MOBILE-3620 filter: Implement filters addons

src/addons/addons.module.ts

@@ -15,10 +15,12 @@
 import { NgModule } from '@angular/core';
 
 import { AddonPrivateFilesModule } from './privatefiles/privatefiles.module';
+import { AddonFilterModule } from './filter/filter.module';
 
 @NgModule({
     imports: [
         AddonPrivateFilesModule,
+        AddonFilterModule,
     ],
 })
 export class AddonsModule {}

src/addons/filter/activitynames/activitynames.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterActivityNamesHandler } from './services/handlers/activitynames';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterActivityNamesHandler],
+            useFactory: (handler: AddonFilterActivityNamesHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterActivityNamesModule {}

src/addons/filter/activitynames/services/handlers/activitynames.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Activity names filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterActivityNamesHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterActivityNamesHandler';
+    filterName = 'activitynames';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/algebra/algebra.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterAlgebraHandler } from './services/handlers/algebra';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterAlgebraHandler],
+            useFactory: (handler: AddonFilterAlgebraHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterAlgebraModule {}

src/addons/filter/algebra/services/handlers/algebra.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Algebra notation filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterAlgebraHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterAlgebraHandler';
+    filterName = 'algebra';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/censor/censor.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterCensorHandler } from './services/handlers/censor';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterCensorHandler],
+            useFactory: (handler: AddonFilterCensorHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterCensorModule {}

src/addons/filter/censor/services/handlers/censor.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Word censorship filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterCensorHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterCensorHandler';
+    filterName = 'censor';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/data/data.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterDataHandler } from './services/handlers/data';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterDataHandler],
+            useFactory: (handler: AddonFilterDataHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterDataModule {}

src/addons/filter/data/services/handlers/data.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Database auto-link filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterDataHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterDataHandler';
+    filterName = 'data';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/displayh5p/displayh5p.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterDisplayH5PHandler } from './services/handlers/displayh5p';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterDisplayH5PHandler],
+            useFactory: (handler: AddonFilterDisplayH5PHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterDisplayH5PModule {}

src/addons/filter/displayh5p/services/handlers/displayh5p.ts

@@ -0,0 +1,110 @@
+// (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 { Injectable, ViewContainerRef, ComponentFactoryResolver } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFilter, CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+// @todo import { CoreH5PPlayerComponent } from '@core/h5p/components/h5p-player/h5p-player';
+
+/**
+ * Handler to support the Display H5P filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterDisplayH5PHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterDisplayH5PHandler';
+    filterName = 'displayh5p';
+
+    protected template = document.createElement('template'); // A template element to convert HTML to element.
+
+    constructor(protected factoryResolver: ComponentFactoryResolver) {
+        super();
+    }
+
+    /**
+     * Filter some text.
+     *
+     * @param text The text to filter.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param siteId Site ID. If not defined, current site.
+     * @return Filtered text (or promise resolved with the filtered text).
+     */
+    filter(
+        text: string,
+        filter: CoreFilterFilter, // eslint-disable-line @typescript-eslint/no-unused-vars
+        options: CoreFilterFormatTextOptions, // eslint-disable-line @typescript-eslint/no-unused-vars
+        siteId?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+    ): string | Promise<string> {
+        this.template.innerHTML = text;
+
+        const h5pIframes = <HTMLIFrameElement[]> Array.from(this.template.content.querySelectorAll('iframe.h5p-iframe'));
+
+        // Replace all iframes with an empty div that will be treated in handleHtml.
+        h5pIframes.forEach((iframe) => {
+            const placeholder = document.createElement('div');
+
+            placeholder.classList.add('core-h5p-tmp-placeholder');
+            placeholder.setAttribute('data-player-src', iframe.src);
+
+            iframe.parentElement?.replaceChild(placeholder, iframe);
+        });
+
+        return this.template.innerHTML;
+    }
+
+    /**
+     * Handle HTML. This function is called after "filter", and it will receive an HTMLElement containing the text that was
+     * filtered.
+     *
+     * @param container The HTML container to handle.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param viewContainerRef The ViewContainerRef where the container is.
+     * @param component Component.
+     * @param componentId Component ID.
+     * @param siteId Site ID. If not defined, current site.
+     * @return If async, promise resolved when done.
+     */
+    handleHtml(
+        container: HTMLElement, // eslint-disable-line @typescript-eslint/no-unused-vars
+        filter: CoreFilterFilter, // eslint-disable-line @typescript-eslint/no-unused-vars
+        options: CoreFilterFormatTextOptions, // eslint-disable-line @typescript-eslint/no-unused-vars
+        viewContainerRef: ViewContainerRef, // eslint-disable-line @typescript-eslint/no-unused-vars
+        component?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+        componentId?: string | number, // eslint-disable-line @typescript-eslint/no-unused-vars
+        siteId?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+    ): void | Promise<void> {
+        // @todo
+
+        // const placeholders = <HTMLElement[]> Array.from(container.querySelectorAll('div.core-h5p-tmp-placeholder'));
+
+        // placeholders.forEach((placeholder) => {
+        //     const url = placeholder.getAttribute('data-player-src');
+
+        //     Create the component to display the player.
+        //     const factory = this.factoryResolver.resolveComponentFactory(CoreH5PPlayerComponent);
+        //     const componentRef = viewContainerRef.createComponent<CoreH5PPlayerComponent>(factory);
+
+        //     componentRef.instance.src = url;
+        //     componentRef.instance.component = component;
+        //     componentRef.instance.componentId = componentId;
+
+        //     // Move the component to its right position.
+        //     placeholder.parentElement?.replaceChild(componentRef.instance.elementRef.nativeElement, placeholder);
+        // });
+    }
+
+}

