export var FeatureGroup = LayerGroup.extend({
  addLayer: function (layer) {
    if (this.hasLayer(layer)) {
      return this;
    }

    layer.addEventParent(this);
    LayerGroup.prototype.addLayer.call(this, layer);
    return this.fire("layeradd", { layer: layer });
  },
  removeLayer: function (layer) {
    if (!this.hasLayer(layer)) {
      return this;
    }

    if (layer in this._layers) {
      layer = this._layers[layer];
    }
    layer.removeEventParent(this);
    LayerGroup.prototype.removeLayer.call(this, layer);

    return this.fire("layerremove", { layer: layer });
  },
  setStyle: function (style) {
    return this.invoke("setStyle", style);
  },
  bringToFront: function () {
    return this.invoke("bringToFront");
  },
  bringToBack: function () {
    return this.invoke("bringToBack");
  },
  getBounds: function () {
    var bounds = new LatLngBounds();

    for (var id in this._layers) {
      var layer = this._layers[id];
      bounds.extend(layer.getBounds ? layer.getBounds() : layer.getLatLng());
    }
    return bounds;
  },
});

export var featureGroup = function (layers, options) {
  return new FeatureGroup(layer, options);
};