/**
 * MetonaEditor i18n - 国际化管理
 * @module i18n
 * @version 0.1.4
 * @description 多语言支持、语言切换和翻译管理
 */

import { LOCALES } from './constants.js';

let currentLocale = 'zh-CN';
let localeListeners = new Set();
let fallbackLocale = 'zh-CN';

/**
 * 获取当前语言
 */
export const getCurrentLocale = () => currentLocale;

/**
 * 设置当前语言
 */
export const setCurrentLocale = (locale) => {
  let target = locale;
  if (!LOCALES[target]) {
    console.warn(`Locale "${target}" not found, falling back to "${fallbackLocale}"`);
    target = fallbackLocale;
  }

  currentLocale = target;
  notifyLocaleListeners(target);
  saveLocale(target);
};

/**
 * 翻译函数
 */
export const t = (key, params = {}) => {
  const currentTranslation = getTranslation(currentLocale, key);
  if (currentTranslation !== undefined) {
    return interpolate(currentTranslation, params);
  }

  if (currentLocale !== fallbackLocale) {
    const fallbackTranslation = getTranslation(fallbackLocale, key);
    if (fallbackTranslation !== undefined) {
      return interpolate(fallbackTranslation, params);
    }
  }

  console.warn(`Translation missing for key "${key}" in locale "${currentLocale}"`);
  return key;
};

/**
 * 获取翻译
 */
const getTranslation = (locale, key) => {
  const localeData = LOCALES[locale];
  if (!localeData) return undefined;

  const keys = key.split('.');
  let result = localeData;

  for (const k of keys) {
    if (result && typeof result === 'object' && k in result) {
      result = result[k];
    } else {
      return undefined;
    }
  }

  return typeof result === 'string' ? result : undefined;
};

/**
 * 插值函数
 */
const interpolate = (str, params) => {
  return str.replace(/\{(\w+)\}/g, (match, key) => {
    return params[key] !== undefined ? params[key] : match;
  });
};

/**
 * 检查翻译是否存在
 */
export const hasTranslation = (key) => {
  return getTranslation(currentLocale, key) !== undefined ||
         getTranslation(fallbackLocale, key) !== undefined;
};

/**
 * 获取所有翻译
 */
export const getTranslations = (locale) => {
  return LOCALES[locale] || {};
};

/**
 * 添加翻译
 */
export const addTranslations = (locale, translations) => {
  if (!LOCALES[locale]) {
    LOCALES[locale] = {};
  }

  deepMerge(LOCALES[locale], translations);
};

/**
 * 深度合并对象
 */
const deepMerge = (target, source) => {
  for (const key in source) {
    if (source[key] instanceof Object && key in target && target[key] instanceof Object) {
      deepMerge(target[key], source[key]);
    } else {
      target[key] = source[key];
    }
  }
  return target;
};

/**
 * 获取支持的语言列表
 */
export const getSupportedLocales = () => {
  return Object.keys(LOCALES);
};

/**
 * 检查语言是否支持
 */
export const isLocaleSupported = (locale) => {
  return locale in LOCALES;
};

/**
 * 获取语言名称
 */
export const getLocaleName = (locale) => {
  const names = {
    'zh-CN': '简体中文',
    'zh-TW': '繁體中文',
    'en-US': 'English (US)',
    'en-GB': 'English (UK)',
    'ja': '日本語',
    'ko': '한국어',
    'fr': 'Français',
    'de': 'Deutsch',
    'es': 'Español',
    'pt': 'Português',
    'ru': 'Русский',
    'ar': 'العربية',
    'hi': 'हिन्दी',
    'th': 'ไทย',
    'vi': 'Tiếng Việt',
    'id': 'Bahasa Indonesia',
    'ms': 'Bahasa Melayu',
    'tr': 'Türkçe',
    'it': 'Italiano',
    'nl': 'Nederlands',
    'pl': 'Polski',
  };

  return names[locale] || locale;
};

/**
 * 获取语言方向
 */
export const getLocaleDirection = (locale) => {
  const rtlLocales = ['ar', 'he', 'fa', 'ur', 'yi', 'ps', 'sd', 'ug'];
  return rtlLocales.includes(locale) ? 'rtl' : 'ltr';
};

/**
 * 格式化数字
 */
export const formatNumber = (number, options = {}) => {
  try {
    return new Intl.NumberFormat(currentLocale, options).format(number);
  } catch (e) {
    return number.toString();
  }
};