src/addons/filter/emailprotect/emailprotect.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterEmailProtectHandler } from './services/handlers/emailprotect';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterEmailProtectHandler],
+            useFactory: (handler: AddonFilterEmailProtectHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterEmailProtectModule {}

src/addons/filter/emailprotect/services/handlers/emailprotect.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Email protection filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterEmailProtectHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterEmailProtectHandler';
+    filterName = 'emailprotect';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/emoticon/emoticon.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterEmoticonHandler } from './services/handlers/emoticon';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterEmoticonHandler],
+            useFactory: (handler: AddonFilterEmoticonHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterEmoticonModule {}

src/addons/filter/emoticon/services/handlers/emoticon.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Emoticon filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterEmoticonHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterEmoticonHandler';
+    filterName = 'emoticon';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/filter.module.ts

@@ -0,0 +1,53 @@
+// (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 { NgModule } from '@angular/core';
+
+import { AddonFilterActivityNamesModule } from './activitynames/activitynames.module';
+import { AddonFilterAlgebraModule } from './algebra/algebra.module';
+import { AddonFilterCensorModule } from './censor/censor.module';
+import { AddonFilterDataModule } from './data/data.module';
+import { AddonFilterDisplayH5PModule } from './displayh5p/displayh5p.module';
+import { AddonFilterEmailProtectModule } from './emailprotect/emailprotect.module';
+import { AddonFilterEmoticonModule } from './emoticon/emoticon.module';
+import { AddonFilterGlossaryModule } from './glossary/glossary.module';
+import { AddonFilterMathJaxLoaderModule } from './mathjaxloader/mathjaxloader.module';
+import { AddonFilterMediaPluginModule } from './mediaplugin/mediaplugin.module';
+import { AddonFilterMultilangModule } from './multilang/multilang.module';
+import { AddonFilterTexModule } from './tex/tex.module';
+import { AddonFilterTidyModule } from './tidy/tidy.module';
+import { AddonFilterUrlToLinkModule } from './urltolink/urltolink.module';
+
+@NgModule({
+    declarations: [],
+    imports: [
+        AddonFilterActivityNamesModule,
+        AddonFilterAlgebraModule,
+        AddonFilterCensorModule,
+        AddonFilterDataModule,
+        AddonFilterDisplayH5PModule,
+        AddonFilterEmailProtectModule,
+        AddonFilterEmoticonModule,
+        AddonFilterGlossaryModule,
+        AddonFilterMathJaxLoaderModule,
+        AddonFilterMediaPluginModule,
+        AddonFilterMultilangModule,
+        AddonFilterTexModule,
+        AddonFilterTidyModule,
+        AddonFilterUrlToLinkModule,
+    ],
+    providers: [],
+    exports: [],
+})
+export class AddonFilterModule { }

