L.TileLayer.BetterWMS = L.TileLayer.WMS.extend({

  onAdd: function (map) {
    // Triggered when the layer is added to a map.
    //   Register a click listener, then do all the upstream WMS things
    L.TileLayer.WMS.prototype.onAdd.call(this, map);
    map.on('click', this.getFeatureInfo, this);
  },

  onRemove: function (map) {
    // Triggered when the layer is removed from a map.
    //   Unregister a click listener, then do all the upstream WMS things
    L.TileLayer.WMS.prototype.onRemove.call(this, map);
    map.off('click', this.getFeatureInfo, this);
  },

  getFeatureInfo: function (evt) {
    // Make an AJAX request to the server and hope for the best
    var url = this.getFeatureInfoUrl(evt.latlng),
        showResults = L.Util.bind(this.showGetFeatureInfo, this);
    $.ajax({
      url: url,
      success: function (data, status, xhr) {
        var err = typeof data === 'string' ? null : data;
        showResults(err, evt.latlng, data);
      },
      error: function (xhr, status, error) {
        showResults(error);
      }
    });
  },

  getFeatureInfoUrl: function (latlng) {
    // Construct a GetFeatureInfo request URL given a point
    var point = this._map.latLngToContainerPoint(latlng, this._map.getZoom()),
        size = this._map.getSize(),

        params = {
          request: 'GetFeatureInfo',
          service: 'WMS',
          srs: 'EPSG:4326',
          styles: this.wmsParams.styles,
          transparent: this.wmsParams.transparent,
          version: this.wmsParams.version,
          format: this.wmsParams.format,
          bbox: this._map.getBounds().toBBoxString(),
          height: size.y,
          width: size.x,
          layers: this.wmsParams.layers,
          query_layers: this.wmsParams.layers,
          info_format: 'application/json' //'text/html'
        };

    // To solve the bug of incorrect X and Y
    const X = point.x.toFixed();
    const Y = point.y.toFixed();

    params[params.version === '1.3.0' ? 'i' : 'x'] = X //point.x;
    params[params.version === '1.3.0' ? 'j' : 'y'] = Y //point.y;

    return this._url + L.Util.getParamString(params, this._url, true);
  },

  showGetFeatureInfo: function (err, latlng, content) {
    if (err) { console.log(err); return; } // do nothing if there's an error


    const properties = JSON.parse(content).features[0].properties;
    console.debug('betterwms properties: ', properties);
    // if belongs to grid layer treat it as an entity
    if (properties.hasOwnProperty('cellcode')) {
      moreInfoPopup(properties);
    } else {
      mruPopup(properties);
    }
    // Otherwise show the content in a popup, or something.
    // L.popup({ maxWidth: 800})
    //   .setLatLng(latlng)
    //   .setContent('placeholder')
    //   .openOn(this._map);
  }
});

L.tileLayer.betterWms = function (url, options) {
  return new L.TileLayer.BetterWMS(url, options);
};