/**
 * 格式化货币
 */
export const formatCurrency = (amount, currency = 'USD', options = {}) => {
  try {
    return new Intl.NumberFormat(currentLocale, {
      style: 'currency',
      currency,
      ...options,
    }).format(amount);
  } catch (e) {
    return amount.toString();
  }
};

/**
 * 格式化日期
 */
export const formatDate = (date, options = {}) => {
  try {
    const dateObj = date instanceof Date ? date : new Date(date);
    return new Intl.DateTimeFormat(currentLocale, options).format(dateObj);
  } catch (e) {
    return date.toString();
  }
};

/**
 * 添加语言监听器
 */
export const addLocaleListener = (listener) => {
  localeListeners.add(listener);

  return () => {
    localeListeners.delete(listener);
  };
};

/**
 * 移除语言监听器
 */
export const removeLocaleListener = (listener) => {
  localeListeners.delete(listener);
};

/**
 * 通知语言监听器
 */
const notifyLocaleListeners = (locale) => {
  localeListeners.forEach((listener) => {
    try {
      listener(locale);
    } catch (e) {
      console.error('Locale listener error:', e);
    }
  });
};

/**
 * 清除所有语言监听器
 */
export const clearLocaleListeners = () => {
  localeListeners.clear();
};

/**
 * 保存语言到本地存储
 */
export const saveLocale = (locale) => {
  if (typeof localStorage !== 'undefined') {
    try {
      localStorage.setItem('metona-editor-locale', locale);
    } catch (e) {
      console.warn('Failed to save locale:', e);
    }
  }
};

/**
 * 从本地存储加载语言
 */
export const loadLocale = () => {
  if (typeof localStorage !== 'undefined') {
    try {
      return localStorage.getItem('metona-editor-locale') || getDefaultLocale();
    } catch (e) {
      console.warn('Failed to load locale:', e);
    }
  }
  return getDefaultLocale();
};

/**
 * 获取默认语言
 */
export const getDefaultLocale = () => {
  if (typeof navigator !== 'undefined') {
    const browserLocale = navigator.language || navigator.userLanguage;
    if (browserLocale && isLocaleSupported(browserLocale)) {
      return browserLocale;
    }

    const shortLocale = browserLocale?.split('-')[0];
    if (shortLocale && isLocaleSupported(shortLocale)) {
      return shortLocale;
    }
  }

  return fallbackLocale;
};

/**
 * 初始化国际化系统
 */
export const initI18n = () => {
  const savedLocale = loadLocale();
  setCurrentLocale(savedLocale);
};

/**
 * 切换语言
 */
export const switchLocale = (locale) => {
  setCurrentLocale(locale);
};

/**
 * 国际化工具 — 代理层
 */
export const i18nUtils = {
  t,
  getCurrentLocale,
  setCurrentLocale,
  switchLocale,
  getFallbackLocale: () => fallbackLocale,
  setFallbackLocale: (locale) => { fallbackLocale = locale; },
  hasTranslation,
  getTranslations,
  addTranslations,
  getSupportedLocales,
  isLocaleSupported,
  getLocaleName,
  getLocaleDirection,
  formatNumber,
  formatCurrency,
  formatDate,
  addLocaleListener,
  removeLocaleListener,
  clearLocaleListeners,
  initI18n,
  saveLocale,
  loadLocale,
  getDefaultLocale,
};

/**
 * 预设语言包
 */
export const presetLocales = {
  'zh-CN': {
    name: '简体中文',
    nativeName: '简体中文',
    direction: 'ltr',
    translations: LOCALES['zh-CN'],
  },
  'en-US': {
    name: 'English (US)',
    nativeName: 'English (US)',
    direction: 'ltr',
    translations: LOCALES['en-US'],
  },
};

/**
 * 创建国际化管理器
 */
export const createI18nManager = () => {
  return {
    t,
    getCurrentLocale,
    setCurrentLocale,
    switchLocale,
    getFallbackLocale: () => fallbackLocale,
    setFallbackLocale: (locale) => { fallbackLocale = locale; },
    hasTranslation,
    getTranslations,
    addTranslations,
    getSupportedLocales,
    isLocaleSupported,
    getLocaleName,
    getLocaleDirection,
    formatNumber,
    formatCurrency,
    formatDate,
    addLocaleListener,
    removeLocaleListener,
    clearLocaleListeners,
    initI18n,
    saveLocale,
    loadLocale,
    getDefaultLocale,
  };
};

export { i18nUtils as default };