src/addons/filter/glossary/glossary.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterGlossaryHandler } from './services/handlers/glossary';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterGlossaryHandler],
+            useFactory: (handler: AddonFilterGlossaryHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterGlossaryModule {}

src/addons/filter/glossary/services/handlers/glossary.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Glossary auto-link filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterGlossaryHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterGlossaryHandler';
+    filterName = 'glossary';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/mathjaxloader/mathjaxloader.module.ts

@@ -0,0 +1,38 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterMathJaxLoaderHandler } from './services/handlers/mathjaxloader';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterMathJaxLoaderHandler],
+            useFactory: (handler: AddonFilterMathJaxLoaderHandler) => async () => {
+                CoreFilterDelegate.instance.registerHandler(handler);
+
+                await handler.initialize();
+            },
+        },
+    ],
+})
+export class AddonFilterMathJaxLoaderModule {}

src/addons/filter/mathjaxloader/services/handlers/mathjaxloader.ts

@@ -0,0 +1,410 @@
+// (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 { Injectable, ViewContainerRef } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFilter, CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreLang } from '@services/lang';
+import { CoreSites } from '@services/sites';
+import { CoreTextUtils } from '@services/utils/text';
+import { CoreUtils } from '@services/utils/utils';
+import { CoreEvents } from '@singletons/events';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the MathJax filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterMathJaxLoaderHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterMathJaxLoaderHandler';
+    filterName = 'mathjaxloader';
+
+    // Default values for MathJax config for sites where we cannot retrieve it.
+    protected readonly DEFAULT_URL = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.2/MathJax.js';
+    protected readonly DEFAULT_CONFIG = `
+        MathJax.Hub.Config({
+            extensions: [
+                "Safe.js",
+                "tex2jax.js",
+                "mml2jax.js",
+                "MathEvents.js",
+                "MathZoom.js",
+                "MathMenu.js",
+                "toMathML.js",
+                "TeX/noErrors.js",
+                "TeX/noUndefined.js",
+                "TeX/AMSmath.js",
+                "TeX/AMSsymbols.js",
+                "fast-preview.js",
+                "AssistiveMML.js",
+                "[a11y]/accessibility-menu.js"
+            ],
+            jax: ["input/TeX","input/MathML","output/SVG"],
+            showMathMenu: false,
+            errorSettings: { message: ["!"] },
+            skipStartupTypeset: true,
+            messageStyle: "none"
+        });
+    `;
+
+    // List of language codes found in the MathJax/localization/ directory.
+    protected readonly MATHJAX_LANG_CODES = [
+        'ar', 'ast', 'bcc', 'bg', 'br', 'ca', 'cdo', 'ce', 'cs', 'cy', 'da', 'de', 'diq', 'en', 'eo', 'es', 'fa',
+        'fi', 'fr', 'gl', 'he', 'ia', 'it', 'ja', 'kn', 'ko', 'lb', 'lki', 'lt', 'mk', 'nl', 'oc', 'pl', 'pt',
+        'pt-br', 'qqq', 'ru', 'scn', 'sco', 'sk', 'sl', 'sv', 'th', 'tr', 'uk', 'vi', 'zh-hans', 'zh-hant',
+    ];
+
+    // List of explicit mappings and known exceptions (moodle => mathjax).
+    protected readonly EXPLICIT_MAPPING = {
+        'zh-tw': 'zh-hant',
+        'zh-cn': 'zh-hans',
+    };
+
+    protected window: MathJaxWindow = window;
+
+    /**
+     * Initialize MathJax.
+     *
+     * @return Promise resolved when done.
+     */
+    async initialize(): Promise<void> {
+        this.loadJS();
+
+        // Update MathJax locale if app language changes.
+        CoreEvents.on(CoreEvents.LANGUAGE_CHANGED, (lang: string) => {
+            if (typeof this.window.MathJax == 'undefined') {
+                return;
+            }
+
+            this.window.MathJax.Hub.Queue(() => {
+                this.window.MathJax.Localization.setLocale(this.mapLanguageCode(lang));
+            });
