Escape markdown sequences (#2208)

* escape inline markdown character

* fix typo

* improve document around custom markdown plugin and add escape sequence utils

* recover inline escape sequences on edit

* remove escape sequences from plain text body

* use `s` for strike-through instead of del

* escape block markdown sequences

* fix remove escape sequence was not removing all slashes from plain text

* recover block sequences on edit

src/app/components/editor/output.ts

@@ -3,7 +3,12 @@ import { Descendant, Text } from 'slate';
 import { sanitizeText } from '../../utils/sanitize';
 import { BlockType } from './types';
 import { CustomElement } from './slate';
-import { parseBlockMD, parseInlineMD } from '../../plugins/markdown';
+import {
+  parseBlockMD,
+  parseInlineMD,
+  unescapeMarkdownBlockSequences,
+  unescapeMarkdownInlineSequences,
+} from '../../plugins/markdown';
 import { findAndReplace } from '../../utils/findAndReplace';
 import { sanitizeForRegex } from '../../utils/regex';
 
@@ -19,7 +24,7 @@ const textToCustomHtml = (node: Text, opts: OutputOptions): string => {
     if (node.bold) string = `<strong>${string}</strong>`;
     if (node.italic) string = `<i>${string}</i>`;
     if (node.underline) string = `<u>${string}</u>`;
-    if (node.strikeThrough) string = `<del>${string}</del>`;
+    if (node.strikeThrough) string = `<s>${string}</s>`;
     if (node.code) string = `<code>${string}</code>`;
     if (node.spoiler) string = `<span data-mx-spoiler>${string}</span>`;
   }
@@ -102,7 +107,8 @@ export const toMatrixCustomHTML = (
         allowBlockMarkdown: false,
       })
         .replace(/<br\/>$/, '\n')
-        .replace(/^&gt;/, '>');
+        .replace(/^(\\*)&gt;/, '$1>');
+
       markdownLines += line;
       if (index === targetNodes.length - 1) {
         return parseBlockMD(markdownLines, ignoreHTMLParseInlineMD);
@@ -157,11 +163,14 @@ const elementToPlainText = (node: CustomElement, children: string): string => {
   }
 };
 
-export const toPlainText = (node: Descendant | Descendant[]): string => {
-  if (Array.isArray(node)) return node.map((n) => toPlainText(n)).join('');
-  if (Text.isText(node)) return node.text;
+export const toPlainText = (node: Descendant | Descendant[], isMarkdown: boolean): string => {
+  if (Array.isArray(node)) return node.map((n) => toPlainText(n, isMarkdown)).join('');
+  if (Text.isText(node))
+    return isMarkdown
+      ? unescapeMarkdownBlockSequences(node.text, unescapeMarkdownInlineSequences)
+      : node.text;
 
-  const children = node.children.map((n) => toPlainText(n)).join('');
+  const children = node.children.map((n) => toPlainText(n, isMarkdown)).join('');
   return elementToPlainText(node, children);
 };