Development: Upgrade markdown library to markdown-it

angular.json

@@ -44,9 +44,7 @@
               "react-is",
               "rfdc",
               "shallowequal",
-              "showdown-highlight",
-              "showdown-katex",
-              "showdown",
+              "markdown-it-class",
               "smoothscroll-polyfill",
               "sockjs-client",
               "use-sync-external-store/shim",

docs/user/markdown-support.rst

@@ -9,7 +9,7 @@ Markdown Support
 
 `Markdown <https://daringfireball.net/projects/markdown/>`__ is an easy-to-read, easy-to-write syntax for formatting plain text.
 
-A markdown playground can be found  `here <http://demo.showdownjs.com/>`__.
+A markdown playground can be found  `here <https://markdown-it.github.io/>`__.
 
 Artemis extends the basic `Markdown <https://daringfireball.net/projects/markdown/>`__ syntax to support Artemis-specific features. This Artemis flavored Markdown is used to format text content across the platform using an integrated markdown editor.
 
@@ -52,9 +52,9 @@ Markdown is also supported in the context of :ref:`communicating<communication>`
 Supported Syntax
 ^^^^^^^^^^^^^^^^
 
-The integrated markdown editor uses `Showdown <https://github.com/showdownjs/showdown>`__. A quick description of the supported syntax can be found `here <https://github.com/showdownjs/showdown/wiki/Showdown's-Markdown-syntax>`__.
+The integrated markdown editor uses `MarkdownIt <https://github.com/markdown-it/markdown-it>`__. A quick description of the supported syntax can be found `here <https://www.markdownguide.org/basic-syntax/>`__.
 
-The following Showdown extensions are activated:
+The following Plugins are activated:
 
-- `Showdown Katex <https://obedm503.github.io/showdown-katex>`__ to render LaTeX math and AsciiMath using KaTeX.
-- `Showdown Highlight <https://github.com/Bloggify/showdown-highlight>`__ for syntax highlighting in code blocks.
+- `MarkdownIt Katex <https://github.com/microsoft/vscode-markdown-it-katex>`__ to render LaTeX math and AsciiMath using KaTeX.
+- `MarkdownIt HighlightJS <https://github.com/valeriangalliat/markdown-it-highlightjs>`__ for syntax highlighting in code blocks.

package.json

@@ -41,6 +41,7 @@
         "@swimlane/ngx-charts": "20.5.0",
         "@swimlane/ngx-graph": "8.4.0",
         "@vscode/codicons": "0.0.36",
+        "@vscode/markdown-it-katex": "1.1.0",
         "bootstrap": "5.3.3",
         "compare-versions": "6.1.1",
         "core-js": "3.38.1",
@@ -57,6 +58,9 @@
         "js-video-url-parser": "0.5.1",
         "jszip": "3.10.1",
         "lodash-es": "4.17.21",
+        "markdown-it": "14.1.0",
+        "markdown-it-class": "1.0.0",
+        "markdown-it-highlightjs": "4.2.0",
         "mobile-drag-drop": "3.0.0-rc.0",
         "monaco-editor": "0.51.0",
         "ngx-infinite-scroll": "18.0.0",
@@ -65,15 +69,13 @@
         "pdfjs-dist": "4.6.82",
         "posthog-js": "1.166.1",
         "rxjs": "7.8.1",
-        "showdown": "2.1.0",
-        "showdown-highlight": "3.1.0",
-        "showdown-katex": "0.6.0",
         "simple-statistics": "7.8.5",
         "smoothscroll-polyfill": "0.4.4",
         "sockjs-client": "1.6.1",
         "split.js": "1.6.5",
         "ts-cacheable": "1.0.10",
         "tslib": "2.7.0",
+        "turndown": "7.2.0",
         "uuid": "10.0.0",
         "webstomp-client": "1.2.6",
         "xlsx": "https://cdn.sheetjs.com/xlsx-0.20.3/xlsx-0.20.3.tgz",
@@ -102,13 +104,9 @@
         },
         "express": "4.21.0",
         "jsdom": "25.0.1",
-        "katex": "0.16.11",
         "postcss": "8.4.47",
         "rimraf": "6.0.1",
         "semver": "7.6.3",
-        "showdown-katex": {
-            "showdown": "2.1.0"
-        },
         "tough-cookie": "5.0.0",
         "vite": "5.4.8",
         "webpack-dev-middleware": "7.4.2",
@@ -134,11 +132,12 @@
         "@types/dompurify": "3.0.5",
         "@types/jest": "29.5.13",
         "@types/lodash-es": "4.17.12",
+        "@types/markdown-it": "14.1.2",
         "@types/node": "22.7.4",
         "@types/papaparse": "5.3.14",
-        "@types/showdown": "2.0.6",
         "@types/smoothscroll-polyfill": "0.3.4",
         "@types/sockjs-client": "1.5.4",
+        "@types/turndown": "5.0.5",
         "@types/uuid": "10.0.0",
         "@typescript-eslint/eslint-plugin": "8.8.0",
         "@typescript-eslint/parser": "8.8.0",