+        });
+
+        // Get the current language.
+        const lang = await CoreLang.instance.getCurrentLanguage();
+
+        // Now call the configure function.
+        this.window.M!.filter_mathjaxloader!.configure({
+            mathjaxconfig: this.DEFAULT_CONFIG,
+            lang: this.mapLanguageCode(lang),
+        });
+    }
+
+    /**
+     * Filter some text.
+     *
+     * @param text The text to filter.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param siteId Site ID. If not defined, current site.
+     * @return Filtered text (or promise resolved with the filtered text).
+     */
+    async filter(
+        text: string,
+        filter: CoreFilterFilter,
+        options: CoreFilterFormatTextOptions,
+        siteId?: string,
+    ): Promise<string> {
+
+        const site = await CoreSites.instance.getSite(siteId);
+
+        // Don't apply this filter if Moodle is 3.7 or higher and the WS already filtered the content.
+        if (!options.wsNotFiltered && site.isVersionGreaterEqualThan('3.7')) {
+            return text;
+        }
+
+        if (text.indexOf('class="filter_mathjaxloader_equation"') != -1) {
+            // The content seems to have treated mathjax already, don't do it.
+            return text;
+        }
+
+        // We cannot get the filter settings, so we cannot know if it can be used as a replacement for the TeX filter.
+        // Assume it cannot (default value).
+        let hasDisplayOrInline = false;
+        if (text.match(/\\[[(]/) || text.match(/\$\$/)) {
+            // Only parse the text if there are mathjax symbols in it.
+            // The recognized math environments are \[ \] and $$ $$ for display mathematics and \( \) for inline mathematics.
+            // Wrap display and inline math environments in nolink spans.
+            const result = this.wrapMathInNoLink(text);
+            text = result.text;
+            hasDisplayOrInline = result.changed;
+        }
+
+        if (hasDisplayOrInline) {
+            return '<span class="filter_mathjaxloader_equation">' + text + '</span>';
+        }
+
+        return text;
+    }
+
+    /**
+     * Handle HTML. This function is called after "filter", and it will receive an HTMLElement containing the text that was
+     * filtered.
+     *
+     * @param container The HTML container to handle.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param viewContainerRef The ViewContainerRef where the container is.
+     * @param component Component.
+     * @param componentId Component ID.
+     * @param siteId Site ID. If not defined, current site.
+     * @return If async, promise resolved when done.
+     */
+    async handleHtml(
+        container: HTMLElement,
+        filter: CoreFilterFilter, // eslint-disable-line @typescript-eslint/no-unused-vars
+        options: CoreFilterFormatTextOptions, // eslint-disable-line @typescript-eslint/no-unused-vars
+        viewContainerRef: ViewContainerRef, // eslint-disable-line @typescript-eslint/no-unused-vars
+        component?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+        componentId?: string | number, // eslint-disable-line @typescript-eslint/no-unused-vars
+        siteId?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+    ): Promise<void> {
+        await this.waitForReady();
+
+        this.window.M!.filter_mathjaxloader!.typeset(container);
+    }
+
+    /**
+     * Wrap a portion of the $text inside a no link span. The whole text is then returned.
+     *
+     * @param text The text to modify.
+     * @param start The start index of the substring in text that should be wrapped in the span.
+     * @param end The end index of the substring in text that should be wrapped in the span.
+     * @return The whole text with the span inserted around the defined substring.
+     */
+    protected insertSpan(text: string, start: number, end: number): string {
+        return CoreTextUtils.instance.substrReplace(
+            text,
+            '<span class="nolink">' + text.substr(start, end - start + 1) + '</span>',
+            start,
+            end - start + 1,
+        );
+    }
+
+    /**
+     * Load the JS to make MathJax work in the app. The JS loaded is extracted from Moodle filter's loader JS file.
+     */
+    protected loadJS(): void {
