Interactive CLI with Readline

import * as readline from 'readline';

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  completer: (line: string) => {
    const commands = ['help', 'list', 'add', 'remove', 'quit'];
    const hits = commands.filter(c => c.startsWith(line));
    return [hits.length ? hits : commands, line];
  },
});

const items: string[] = [];

function prompt() {
  rl.question('> ', (input) => {
    const [cmd, ...args] = input.trim().split(' ');

    switch (cmd) {
      case 'add':
        const item = args.join(' ');
        if (item) { items.push(item); console.log(`Added: ${item}`); }
        else console.log('Usage: add <item>');
        break;
      case 'list':
        if (items.length === 0) console.log('No items');
        else items.forEach((item, i) => console.log(`  ${i + 1}. ${item}`));
        break;
      case 'remove':
        const idx = parseInt(args[0]) - 1;
        if (idx >= 0 && idx < items.length) {
          const removed = items.splice(idx, 1);
          console.log(`Removed: ${removed[0]}`);
        } else console.log('Invalid index');
        break;
      case 'help':
        console.log('Commands: add, list, remove, help, quit');
        break;
      case 'quit':
        rl.close();
        return;
      default:
        console.log(`Unknown command: ${cmd}. Type 'help'`);
    }
    prompt();
  });
}

console.log('Interactive CLI — type help for commands');
prompt();