/**
 * You can customize the initial state of the module from the editor initialization, by passing the following [Configuration Object](https://github.com/GrapesJS/grapesjs/blob/master/src/i18n/config.ts)
 * ```js
 * const editor = grapesjs.init({
 *  i18n: {
 *    locale: 'en',
 *    localeFallback: 'en',
 *    messages: {
 *      it: { hello: 'Ciao', ... },
 *      ...
 *    }
 *  }
 * })
 * ```
 *
 * Once the editor is instantiated you can use its API. Before using these methods you should get the module from the instance
 *
 * ```js
 * const i18n = editor.I18n;
 * ```
 *
 * ### Events
 * * `i18n:add` - New set of messages is added
 * * `i18n:update` - The set of messages is updated
 * * `i18n:locale` - Locale changed
 *
 * @module I18n
 */
import { isUndefined, isString } from 'underscore';
import { Module } from '../abstract';
import EditorModel from '../editor/model/Editor';
import { hasWin, deepMerge } from '../utils/mixins';
import defaults, { I18nConfig } from './config';

type Messages = Required<I18nConfig>['messages'];

export default class I18nModule extends Module<I18nConfig & { stylePrefix?: string }> {
  /**
   * Initialize module
   * @param {Object} config Configurations
   * @private
   */
  constructor(em: EditorModel) {
    super(em, 'I18n', defaults);
    const add = this.config.messagesAdd;
    add && this.addMessages(add);

    if (this.config.detectLocale) {
      this.config.locale = this._localLang();
    }
  }

  /**
   * Get configuration object
   * @name getConfig
   * @function
   * @return {Object}
   */

  /**
   * Update current locale
   * @param {String} locale Locale value
   * @returns {this}
   * @example
   * i18n.setLocale('it');
   */
  setLocale(locale: string) {
    const { em, config } = this;
    const evObj = { value: locale, valuePrev: config.locale };
    em && em.trigger('i18n:locale', evObj);
    config.locale = locale;
    return this;
  }

  /**
   * Get current locale
   * @returns {String} Current locale value
   */
  getLocale() {
    return this.config.locale;
  }

  /**
   * Get all messages
   * @param {String} [lang] Specify the language of messages to return
   * @param {Object} [opts] Options
   * @param {Boolean} [opts.debug] Show warnings in case of missing language
   * @returns {Object}
   * @example
   * i18n.getMessages();
   * // -> { en: { hello: '...' }, ... }
   * i18n.getMessages('en');
   * // -> { hello: '...' }
   */
  getMessages(lang: string, opts = {}) {
    const messages = this.config.messages!;
    lang && !messages[lang] && this._debug(`'${lang}' i18n lang not found`, opts);
    return lang ? messages[lang] : messages;
  }

  /**
   * Set new set of messages
   * @param {Object} msg Set of messages
   * @returns {this}
   * @example
   * i18n.getMessages();
   * // -> { en: { msg1: 'Msg 1', msg2: 'Msg 2', } }
   * i18n.setMessages({ en: { msg2: 'Msg 2 up', msg3: 'Msg 3', } });
   * // Set replaced
   * i18n.getMessages();
   * // -> { en: { msg2: 'Msg 2 up', msg3: 'Msg 3', } }
   */
  setMessages(msg: Messages) {
    const { em, config } = this;
    config.messages = msg;
    em && em.trigger('i18n:update', msg);
    return this;
  }

  /**
   * Update messages
   * @param {Object} msg Set of messages to add
   * @returns {this}
   * @example
   * i18n.getMessages();
   * // -> { en: { msg1: 'Msg 1', msg2: 'Msg 2', } }
   * i18n.addMessages({ en: { msg2: 'Msg 2 up', msg3: 'Msg 3', } });
   * // Set updated
   * i18n.getMessages();
   * // -> { en: { msg1: 'Msg 1', msg2: 'Msg 2 up', msg3: 'Msg 3', } }
   */
  addMessages(msg: Messages) {
    const { em } = this;
    const { messages } = this.config;
    em && em.trigger('i18n:add', msg);
    this.setMessages(deepMerge(messages!, msg));

    return this;
  }

  /**
   * Translate the locale message
   * @param {String} key Label to translate
   * @param {Object} [opts] Options for the translation
   * @param {Object} [opts.params] Params for the translation
   * @param {Boolean} [opts.debug] Show warnings in case of missing resources
   * @returns {String}
   * @example
   * obj.setMessages({
   *  en: { msg: 'Msg', msg2: 'Msg {test}'},
   *  it: { msg2: 'Msg {test} it'},
   * });
   * obj.t('msg');
   * // -> outputs `Msg`
   * obj.t('msg2', { params: { test: 'hello' } });  // use params
   * // -> outputs `Msg hello`
   * obj.t('msg2', { l: 'it', params: { test: 'hello' } });  // custom local
   * // -> outputs `Msg hello it`
   */
  t(key: string, opts: Record<string, any> = {}) {
    const { config } = this;
    const param = opts.params || {};
    const locale = opts.l || this.getLocale();
    const localeFlb = opts.lFlb || config.localeFallback;
    let result = this._getMsg(key, locale, opts);

    // Try with fallback
    if (!result) result = this._getMsg(key, localeFlb, opts);

    !result && this._debug(`'${key}' i18n key not found in '${locale}' lang`, opts);
    result = result && isString(result) ? this._addParams(result, param) : result;

    return result;
  }

  _localLang() {
    const nav = (hasWin() && window.navigator) || {};
    // @ts-ignore
    const lang = nav.language || nav.userLanguage;
    return lang ? lang.split('-')[0] : 'en';
  }

  _addParams(str: string, params: Record<string, any>) {
    const reg = new RegExp('{([\\w\\d-]*)}', 'g');
    return str.replace(reg, (m, val) => params[val] || '').trim();
  }

  _getMsg(key: string, locale: string, opts = {}) {
    const msgSet = this.getMessages(locale, opts);

    // Lang set is missing
    if (!msgSet) return;

    let result = msgSet[key];

    // Check for nested getter
    if (!result && key.indexOf('.') > 0) {
      result = key.split('.').reduce((lang, key) => {
        if (isUndefined(lang)) return;
        return lang[key];
      }, msgSet);
    }

    return result;
  }

  _debug(str: string, opts: { debug?: boolean } = {}) {
    const { em, config } = this;
    (opts.debug || config.debug) && em && em.logWarning(str);
  }

  destroy() {}
}