+        // eslint-disable-next-line @typescript-eslint/no-this-alias
+        const that = this;
+
+        this.window.M = this.window.M || {};
+        this.window.M.filter_mathjaxloader = this.window.M.filter_mathjaxloader || {
+            _lang: '', // eslint-disable-line @typescript-eslint/naming-convention
+            _configured: false, // eslint-disable-line @typescript-eslint/naming-convention
+            // Add the configuration to the head and set the lang.
+            configure: function (params: Record<string, unknown>): void {
+                // Add a js configuration object to the head.
+                const script = document.createElement('script');
+                script.type = 'text/x-mathjax-config';
+                script.text = <string> params.mathjaxconfig;
+                document.head.appendChild(script);
+
+                // Save the lang config until MathJax is actually loaded.
+                this._lang = <string> params.lang; // eslint-disable-line no-underscore-dangle
+            },
+            // Set the correct language for the MathJax menus.
+            _setLocale: function (): void {
+                if (!this._configured) {  // eslint-disable-line no-underscore-dangle
+                    const lang = this._lang;  // eslint-disable-line no-underscore-dangle
+
+                    if (typeof that.window.MathJax != 'undefined') {
+                        that.window.MathJax.Hub.Queue(() => {
+                            that.window.MathJax.Localization.setLocale(lang);
+                        });
+                        that.window.MathJax.Hub.Configured();
+                        this._configured = true;  // eslint-disable-line no-underscore-dangle
+                    }
+                }
+            },
+            // Called by the filter when an equation is found while rendering the page.
+            typeset: function (container: HTMLElement): void {
+                if (!this._configured) { // eslint-disable-line no-underscore-dangle
+                    this._setLocale(); // eslint-disable-line no-underscore-dangle
+                }
+
+                if (typeof that.window.MathJax != 'undefined') {
+                    const processDelay = that.window.MathJax.Hub.processSectionDelay;
+                    // Set the process section delay to 0 when updating the formula.
+                    that.window.MathJax.Hub.processSectionDelay = 0;
+
+                    const equations = Array.from(container.querySelectorAll('.filter_mathjaxloader_equation'));
+                    equations.forEach((node) => {
+                        that.window.MathJax.Hub.Queue(['Typeset', that.window.MathJax.Hub, node]);
+                    });
+
+                    // Set the delay back to normal after processing.
+                    that.window.MathJax.Hub.processSectionDelay = processDelay;
+                }
+            },
+        };
+    }
+
+    /**
+     * Perform a mapping of the app language code to the equivalent for MathJax.
+     *
+     * @param langCode The app language code.
+     * @return The MathJax language code.
+     */
+    protected mapLanguageCode(langCode: string): string {
+
+        // If defined, explicit mapping takes the highest precedence.
+        if (this.EXPLICIT_MAPPING[langCode]) {
+            return this.EXPLICIT_MAPPING[langCode];
+        }
+
+        // If there is exact match, it will be probably right.
+        if (this.MATHJAX_LANG_CODES.indexOf(langCode) != -1) {
+            return langCode;
+        }
+
+        // Finally try to find the best matching mathjax pack.
+        const parts = langCode.split('-');
+        if (this.MATHJAX_LANG_CODES.indexOf(parts[0]) != -1) {
+            return parts[0];
+        }
+
+        // No more guessing, use default language.
+        return CoreLang.instance.getDefaultLanguage();
+    }
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // Only apply the filter if logged in and we're filtering current site.
+        return !!(site && site.getId() == CoreSites.instance.getCurrentSiteId());
+    }
+
+    /**
+     * Wait for the MathJax library and our JS object to be loaded.
+     *
+     * @param retries Number of times this has been retried.
+     * @return Promise resolved when ready or if it took too long to load.
