// Converse.js (A browser based XMPP chat client)
// https://conversejs.org
//
// This is the internationalization module.
//
// Copyright (c) 2013-2017, Jan-Carel Brand <jc@opkode.com>
// Licensed under the Mozilla Public License (MPLv2)
//
/*global define */

import 'dayjs/locale/af';
import 'dayjs/locale/ar';
import 'dayjs/locale/bg';
import 'dayjs/locale/ca';
import 'dayjs/locale/cs';
import 'dayjs/locale/de';
import 'dayjs/locale/eo';
import 'dayjs/locale/es';
import 'dayjs/locale/eu';
import 'dayjs/locale/fr';
import 'dayjs/locale/gl';
import 'dayjs/locale/he';
import 'dayjs/locale/hi';
import 'dayjs/locale/hu';
import 'dayjs/locale/id';
import 'dayjs/locale/it';
import 'dayjs/locale/ja';
import 'dayjs/locale/nb';
import 'dayjs/locale/nl';
import 'dayjs/locale/pl';
import 'dayjs/locale/pt-br';
import 'dayjs/locale/ro';
import 'dayjs/locale/ru';
import 'dayjs/locale/tr';
import 'dayjs/locale/uk';
import 'dayjs/locale/zh-cn';
import 'dayjs/locale/zh-tw';
import Jed from "jed";
import Promise from "es6-promise/dist/es6-promise.auto";
import _ from "./lodash.noconflict";
import dayjs from "dayjs";


function detectLocale (library_check) {
    /* Determine which locale is supported by the user's system as well
     * as by the relevant library (e.g. converse.js or dayjs).
     * @param { Function } library_check - Returns a boolean indicating whether
     *   the locale is supported.
     */
    var locale, i;
    if (window.navigator.userLanguage) {
        locale = isLocaleAvailable(window.navigator.userLanguage, library_check);
    }
    if (window.navigator.languages && !locale) {
        for (i=0; i<window.navigator.languages.length && !locale; i++) {
            locale = isLocaleAvailable(window.navigator.languages[i], library_check);
        }
    }
    if (window.navigator.browserLanguage && !locale) {
        locale = isLocaleAvailable(window.navigator.browserLanguage, library_check);
    }
    if (window.navigator.language && !locale) {
        locale = isLocaleAvailable(window.navigator.language, library_check);
    }
    if (window.navigator.systemLanguage && !locale) {
        locale = isLocaleAvailable(window.navigator.systemLanguage, library_check);
    }
    return locale || 'en';
}

function isConverseLocale (locale, supported_locales) {
    return _.isString(locale) && _.includes(supported_locales, locale);
}

function getLocale (preferred_locale, isSupportedByLibrary) {
    if (_.isString(preferred_locale)) {
        if (preferred_locale === 'en' || isSupportedByLibrary(preferred_locale)) {
            return preferred_locale;
        }
    }
    return detectLocale(isSupportedByLibrary) || 'en';
}

/* Check whether the locale or sub locale (e.g. en-US, en) is supported.
 * @param { String } locale - The locale to check for
 * @param { Function } available - Returns a boolean indicating whether the locale is supported
 */
function isLocaleAvailable (locale, available) {
    if (available(locale)) {
        return locale;
    } else {
        var sublocale = locale.split("-")[0];
        if (sublocale !== locale && available(sublocale)) {
            return sublocale;
        }
    }
}

let jed_instance;

/**
 * @namespace i18n
 */
export default {

    setLocales (preferred_locale, _converse) {
        _converse.locale = getLocale(
            preferred_locale,
            _.partial(isConverseLocale, _, _converse.locales)
        );
        dayjs.locale(getLocale(preferred_locale, l => dayjs.locale(l)));
    },

    translate (str) {
        if (_.isNil(jed_instance)) {
            return Jed.sprintf.apply(Jed, arguments);
        }
        const t = jed_instance.translate(str);
        if (arguments.length > 1) {
            return t.fetch.apply(t, [].slice.call(arguments, 1));
        } else {
            return t.fetch();
        }
    },

    /**
     * Fetch the translations for the given local at the given URL.
     * @private
     * @method i18n#fetchTranslations
     * @param { String } locale -The given i18n locale
     * @param { Array } supported_locales -  List of locales supported
     * @param { String } locale_url - The URL from which the translations should be fetched
     */
    fetchTranslations (locale, supported_locales, locale_url) {
        return new Promise((resolve, reject) => {
            if (!isConverseLocale(locale, supported_locales) || locale === 'en') {
                return resolve();
            }
            const xhr = new XMLHttpRequest();
            xhr.open('GET', locale_url, true);
            xhr.setRequestHeader(
                'Accept',
                "application/json, text/javascript"
            );
            xhr.onload = function () {
                if (xhr.status >= 200 && xhr.status < 400) {
                    try {
                        const data = window.JSON.parse(xhr.responseText);
                        jed_instance = new Jed(data);
                        resolve();
                    } catch (e) {
                        xhr.onerror(e);
                    }
                } else {
                    xhr.onerror();
                }
            };
            xhr.onerror = (e) => {
                const err_message = e ? ` Error: ${e.message}` : '';
                reject(new Error(`Could not fetch translations. Status: ${xhr.statusText}. ${err_message}`));
            }
            xhr.send();
        });
    }
};