Reset cursor if updated text is shorter than the last one (#60)

package.json

@@ -51,7 +51,7 @@
 		"eslint-plugin-react": "^7.20.0",
 		"eslint-plugin-react-hooks": "^4.0.4",
 		"husky": "^4.2.5",
-		"ink": "^3.0.0-3",
+		"ink": "^3.0.5",
 		"ink-testing-library": "^2.0.0",
 		"prettier": "^2.0.5",
 		"pretty-quick": "^2.0.1",

source/index.tsx

@@ -1,5 +1,5 @@
 import * as React from 'react';
-import {useState} from 'react';
+import {useState, useEffect} from 'react';
 import type {FC} from 'react';
 import {Text, useInput} from 'ink';
 import chalk = require('chalk');
@@ -63,6 +63,25 @@ const TextInput: FC<Props> = ({
 		cursorWidth: 0
 	});
 
+	useEffect(() => {
+		setState(previousState => {
+			if (!focus || !showCursor) {
+				return previousState;
+			}
+
+			const newValue = originalValue || '';
+
+			if (previousState.cursorOffset > newValue.length - 1) {
+				return {
+					cursorOffset: newValue.length,
+					cursorWidth: 0
+				};
+			}
+
+			return previousState;
+		});
+	}, [originalValue, focus, showCursor]);
+
 	const cursorActualWidth = highlightPastedText ? cursorWidth : 0;
 
 	const value = mask ? mask.repeat(originalValue.length) : originalValue;

test.js

@@ -214,3 +214,30 @@ test('delete at the beginning of text', async t => {
 
 	t.is(lastFrame(), `${chalk.inverse('T')}est`);
 });
+
+test('adjust cursor when text is shorter than last value', async t => {
+	const Test = () => {
+		const [value, setValue] = useState('');
+		const submit = () => setValue('');
+
+		return <TextInput value={value} onChange={setValue} onSubmit={submit} />;
+	};
+
+	const {stdin, lastFrame} = render(<Test />);
+
+	await delay(100);
+	stdin.write('A');
+	await delay(100);
+	stdin.write('B');
+	await delay(100);
+	t.is(lastFrame(), `AB${chalk.inverse(' ')}`);
+	stdin.write('\r');
+	await delay(100);
+	t.is(lastFrame(), chalk.inverse(' '));
+	stdin.write('A');
+	await delay(100);
+	t.is(lastFrame(), `A${chalk.inverse(' ')}`);
+	stdin.write('B');
+	await delay(100);
+	t.is(lastFrame(), `AB${chalk.inverse(' ')}`);
+});