/**
 * 缓存基类
 * @return {[type]} [description]
 */
/**
 * 缓存数据
 * @type {Object}
 */
var cacheData = {};
/**
 * 定时器
 * @type {Number}
 */
var gcTimer = {};
/**
 * 清除已经过期的Cache
 * @return {[type]} [description]
 */
var gc = function(instance){
  'use strict';
  if (APP_DEBUG || APP_MODE === 'cli' || gcTimer[instance.gcType]) {
    return;
  }
  gcTimer[instance.gcType] = setInterval(function(){
    var hour = (new Date()).getHours();
    if (C('cache_gc_hour').indexOf(hour) === -1) {
      return;
    }
    var now = Date.now();
    if (instance.gc) {
      console.log('gc clean: ', instance.gcType, (new Date()).toUTCString());
      instance.gc(now);
    }
  }, 3600 * 1000);
};

module.exports = Class(function(){
  'use strict';
  return {
    /**
     * gc的类型，用于定时器类型判断
     * @type {String}
     */
    gcType: 'Cache',
    /**
     * 初始化
     * @param  {[type]} options [description]
     * @return {[type]}         [description]
     */
    init: function(options){
      options = options || {};
      if (options.cacheData) {
        this.cacheData = options.cacheData;
      }else{
        this.cacheData = cacheData;
      }
      if (options.gcType) {
        this.gcType = options.gcType;
      }
      if (!options.timeout) {
        options.timeout = C('cache_timeout')
      }
      this.options = options;
      //操作的key
      this.key = '';
      //是否更新expire值
      this.updateExpire = false;
      gc(this);
    },
    /**
     * 获取缓存值，返回一个promise
     * @param  {[type]} name [description]
     * @return {[type]}      [description]
     */
    get: function(name){
      var key = this.key || name;
      if (!(key in this.cacheData)) {
        return getPromise();
      }
      var value = this.cacheData[key];
      if (Date.now() > value.expire) {
        delete this.cacheData[key];
        return getPromise();
      }
      if (this.updateExpire) {
        this.cacheData[key].expire = Date.now() + value.timeout * 1000;
      }
      var data = value.data[name];
      //如果data是个对象或者数组，需要深度拷贝
      if (isObject(data)) {
        data = extend({}, data);
      }else if (isArray(data)) {
        data = extend([], data);
      }
      return getPromise(data);
    },
    /**
     * 设置缓存值
     * @param {[type]} name   [description]
     * @param {[type]} value  [description]
     */
    set: function(name, value, timeout){
      if (timeout === undefined) {
        timeout = this.options.timeout;
      }
      var key = this.key || name;
      //如果value是个对象或者数组，这里需要深度拷贝，防止程序里修改值导致缓存值被修改
      if (isObject(value)) {
        value = extend({}, value);
      }else if (isArray(value)) {
        value = extend([], value);
      }
      if (key in this.cacheData) {
        this.cacheData[key].data[name] = value;
      }else{
        this.cacheData[key] = {
          data: getObject(name, value),
          timeout: timeout,
          expire: Date.now() + timeout * 1000
        };
      }
      return getPromise();
    },
    /**
     * 移除缓存值
     * @param  {[type]} name [description]
     * @return {[type]}      [description]
     */
    rm: function(name){
      var key = this.key || name;
      if (key in this.cacheData) {
        delete this.cacheData[key].data[name];
      }
      return getPromise();
    },
    /**
     * gc
     * @param  {[type]} now [description]
     * @return {[type]}     [description]
     */
    gc: function(now){
      for(var key in this.cacheData){
        var item = this.cacheData[key] || {};
        if (now > item.expire) {
          delete this.cacheData[key];
        }
      }
    }
  };
});