export default function Database() {
  /**
   * 数据库对象
   * @param {[type]} option [description]
   */
  // var option = {
  //   dbName: '', // 数据库名
  //   version: 1, // 数据库版本号
  //   primaryKey: 'id' // 需要保存的数据字段
  //   keyNames: [{ // 需要保存的数据字段
  //     key: '', // 字段名
  //     unique: // 当前这条数据是否能重复 (最常用) 默认false
  //   }]
  // };
  var IndexedDB = function IndexedDB(option) {
    // 设置unique默认值为false
    var list;
    if (option.keyNames) {
      list = option.keyNames;
      for (var i = 0; i < list.length; i++) {
        if (!list[i].unique) {
          list[i].unique = false;
        }
      }
    }

    this.dbName = option.dbName;
    this.version = option.version;
    this.primaryKey = option.primaryKey || "id";
    this.keyNames = option.keyNames;
    this.db = null; // 存储数据库对象
    this.allData = []; // 存储返回的所有数据
  };

  IndexedDB.prototype = {
    /**
     * 初始化数据库
     * @return {[type]} [description]
     */
    init: function () {
      const _this = this;
      return new Promise((resolve, reject) => {
        var dbName = _this.dbName,
          version = _this.version,
          primaryKey = _this.primaryKey,
          keyNames = _this.keyNames;

        var indexedDB =
          window.indexedDB ||
          window.mozIndexedDB ||
          window.webkitIndexedDB ||
          window.msIndexedDB;

        // 判断浏览器是否支持indexedDB
        if (!indexedDB) {
          reject(new Error("您的浏览器不支持当前内容"));
          return false;
        }

        // 判断数据库名称是否为空
        if (!dbName) {
          reject(new Error(null, "数据库名称不能为空"));
          return false;
        }

        // 打开数据库
        var DBOpenRequest = window.indexedDB.open(dbName, version);

        // 数据库打开成功
        DBOpenRequest.onsuccess = function (event) {
          _this.db = DBOpenRequest.result;
          resolve(event);
        };

        // 数据库打开失败
        DBOpenRequest.onerror = function (event) {
          reject(event);
        };

        // 首次创建或者版本变更（更高版本）
        DBOpenRequest.onupgradeneeded = function (event) {
          _this.db = event.target.result;
          _this.db.onerror = function (event) {
            console.log(event);
            reject(new Error("数据库打开失败"));
          };

          // 创建一个数据库存储对象
          /*
            // createIndex的语法
            objectStore.createIndex(indexName, keyPath, {
            unique: false,  // true
            multiEntry: false,  // 如果为true，同时keyPath是数组元素，则所以会加到所有数组元素上
            locale: 'auto'  // 目前仅Firefox支持，可以是字符串，类似en-US, 或 zh，也可以是auto或者null, undefined
          })
          */

          if (!_this.db.objectStoreNames.contains(dbName)) {
            var objectStore = _this.db.createObjectStore(dbName, {
              keyPath: primaryKey,
              autoIncrement: true,
            });
          }

          keyNames.forEach(function (currentValue, index, array) {
            /**
             * 创建索引
             * @string indexName 设置当前 index 的名字
             * @string property 从存储数据中，指明 index 所指的属性。
             * @string property 从存储数据中，指明 index 所指的属性。
             * @object options options 有三个选项：
             * unique: 当前这条数据是否能重复 (最常用)
             * multiEntry: 设置当前的 property 为数组时，会给数组里面每个元素都设置一个 index 值。
             * locale：目前仅支持Firefox（43+），这允许您为索引指定区域设置。
             */
            console.log(index, array);
            // objectStore.createIndex('indexName', 'property', options);
            objectStore.createIndex(currentValue.key, currentValue.key, {
              unique: currentValue.unique || false,
            });
          });
        };
      });
    },

    /**
     * 添加数据
     * @param {Array || Object} option 存入数据库的数据
     */
    set: function (option) {
      var _this = this;
      var dbName = _this.dbName;
      // version = _this.version,
      // primaryKey = _this.primaryKey,
      // keyNames = _this.keyNames;

      var transaction = this.db.transaction([dbName], "readwrite");
      var objectStore = transaction.objectStore(dbName);

      if (Array.isArray(option)) {
        for (var i = 0; i < option.length; i++) {
          objectStore.add(option[i]).onsuccess = function (event) {
            console.log("数据写入成功", event);
          };

          transaction.onerror = function (event) {
            console.log("数据库中已有该数据", event);
          };
        }
      } else {
        objectStore.add(option).onsuccess = function (event) {
          console.log("数据写入成功", event);
        };

        transaction.onerror = function (event) {
          console.log("数据库中已有该数据", event);
        };
      }
    },

