'use strict';
var _ = require('lodash');
var MuteStream = require('mute-stream');
var readline = require('readline');

/**
 * Base interface class other can inherits from
 */

var UI = module.exports = function (opt) {
  // Instantiate the Readline interface
  // @Note: Don't reassign if already present (allow test to override the Stream)
  if (!this.rl) {
    this.rl = readline.createInterface(setupReadlineOptions(opt));
  }
  this.rl.resume();

  this.onForceClose = this.onForceClose.bind(this);

  // Make sure new prompt start on a newline when closing
  process.on('exit', this.onForceClose);

  // Terminate process on SIGINT (which will call process.on('exit') in return)
  this.rl.on('SIGINT', this.onForceClose);
};

/**
 * Handle the ^C exit
 * @return {null}
 */

UI.prototype.onForceClose = function () {
  this.close();
  process.kill(process.pid, 'SIGINT');
  console.log('');
};

/**
 * Close the interface and cleanup listeners
 */

UI.prototype.close = function () {
  // Remove events listeners
  this.rl.removeListener('SIGINT', this.onForceClose);
  process.removeListener('exit', this.onForceClose);

  this.rl.output.unmute();

  if (this.activePrompt && typeof this.activePrompt.close === 'function') {
    this.activePrompt.close();
  }

  // Close the readline
  this.rl.output.end();
  this.rl.pause();
  this.rl.close();
};

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

  // Default `input` to stdin
  var input = opt.input || process.stdin;

  // Add mute capabilities to the output
  var ms = new MuteStream();
  ms.pipe(opt.output || process.stdout);
  var output = ms;

  return _.extend({
    terminal: true,
    input: input,
    output: output
  }, _.omit(opt, ['input', 'output']));
}