+     */
+    protected async waitForReady(retries: number = 0): Promise<void> {
+        if (this.window.MathJax || retries >= 20) {
+            // Loaded or too many retries, stop.
+            return;
+        }
+
+        const deferred = CoreUtils.instance.promiseDefer<void>();
+
+        setTimeout(async () => {
+            try {
+                await this.waitForReady(retries + 1);
+            } finally {
+                deferred.resolve();
+            }
+        }, 250);
+
+        return deferred.promise;
+    }
+
+    /**
+     * Find math environments in the $text and wrap them in no link spans
+     * (<span class="nolink"></span>). If math environments are nested, only
+     * the outer environment is wrapped in the span.
+     *
+     * The recognized math environments are \[ \] and $$ $$ for display
+     * mathematics and \( \) for inline mathematics.
+     *
+     * @param text The text to filter.
+     * @return Object containing the potentially modified text and a boolean that is true if any changes were made to the text.
+     */
+    protected wrapMathInNoLink(text: string): {text: string; changed: boolean} {
+        let len = text.length;
+        let i = 1;
+        let displayStart = -1;
+        let displayBracket = false;
+        let displayDollar = false;
+        let inlineStart = -1;
+        let changesDone = false;
+
+        // Loop over the $text once.
+        while (i < len) {
+            if (displayStart === -1) {
+                // No display math has started yet.
+                if (text[i - 1] === '\\') {
+
+                    if (text[i] === '[') {
+                        // Display mode \[ begins.
+                        displayStart = i - 1;
+                        displayBracket = true;
+                    } else if (text[i] === '(') {
+                        // Inline math \( begins, not nested inside display math.
+                        inlineStart = i - 1;
+                    } else if (text[i] === ')' && inlineStart > -1) {
+                        // Inline math ends, not nested inside display math. Wrap the span around it.
+                        text = this.insertSpan(text, inlineStart, i);
+
+                        inlineStart = -1; // Reset.
+                        i += 28; // The text length changed due to the <span>.
+                        len += 28;
+                        changesDone = true;
+                    }
+
+                } else if (text[i - 1] === '$' && text[i] === '$') {
+                    // Display mode $$ begins.
+                    displayStart = i - 1;
+                    displayDollar = true;
+                }
+
+            } else {
+                // Display math open.
+                if ((text[i - 1] === '\\' && text[i] === ']' && displayBracket) ||
+                        (text[i - 1] === '$' && text[i] === '$' && displayDollar)) {
+                    // Display math ends, wrap the span around it.
+                    text = this.insertSpan(text, displayStart, i);
+
+                    displayStart = -1; // Reset.
+                    displayBracket = false;
+                    displayDollar = false;
+                    i += 28; // The text length changed due to the <span>.
+                    len += 28;
+                    changesDone = true;
+                }
+            }
+
+            i++;
+        }
+
+        return {
+            text: text,
+            changed: changesDone,
+        };
+    }
+
+}
+
+type MathJaxWindow = Window & {
+    MathJax?: any; // eslint-disable-line @typescript-eslint/naming-convention, @typescript-eslint/no-explicit-any
+    M?: { // eslint-disable-line @typescript-eslint/naming-convention
+        filter_mathjaxloader?: { // eslint-disable-line @typescript-eslint/naming-convention
+            _lang: ''; // eslint-disable-line @typescript-eslint/naming-convention
+            _configured: false; // eslint-disable-line @typescript-eslint/naming-convention
+            // Add the configuration to the head and set the lang.
+            configure: (params: Record<string, unknown>) => void;
+            _setLocale: () => void; // eslint-disable-line @typescript-eslint/naming-convention
+            typeset: (container: HTMLElement) => void;
+        };
+    };
+};