src/main/webapp/app/exercises/programming/shared/instructions-render/extensions/programming-exercise-plant-uml.extension.ts

@@ -1,20 +1,19 @@
 import { Injectable } from '@angular/core';
 import { ProgrammingExerciseTestCase } from 'app/entities/programming/programming-exercise-test-case.model';
+import { ArtemisTextReplacementPlugin } from 'app/shared/markdown-editor/extensions/ArtemisTextReplacementPlugin';
+import { escapeStringForUseInRegex } from 'app/shared/util/global.utils';
 import { Subject } from 'rxjs';
 import { tap } from 'rxjs/operators';
-import { escapeStringForUseInRegex } from 'app/shared/util/global.utils';
 import { ProgrammingExerciseInstructionService, TestCaseState } from 'app/exercises/programming/shared/instructions-render/service/programming-exercise-instruction.service';
 import { ProgrammingExercisePlantUmlService } from 'app/exercises/programming/shared/instructions-render/service/programming-exercise-plant-uml.service';
-import { ArtemisShowdownExtensionWrapper } from 'app/shared/markdown-editor/extensions/artemis-showdown-extension-wrapper';
 import { Result } from 'app/entities/result.model';
-import { ShowdownExtension } from 'showdown';
 import DOMPurify from 'dompurify';
 
 // This regex is the same as in the server: ProgrammingExerciseTaskService.java
 const testsColorRegex = /testsColor\((\s*[^()\s]+(\([^()]*\))?)\)/g;
 
 @Injectable({ providedIn: 'root' })
-export class ProgrammingExercisePlantUmlExtensionWrapper implements ArtemisShowdownExtensionWrapper {
+export class ProgrammingExercisePlantUmlExtensionWrapper extends ArtemisTextReplacementPlugin {
     private latestResult?: Result;
     private testCases?: ProgrammingExerciseTestCase[];
     private injectableElementsFoundSubject = new Subject<() => void>();
@@ -25,7 +24,9 @@ export class ProgrammingExercisePlantUmlExtensionWrapper implements ArtemisShowd
     constructor(
         private programmingExerciseInstructionService: ProgrammingExerciseInstructionService,
         private plantUmlService: ProgrammingExercisePlantUmlService,
-    ) {}
+    ) {
+        super();
+    }
 
     /**
      * Sets latest result according to parameter.
@@ -67,7 +68,6 @@ export class ProgrammingExercisePlantUmlExtensionWrapper implements ArtemisShowd
     }
 
