     *
     * @param text Text to treat.
     * @return Treated text.
     */
    protected treatWindowOpen(text: string): string {
        // Get HTML tags that include window.open. Script tags aren't executed so there's no need to treat them.
        const matches = text.match(/<[^>]+window\.open\([^)]*\)[^>]*>/g);

        if (matches) {
            matches.forEach((match) => {
                // Replace all the window.open inside the tag.
                const treated = match.replace(/window\.open\(/g, 'window.openWindowSafely(');

                text = text.replace(match, treated);
            });
        }

        return text;
    }

}

type FormatContentsResult = {
    div: HTMLElement;
    filters: CoreFilterFilter[];
    options: CoreFilterFormatTextOptions;
    siteId?: string;
};