/**
   * `list` type prompt
   */
  
  var _ = require("lodash");
  var util = require("util");
  var chalk = require("chalk");
  var figures = require("figures");
  var cliCursor = require("cli-cursor");
  var Base = require("./base");
  var observe = require("../utils/events");
  var Paginator = require("../utils/paginator");
  
  
  /**
   * Module exports
   */
  
  module.exports = Prompt;
  
  
  /**
   * Constructor
   */
  
  function Prompt() {
    Base.apply( this, arguments );
  
    if (!this.opt.choices) {
      this.throwParamError("choices");
    }
  
    this.firstRender = true;
    this.selected = 0;
  
    var def = this.opt.default;
  
    // Default being a Number
    if ( _.isNumber(def) && def >= 0 && def < this.opt.choices.realLength ) {
      this.selected = def;
    }
  
    // Default being a String
    if ( _.isString(def) ) {
      this.selected = this.opt.choices.pluck("value").indexOf( def );
    }
  
    // Make sure no default is set (so it won't be printed)
    this.opt.default = null;
  
    this.paginator = new Paginator();
  }
  util.inherits( Prompt, Base );
  
  
  /**
   * Start the Inquiry session
   * @param  {Function} cb      Callback when prompt is done
   * @return {this}
   */
  
  Prompt.prototype._run = function( cb ) {
    this.done = cb;
  
    var events = observe(this.rl);
    events.normalizedUpKey.takeUntil( events.line ).forEach( this.onUpKey.bind(this) );
    events.normalizedDownKey.takeUntil( events.line ).forEach( this.onDownKey.bind(this) );
    events.numberKey.takeUntil( events.line ).forEach( this.onNumberKey.bind(this) );
    events.line.take(1).forEach( this.onSubmit.bind(this) );
  
    // Init the prompt
    cliCursor.hide();
    this.render();
  
    return this;
  };
  
  
  /**
   * Render the prompt to screen
   * @return {Prompt} self
   */
  
  Prompt.prototype.render = function() {
    // Render question
    var message = this.getQuestion();
  
    if ( this.firstRender ) {
      message += chalk.dim( "(Use arrow keys)" );
    }
  
    // Render choices or answer depending on the state
    if ( this.status === "answered" ) {
      message += chalk.cyan( this.opt.choices.getChoice(this.selected).short );
    } else {
      var choicesStr = listRender(this.opt.choices, this.selected );
      var indexPosition = this.opt.choices.indexOf(this.opt.choices.getChoice(this.selected));
      message += "
  " + this.paginator.paginate(choicesStr, indexPosition, this.opt.pageSize);
    }
  
    this.firstRender = false;
  
    this.screen.render(message);
  };
  
  
  /**
   * When user press `enter` key
   */
  
  Prompt.prototype.onSubmit = function() {
    var choice = this.opt.choices.getChoice( this.selected );
    this.status = "answered";
  
    // Rerender prompt
    this.render();
  
    this.screen.done();
    cliCursor.show();
    this.done( choice.value );
  };
  
  
  /**
   * When user press a key
   */
  Prompt.prototype.onUpKey = function() {
    var len = this.opt.choices.realLength;
    this.selected = (this.selected > 0) ? this.selected - 1 : len - 1;
    this.render();
  };
  
  Prompt.prototype.onDownKey = function() {
    var len = this.opt.choices.realLength;
    this.selected = (this.selected < len - 1) ? this.selected + 1 : 0;
    this.render();
  };
  
  Prompt.prototype.onNumberKey = function( input ) {
    if ( input <= this.opt.choices.realLength ) {
      this.selected = input - 1;
    }
    this.render();
  };
  
  
  /**
   * Function for rendering list choices
   * @param  {Number} pointer Position of the pointer
   * @return {String}         Rendered content
   */
   function listRender(choices, pointer) {
    var output = '';
    var separatorOffset = 0;
  
    choices.forEach(function (choice, i) {
      if (choice.type === 'separator') {
        separatorOffset++;
        output += '  ' + choice + '
  ';
        return;
      }
  
      var isSelected = (i - separatorOffset === pointer);
      var line = (isSelected ? figures.pointer + ' ' : '  ') + choice.name;
      if (isSelected) {
        line = chalk.cyan(line);
      }
      output += line + ' 
  ';
    });
  
    return output.replace(/
  $/, '');
  }