     /**
-     * Creates and returns an extension to current exercise.
      * The extension provides a custom rendering mechanism for embedded plantUml diagrams.
      * The mechanism works as follows:
      * 1) Find (multiple) embedded plantUml diagrams based on a regex (startuml, enduml).
@@ -76,55 +76,49 @@ export class ProgrammingExercisePlantUmlExtensionWrapper implements ArtemisShowd
      * 4) Send the plantUml content to the server for rendering a svg (the result will be cached for performance reasons)
      * 5) Inject the computed svg for the plantUml (from the server) into the plantUml div container based on the unique placeholder id (see step 2)
      */
-    getExtension() {
-        const extension: ShowdownExtension = {
-            type: 'lang',
-            filter: (text: string) => {
-                const idPlaceholder = '%idPlaceholder%';
-                // E.g. [task][Implement BubbleSort](testBubbleSort)
-                const plantUmlRegex = /@startuml([^@]*)@enduml/g;
-                // E.g. Implement BubbleSort, testBubbleSort
-                const plantUmlContainer = `<div class="mb-4" id="plantUml-${idPlaceholder}"></div>`;
-                // Replace test status markers.
-                const plantUmls = text.match(plantUmlRegex) ?? [];
-                // Assign unique ids to uml data structure at the beginning.
-                const plantUmlsIndexed = plantUmls.map((plantUml) => {
-                    const nextIndex = this.plantUmlIndex;
-                    // increase the global unique index so that the next plantUml gets a unique global id
-                    this.plantUmlIndex++;
-                    return { plantUmlId: nextIndex, plantUml };
-                });
-                // custom markdown to html rendering: replace the plantUml in the markdown with a simple <div></div> container with a unique id placeholder
-                // with the global unique id so that we can find the plantUml later on, when it was rendered, and then inject the 'actual' inner html (actually a svg image)
-                const replacedText = plantUmlsIndexed.reduce((acc: string, umlIndexed: { plantUmlId: number; plantUml: string }): string => {
-                    return acc.replace(new RegExp(escapeStringForUseInRegex(umlIndexed.plantUml), 'g'), plantUmlContainer.replace(idPlaceholder, umlIndexed.plantUmlId.toString()));
-                }, text);
-                // before we send the plantUml to the server for rendering, we need to inject the current test status so that the colors can be adapted
-                // (green == implemented, red == not yet implemented, grey == unknown)
-                const plantUmlsValidated = plantUmlsIndexed.map((plantUmlIndexed: { plantUmlId: number; plantUml: string }) => {
-                    plantUmlIndexed.plantUml = plantUmlIndexed.plantUml.replace(testsColorRegex, (match: any, capture: string) => {
-                        const tests = this.programmingExerciseInstructionService.convertTestListToIds(capture, this.testCases);
-                        const { testCaseState } = this.programmingExerciseInstructionService.testStatusForTask(tests, this.latestResult);
-                        switch (testCaseState) {
-                            case TestCaseState.SUCCESS:
-                                return 'green';
-                            case TestCaseState.FAIL:
-                                return 'red';
-                            default:
-                                return 'grey';
-                        }
-                    });
-                    return plantUmlIndexed;
-                });
-                // send the adapted plantUml to the server for rendering and inject the result into the html DOM based on the unique plantUml id
-                this.injectableElementsFoundSubject.next(() => {
-                    plantUmlsValidated.forEach((plantUmlIndexed: { plantUmlId: number; plantUml: string }) => {
-                        this.loadAndInjectPlantUml(plantUmlIndexed.plantUml, plantUmlIndexed.plantUmlId);
-                    });
-                });
-                return replacedText;
-            },
-        };
-        return extension;
+    replaceText(text: string): string {
+        const idPlaceholder = '%idPlaceholder%';
+        // E.g. [task][Implement BubbleSort](testBubbleSort)
+        const plantUmlRegex = /@startuml([^@]*)@enduml/g;
+        // E.g. Implement BubbleSort, testBubbleSort
+        const plantUmlContainer = `<div class="mb-4" id="plantUml-${idPlaceholder}"></div>`;
+        // Replace test status markers.
+        const plantUmls = text.match(plantUmlRegex) ?? [];
+        // Assign unique ids to uml data structure at the beginning.
+        const plantUmlsIndexed = plantUmls.map((plantUml) => {
+            const nextIndex = this.plantUmlIndex;
+            // increase the global unique index so that the next plantUml gets a unique global id
+            this.plantUmlIndex++;
+            return { plantUmlId: nextIndex, plantUml };
+        });
+        // custom markdown to html rendering: replace the plantUml in the markdown with a simple <div></div> container with a unique id placeholder
+        // with the global unique id so that we can find the plantUml later on, when it was rendered, and then inject the 'actual' inner html (actually a svg image)
+        const replacedText = plantUmlsIndexed.reduce((acc: string, umlIndexed: { plantUmlId: number; plantUml: string }): string => {
+            return acc.replace(new RegExp(escapeStringForUseInRegex(umlIndexed.plantUml), 'g'), plantUmlContainer.replace(idPlaceholder, umlIndexed.plantUmlId.toString()));
+        }, text);
+        // before we send the plantUml to the server for rendering, we need to inject the current test status so that the colors can be adapted
+        // (green == implemented, red == not yet implemented, grey == unknown)
+        const plantUmlsValidated = plantUmlsIndexed.map((plantUmlIndexed: { plantUmlId: number; plantUml: string }) => {
+            plantUmlIndexed.plantUml = plantUmlIndexed.plantUml.replace(testsColorRegex, (match: string, capture: string) => {
+                const tests = this.programmingExerciseInstructionService.convertTestListToIds(capture, this.testCases);
+                const { testCaseState } = this.programmingExerciseInstructionService.testStatusForTask(tests, this.latestResult);
+                switch (testCaseState) {
+                    case TestCaseState.SUCCESS:
+                        return 'green';
+                    case TestCaseState.FAIL:
+                        return 'red';
+                    default:
+                        return 'grey';
+                }
+            });
+            return plantUmlIndexed;
+        });
+        // send the adapted plantUml to the server for rendering and inject the result into the html DOM based on the unique plantUml id
+        this.injectableElementsFoundSubject.next(() => {
+            plantUmlsValidated.forEach((plantUmlIndexed: { plantUmlId: number; plantUml: string }) => {
+                this.loadAndInjectPlantUml(plantUmlIndexed.plantUml, plantUmlIndexed.plantUmlId);
+            });
+        });
+        return replacedText;
     }
 }

