"use strict";

const fs = require("fs");
const path = require("path");

// node.js needs Intl.PluralRules polyfill
require("intl-pluralrules");

const { FluentBundle } = require("fluent");

const AppConstants = require("./app-constants");
const mozlog = require("./log");


const log = mozlog("locale-utils");

const localesDir = "locales";

const availableLanguages = [];
const fluentBundles = {};


class FluentError extends Error {
  constructor(fluentID = null, ...params) {
    super(...params);

    if (Error.captureStackTrace) {
      Error.captureStackTrace(this, FluentError);
    }

    this.fluentID = fluentID;
    this.message = fluentID;
  }
}


const LocaleUtils = {
  init() {
    const supportedLocales = AppConstants.SUPPORTED_LOCALES;
    let languageDirectories = supportedLocales.split(",");
    if (supportedLocales === "*") {
      languageDirectories = fs.readdirSync( localesDir ).filter(item => {
        return (!item.startsWith(".") && fs.lstatSync(path.join(localesDir, item)).isDirectory());
      });
    }
    for (const lang of languageDirectories) {
      try {
        const langBundle = new FluentBundle(lang, {useIsolating: false});
        const ftlFiles = fs.readdirSync(path.join(localesDir, lang)).filter(item => {
          return (item.endsWith(".ftl"));
        });
        for (const file of ftlFiles) {
          const langFTLSource = fs.readFileSync(path.join(localesDir, lang, file), "utf8");
          langBundle.addMessages(langFTLSource);
        }
        fluentBundles[lang] = langBundle;
        availableLanguages.push(lang);
      } catch (e) {
        log.error("loadFluentBundle", {stack: e.stack});
      }
    }
    log.info("LocaleUtils.init", {availableLanguages});
    log.info("LocaleUtils.init", {fluentBundles});
    return {availableLanguages, fluentBundles};
  },

  loadLanguagesIntoApp (app) {
    app.locals.AVAILABLE_LANGUAGES = availableLanguages;
    app.locals.FLUENT_BUNDLES = fluentBundles;
  },

  fluentFormat (supportedLocales, id, args=null, errors=null) {
    for (const locale of supportedLocales) {
      const bundle = fluentBundles[locale];
      if (bundle.hasMessage(id)) {
        const message = bundle.getMessage(id);
        return bundle.format(message, args);
      }
    }
    return id;
  },
};

module.exports = {
  FluentError,
  LocaleUtils,
};