src/addons/filter/mediaplugin/mediaplugin.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterMediaPluginHandler } from './services/handlers/mediaplugin';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterMediaPluginHandler],
+            useFactory: (handler: AddonFilterMediaPluginHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterMediaPluginModule {}

src/addons/filter/mediaplugin/services/handlers/mediaplugin.ts

@@ -0,0 +1,98 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFilter, CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreTextUtils } from '@services/utils/text';
+import { CoreUrlUtils } from '@services/utils/url';
+
+/**
+ * Handler to support the Multimedia filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterMediaPluginHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterMediaPluginHandler';
+    filterName = 'mediaplugin';
+
+    protected template = document.createElement('template'); // A template element to convert HTML to element.
+
+    /**
+     * Filter some text.
+     *
+     * @param text The text to filter.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param siteId Site ID. If not defined, current site.
+     * @return Filtered text (or promise resolved with the filtered text).
+     */
+    filter(
+        text: string,
+        filter: CoreFilterFilter, // eslint-disable-line @typescript-eslint/no-unused-vars
+        options: CoreFilterFormatTextOptions, // eslint-disable-line @typescript-eslint/no-unused-vars
+        siteId?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+    ): string | Promise<string> {
+        this.template.innerHTML = text;
+
+        const videos = Array.from(this.template.content.querySelectorAll('video'));
+
+        videos.forEach((video) => {
+            this.treatVideoFilters(video);
+        });
+
+        return this.template.innerHTML;
+    }
+
+    /**
+     * Treat video filters. Currently only treating youtube video using video JS.
+     *
+     * @param el Video element.
+     * @param navCtrl NavController to use.
+     */
+    protected treatVideoFilters(video: HTMLElement): void {
+        // Treat Video JS Youtube video links and translate them to iframes.
+        if (!video.classList.contains('video-js')) {
+            return;
+        }
+
+        const dataSetupString = video.getAttribute('data-setup') || video.getAttribute('data-setup-lazy') || '{}';
+        const data = <VideoDataSetup> CoreTextUtils.instance.parseJSON(dataSetupString, {});
+        const youtubeUrl = data.techOrder?.[0] == 'youtube' && CoreUrlUtils.instance.getYoutubeEmbedUrl(data.sources?.[0]?.src);
+
+        if (!youtubeUrl) {
+            return;
+        }
+
+        const iframe = document.createElement('iframe');
+        iframe.id = video.id;
+        iframe.src = youtubeUrl;
+        iframe.setAttribute('frameborder', '0');
+        iframe.setAttribute('allowfullscreen', '1');
+        iframe.width = '100%';
+        iframe.height = '300';
+
+        // Replace video tag by the iframe.
+        video.parentNode?.replaceChild(iframe, video);
+    }
+
+}
+
+type VideoDataSetup = {
+    techOrder?: string[];
+    sources?: {
+        src?: string;
+    }[];
+};

src/addons/filter/multilang/multilang.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterMultilangHandler } from './services/handlers/multilang';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterMultilangHandler],
+            useFactory: (handler: AddonFilterMultilangHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterMultilangModule {}

src/addons/filter/multilang/services/handlers/multilang.ts

@@ -0,0 +1,84 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreLang } from '@services/lang';
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFilter, CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the Multilang filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterMultilangHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterMultilangHandler';
+    filterName = 'multilang';
+
+    /**
+     * Filter some text.
+     *
+     * @param text The text to filter.
+     * @param filter The filter.
+     * @param options Options passed to the filters.
+     * @param siteId Site ID. If not defined, current site.
+     * @return Filtered text (or promise resolved with the filtered text).
+     */
+    async filter(
+        text: string,
+        filter: CoreFilterFilter, // eslint-disable-line @typescript-eslint/no-unused-vars
+        options: CoreFilterFormatTextOptions, // eslint-disable-line @typescript-eslint/no-unused-vars
+        siteId?: string, // eslint-disable-line @typescript-eslint/no-unused-vars
+    ): Promise<string> {
+        let language = await CoreLang.instance.getCurrentLanguage();
+
+        // Match the current language.
+        const anyLangRegEx = /<(?:lang|span)[^>]+lang="[a-zA-Z0-9_-]+"[^>]*>(.*?)<\/(?:lang|span)>/g;
+        let currentLangRegEx = new RegExp('<(?:lang|span)[^>]+lang="' + language + '"[^>]*>(.*?)</(?:lang|span)>', 'g');
+
+        if (!text.match(currentLangRegEx)) {
+            // Current lang not found. Try to find the first language.
+            const matches = text.match(anyLangRegEx);
+            if (matches?.[0]) {
+                language = matches[0].match(/lang="([a-zA-Z0-9_-]+)"/)?.[1] || language;
+                currentLangRegEx = new RegExp('<(?:lang|span)[^>]+lang="' + language + '"[^>]*>(.*?)</(?:lang|span)>', 'g');
+            } else {
+                // No multi-lang tag found, stop.
+                return text;
+            }
+        }
+
+        // Extract contents of current language.
+        text = text.replace(currentLangRegEx, '$1');
+        // Delete the rest of languages
+        text = text.replace(anyLangRegEx, '');
+
+        return text;
+    }
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // The filter should be applied if site is older than 3.7 or the WS didn't filter the text.
+        return !!(options.wsNotFiltered || (site && !site.isVersionGreaterEqualThan('3.7')));
+    }
+
+}

