// state.js

// GlobalState 类用于管理全局状态，它通过保存用户和主题信息来维护应用的状态
class GlobalState {
  // 构造函数确保只有一个实例被创建，它初始化用户和主题状态
  constructor() {
    if (!GlobalState.instance) {
      this.user = null; // 初始用户状态为 null
      this.theme = "light"; // 初始主题为 light
      GlobalState.instance = this; // 保存实例
    }
    return GlobalState.instance; // 返回实例，防止新实例创建
  }

  setUser(user) {
    this.user = user;
  }

  setTheme(theme) {
    this.theme = theme;
  }
}

const globalState = new GlobalState();

Object.freeze(globalState); // 冻结实例以防止修改，确保状态管理的完整性

export default globalState;

// someone.vue
// 在组件中使用
import globalState from './state.js';

export default {
    created(){
        globalState.setUser({name:'John Doe'})
        globalState.setTheme('dark')
    }
}

// logger.js
class Logger {
  constructor() {
    if (!Logger.instance) {
      this.logs = [];
      Logger.instance = this;
    }
    return Logger.instance;
  }

  // 记录一条日志信息
  log(message) {
    this.logs.push(message);
  }
}

const logger = new Logger();
Object.freeze(logger);

export default logger;

// someone.vue  在组件中使用
import logger from "./logger.js";

export default {
  created() {
    logger.log("component created");
  },
};

// modalManager.js
class ModalManager {
  constructor() {
    if (!ModalManager.instance) {
      this.modal = null;
      ModalManager.instance = this;
    }
    return ModalManager.instance;
  }

  openModal(modal) {
    if (!this.modal) {
      this.modal = modal;
      // 打开弹框的逻辑
    }
  }

  closeModal() {
    if (this.modal) {
      // 关闭弹框的逻辑
      this.modal = null;
    }
  }
}

const modalManager = new ModalManager();
Object.freeze(modalManager);

export default modalManager;

//someone.vue  在组件中使用

import modalManager from "./modalManager.js";

export default {
  methods: {
    showModal() {
      modalManager.openModal("confirm Modal");
    },
    hideModal() {
      modalManager.closeModal();
    }
  }
};

// dbConnection.js
class DBConnection {
  constructor() {
    if (!DBConnection.instance) {
      this.db = null;
      this.initDB();
      DBConnection.instance = this;
    }
    return DBConnection.instance;
  }

  // 初始化数据库连接
  async initDB() {
    // 使用 indexedDB 创建一个名为 'myDB' 的数据库
    const request = indexedDB.open("myDB", 1);
    request.onsuccess = (event) => {
      this.db = event.target.result;
    };
    request.onerror = (event) => {
      console.error("Error opening database:", event.target.error);
    };
  }

  getDB() {
    return this.db;
  }
}

const dbConnection = new DBConnection();
Object.freeze(dbConnection);

export default dbConnection;

// someone.vue  在组件中使用

import  dbConnection from './dbConnection.js'

export default {
    async created(){
        const db = dbConnection.getDB()
        if(db){
            // 进行数据库操作
        }
    }
}

// cacheManager.js
class CacheManager {
  constructor() {
    if (!CacheManager.instance) {
      this.cache = {};
      CacheManager.instance = this;
    }
    return CacheManager.instance;
  }

  set(key, value) {
    this.cache[key] = value;
  }
  get(key) {
    return this.cache[key];
  }
  remove(key) {
    delete this.cache[key];
  }
}

const cacheManager = new CacheManager();
Object.freeze(cacheManager);
export default cacheManager;

// someone.vue  在组件中使用
import cacheManager from "./cacheManager.js";

export default {
  created() {
    cacheManager.set("data", { name: "John" });
    const data = cacheManager.get("data");
    console.log(data);
  },
};