/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

function _isTruthy(value: undefined | string): boolean {
  // Returns true if value is a string that is anything but 0 or false.
  return value !== undefined && value !== '0' && value.toUpperCase() !== 'FALSE';
}

export function isTTY(): boolean {
  // If we force TTY, we always return true.
  const force = process.env['NG_FORCE_TTY'];
  if (force !== undefined) {
    return _isTruthy(force);
  }

  return !!process.stdout.isTTY && !_isTruthy(process.env['CI']);
}