[IMPROVE] Add support to Linebreak and Katex on markdown (#4361)

* fix enableMessageParser logic

* create LineBreak component

* fix code style

* add KaTeX support

* add Katex and Inline Katex stories

* update snapshots

* add color prop

* update snapshot

* update snapshot

app/containers/markdown/index.tsx

@@ -138,7 +138,7 @@ class Markdown extends PureComponent<IMarkdownProps, any> {
 
 	get isNewMarkdown(): boolean {
 		const { md, enableMessageParser } = this.props;
-		return !!enableMessageParser && !!md;
+		return (enableMessageParser ?? true) && !!md;
 	}
 
 	renderText = ({ context, literal }: { context: []; literal: string }) => {

app/containers/markdown/new/Code.tsx

@@ -1,27 +1,25 @@
 import React from 'react';
-import { Text } from 'react-native';
+import { View } from 'react-native';
 import { Code as CodeProps } from '@rocket.chat/message-parser';
 
 import styles from '../styles';
-import { themes } from '../../../lib/constants';
 import { useTheme } from '../../../theme';
 import CodeLine from './CodeLine';
 
 interface ICodeProps {
 	value: CodeProps['value'];
 }
 
-const Code = ({ value }: ICodeProps) => {
-	const { theme } = useTheme();
+const Code = ({ value }: ICodeProps): React.ReactElement => {
+	const { colors } = useTheme();
 
 	return (
-		<Text
+		<View
 			style={[
 				styles.codeBlock,
 				{
-					color: themes[theme].bodyText,
-					backgroundColor: themes[theme].bannerBackground,
-					borderColor: themes[theme].borderColor
+					backgroundColor: colors.bannerBackground,
+					borderColor: colors.borderColor
 				}
 			]}>
 			{value.map(block => {
@@ -32,7 +30,7 @@ const Code = ({ value }: ICodeProps) => {
 						return null;
 				}
 			})}
-		</Text>
+		</View>
 	);
 };
 

app/containers/markdown/new/CodeLine.tsx

@@ -1,17 +1,21 @@
+import { CodeLine as CodeLineProps } from '@rocket.chat/message-parser';
 import React from 'react';
 import { Text } from 'react-native';
-import { CodeLine as CodeLineProps } from '@rocket.chat/message-parser';
+
+import { useTheme } from '../../../theme';
+import styles from '../styles';
 
 interface ICodeLineProps {
 	value: CodeLineProps['value'];
 }
 
-const CodeLine = ({ value }: ICodeLineProps) => {
+const CodeLine = ({ value }: ICodeLineProps): React.ReactElement | null => {
+	const { colors } = useTheme();
 	if (value.type !== 'PLAIN_TEXT') {
 		return null;
 	}
 
-	return <Text>{value.value}</Text>;
+	return <Text style={[styles.codeBlockText, { color: colors.bodyText }]}>{value.value}</Text>;
 };
 
 export default CodeLine;

app/containers/markdown/new/Inline.tsx

@@ -14,12 +14,13 @@ import Emoji from './Emoji';
 import InlineCode from './InlineCode';
 import Image from './Image';
 import MarkdownContext from './MarkdownContext';
+// import { InlineKaTeX, KaTeX } from './Katex';
 
 interface IParagraphProps {
 	value: ParagraphProps['value'];
 }
 
-const Inline = ({ value }: IParagraphProps) => {
+const Inline = ({ value }: IParagraphProps): React.ReactElement | null => {
 	const { useRealName, username, navToRoomInfo, mentions, channels } = useContext(MarkdownContext);
 	return (
 		<Text style={styles.inline}>
@@ -53,6 +54,9 @@ const Inline = ({ value }: IParagraphProps) => {
 						return <Hashtag hashtag={block.value.value} navToRoomInfo={navToRoomInfo} channels={channels} />;
 					case 'INLINE_CODE':
 						return <InlineCode value={block.value} />;
+					case 'INLINE_KATEX':
+						// return <InlineKaTeX value={block.value} />;
+						return <Text>{block.value}</Text>;
 					default:
 						return null;
 				}

app/containers/markdown/new/Katex.tsx

@@ -0,0 +1,20 @@
+import React from 'react';
+import { KaTeX as KaTeXProps } from '@rocket.chat/message-parser';
+// eslint-disable-next-line import/no-unresolved
+import MathView, { MathText } from 'react-native-math-view';
+
+import { useTheme } from '../../../theme';
+
+interface IKaTeXProps {
+	value: KaTeXProps['value'];
+}
+
+export const KaTeX = ({ value }: IKaTeXProps): React.ReactElement | null => {
+	const { colors } = useTheme();
+	return <MathView math={value} style={{ color: colors.bodyText }} />;
+};
+
+export const InlineKaTeX = ({ value }: IKaTeXProps): React.ReactElement | null => {
+	const { colors } = useTheme();
+	return <MathText color value={`$$${value}$$`} direction='ltr' style={{ color: colors.bodyText }} />;
+};

