import React, { createContext, useContext } from 'react';
import usePersistedState from './common/usePersistedState';

import en from '../../web/l10n/en.json';
import es from '../../web/l10n/es.json';

const languages = {
  en: { data: en, name: 'English' },
  es: { data: es, name: 'Español' },
};

const getDefaultLanguage = () => {
  const browserLanguages = window.navigator.languages ? window.navigator.languages.slice() : [];
  const browserLanguage = window.navigator.userLanguage || window.navigator.language;
  browserLanguages.push(browserLanguage);
  browserLanguages.push(browserLanguage.substring(0, 2));

  for (let i = 0; i < browserLanguages.length; i += 1) {
    let language = browserLanguages[i].replace('-', '');
    if (language in languages) {
      return language;
    }
    if (language.length > 2) {
      language = language.substring(0, 2);
      if (language in languages) {
        return language;
      }
    }
  }
  return 'es';
};

const LocalizationContext = createContext({
  languages,
  language: 'es',
  setLanguage: () => {},
});

export const LocalizationProvider = ({ children }) => {
  const [language, setLanguage] = usePersistedState('language', getDefaultLanguage());

  return (
    <LocalizationContext.Provider value={{ languages, language, setLanguage }}>
      {children}
    </LocalizationContext.Provider>
  );
};

export const useLocalization = () => useContext(LocalizationContext);


export const useTranslation = () => {
  const context = useContext(LocalizationContext);
  const { data } = context.languages[context.language];
  return (key, args = {}) => {
    if (Object.keys(args).length) {
      let str = data[key];
      Object.keys(args).forEach(k => {
        str = str.replace(new RegExp(`\\{${k}\\}`, 'gi'), args[k].toString());
      });
      return str;
    } else {
      return data[key];
    }
  }
};

export const useTranslationKeys = (predicate) => {
  const context = useContext(LocalizationContext);
  const { data } = context.languages[context.language];
  return Object.keys(data).filter(predicate);
};