Inline markdown in editor

src/app/components/editor/output.ts

@@ -2,15 +2,28 @@ import { Descendant, Text } from 'slate';
 import { sanitizeText } from '../../utils/sanitize';
 import { BlockType } from './Elements';
 import { CustomElement, FormattedText } from './slate';
+import { parseInlineMD } from '../../utils/markdown';
 
-const textToCustomHtml = (node: FormattedText): string => {
+export type OutputOptions = {
+  allowTextFormatting?: boolean;
+  allowMarkdown?: boolean;
+};
+
+const textToCustomHtml = (node: FormattedText, opts: OutputOptions): string => {
   let string = sanitizeText(node.text);
-  if (node.bold) string = `<strong>${string}</strong>`;
-  if (node.italic) string = `<i>${string}</i>`;
-  if (node.underline) string = `<u>${string}</u>`;
-  if (node.strikeThrough) string = `<s>${string}</s>`;
-  if (node.code) string = `<code>${string}</code>`;
-  if (node.spoiler) string = `<span data-mx-spoiler>${string}</span>`;
+  if (opts.allowTextFormatting) {
+    if (node.bold) string = `<strong>${string}</strong>`;
+    if (node.italic) string = `<i>${string}</i>`;
+    if (node.underline) string = `<u>${string}</u>`;
+    if (node.strikeThrough) string = `<s>${string}</s>`;
+    if (node.code) string = `<code>${string}</code>`;
+    if (node.spoiler) string = `<span data-mx-spoiler>${string}</span>`;
+  }
+
+  if (opts.allowMarkdown && string === sanitizeText(node.text)) {
+    string = parseInlineMD(string);
+  }
+
   return string;
 };
 
@@ -47,11 +60,19 @@ const elementToCustomHtml = (node: CustomElement, children: string): string => {
   }
 };
 
-export const toMatrixCustomHTML = (node: Descendant | Descendant[]): string => {
-  if (Array.isArray(node)) return node.map((n) => toMatrixCustomHTML(n)).join('');
-  if (Text.isText(node)) return textToCustomHtml(node);
+export const toMatrixCustomHTML = (
+  node: Descendant | Descendant[],
+  opts: OutputOptions
+): string => {
+  const parseNode = (n: Descendant) => {
+    const isCodeLine = 'type' in n && n.type === BlockType.CodeLine;
+    if (isCodeLine) return toMatrixCustomHTML(n, {});
+    return toMatrixCustomHTML(n, opts);
+  };
+  if (Array.isArray(node)) return node.map(parseNode).join('');
+  if (Text.isText(node)) return textToCustomHtml(node, opts);
 
-  const children = node.children.map((n) => toMatrixCustomHTML(n)).join('');
+  const children = node.children.map(parseNode).join('');
   return elementToCustomHtml(node, children);
 };
 

src/app/organisms/room/RoomInput.tsx

@@ -108,6 +108,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
   ({ editor, roomViewRef, roomId }, ref) => {
     const mx = useMatrixClient();
     const room = mx.getRoom(roomId);
+    const [isMarkdown] = useSetting(settingsAtom, 'isMarkdown');
 
     const [msgDraft, setMsgDraft] = useAtom(roomIdToMsgDraftAtomFamily(roomId));
     const [replyDraft, setReplyDraft] = useAtom(roomIdToReplyDraftAtomFamily(roomId));
@@ -251,7 +252,12 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
       uploadBoardHandlers.current?.handleSend();
 
       const plainText = toPlainText(editor.children).trim();
-      const customHtml = trimCustomHtml(toMatrixCustomHTML(editor.children));
+      const customHtml = trimCustomHtml(
+        toMatrixCustomHTML(editor.children, {
+          allowTextFormatting: true,
+          allowMarkdown: isMarkdown,
+        })
+      );
 
       if (plainText === '') return;
 
@@ -288,7 +294,7 @@ export const RoomInput = forwardRef<HTMLDivElement, RoomInputProps>(
       resetEditorHistory(editor);
       setReplyDraft();
       sendTypingStatus(false);
-    }, [mx, roomId, editor, replyDraft, sendTypingStatus, setReplyDraft]);
+    }, [mx, roomId, editor, replyDraft, sendTypingStatus, setReplyDraft, isMarkdown]);
 