src/main/webapp/app/exercises/programming/shared/instructions-render/extensions/programming-exercise-task.extension.ts

@@ -1,8 +1,7 @@
 import { Injectable, ViewContainerRef } from '@angular/core';
 import { TaskArrayWithExercise } from 'app/exercises/programming/shared/instructions-render/task/programming-exercise-task.model';
-import { ArtemisShowdownExtensionWrapper } from 'app/shared/markdown-editor/extensions/artemis-showdown-extension-wrapper';
+import { ArtemisTextReplacementPlugin } from 'app/shared/markdown-editor/extensions/ArtemisTextReplacementPlugin';
 import { Observable, Subject } from 'rxjs';
-import { ShowdownExtension } from 'showdown';
 
 /**
  * Regular expression for finding tasks.
@@ -18,15 +17,12 @@ import { ShowdownExtension } from 'showdown';
 export const taskRegex = /\[task]\[([^[\]]+)]\(((?:[^(),]+(?:\([^()]*\)[^(),]*)?(?:,[^(),]+(?:\([^()]*\)[^(),]*)?)*)?)\)/g;
 
 @Injectable({ providedIn: 'root' })
-export class ProgrammingExerciseTaskExtensionWrapper implements ArtemisShowdownExtensionWrapper {
+export class ProgrammingExerciseTaskExtensionWrapper extends ArtemisTextReplacementPlugin {
     // We don't have a provider for ViewContainerRef, so we pass it from ProgrammingExerciseInstructionComponent
     viewContainerRef: ViewContainerRef;
 
     private testsForTaskSubject = new Subject<TaskArrayWithExercise>();
     private injectableElementsFoundSubject = new Subject<() => void>();
-
-    constructor() {}
-
     /**
      * Subscribes to injectableElementsFoundSubject.
      */
@@ -35,23 +31,12 @@ export class ProgrammingExerciseTaskExtensionWrapper implements ArtemisShowdownE
     }
 
