/*
 This file is part of GNU Taler
 (C) 2022 Taler Systems S.A.

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

import { i18n, setupI18n } from "@gnu-taler/taler-util";
import { ComponentChildren, createContext, h, VNode } from "preact";
import { useContext, useEffect } from "preact/hooks";
import { useLang } from "../hooks/index.js";
import { Locale } from "date-fns";
import {
  es as esLocale,
  enGB as enLocale,
  fr as frLocale,
  de as deLocale
} from "date-fns/locale"

export type InternationalizationAPI = typeof i18n;

interface Type {
  lang: string;
  supportedLang: { [id in keyof typeof supportedLang]: string };
  changeLanguage: (l: string) => void;
  i18n: InternationalizationAPI;
  dateLocale: Locale,
  completness: { [id in keyof typeof supportedLang]: number }
}

const supportedLang = {
  es: "Espanol [es]",
  en: "English [en]",
  fr: "Francais [fr]",
  de: "Deutsch [de]",
  sv: "Svenska [sv]",
  it: "Italiane [it]",
};

const initial: Type = {
  lang: "en",
  supportedLang,
  changeLanguage: () => {
    // do not change anything
  },
  i18n,
  dateLocale: enLocale,
  completness: {
    de: 0,
    en: 0,
    es: 0,
    fr: 0,
    it: 0,
    sv: 0,
  }
};
const Context = createContext<Type>(initial);

interface Props {
  initial?: string;
  children: ComponentChildren;
  forceLang?: string;
  source: Record<string, any>;
  completness?: Record<string, number>;
}

// Outmost UI wrapper.
export const TranslationProvider = ({
  initial,
  children,
  forceLang,
  source,
  completness: completnessProp
}: Props): VNode => {
  const completness = {
    de: !completnessProp || !completnessProp["de"] ? 0 : completnessProp["de"],
    en: !completnessProp || !completnessProp["en"] ? 0 : completnessProp["en"],
    es: !completnessProp || !completnessProp["es"] ? 0 : completnessProp["es"],
    fr: !completnessProp || !completnessProp["fr"] ? 0 : completnessProp["fr"],
    it: !completnessProp || !completnessProp["it"] ? 0 : completnessProp["it"],
    sv: !completnessProp || !completnessProp["sv"] ? 0 : completnessProp["sv"],
  }
  const { value: lang, update: changeLanguage } = useLang(initial, completness);

  useEffect(() => {
    if (forceLang) {
      changeLanguage(forceLang);
    }
  });
  useEffect(() => {
    setupI18n(lang, source);
  }, [lang]);
  if (forceLang) {
    setupI18n(forceLang, source);
  } else {
    setupI18n(lang, source);
  }

  const dateLocale = lang === "es" ? esLocale :
    lang === "fr" ? frLocale :
      lang === "de" ? deLocale :
        enLocale;

  return h(Context.Provider, {
    value: { lang, changeLanguage, supportedLang, i18n, dateLocale, completness },
    children,
  });
};

export const useTranslationContext = (): Type => useContext(Context);