/**
   * `rawlist` type prompt
   */
  
  var _ = require("lodash");
  var util = require("util");
  var chalk = require("chalk");
  var Base = require("./base");
  var Separator = require("../objects/separator");
  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.validateChoices( this.opt.choices );
  
    // Add the default `help` (/expand) option
    this.opt.choices.push({
      key   : "h",
      name  : "Help, list all options",
      value : "help"
    });
  
    // Setup the default string (capitalize the default key)
    this.opt.default = this.generateChoicesString( this.opt.choices, this.opt.default );
  
    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;
  
    // Save user answer and update prompt to show selected option.
    var events = observe(this.rl);
    this.lineObs = events.line.forEach( this.onSubmit.bind(this) );
    this.keypressObs = events.keypress.forEach( this.onKeypress.bind(this) );
  
    // Init the prompt
    this.render();
  
    return this;
  };
  
  
  /**
   * Render the prompt to screen
   * @return {Prompt} self
   */
  
  Prompt.prototype.render = function (error, hint) {
    var message = this.getQuestion();
    var bottomContent = '';
  
    if ( this.status === "answered" ) {
      message += chalk.cyan( this.selected.short || this.selected.name );
    } else if ( this.status === "expanded" ) {
      var choicesStr = renderChoices(this.opt.choices, this.selectedKey);
      message += this.paginator.paginate(choicesStr, this.selectedKey, this.opt.pageSize);
      message += "
    Answer: ";
    }
  
    message += this.rl.line;
  
    if (error) {
      bottomContent = chalk.red('>> ') + error;
    }
  
    if (hint) {
      bottomContent = chalk.cyan('>> ') + hint;
    }
  
    this.screen.render(message, bottomContent);
  };
  
  
  /**
   * Generate the prompt choices string
   * @return {String}  Choices string
   */
  
  Prompt.prototype.getChoices = function() {
    var output = "";
  
    this.opt.choices.forEach(function( choice, i ) {
      output += "
    ";
  
      if ( choice.type === "separator" ) {
        output += " " + choice;
        return;
      }
  
      var choiceStr = choice.key + ") " + choice.name;
      if ( this.selectedKey === choice.key ) {
        choiceStr = chalk.cyan( choiceStr );
      }
      output += choiceStr;
    }.bind(this));
  
    return output;
  };
  
  
  /**
   * When user press `enter` key
   */
  
  Prompt.prototype.onSubmit = function( input ) {
    if ( input == null || input === "" ) {
      input = this.rawDefault;
    }
  
    var selected = this.opt.choices.where({ key : input.toLowerCase().trim() })[0];
  
    if ( selected != null && selected.key === "h" ) {
      this.selectedKey = "";
      this.status = "expanded";
      this.render();
      return;
    }
  
    if ( selected != null ) {
      this.status = "answered";
      this.selected = selected;
  
      // Re-render prompt
      this.render();
  
      this.lineObs.dispose();
      this.keypressObs.dispose();
      this.screen.done();
      this.done( this.selected.value );
      return;
    }
  
    // Input is invalid
    this.render("Please enter a valid command");
  };
  
  
  /**
   * When user press a key
   */
  
  Prompt.prototype.onKeypress = function( s, key ) {
    this.selectedKey = this.rl.line.toLowerCase();
    var selected = this.opt.choices.where({ key : this.selectedKey })[0];
    if ( this.status === "expanded" )  {
      this.render();
    } else {
      this.render(null, selected ? selected.name : null);
    }
  };
  
  
  /**
   * Validate the choices
   * @param {Array} choices
   */
  
  Prompt.prototype.validateChoices = function( choices ) {
    var formatError;
    var errors = [];
    var keymap = {};
    choices.filter(Separator.exclude).map(function( choice ) {
      if ( !choice.key || choice.key.length !== 1 ) {
        formatError = true;
      }
      if ( keymap[choice.key] ) {
        errors.push(choice.key);
      }
      keymap[ choice.key ] = true;
      choice.key = String( choice.key ).toLowerCase();
    });
  
    if ( formatError ) {
      throw new Error("Format error: `key` param must be a single letter and is required.");
    }
    if ( keymap.h ) {
      throw new Error("Reserved key error: `key` param cannot be `h` - this value is reserved.");
    }
    if ( errors.length ) {
      throw new Error( "Duplicate key error: `key` param must be unique. Duplicates: " +
          _.uniq(errors).join(", ") );
    }
  };
  
  /**
   * Generate a string out of the choices keys
   * @param  {Array}  choices
   * @param  {Number} defaultIndex - the choice index to capitalize
   * @return {String} The rendered choices key string
   */
  Prompt.prototype.generateChoicesString = function( choices, defaultIndex ) {
    var defIndex = 0;
    if ( _.isNumber(defaultIndex) && this.opt.choices.getChoice(defaultIndex) ) {
      defIndex = defaultIndex;
    }
    var defStr = this.opt.choices.pluck("key");
    this.rawDefault = defStr[ defIndex ];
    defStr[ defIndex ] = String( defStr[defIndex] ).toUpperCase();
    return defStr.join("");
  };
  
  
  /**
   * Function for rendering checkbox choices
   * @param  {String} pointer Selected key
   * @return {String}         Rendered content
   */
  
  function renderChoices (choices, pointer) {
    var output = '';
  
    choices.forEach(function (choice, i) {
      output += '
    ';
  
      if (choice.type === 'separator') {
        output += ' ' + choice;
        return;
      }
  
      var choiceStr = choice.key + ') ' + choice.name;
      if (pointer === choice.key) {
        choiceStr = chalk.cyan(choiceStr);
      }
      output += choiceStr;
    });
  
    return output;
  }