Show current user mention in MarkdownTextInput with green outline

src/components/RNMarkdownTextInput.tsx

@@ -1,8 +1,9 @@
-import type {MarkdownTextInputProps} from '@expensify/react-native-live-markdown';
+import type {MarkdownRange, MarkdownTextInputProps} from '@expensify/react-native-live-markdown';
 import {MarkdownTextInput, parseExpensiMark} from '@expensify/react-native-live-markdown';
 import type {ForwardedRef} from 'react';
-import React from 'react';
+import React, {forwardRef, useCallback} from 'react';
 import Animated from 'react-native-reanimated';
+import useCurrentUserPersonalDetails from '@hooks/useCurrentUserPersonalDetails';
 import useTheme from '@hooks/useTheme';
 import CONST from '@src/CONST';
 
@@ -11,25 +12,70 @@ const AnimatedMarkdownTextInput = Animated.createAnimatedComponent(MarkdownTextI
 
 type AnimatedMarkdownTextInputRef = typeof AnimatedMarkdownTextInput & MarkdownTextInput & HTMLInputElement;
 
-type RNMarkdownTextInputProps = Omit<MarkdownTextInputProps, 'parser'>;
+// Make the parser prop optional for this component because we are always defaulting to `parseExpensiMark`
+type RNMarkdownTextInputWithRefProps = Omit<MarkdownTextInputProps, 'parser'> & {
+    parser?: MarkdownTextInputProps['parser'];
+};
 
-function RNMarkdownTextInputWithRef({maxLength, ...props}: RNMarkdownTextInputProps, ref: ForwardedRef<AnimatedMarkdownTextInputRef>) {
+function decorateRangesWithCurrentUser(ranges: MarkdownRange[], text: string, currentUser: string): MarkdownRange[] {
+    'worklet';
+
+    return ranges.map((range) => {
+        if (range.type === 'mention-user') {
+            const mentionText = text.slice(range.start, range.start + range.length);
+            const isCurrentUser = mentionText === `@${currentUser}`;
+            if (isCurrentUser) {
+                return {
+                    ...range,
+                    type: 'mention-here',
+                };
+            }
+        }
+
+        return range;
+    });
+}
+
+function RNMarkdownTextInputWithRef({maxLength, ...props}: RNMarkdownTextInputWithRefProps, ref: ForwardedRef<AnimatedMarkdownTextInputRef>) {
     const theme = useTheme();
+    const currentUserPersonalDetails = useCurrentUserPersonalDetails();
+
+    const {parser, ...restProps} = props;
+    const currentUserLogin = currentUserPersonalDetails.login;
+
+    // We accept parser passed down as an argument or use expensiMark
+    const parserFunction = useCallback(
+        (text: string) => {
+            'worklet';
+
+            if (parser) {
+                return parser(text);
+            }
+
+            const parsedMentions = parseExpensiMark(text);
+            if (!currentUserLogin) {
+                return parsedMentions;
+            }
+
+            return decorateRangesWithCurrentUser(parsedMentions, text, currentUserLogin);
+        },
+        [currentUserLogin, parser],
+    );
 
     return (
         <AnimatedMarkdownTextInput
             allowFontScaling={false}
             textBreakStrategy="simple"
             keyboardAppearance={theme.colorScheme}
-            parser={parseExpensiMark}
+            parser={parserFunction}
             ref={(refHandle) => {
                 if (typeof ref !== 'function') {
                     return;
                 }
                 ref(refHandle as AnimatedMarkdownTextInputRef);
             }}
             // eslint-disable-next-line
-            {...props}
+            {...restProps}
             /**
              * If maxLength is not set, we should set the it to CONST.MAX_COMMENT_LENGTH + 1, to avoid parsing markdown for large text
              */
@@ -40,5 +86,6 @@ function RNMarkdownTextInputWithRef({maxLength, ...props}: RNMarkdownTextInputPr
 
 RNMarkdownTextInputWithRef.displayName = 'RNTextInputWithRef';
 
-export default React.forwardRef(RNMarkdownTextInputWithRef);
+export default forwardRef(RNMarkdownTextInputWithRef);
+export {decorateRangesWithCurrentUser};
 export type {AnimatedMarkdownTextInputRef};

tests/unit/decorateRangesWithCurrentUserTest.ts

@@ -0,0 +1,63 @@
+import type {MarkdownRange} from '@expensify/react-native-live-markdown';
+import {decorateRangesWithCurrentUser} from '@components/RNMarkdownTextInput';
+
+describe('decorateRangesWithCurrentUser', () => {
+    test('returns empty list for empty text', () => {
+        const result = decorateRangesWithCurrentUser([], '', '');
+        expect(result).toEqual([]);
+    });
+
+    test('returns empty list when there are no mentions', () => {
+        const text = 'Lorem ipsum';
+        const result = decorateRangesWithCurrentUser([], text, '');
+        expect(result).toEqual([]);
+    });
+
+    test('returns unchanged ranges when there are other markups than user-mentions', () => {
+        const text = 'Lorem ipsum';
+        const ranges: MarkdownRange[] = [
+            {
+                type: 'bold',
+                start: 5,
+                length: 3,
+            },
+        ];
+        const result = decorateRangesWithCurrentUser(ranges, text, '');
+        expect(result).toEqual([
+            {
+                type: 'bold',
+                start: 5,
+                length: 3,
+            },
+        ]);
+    });
+
+    test('returns ranges with current user type changed to "mention-here"', () => {
+        const text = 'Lorem ipsum @myUser';
+        const ranges: MarkdownRange[] = [
+            {
+                type: 'bold',
+                start: 5,
+                length: 3,
+            },
+            {
+                type: 'mention-user',
+                start: 12,
+                length: 8,
+            },
+        ];
+        const result = decorateRangesWithCurrentUser(ranges, text, 'myUser');
+        expect(result).toEqual([
+            {
+                type: 'bold',
+                start: 5,
+                length: 3,
+            },
+            {
+                type: 'mention-here',
+                start: 12,
+                length: 8,
+            },
+        ]);
+    });
+});