     /**
-     * Creates and returns an extension to current exercise.
-     * The task regex is coupled to the value used in ProgrammingExerciseTaskService in the server and
-     * `TaskCommand` in the client
+     * The task regex is coupled to the value used in ProgrammingExerciseTaskService in the server
+     * and `TaskCommand` in the client
      * If you change the regex, make sure to change it in all places!
      */
-    getExtension() {
-        const extension: ShowdownExtension = {
-            type: 'lang',
-            filter: (problemStatement: string) => {
-                return this.createTasks(problemStatement);
-            },
-        };
-        return extension;
-    }
-
-    public createTasks(problemStatement: string): string {
-        return problemStatement.replace(taskRegex, (match) => {
+    replaceText(text: string): string {
+        return text.replace(taskRegex, (match) => {
             return this.escapeTaskSpecialCharactersForMarkdown(match);
         });
     }

src/main/webapp/app/exercises/programming/shared/instructions-render/programming-exercise-instruction.component.ts

@@ -16,7 +16,7 @@ import { DomSanitizer, SafeHtml } from '@angular/platform-browser';
 import { ThemeService } from 'app/core/theme/theme.service';
 import { ProgrammingExerciseTestCase } from 'app/entities/programming/programming-exercise-test-case.model';
 import { ProgrammingExerciseGradingService } from 'app/exercises/programming/manage/services/programming-exercise-grading.service';
-import { ShowdownExtension } from 'showdown';
+import type { PluginSimple } from 'markdown-it';
 import { catchError, filter, map, mergeMap, switchMap, tap } from 'rxjs/operators';
 import { Observable, Subscription, merge, of } from 'rxjs';
 import { ProgrammingExercise } from 'app/entities/programming/programming-exercise.model';
@@ -80,7 +80,7 @@ export class ProgrammingExerciseInstructionComponent implements OnChanges, OnDes
     public renderedMarkdown: SafeHtml;
     private injectableContentForMarkdownCallbacks: Array<() => void> = [];
 
-    markdownExtensions: ShowdownExtension[];
+    markdownExtensions: PluginSimple[];
     private injectableContentFoundSubscription: Subscription;
     private tasksSubscription: Subscription;
     private generateHtmlSubscription: Subscription;

src/main/webapp/app/exercises/quiz/shared/short-answer-question-util.service.ts

@@ -373,6 +373,7 @@ export class ShortAnswerQuestionUtil {
             if (firstWord === '') {
                 continue;
             }
+
             const firstWordIndex = element.indexOf(firstWord);
             const whitespace = ' '.repeat(this.getIndentation(originalTextParts[i][0]).length);
             formattedTextParts[i][0] = [element.substring(0, firstWordIndex), whitespace, element.substring(firstWordIndex).trim()].join('');

src/main/webapp/app/index.d.ts

@@ -1,9 +1,4 @@
-declare module 'showdown-katex' {
-    const main: () => ShowDownExtension;
-    export = main;
-}
-
-declare module 'showdown-highlight' {
-    const main: ({ pre: boolean }) => ShowDownExtension;
+declare module 'markdown-it-class' {
+    const main: (md: MarkdownIt) => void;
     export = main;
 }

src/main/webapp/app/shared/markdown-editor/extensions/ArtemisTextReplacementPlugin.ts

@@ -0,0 +1,24 @@
+import type MarkdownIt from 'markdown-it';
+import type { PluginSimple } from 'markdown-it';
+
+/**
+ * Markdown-It plugin that allows replacing text in the raw markdown before tokenizing.
+ * See more about Markdown-It plugins here: https://github.com/markdown-it/markdown-it/tree/master/docs
+ */
+export abstract class ArtemisTextReplacementPlugin {
+    getExtension(): PluginSimple {
+        return (md: MarkdownIt): void => {
+            md.core.ruler.before('normalize', 'artemis_text_replacement', (state) => {
+                // Perform the replacement on the raw markdown text
+                state.src = this.replaceText(state.src);
+            });
+        };
+    }
+
+    /**
+     * Performs text replacement on the raw markdown before parsing.
+     * @param text The raw markdown text.
+     * @returns The modified markdown text after replacements.
+     */
+    abstract replaceText(text: string): string;
+}