function RemoGeoLocation() {
  this._remoteSvrUrl = "https://webapi.amap.com/html/geolocate.html";

  this._callbackList = [];

  this._seqBase = 1;

  this._frameReady = 0;

  this._watchIdMap = {};
}

RemoGeoLocation.prototype = {
  _getSeq: function () {
    return this._seqBase++;
  },
  _onRrameReady: function (callback) {
    if (this._frameReady === 0) {
      if (!this._frameReadyList) {
        this._frameReadyList = [];
      }

      this._frameReadyList.push(callback);

      this._prepareIframe();

      return;
    }

    callback.call(this);
  },
  _prepareIframe: function () {
    if (this._iframeWin) {
      return;
    }

    var ifrm = document.createElement("iframe");

    ifrm.src =
      this._remoteSvrUrl + (this._remoteSvrUrl.indexOf("?") > 0 ? "&" : "?");

    ifrm.width = "0px";
    ifrm.height = "0px";
    ifrm.style.position = "absolute";
    ifrm.style.display = "none";

    var self = this;

    var timeoutId = setTimeout(function () {
      self._frameReady = false;

      self._callbackFrameReadyList();
    }, 5000);

    ifrm.onload = function () {
      clearTimeout(timeoutId);

      self._frameReady = true;

      self._callbackFrameReadyList();

      ifrm.onload = null;
    };

    document.body.appendChild(ifrm);

    this._iframeWin = ifrm.contentWindow;

    window.addEventListener(
      "message",
      function (e) {
        if (self._remoteSvrUrl.indexOf(e["origin"]) !== 0) {
          return;
        }

        self._handleRemoteMsg(e["data"]);
      },
      false
    );
  },
  _callbackFrameReadyList: function () {
    if (this._frameReadyList) {
      var list = this._frameReadyList;
      this._frameReadyList = null;

      for (var i = 0, len = list.length; i < len; i++) {
        list[i].call(this, this._frameReady);
      }
    }
  },
  _pickCallback: function (seqNum, keepInList) {
    var callbackList = this._callbackList;

    for (var i = 0, len = callbackList.length; i < len; i++) {
      var cbkInfo = callbackList[i];

      if (seqNum === cbkInfo.seq) {
        if (!keepInList) {
          callbackList.splice(i, 1);
        }

        return cbkInfo;
      }
    }
  },
  _handleRemoteMsg: function (msg) {
    var seqNum = msg["seq"];

    var cbkInfo = this._pickCallback(seqNum, !!msg["notify"]);

    if (cbkInfo) {
      cbkInfo.cbk.call(null, msg["error"], msg["result"]);
    } else {
      console.warn("Receive remote msg: ", msg);
    }
  },
  _postMessage: function (cmd, args, callback, seq) {
    this._prepareIframe();

    var msg = {
      cmd: cmd,
      args: args,
      seq: seq || this._getSeq(),
    };

    this._callbackList.push({
      cbk: callback,
      seq: msg["seq"],
    });

    this._onRrameReady(function () {
      if (this._frameReady === true) {
        try {
          this._iframeWin.postMessage(msg, "*");
        } catch (e) {
          this._pickCallback(msg["seq"]);

          callback(e);
        }
      } else {
        this._pickCallback(msg["seq"]);

        callback({
          message: "iFrame load failed!",
        });
      }
    });
  },
  getCurrentPosition: function (succHandler, errHandler, options) {
    this._postMessage("getCurrentPosition", [options], function (err, result) {
      if (err) {
        if (errHandler) {
          errHandler(err);
        }
        return;
      }
      if (succHandler) {
        succHandler(result);
      }
    });
  },
  watchPosition: function (succHandler, errHandler, options) {
    var watchKey = "wk" + this._getSeq(),
      cmdSeq = this._getSeq();

    this._watchIdMap[watchKey] = {
      stat: 0,
      seq: cmdSeq,
    };

    var self = this;

    this._postMessage(
      "watchPosition",
      [options],
      function (err, result) {
        var id = null;

        if (result) {
          id = result["id"];
        }

        var watchInfo = self._watchIdMap[watchKey];

        watchInfo.id = id;
        watchInfo.stat = 1;

        if (watchInfo.callbackList) {
          var list = watchInfo.callbackList;
          watchInfo.callbackList = null;

          for (var i = 0, len = list.length; i < len; i++) {
            list[i].call(self, id);
          }
        }

        if (err) {
          if (errHandler) {
            errHandler(err);
          }
          return;
        }

        if (succHandler) {
          succHandler(result["pos"]);
        }
      },
      cmdSeq
    );

    return watchKey;
  },
  clearWatch: function (watchKey, callback) {
    if (!this._watchIdMap[watchKey]) {
      callback("Id not exists: " + watchKey);
      return;
    }

    var watchInfo = this._watchIdMap[watchKey];

    var self = this;

    function clearId(id) {
      self._postMessage("clearWatch", [id], function (err, result) {
        if (!err) {
          self._pickCallback(watchInfo.seq);

          delete self._watchIdMap[watchKey];
        }

        if (callback) {
          callback(err, result);
        }
      });
    }

    if (watchInfo.stat < 1) {
      if (!watchInfo.callbackList) {
        watchInfo.callbackList = [];
      }

      watchInfo.callbackList.push(function (id) {
        clearId(id);
      });
    } else {
      clearId(watchInfo.id);
    }
  },
};

export default RemoGeoLocation;