// Converse.js (A browser based XMPP chat client)
// http://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 */

(function (root, factory) {
    define([
        "es6-promise/dist/es6-promise.auto",
        "jed",
        "./lodash.noconflict",
        "moment",
        'moment/locale/af',
        'moment/locale/ar',
        'moment/locale/bg',
        'moment/locale/ca',
        'moment/locale/cs',
        'moment/locale/de',
        'moment/locale/es',
        'moment/locale/eu',
        'moment/locale/fr',
        'moment/locale/he',
        'moment/locale/hi',
        'moment/locale/hu',
        'moment/locale/id',
        'moment/locale/it',
        'moment/locale/ja',
        'moment/locale/nb',
        'moment/locale/nl',
        'moment/locale/pl',
        'moment/locale/pt-br',
        'moment/locale/ro',
        'moment/locale/ru',
        'moment/locale/tr',
        'moment/locale/uk',
        'moment/locale/zh-cn',
        'moment/locale/zh-tw'
    ], factory);
}(this, function (Promise, Jed, _, moment) {
    'use strict';

    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 moment.js).
         *
         * Parameters:
         *      (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 isMomentLocale (locale) {
        return _.includes(moment.locales(), locale);
    }

    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';
    }

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

    let jed_instance;

    return {

        setLocales (preferred_locale, _converse) {
            _converse.locale = getLocale(
                preferred_locale,
                _.partial(isConverseLocale, _, _converse.locales)
            );
            moment.locale(getLocale(preferred_locale, isMomentLocale));
        },

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

        fetchTranslations (locale, supported_locales, locale_url) {
            /* Fetch the translations for the given local at the given URL.
             *
             * Parameters:
             *  (String) locale:            The given i18n locale
             *  (Array) supported_locales:  List of locales supported
             *  (String) locale_url:        The URL from which the translations
             *                              should be fetched.
             */
            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();
            });
        }
    };
}));