     const handleKeyDown: KeyboardEventHandler = useCallback(
       (evt) => {

src/app/organisms/settings/Settings.jsx

@@ -6,7 +6,7 @@ import cons from '../../../client/state/cons';
 import settings from '../../../client/state/settings';
 import navigation from '../../../client/state/navigation';
 import {
-  toggleSystemTheme, toggleMarkdown,
+  toggleSystemTheme,
   toggleNotifications, toggleNotificationSounds,
 } from '../../../client/action/settings';
 import { usePermission } from '../../hooks/usePermission';
@@ -52,6 +52,7 @@ function AppearanceSection() {
   const [messageLayout, setMessageLayout] = useSetting(settingsAtom, 'messageLayout');
   const [messageSpacing, setMessageSpacing] = useSetting(settingsAtom, 'messageSpacing');
   const [useSystemEmoji, setUseSystemEmoji] = useSetting(settingsAtom, 'useSystemEmoji');
+  const [isMarkdown, setIsMarkdown] = useSetting(settingsAtom, 'isMarkdown');
   const [hideMembershipEvents, setHideMembershipEvents] = useSetting(settingsAtom, 'hideMembershipEvents');
   const [hideNickAvatarEvents, setHideNickAvatarEvents] = useSetting(settingsAtom, 'hideNickAvatarEvents');
   const [mediaAutoLoad, setMediaAutoLoad] = useSetting(settingsAtom, 'mediaAutoLoad');
@@ -138,14 +139,14 @@ function AppearanceSection() {
           }
         />
         <SettingTile
-          title="Markdown formatting"
+          title="Inline Markdown formatting"
           options={(
             <Toggle
-              isActive={settings.isMarkdown}
-              onToggle={() => { toggleMarkdown(); updateState({}); }}
+              isActive={isMarkdown}
+              onToggle={() => setIsMarkdown(!isMarkdown) }
             />
           )}
-          content={<Text variant="b3">Format messages with markdown syntax before sending.</Text>}
+          content={<Text variant="b3">Format messages with inline markdown syntax before sending.</Text>}
         />
         <SettingTile
           title="Hide membership events"