app/containers/markdown/new/LineBreak.tsx

@@ -0,0 +1,6 @@
+import React from 'react';
+import { View } from 'react-native';
+
+export default function LineBreak() {
+	return <View style={{ height: 8 }} />;
+}

app/containers/markdown/new/index.tsx

@@ -12,6 +12,8 @@ import UnorderedList from './UnorderedList';
 import { IUserMention, IUserChannel, TOnLinkPress } from '../interfaces';
 import TaskList from './TaskList';
 import MarkdownContext from './MarkdownContext';
+import LineBreak from './LineBreak';
+import { KaTeX } from './Katex';
 
 interface IBodyProps {
 	tokens?: MarkdownAST;
@@ -35,7 +37,7 @@ const Body = ({
 	getCustomEmoji,
 	baseUrl,
 	onLinkPress
-}: IBodyProps) => {
+}: IBodyProps): React.ReactElement | null => {
 	if (isEmpty(tokens)) {
 		return null;
 	}
@@ -70,6 +72,14 @@ const Body = ({
 						return <Code value={block.value} />;
 					case 'HEADING':
 						return <Heading value={block.value} level={block.level} />;
+					case 'LINE_BREAK':
+						return <LineBreak />;
+					// This prop exists, but not even on the web it is treated, so...
+					// https://github.com/RocketChat/Rocket.Chat/blob/develop/packages/gazzodown/src/Markup.tsx
+					// case 'LIST_ITEM':
+					// 	return <View />;
+					case 'KATEX':
+						return <KaTeX value={block.value} />;
 					default:
 						return null;
 				}

app/containers/markdown/styles.ts

@@ -83,13 +83,15 @@ export default StyleSheet.create({
 		paddingTop: 2
 	},
 	codeBlock: {
-		fontSize: 16,
-		...sharedStyles.textRegular,
-		...codeFontFamily,
 		borderWidth: 1,
 		borderRadius: 4,
 		padding: 4
 	},
+	codeBlockText: {
+		fontSize: 16,
+		...sharedStyles.textRegular,
+		...codeFontFamily
+	},
 	link: {
 		fontSize: 16,
 		...sharedStyles.textRegular

app/externalModules.d.ts

@@ -11,3 +11,4 @@ declare module 'react-native-mime-types';
 declare module 'react-native-restart';
 declare module 'react-native-jitsi-meet';
 declare module 'rn-root-view';
+declare module 'react-native-math-view';

jest.setup.js

@@ -68,3 +68,13 @@ jest.mock('@gorhom/bottom-sheet', () => {
 		BottomSheetScrollView: react.ScrollView
 	};
 });
+
+// If you need to manually mock a lib use this mock pattern and set exports.
+jest.mock('react-native-math-view', () => {
+	const react = require('react-native');
+	return {
+		__esModule: true,
+		default: react.View, // Default export
+		MathText: react.View // {...} Named export
+	};
+});

package.json

@@ -97,6 +97,7 @@
 		"react-native-jitsi-meet": "RocketChat/react-native-jitsi-meet",
 		"react-native-keycommands": "2.0.3",
 		"react-native-localize": "2.1.1",
+		"react-native-math-view": "^3.9.5",
 		"react-native-mime-types": "2.3.0",
 		"react-native-mmkv-storage": "0.6.12",
 		"react-native-modal": "11.10.0",

storybook/stories/NewMarkdown.js

@@ -692,3 +692,42 @@ stories.add('Lists', () => (
 		<NewMarkdown tokens={tasks} mentions={listMentions} channels={listChannels} />
 	</View>
 ));
+
+const katex = [
+	{
+		type: 'KATEX',
+		value: ' f(x) = \\int_{-\\infty}^\\infty \\hat f(\\xi)\\,e^{2 \\pi i \\xi x} \\,d\\xi '
+	}
+];
+
+const inlineKatex = [
+	{
+		type: 'PARAGRAPH',
+		value: [
+			{
+				type: 'INLINE_KATEX',
+				value: 'This text includes math notations and should be wrapped correctly for $\\alpha$ and $\\beta$ within the view.'
+			},
+			{
+				type: 'INLINE_KATEX',
+				value: "The following formula shouldn't be inline:$$x_{1,2} = {-b \\pm \\sqrt{b^2-4ac} \\over 2a}$$"
+			},
+			{
+				type: 'INLINE_KATEX',
+				value: 'However the following formula should be inline with the text: \\( a^2 + b^2 = c^2 \\)'
+			}
+		]
+	}
+];
+
+stories.add('Katex', () => (
+	<View style={styles.container}>
+		<NewMarkdown tokens={katex} />
+	</View>
+));
+
+stories.add('Inline Katex', () => (
+	<View style={styles.container}>
+		<NewMarkdown tokens={inlineKatex} />
+	</View>
+));