node_modules/inquirer/lib/ui/bottom-bar.js

/**
 * Sticky bottom bar user interface
 */

var util = require('util');
var through = require('through');
var Base = require('./baseUI');
var rlUtils = require('../utils/readline');
var _ = require('lodash');

/**
 * Module exports
 */

module.exports = Prompt;

/**
 * Constructor
 */

function Prompt(opt) {
  opt || (opt = {});

  Base.apply(this, arguments);

  this.log = through(this.writeLog.bind(this));
  this.bottomBar = opt.bottomBar || '';
  this.render();
}
util.inherits(Prompt, Base);

/**
 * Render the prompt to screen
 * @return {Prompt} self
 */

Prompt.prototype.render = function () {
  this.write(this.bottomBar);
  return this;
};

Prompt.prototype.clean = function () {
  rlUtils.clearLine(this.rl, this.bottomBar.split('\n').length);
  return this;
};

/**
 * Update the bottom bar content and rerender
 * @param  {String} bottomBar Bottom bar content
 * @return {Prompt}           self
 */

Prompt.prototype.updateBottomBar = function (bottomBar) {
  rlUtils.clearLine(this.rl, 1);
  this.rl.output.unmute();
  this.clean();
  this.bottomBar = bottomBar;
  this.render();
  this.rl.output.mute();
  return this;
};

/**
 * Write out log data
 * @param {String} data - The log data to be output
 * @return {Prompt} self
 */

Prompt.prototype.writeLog = function (data) {
  this.rl.output.unmute();
  this.clean();
  this.rl.output.write(this.enforceLF(data.toString()));
  this.render();
  this.rl.output.mute();
  return this;
};

/**
 * Make sure line end on a line feed
 * @param  {String} str Input string
 * @return {String}     The input string with a final line feed
 */

Prompt.prototype.enforceLF = function (str) {
  return str.match(/[\r\n]$/) ? str : str + '\n';
};

/**
 * Helper for writing message in Prompt
 * @param {Prompt} prompt  - The Prompt object that extends tty
 * @param {String} message - The message to be output
 */
Prompt.prototype.write = function (message) {
  var msgLines = message.split(/\n/);
  this.height = msgLines.length;

  // Write message to screen and setPrompt to control backspace
  this.rl.setPrompt(_.last(msgLines));

  if (this.rl.output.rows === 0 && this.rl.output.columns === 0) {
    /* When it's a tty through serial port there's no terminal info and the render will malfunction,
       so we need enforce the cursor to locate to the leftmost position for rendering. */
    rlUtils.left(this.rl, message.length + this.rl.line.length);
  }
  this.rl.output.write(message);
};