    /**
     * 更新单条或多条数据
     * @param  {Array || object} option       更新的数据
     * @return {[type]}              [description]
     */
    updateData: function (option) {
      var _this = this;
      var dbName = _this.dbName;

      var transaction = _this.db.transaction([dbName], "readwrite");
      var objectStore = transaction.objectStore(dbName);

      if (Array.isArray(option)) {
        for (var i = 0; i < option.length; i++) {
          objectStore.put(option[i]).onsuccess = function (event) {
            console.log("数据更新成功", event);
          };

          transaction.onerror = function (event) {
            console.log("数据更新成功", event);
          };
        }
      } else {
        objectStore.put(option).onsuccess = function (event) {
          console.log("数据更新成功", event);
        };

        transaction.onerror = function (event) {
          console.log("数据更新成功", event);
        };
      }
    },

    /**
     * 遍历数据表里所有的数据
     * @return {Array || Obiect}             返回数据表里所有的数据
     */
    getAllData: function (callback) {
      var _this = this;
      var dbName = _this.dbName;
      return new Promise((resolve, reject) => {
        _this.allData = [];
        var objectStore = _this.db.transaction(dbName).objectStore(dbName);
        objectStore.openCursor().onsuccess = function (event) {
          var cursor = event.target.result;
          if (cursor) {
            if (callback && callback(cursor.value)) {
              _this.allData.push(cursor.value);
            }
            cursor.continue();
          } else {
            resolve(_this.allData);
          }
        };

        objectStore.openCursor().onerror = function (event) {
          reject(new Error(event));
        };
      });
    },

    /**
     * 获取数据表里单条数据
     * @param  {String || Number} value        数据字段的值（按主键搜索）
     * @return {[type]}              [description]
     */
    getData: function (value) {
      var _this = this;
      var dbName = _this.dbName;

      return new Promise((resolve, reject) => {
        var objectStore = _this.db.transaction(dbName).objectStore(dbName);
        var request = objectStore.get(value);

        request.onerror = function (event) {
          console.log("获取失败", event);
          reject(new Error(event));
        };

        request.onsuccess = function (event) {
          if (request.result) {
            console.log(request.result);
            resolve(request.result);
          } else {
            console.log("未获得数据记录", event);
            reject(new Error(event));
          }
        };
      });
    },

    /**
     * 删除数据库
     * @return {[type]}              [description]
     */
    deleteDB: function () {
      var _this = this;
      var dbName = _this.dbName;
      window.indexedDB.deleteDatabase(dbName);
      console.log(dbName + "数据库已删除");
    },

    /**
     * 关闭数据库
     * @return {[type]} [description]
     */
    closeDB: function () {
      var _this = this;
      _this.db.close();
      console.log("数据库已关闭");
    },

    /**
     * 删除某一条记录
     * @param  {String || Number} value        主键的值
     * @return {[type]}              [description]
     */
    deleteData: function (value) {
      var _this = this;
      var dbName = _this.dbName;

      return new Promise((resolve, reject) => {
        var request = _this.db
          .transaction(dbName, "readwrite")
          .objectStore(dbName)
          .delete(value);

        request.onsuccess = function (event) {
          console.log("删除成功", event);
          resolve(event);
        };

        request.onerror = function (event) {
          console.log("删除成功", event);
          reject(new Error(event));
        };
      });
    },

    /**
     * 删除存储空间全部记录
     * @return {[type]}              [description]
     */
    clearData: function () {
      var _this = this;
      var dbName = _this.dbName;
      var store = _this.db.transaction(dbName, "readwrite").objectStore(dbName);
      store.clear();
      console.log("已删除存储空间" + dbName + "全部记录");
    },

    /**
     * 数据查询
     * @param  {String} key          数据字段名
     * @param  {String || Number} value        按字段查询的值
     * @return {[type]}              [description]
     */
    searchData: function (key, value) {
      var _this = this;
      var dbName = _this.dbName;

      return new Promise((resolve, reject) => {
        var store = _this.db
          .transaction(dbName, "readonly")
          .objectStore(dbName);
        var index = store.index(key);
        var request = index.get(value);

        request.onerror = function (event) {
          console.error("搜索出错");
          reject(new Error(event));
        };

        request.onsuccess = function (e) {
          var result = e.target.result;
          if (result) {
            resolve(result);
          } else {
            console.log("您搜索的数据不存在");
            resolve(null);
          }
        };
      });
    },
  };
  return IndexedDB;
}