src/addons/filter/tex/services/handlers/tex.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the TeX notation filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterTexHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterTexHandler';
+    filterName = 'tex';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/tex/tex.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterTexHandler } from './services/handlers/tex';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterTexHandler],
+            useFactory: (handler: AddonFilterTexHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterTexModule {}

src/addons/filter/tidy/services/handlers/tidy.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the HTML tidy filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterTidyHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterTidyHandler';
+    filterName = 'tidy';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/tidy/tidy.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterTidyHandler } from './services/handlers/tidy';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterTidyHandler],
+            useFactory: (handler: AddonFilterTidyHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterTidyModule {}

src/addons/filter/urltolink/services/handlers/urltolink.ts

@@ -0,0 +1,43 @@
+// (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 { Injectable } from '@angular/core';
+
+import { CoreFilterDefaultHandler } from '@features/filter/services/handlers/default-filter';
+import { CoreFilterFormatTextOptions } from '@features/filter/services/filter';
+import { CoreSite } from '@classes/site';
+
+/**
+ * Handler to support the URL to link and images filter.
+ */
+@Injectable({ providedIn: 'root' })
+export class AddonFilterUrlToLinkHandler extends CoreFilterDefaultHandler {
+
+    name = 'AddonFilterUrlToLinkHandler';
+    filterName = 'urltolink';
+
+    /**
+     * Check if the filter should be applied in a certain site based on some filter options.
+     *
+     * @param options Options.
+     * @param site Site.
+     * @return Whether filter should be applied.
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    shouldBeApplied(options: CoreFilterFormatTextOptions, site?: CoreSite): boolean {
+        // This filter is handled by Moodle, nothing to do in the app.
+        return false;
+    }
+
+}

src/addons/filter/urltolink/urltolink.module.ts

@@ -0,0 +1,34 @@
+// (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 { APP_INITIALIZER, NgModule } from '@angular/core';
+
+import { CoreFilterDelegate } from '@features/filter/services/filter-delegate';
+import { AddonFilterUrlToLinkHandler } from './services/handlers/urltolink';
+
+@NgModule({
+    declarations: [
+    ],
+    imports: [
+    ],
+    providers: [
+        {
+            provide: APP_INITIALIZER,
+            multi: true,
+            deps: [AddonFilterUrlToLinkHandler],
+            useFactory: (handler: AddonFilterUrlToLinkHandler) => () => CoreFilterDelegate.instance.registerHandler(handler),
+        },
+    ],
+})
+export class AddonFilterUrlToLinkModule {}

src/core/services/utils/url.ts

@@ -255,7 +255,7 @@ export class CoreUrlUtilsProvider {
      * @param  url URL
      * @return Youtube Embed Video URL or null if not found.
      */
-    getYoutubeEmbedUrl(url: string): string | void {
+    getYoutubeEmbedUrl(url?: string): string | void {
         if (!url) {
             return;
         }