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: 'text/html'
        };
    
    params[params.version === '1.3.0' ? 'i' : 'x'] = point.x;
    params[params.version === '1.3.0' ? 'j' : '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
    
    // Otherwise show the content in a popup, or something.
    L.popup({ maxWidth: 800})
      .setLatLng(latlng)
      .setContent(content)
      .openOn(this._map);
  }
});

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

/*
 * L.Control.WMSLegend is used to add a WMS Legend to the map
 */

L.Control.WMSLegend = L.Control.extend({
    options: {
        position: 'topleft',
        uri: ''
    },

    onAdd: function () {
        var controlClassName = 'leaflet-control-wms-legend',
            legendClassName = 'wms-legend',
            stop = L.DomEvent.stopPropagation;
        this.container = L.DomUtil.create('div', controlClassName);
        this.img = L.DomUtil.create('img', legendClassName, this.container);
        this.img.src = this.options.uri;
        this.img.alt = 'Legend';

        L.DomEvent
            .on(this.img, 'click', this._click, this)
            .on(this.container, 'click', this._click, this)
            .on(this.img, 'mousedown', stop)
            .on(this.img, 'dblclick', stop)
            .on(this.img, 'click', L.DomEvent.preventDefault)
            .on(this.img, 'click', stop);
        this.height = null;
        this.width = null;
        return this.container;
    },
    _click: function (e) {
        L.DomEvent.stopPropagation(e);
        L.DomEvent.preventDefault(e);
        // toggle legend visibility
        var style = window.getComputedStyle(this.img);
        if (style.display === 'none') {
            this.container.style.height = this.height + 'px';
            this.container.style.width = this.width + 'px';
            this.img.style.display = this.displayStyle;
        }
        else {
            if (this.width === null && this.height === null) {
                // Only do inside the above check to prevent the container
                // growing on successive uses
                this.height = this.container.offsetHeight;
                this.width = this.container.offsetWidth;
            }
            this.displayStyle = this.img.style.display;
            this.img.style.display = 'none';
            this.container.style.height = '20px';
            this.container.style.width = '20px';
        }
    },
});

L.wmsLegend = function (uri) {
    var wmsLegendControl = new L.Control.WMSLegend;
    wmsLegendControl.options.uri = uri;
    map.addControl(wmsLegendControl);
    return wmsLegendControl;
};