feat(frontend): add fork awesome linter

This linter will tell users that their fork awesome icon is deprecated and will stop working in the future and that they should replace it with a new bootstrap icon.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

frontend/locales/en.json

@@ -222,7 +222,8 @@
       "sequence": "The use of 'sequence' as code block language is deprecated and will be removed in a future release.",
       "shortcode": "The {{shortcode}} short-code is deprecated and will be removed in a future release. Use a single line URL instead.",
       "frontmatter": "The yaml-metadata is invalid.",
-      "frontmatter-tags": "The comma-separated definition of tags in the yaml-metadata is deprecated. Use a yaml-array instead."
+      "frontmatter-tags": "The comma-separated definition of tags in the yaml-metadata is deprecated. Use a yaml-array instead.",
+      "fork-awesome": "Fork Awesome is deprecated and will be removed in future release. Please use the new bootstrap icons instead. See {{link}} for more information."
     },
     "upload": {
       "uploadFile": {

frontend/src/components/editor-page/editor-pane/linter/single-line-regex-linter.ts

@@ -1,10 +1,10 @@
 /*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import type { Linter } from './linter'
-import type { Diagnostic } from '@codemirror/lint'
+import type { Action, Diagnostic } from '@codemirror/lint'
 import type { EditorView } from '@codemirror/view'
 import { t } from 'i18next'
 
@@ -25,7 +25,7 @@ export class SingleLineRegexLinter implements Linter {
   constructor(
     private regex: RegExp,
     private message: string,
-    private replace: (match: string) => string,
+    private replace?: (match: string) => string,
     private actionLabel?: string
   ) {}
 
@@ -52,11 +52,10 @@ export class SingleLineRegexLinter implements Linter {
   }
 
   private createDiagnostic(from: number, found: RegExpExecArray): Diagnostic {
+    let actions: Action[] = []
+    if (this.replace !== undefined) {
       const replacedText = this.replace(found[1])
-    return {
-      from: from,
-      to: from + found[0].length,
-      actions: [
+      actions = [
         {
           name: t(this.actionLabel ?? 'editor.linter.defaultAction'),
           apply: (view: EditorView, from: number, to: number) => {
@@ -65,7 +64,12 @@ export class SingleLineRegexLinter implements Linter {
             })
           }
         }
-      ],
+      ]
+    }
+    return {
+      from: from,
+      to: from + found[0].length,
+      actions: actions,
       message: this.message,
       severity: 'warning'
     }

frontend/src/extensions/extra-integrations/fork-awesome/fork-awesome-app-extension.ts

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import type { Linter } from '../../../components/editor-page/editor-pane/linter/linter'
+import { SingleLineRegexLinter } from '../../../components/editor-page/editor-pane/linter/single-line-regex-linter'
+import { AppExtension } from '../../base/app-extension'
+import { t } from 'i18next'
+
+export const forkAwesomeRegex = /<i class=["']fa fa-[\w-]+["'](?: aria-hidden=["']true["'])?\/?>(?:<\/i>)?/
+
+/**
+ * Adds support for flow charts to the markdown rendering.
+ */
+export class ForkAwesomeAppExtension extends AppExtension {
+  buildCodeMirrorLinter(): Linter[] {
+    return [
+      new SingleLineRegexLinter(
+        forkAwesomeRegex,
+        t('editor.linter.fork-awesome', { link: 'https://docs.hedgedoc.org' }) // ToDo: Add correct link here
+      )
+    ]
+  }
+}

frontend/src/extensions/extra-integrations/optional-app-extensions.ts

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -9,6 +9,7 @@ import { AlertAppExtension } from './alert/alert-app-extension'
 import { BlockquoteAppExtension } from './blockquote/blockquote-app-extension'
 import { CsvTableAppExtension } from './csv/csv-table-app-extension'
 import { FlowchartAppExtension } from './flowchart/flowchart-app-extension'
+import { ForkAwesomeAppExtension } from './fork-awesome/fork-awesome-app-extension'
 import { GistAppExtension } from './gist/gist-app-extension'
 import { GraphvizAppExtension } from './graphviz/graphviz-app-extension'
 import { HighlightedCodeFenceAppExtension } from './highlighted-code-fence/highlighted-code-fence-app-extension'
@@ -44,5 +45,6 @@ export const optionalAppExtensions: AppExtension[] = [
   new VimeoAppExtension(),
   new YoutubeAppExtension(),
   new TaskListCheckboxAppExtension(),
-  new HighlightedCodeFenceAppExtension()
+  new HighlightedCodeFenceAppExtension(),
+  new ForkAwesomeAppExtension()
 ]