/**
 * Internationalization: language detection and translations for webapp.
 */

import { getInitData } from "./auth.js";

/** @type {Record<string, Record<string, string>>} */
export const MESSAGES = {
  en: {
    "app.title": "Duty Calendar",
    loading: "Loading…",
    access_denied: "Access denied.",
    error_load_failed: "Load failed",
    error_network: "Could not load data. Check your connection.",
    error_generic: "Could not load data.",
    "nav.prev_month": "Previous month",
    "nav.next_month": "Next month",
    "weekdays.mon": "Mon",
    "weekdays.tue": "Tue",
    "weekdays.wed": "Wed",
    "weekdays.thu": "Thu",
    "weekdays.fri": "Fri",
    "weekdays.sat": "Sat",
    "weekdays.sun": "Sun",
    "month.jan": "January",
    "month.feb": "February",
    "month.mar": "March",
    "month.apr": "April",
    "month.may": "May",
    "month.jun": "June",
    "month.jul": "July",
    "month.aug": "August",
    "month.sep": "September",
    "month.oct": "October",
    "month.nov": "November",
    "month.dec": "December",
    "aria.duty": "On duty",
    "aria.unavailable": "Unavailable",
    "aria.vacation": "Vacation",
    "aria.day_info": "Day info",
    "event_type.duty": "Duty",
    "event_type.unavailable": "Unavailable",
    "event_type.vacation": "Vacation",
    "duty.now_on_duty": "On duty now",
    "duty.none_this_month": "No duties this month.",
    "duty.today": "Today",
    "duty.until": "until {time}",
    "hint.from": "from",
    "hint.to": "until",
    "hint.duty_title": "Duty:",
    "hint.events": "Events:",
    "day_detail.close": "Close",
    "contact.label": "Contact",
    "contact.show": "Contacts",
    "contact.back": "Back",
    "contact.phone": "Phone",
    "contact.telegram": "Telegram",
    "current_duty.title": "Current Duty",
    "current_duty.no_duty": "No one is on duty right now",
    "current_duty.shift": "Shift",
    "current_duty.remaining": "Remaining: {hours}h {minutes}min",
    "current_duty.back": "Back to calendar"
  },
  ru: {
    "app.title": "Календарь дежурств",
    loading: "Загрузка…",
    access_denied: "Доступ запрещён.",
    error_load_failed: "Ошибка загрузки",
    error_network: "Не удалось загрузить данные. Проверьте интернет.",
    error_generic: "Не удалось загрузить данные.",
    "nav.prev_month": "Предыдущий месяц",
    "nav.next_month": "Следующий месяц",
    "weekdays.mon": "Пн",
    "weekdays.tue": "Вт",
    "weekdays.wed": "Ср",
    "weekdays.thu": "Чт",
    "weekdays.fri": "Пт",
    "weekdays.sat": "Сб",
    "weekdays.sun": "Вс",
    "month.jan": "Январь",
    "month.feb": "Февраль",
    "month.mar": "Март",
    "month.apr": "Апрель",
    "month.may": "Май",
    "month.jun": "Июнь",
    "month.jul": "Июль",
    "month.aug": "Август",
    "month.sep": "Сентябрь",
    "month.oct": "Октябрь",
    "month.nov": "Ноябрь",
    "month.dec": "Декабрь",
    "aria.duty": "Дежурные",
    "aria.unavailable": "Недоступен",
    "aria.vacation": "Отпуск",
    "aria.day_info": "Информация о дне",
    "event_type.duty": "Дежурство",
    "event_type.unavailable": "Недоступен",
    "event_type.vacation": "Отпуск",
    "duty.now_on_duty": "Сейчас дежурит",
    "duty.none_this_month": "В этом месяце дежурств нет.",
    "duty.today": "Сегодня",
    "duty.until": "до {time}",
    "hint.from": "с",
    "hint.to": "до",
    "hint.duty_title": "Дежурство:",
    "hint.events": "События:",
    "day_detail.close": "Закрыть",
    "contact.label": "Контакт",
    "contact.show": "Контакты",
    "contact.back": "Назад",
    "contact.phone": "Телефон",
    "contact.telegram": "Telegram",
    "current_duty.title": "Текущее дежурство",
    "current_duty.no_duty": "Сейчас никто не дежурит",
    "current_duty.shift": "Смена",
    "current_duty.remaining": "Осталось: {hours}ч {minutes}мин",
    "current_duty.back": "Назад к календарю"
  }
};

const MONTH_KEYS = [
  "month.jan", "month.feb", "month.mar", "month.apr", "month.may", "month.jun",
  "month.jul", "month.aug", "month.sep", "month.oct", "month.nov", "month.dec"
];

const WEEKDAY_KEYS = [
  "weekdays.mon", "weekdays.tue", "weekdays.wed", "weekdays.thu",
  "weekdays.fri", "weekdays.sat", "weekdays.sun"
];

/**
 * Normalize language code to 'ru' or 'en'.
 * @param {string} code - e.g. 'ru', 'en', 'uk'
 * @returns {'ru'|'en'}
 */
function normalizeLang(code) {
  if (!code || typeof code !== "string") return "ru";
  const lower = code.toLowerCase();
  if (lower.startsWith("ru")) return "ru";
  return "en";
}

/**
 * Detect language: Telegram initData user.language_code → navigator → fallback 'ru'.
 * @returns {'ru'|'en'}
 */
export function getLang() {
  const initData = getInitData();
  if (initData) {
    try {
      const params = new URLSearchParams(initData);
      const userStr = params.get("user");
      if (userStr) {
        const user = JSON.parse(decodeURIComponent(userStr));
        const code = user && user.language_code;
        if (code) return normalizeLang(code);
      }
    } catch (e) {
      /* ignore */
    }
  }
  const nav = navigator.language || (navigator.languages && navigator.languages[0]) || "";
  return normalizeLang(nav);
}

/**
 * Get translated string; fallback to en if key missing in lang. Supports {placeholder}.
 * @param {'ru'|'en'} lang
 * @param {string} key - e.g. 'app.title', 'duty.until'
 * @param {Record<string, string>} [params] - e.g. { time: '14:00' }
 * @returns {string}
 */
export function t(lang, key, params = {}) {
  const dict = MESSAGES[lang] || MESSAGES.en;
  let s = dict[key];
  if (s === undefined) s = MESSAGES.en[key];
  if (s === undefined) return key;
  Object.keys(params).forEach((k) => {
    s = s.replace(new RegExp("\\{" + k + "\\}", "g"), params[k]);
  });
  return s;
}

/**
 * Get month name by 0-based index.
 * @param {'ru'|'en'} lang
 * @param {number} month - 0–11
 * @returns {string}
 */
export function monthName(lang, month) {
  const key = MONTH_KEYS[month];
  return key ? t(lang, key) : "";
}

/**
 * Get weekday short labels (Mon–Sun order) for given lang.
 * @param {'ru'|'en'} lang
 * @returns {string[]}
 */
export function weekdayLabels(lang) {
  return WEEKDAY_KEYS.map((k) => t(lang, k));
}