Add markdown-extension-collection.ts

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

src/components/markdown-renderer/markdown-extension/markdown-extension-collection.ts

@@ -0,0 +1,57 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import type { MarkdownExtension } from './markdown-extension'
+import type { ComponentReplacer } from '../replace-components/component-replacer'
+import type { Document } from 'domhandler'
+import type MarkdownIt from 'markdown-it'
+import { SanitizerMarkdownExtension } from './sanitizer/sanitizer-markdown-extension'
+
+/**
+ * Contains multiple {@link MarkdownExtension} and uses them to configure parts of the renderer.
+ */
+export class MarkdownExtensionCollection {
+  private extensions: MarkdownExtension[]
+
+  public constructor(additionalExtensions: MarkdownExtension[]) {
+    const tagWhiteLists = additionalExtensions.flatMap((extension) => extension.buildTagNameWhitelist())
+
+    this.extensions = [...additionalExtensions, new SanitizerMarkdownExtension(tagWhiteLists)]
+  }
+
+  /**
+   * Configures the given {@link MarkdownIt markdown-it instance} using every saved {@link MarkdownExtension extension}.
+   *
+   * @param markdownIt The markdown-it instance to configure.
+   */
+  public configureMarkdownIt(markdownIt: MarkdownIt): void {
+    this.extensions.forEach((extension) => markdownIt.use((markdownIt) => extension.configureMarkdownIt(markdownIt)))
+    this.extensions.forEach((extension) =>
+      markdownIt.use((markdownIt) => extension.configureMarkdownItPost(markdownIt))
+    )
+  }
+
+  /**
+   * Creates a node processor that applies the node processor of every saved {@link MarkdownExtension extension}.
+   *
+   * @return the created node processor function
+   */
+  public buildFlatNodeProcessor(): (document: Document) => Document {
+    return this.extensions
+      .flatMap((extension) => extension.buildNodeProcessors())
+      .reduce(
+        (state, processor) => (document: Document) => state(processor.process(document)),
+        (document: Document) => document
+      )
+  }
+
+  /**
+   * Collects all {@link ComponentReplacer component replacers} from all saved {@link MarkdownExtension extension}.
+   */
+  public buildReplacers(): ComponentReplacer[] {
+    return this.extensions.flatMap((extension) => extension.buildReplacers())
+  }
+}