import { defineStore } from 'pinia';
import { i18n, setLanguage, getLanguage, type LanguageCode } from '@src/i18n';
import { SUPPORTED_LANGUAGES, SUPPORTED_LANGUAGE_CODES } from '@src/i18n/constants';
import { resolveSupportedLanguage, detectSystemLanguage } from '@src/i18n/resolver';

// 持久化键
const STORAGE_KEY = 'diona-language';

interface LocaleState {
  language: LanguageCode;
  initialized: boolean;
}

export const useLocaleStore = defineStore('locale', {
  state: (): LocaleState => ({
    language: 'zh',
    initialized: false,
  }),

  getters: {
    currentLanguage: (state) => state.language,
    isChinese: (state) => state.language === 'zh',
    isEnglish: (state) => state.language === 'en',
    isJapanese: (state) => state.language === 'ja',
    languageLabel: (state) => {
      const lang = SUPPORTED_LANGUAGES.find(l => l.code === state.language);
      return lang?.label || '中文';
    },
  },

  actions: {
    /**
     * 初始化语言设置
     * 优先级：持久化设置 > 系统语言 > 默认中文
     */
    async init() {
      if (this.initialized) return;

      try {
        // 1. 尝试从 localStorage 读取持久化设置
        const saved = localStorage.getItem(STORAGE_KEY);
        let lang: LanguageCode = 'zh';

        if (saved && SUPPORTED_LANGUAGE_CODES.includes(saved as LanguageCode)) {
          lang = saved as LanguageCode;
        } else {
          // 2. 检测系统语言
          lang = detectSystemLanguage();
        }

        // 3. 应用语言设置
        await this.setLanguage(lang, false); // 不持久化，因为已经是持久化的值

        this.initialized = true;
      } catch (error) {
        console.error('Failed to initialize locale store:', error);
        // 降级处理：使用默认中文
        await this.setLanguage('zh', false);
        this.initialized = true;
      }
    },

    /**
     * 设置语言
     * @param language 目标语言代码
     * @param persist 是否持久化到 localStorage（默认为 true）
     */
    async setLanguage(language: LanguageCode, persist: boolean = true) {
      // 验证语言代码有效性
      const resolvedLang = resolveSupportedLanguage(language);
      
      if (resolvedLang === this.language) {
        return; // 语言未变化
      }

      try {
        // 1. 更新 i18n 实例
        await setLanguage(resolvedLang, i18n);

        // 2. 更新 store 状态
        this.language = resolvedLang;

        // 3. 持久化到 localStorage
        if (persist) {
          localStorage.setItem(STORAGE_KEY, resolvedLang);
        }

        // 4. 触发语言变化事件（供其他组件监听）
        window.dispatchEvent(new CustomEvent('language-changed', { 
          detail: { language: resolvedLang } 
        }));
      } catch (error) {
        console.error('Failed to set language:', error);
        throw error;
      }
    },

    /**
     * 切换语言（轮换支持的语言）
     */
    async toggleLanguage() {
      const currentIndex = SUPPORTED_LANGUAGE_CODES.indexOf(this.language);
      const nextIndex = (currentIndex + 1) % SUPPORTED_LANGUAGE_CODES.length;
      const nextLanguage = SUPPORTED_LANGUAGE_CODES[nextIndex];
      await this.setLanguage(nextLanguage);
    },

    /**
     * 重置为系统语言
     */
    async resetToSystemLanguage() {
      const systemLang = detectSystemLanguage();
      await this.setLanguage(systemLang);
    },

    /**
     * 同步 i18n 实例与 store 状态（用于外部更改的情况）
     */
    syncWithI18n() {
      const currentLang = getLanguage();
      if (currentLang !== this.language) {
        this.language = currentLang as LanguageCode;
      }
    },
  },
});

// 导出类型
export type { LanguageCode };