text: 'use strict';
  
  const ajax = require('../util/ajax');
  const rewind = require('geojson-rewind');
  const GeoJSONWrapper = require('./geojson_wrapper');
  const vtpbf = require('vt-pbf');
  const supercluster = require('supercluster');
  const geojsonvt = require('geojson-vt');
  
  const VectorTileWorkerSource = require('./vector_tile_worker_source');
  
  /**
   * The {@link WorkerSource} implementation that supports {@link GeoJSONSource}.
   * This class is designed to be easily reused to support custom source types
   * for data formats that can be parsed/converted into an in-memory GeoJSON
   * representation.  To do so, create it with
   * `new GeoJSONWorkerSource(actor, layerIndex, customLoadGeoJSONFunction)`.  For a full example, see [mapbox-gl-topojson](https://github.com/developmentseed/mapbox-gl-topojson).
   *
   * @private
   */
  class GeoJSONWorkerSource extends VectorTileWorkerSource {
      /**
       * @param {Function} [loadGeoJSON] Optional method for custom loading/parsing of GeoJSON based on parameters passed from the main-thread Source.  See {@link GeoJSONWorkerSource#loadGeoJSON}.
       */
      constructor (actor, layerIndex, loadGeoJSON) {
          super(actor, layerIndex);
          if (loadGeoJSON) {
              this.loadGeoJSON = loadGeoJSON;
          }
          // object mapping source ids to geojson-vt-like tile indexes
          this._geoJSONIndexes = {};
      }
  
      /**
       * See {@link VectorTileWorkerSource#loadTile}.
       */
      loadVectorData(params, callback) {
          const source = params.source,
              coord = params.coord;
  
          if (!this._geoJSONIndexes[source]) {
              return callback(null, null);  // we couldn't load the file
          }
  
          const geoJSONTile = this._geoJSONIndexes[source].getTile(Math.min(coord.z, params.maxZoom), coord.x, coord.y);
          if (!geoJSONTile) {
              return callback(null, null); // nothing in the given tile
          }
  
          // Encode the geojson-vt tile into binary vector tile form form.  This
          // is a convenience that allows `FeatureIndex` to operate the same way
          // across `VectorTileSource` and `GeoJSONSource` data.
          const geojsonWrapper = new GeoJSONWrapper(geoJSONTile.features);
          geojsonWrapper.name = '_geojsonTileLayer';
          let pbf = vtpbf({ layers: { '_geojsonTileLayer': geojsonWrapper }});
          if (pbf.byteOffset !== 0 || pbf.byteLength !== pbf.buffer.byteLength) {
              // Compatibility with node Buffer (https://github.com/mapbox/pbf/issues/35)
              pbf = new Uint8Array(pbf);
          }
          geojsonWrapper.rawData = pbf.buffer;
          callback(null, geojsonWrapper);
      }
  
      /**
       * Fetches (if appropriate), parses, and index geojson data into tiles. This
       * preparatory method must be called before {@link GeoJSONWorkerSource#loadTile}
       * can correctly serve up tiles.
       *
       * Defers to {@link GeoJSONWorkerSource#loadGeoJSON} for the fetching/parsing,
       * expecting `callback(error, data)` to be called with either an error or a
       * parsed GeoJSON object.
       * @param {Object} params
       * @param {string} params.source The id of the source.
       * @param {Function} callback
       */
      loadData(params, callback) {
          const handleData = function(err, data) {
              if (err) return callback(err);
              if (typeof data != 'object') {
                  return callback(new Error("Input data is not a valid GeoJSON object."));
              }
              rewind(data, true);
              this._indexData(data, params, (err, indexed) => {
                  if (err) { return callback(err); }
                  this._geoJSONIndexes[params.source] = indexed;
                  callback(null);
              });
          }.bind(this);
  
          this.loadGeoJSON(params, handleData);
      }
  
      /**
       * Fetch and parse GeoJSON according to the given params.  Calls `callback`
       * with `(err, data)`, where `data` is a parsed GeoJSON object.
       *
       * GeoJSON is loaded and parsed from `params.url` if it exists, or else
       * expected as a literal (string or object) `params.data`.
       *
       * @param {Object} params
       * @param {string} [params.url] A URL to the remote GeoJSON data.
       * @param {Object} [params.data] Literal GeoJSON data. Must be provided if `params.url` is not.
       */
      loadGeoJSON(params, callback) {
          // Because of same origin issues, urls must either include an explicit
          // origin or absolute path.
          // ie: /foo/bar.json or http://example.com/bar.json
          // but not ../foo/bar.json
          if (params.url) {
              ajax.getJSON(params.url, callback);
          } else if (typeof params.data === 'string') {
              try {
                  return callback(null, JSON.parse(params.data));
              } catch (e) {
                  return callback(new Error("Input data is not a valid GeoJSON object."));
              }
          } else {
              return callback(new Error("Input data is not a valid GeoJSON object."));
          }
      }
  
      removeSource(params) {
          if (this._geoJSONIndexes[params.source]) {
              delete this._geoJSONIndexes[params.source];
          }
      }
  
      /**
       * Index the data using either geojson-vt or supercluster
       * @param {GeoJSON} data
       * @param {Object} params forwarded from loadTile.
       * @param {callback} (err, indexedData)
       * @private
       */
      _indexData(data, params, callback) {
          try {
              if (params.cluster) {
                  callback(null, supercluster(params.superclusterOptions).load(data.features));
              } else {
                  callback(null, geojsonvt(data, params.geojsonVtOptions));
              }
          } catch (err) {
              return callback(err);
          }
      }
  }
  
  module.exports = GeoJSONWorkerSource;
  