now-cli/lib/utils/output/prompt-bool.js

const chalk = require('chalk')

module.exports = (label, {
  defaultValue = false,
  abortSequences = new Set(['\x03']),
  resolveChars = new Set(['\r']),
  yesChar = 'y',
  noChar = 'n',
  stdin = process.stdin,
  stdout = process.stdout
} = {}) => {
  return new Promise((resolve, reject) => {
    const isRaw = process.stdin.isRaw

    stdin.setRawMode(true)
    stdin.resume()

    function restore() {
      stdin.setRawMode(isRaw)
      stdin.pause()
      stdin.removeListener('data', onData)
    }

    function onData(buffer) {
      const data = buffer.toString()

      if (abortSequences.has(data)) {
        restore()
        return reject(new Error('USER_ABORT'))
      }

      if (resolveChars.has(data[0])) {
        restore()
        resolve(defaultValue)
      } else if (data[0].toLowerCase() === yesChar) {
        restore()
        resolve(true)
      } else if (data[0].toLowerCase() === noChar) {
        restore()
        resolve(false)
      } else {
        // ignore extraneous input
      }
    }

    const defaultText = defaultValue === null ?
      `[${yesChar}|${noChar}]` :
      defaultValue ?
        `[${chalk.bold(yesChar.toUpperCase())}|${noChar}]` :
        `[${yesChar}|${chalk.bold(noChar.toUpperCase())}]`
    stdout.write(`${chalk.gray('-')} ${label} ${chalk.gray(defaultText)} `)
    stdin.on('data', onData)
  })
}