src/app/utils/markdown.ts

@@ -0,0 +1,191 @@
+export type PlainMDParser = (text: string) => string;
+export type MatchResult = RegExpMatchArray | RegExpExecArray;
+export type RuleMatch = (text: string) => MatchResult | null;
+export type MatchConverter = (parse: PlainMDParser, match: MatchResult) => string;
+
+export type MDRule = {
+  match: RuleMatch;
+  html: MatchConverter;
+};
+
+export type MatchReplacer = (
+  parse: PlainMDParser,
+  text: string,
+  match: MatchResult,
+  content: string
+) => string;
+
+export type RuleRunner = (parse: PlainMDParser, text: string, rule: MDRule) => string | undefined;
+export type RulesRunner = (
+  parse: PlainMDParser,
+  text: string,
+  rules: MDRule[]
+) => string | undefined;
+
+const MIN_ANY = '(.+?)';
+
+const BOLD_MD_1 = '**';
+const BOLD_PREFIX_1 = '\\*{2}';
+const BOLD_NEG_LA_1 = '(?!\\*)';
+const BOLD_REG_1 = new RegExp(`${BOLD_PREFIX_1}${MIN_ANY}${BOLD_PREFIX_1}${BOLD_NEG_LA_1}`);
+const BoldRule: MDRule = {
+  match: (text) => text.match(BOLD_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    const child = parse(g1);
+    return `<strong data-md="${BOLD_MD_1}">${child}</strong>`;
+  },
+};
+
+const ITALIC_MD_1 = '*';
+const ITALIC_PREFIX_1 = '\\*';
+const ITALIC_NEG_LA_1 = '(?!\\*)';
+const ITALIC_REG_1 = new RegExp(`${ITALIC_PREFIX_1}${MIN_ANY}${ITALIC_PREFIX_1}${ITALIC_NEG_LA_1}`);
+const ItalicRule1: MDRule = {
+  match: (text) => text.match(ITALIC_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<i data-md="${ITALIC_MD_1}">${parse(g1)}</i>`;
+  },
+};
+
+const ITALIC_MD_2 = '_';
+const ITALIC_PREFIX_2 = '_';
+const ITALIC_NEG_LA_2 = '(?!_)';
+const ITALIC_REG_2 = new RegExp(`${ITALIC_PREFIX_2}${MIN_ANY}${ITALIC_PREFIX_2}${ITALIC_NEG_LA_2}`);
+const ItalicRule2: MDRule = {
+  match: (text) => text.match(ITALIC_REG_2),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<i data-md="${ITALIC_MD_2}">${parse(g1)}</i>`;
+  },
+};
+
+const UNDERLINE_MD_1 = '__';
+const UNDERLINE_PREFIX_1 = '_{2}';
+const UNDERLINE_NEG_LA_1 = '(?!_)';
+const UNDERLINE_REG_1 = new RegExp(
+  `${UNDERLINE_PREFIX_1}${MIN_ANY}${UNDERLINE_PREFIX_1}${UNDERLINE_NEG_LA_1}`
+);
+const UnderlineRule: MDRule = {
+  match: (text) => text.match(UNDERLINE_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<u data-md="${UNDERLINE_MD_1}">${parse(g1)}</u>`;
+  },
+};
+
+const STRIKE_MD_1 = '~~';
+const STRIKE_PREFIX_1 = '~{2}';
+const STRIKE_NEG_LA_1 = '(?!~)';
+const STRIKE_REG_1 = new RegExp(`${STRIKE_PREFIX_1}${MIN_ANY}${STRIKE_PREFIX_1}${STRIKE_NEG_LA_1}`);
+const StrikeRule: MDRule = {
+  match: (text) => text.match(STRIKE_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<s data-md="${STRIKE_MD_1}">${parse(g1)}</s>`;
+  },
+};
+
+const CODE_MD_1 = '`';
+const CODE_PREFIX_1 = '`';
+const CODE_NEG_LA_1 = '(?!`)';
+const CODE_REG_1 = new RegExp(`${CODE_PREFIX_1}${MIN_ANY}${CODE_PREFIX_1}${CODE_NEG_LA_1}`);
+const CodeRule: MDRule = {
+  match: (text) => text.match(CODE_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<code data-md="${CODE_MD_1}">${g1}</code>`;
+  },
+};
+
+const SPOILER_MD_1 = '||';
+const SPOILER_PREFIX_1 = '\\|{2}';
+const SPOILER_NEG_LA_1 = '(?!\\|)';
+const SPOILER_REG_1 = new RegExp(
+  `${SPOILER_PREFIX_1}${MIN_ANY}${SPOILER_PREFIX_1}${SPOILER_NEG_LA_1}`
+);
+const SpoilerRule: MDRule = {
+  match: (text) => text.match(SPOILER_REG_1),
+  html: (parse, match) => {
+    const [, g1] = match;
+    return `<span data-md="${SPOILER_MD_1}" data-mx-spoiler>${parse(g1)}</span>`;
+  },
+};
+
+const LINK_ALT = `\\[${MIN_ANY}\\]`;
+const LINK_URL = `\\((https?:\\/\\/.+?)\\)`;
+const LINK_REG_1 = new RegExp(`${LINK_ALT}${LINK_URL}`);
+const LinkRule: MDRule = {
+  match: (text) => text.match(LINK_REG_1),
+  html: (parse, match) => {
+    const [, g1, g2] = match;
+    return `<a data-md href="${g2}">${parse(g1)}</a>`;
+  },
+};
+
+const beforeMatch = (text: string, match: RegExpMatchArray | RegExpExecArray): string =>
+  text.slice(0, match.index);
+const afterMatch = (text: string, match: RegExpMatchArray | RegExpExecArray): string =>
+  text.slice((match.index ?? 0) + match[0].length);
+
+const replaceMatch: MatchReplacer = (parse, text, match, content) =>
+  `${parse(beforeMatch(text, match))}${content}${parse(afterMatch(text, match))}`;
+
+const runRule: RuleRunner = (parse, text, rule) => {
+  const matchResult = rule.match(text);
+  if (matchResult) {
+    const content = rule.html(parse, matchResult);
+    return replaceMatch(parse, text, matchResult, content);
+  }
+  return undefined;
+};
+
+/**
+ * Runs multiple rules at the same time to better handle nested rules.
+ * Rules will be run in the order they appear.
+ */
+const runRules: RulesRunner = (parse, text, rules) => {
+  const matchResults = rules.map((rule) => rule.match(text));
+
+  let targetRule: MDRule | undefined;
+  let targetResult: MatchResult | undefined;
+
+  for (let i = 0; i < matchResults.length; i += 1) {
+    const currentResult = matchResults[i];
+    if (currentResult && typeof currentResult.index === 'number') {
+      if (
+        !targetResult ||
+        (typeof targetResult?.index === 'number' && currentResult.index < targetResult.index)
+      ) {
+        targetResult = currentResult;
+        targetRule = rules[i];
+      }
+    }
+  }
+
+  if (targetRule && targetResult) {
+    const content = targetRule.html(parse, targetResult);
+    return replaceMatch(parse, text, targetResult, content);
+  }
+  return undefined;
+};
+
+const LeveledRules = [
+  BoldRule,
+  ItalicRule1,
+  UnderlineRule,
+  ItalicRule2,
+  StrikeRule,
+  SpoilerRule,
+  LinkRule,
+];
+
+export const parseInlineMD = (text: string): string => {
+  let result: string | undefined;
+  if (!result) result = runRule(parseInlineMD, text, CodeRule);
+
+  if (!result) result = runRules(parseInlineMD, text, LeveledRules);
+
+  return result ?? text;
+};