'use strict';
/**
 * Base prompt implementation
 * Should be extended by prompt types.
 */

var _ = require('lodash');
var chalk = require('chalk');
var runAsync = require('run-async');
var Choices = require('../objects/choices');
var ScreenManager = require('../utils/screen-manager');

class Prompt {
  constructor(question, rl, answers) {
    // Setup instance defaults property
    _.assign(this, {
      answers: answers,
      status: 'pending'
    });

    // Set defaults prompt options
    this.opt = _.defaults(_.clone(question), {
      validate: () => true,
      filter: val => val,
      when: () => true,
      suffix: '',
      prefix: chalk.green('?')
    });

    // Check to make sure prompt requirements are there
    if (!this.opt.message) {
      this.throwParamError('message');
    }
    if (!this.opt.name) {
      this.throwParamError('name');
    }

    // Normalize choices
    if (Array.isArray(this.opt.choices)) {
      this.opt.choices = new Choices(this.opt.choices, answers);
    }

    this.rl = rl;
    this.screen = new ScreenManager(this.rl);
  }

  /**
   * Start the Inquiry session and manage output value filtering
   * @return {Promise}
   */

  run() {
    return new Promise(resolve => {
      this._run(value => resolve(value));
    });
  }

  // Default noop (this one should be overwritten in prompts)
  _run(cb) {
    cb();
  }

  /**
   * Throw an error telling a required parameter is missing
   * @param  {String} name Name of the missing param
   * @return {Throw Error}
   */

  throwParamError(name) {
    throw new Error('You must provide a `' + name + '` parameter');
  }

  /**
   * Called when the UI closes. Override to do any specific cleanup necessary
   */
  close() {
    this.screen.releaseCursor();
  }

  /**
   * Run the provided validation method each time a submit event occur.
   * @param  {Rx.Observable} submit - submit event flow
   * @return {Object}        Object containing two observables: `success` and `error`
   */
  handleSubmitEvents(submit) {
    var self = this;
    var validate = runAsync(this.opt.validate);
    var filter = runAsync(this.opt.filter);
    var validation = submit
      .flatMap(value =>
        filter(value, self.answers).then(
          filteredValue =>
            validate(filteredValue, self.answers).then(
              isValid => ({ isValid: isValid, value: filteredValue }),
              err => ({ isValid: err })
            ),
          err => ({ isValid: err })
        )
      )
      .share();

    var success = validation.filter(state => state.isValid === true).take(1);
    var error = validation.filter(state => state.isValid !== true).takeUntil(success);

    return {
      success: success,
      error: error
    };
  }

  /**
   * Generate the prompt question string
   * @return {String} prompt question string
   */

  getQuestion() {
    var message =
      this.opt.prefix +
      ' ' +
      chalk.bold(this.opt.message) +
      this.opt.suffix +
      chalk.reset(' ');

    // Append the default if available, and if question isn't answered
    if (this.opt.default != null && this.status !== 'answered') {
      message += chalk.dim('(' + this.opt.default + ') ');
    }

    return message;
  }
}

module.exports = Prompt;
