text: /**
   * @module ol/source/Cluster
   */
  
  import EventType from '../events/EventType.js';
  import Feature from '../Feature.js';
  import GeometryType from '../geom/GeometryType.js';
  import Point from '../geom/Point.js';
  import VectorSource from './Vector.js';
  import {add as addCoordinate, scale as scaleCoordinate} from '../coordinate.js';
  import {assert} from '../asserts.js';
  import {
    buffer,
    createEmpty,
    createOrUpdateFromCoordinate,
    getCenter,
  } from '../extent.js';
  import {getUid} from '../util.js';
  
  /**
   * @typedef {Object} Options
   * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
   * @property {number} [distance=20] Distance in pixels within which features will
   * be clustered together.
   * @property {number} [minDistance=0] Minimum distance in pixels between clusters.
   * Will be capped at the configured distance.
   * By default no minimum distance is guaranteed. This config can be used to avoid
   * overlapping icons. As a tradoff, the cluster feature's position will no longer be
   * the center of all its features.
   * @property {function(Feature):Point} [geometryFunction]
   * Function that takes an {@link module:ol/Feature} as argument and returns an
   * {@link module:ol/geom/Point} as cluster calculation point for the feature. When a
   * feature should not be considered for clustering, the function should return
   * `null`. The default, which works when the underlying source contains point
   * features only, is
   * ```js
   * function(feature) {
   *   return feature.getGeometry();
   * }
   * ```
   * See {@link module:ol/geom/Polygon~Polygon#getInteriorPoint} for a way to get a cluster
   * calculation point for polygons.
   * @property {function(Point, Array<Feature>):Feature} [createCluster]
   * Function that takes the cluster's center {@link module:ol/geom/Point} and an array
   * of {@link module:ol/Feature} included in this cluster. Must return a
   * {@link module:ol/Feature} that will be used to render. Default implementation is:
   * ```js
   * function(point, features) {
   *   return new Feature({
   *     geometry: point,
   *     features: features
   *   });
   * }
   * ```
   * @property {VectorSource} [source] Source.
   * @property {boolean} [wrapX=true] Whether to wrap the world horizontally.
   */
  
  /**
   * @classdesc
   * Layer source to cluster vector data. Works out of the box with point
   * geometries. For other geometry types, or if not all geometries should be
   * considered for clustering, a custom `geometryFunction` can be defined.
   *
   * If the instance is disposed without also disposing the underlying
   * source `setSource(null)` has to be called to remove the listener reference
   * from the wrapped source.
   * @api
   */
  class Cluster extends VectorSource {
    /**
     * @param {Options} options Cluster options.
     */
    constructor(options) {
      super({
        attributions: options.attributions,
        wrapX: options.wrapX,
      });
  
      /**
       * @type {number|undefined}
       * @protected
       */
      this.resolution = undefined;
  
      /**
       * @type {number}
       * @protected
       */
      this.distance = options.distance !== undefined ? options.distance : 20;
  
      /**
       * @type {number}
       * @protected
       */
      this.minDistance = options.minDistance || 0;
  
      /**
       * @type {number}
       * @protected
       */
      this.interpolationRatio = 0;
  
      /**
       * @type {Array<Feature>}
       * @protected
       */
      this.features = [];
  
      /**
       * @param {Feature} feature Feature.
       * @return {Point} Cluster calculation point.
       * @protected
       */
      this.geometryFunction =
        options.geometryFunction ||
        function (feature) {
          const geometry = feature.getGeometry();
          assert(geometry.getType() == GeometryType.POINT, 10); // The default `geometryFunction` can only handle `Point` geometries
          return geometry;
        };
  
      /**
       * @type {function(Point, Array<Feature>):Feature}
       * @private
       */
      this.createCustomCluster_ = options.createCluster;
  
      /**
       * @type {VectorSource}
       * @protected
       */
      this.source = null;
  
      this.boundRefresh_ = this.refresh.bind(this);
  
      this.updateDistance(this.distance, this.minDistance);
      this.setSource(options.source || null);
    }
  
    /**
     * Remove all features from the source.
     * @param {boolean} [opt_fast] Skip dispatching of {@link module:ol/source/Vector.VectorSourceEvent#removefeature} events.
     * @api
     */
    clear(opt_fast) {
      this.features.length = 0;
      super.clear(opt_fast);
    }
  
    /**
     * Get the distance in pixels between clusters.
     * @return {number} Distance.
     * @api
     */
    getDistance() {
      return this.distance;
    }
  
    /**
     * Get a reference to the wrapped source.
     * @return {VectorSource} Source.
     * @api
     */
    getSource() {
      return this.source;
    }
  
    /**
     * @param {import("../extent.js").Extent} extent Extent.
     * @param {number} resolution Resolution.
     * @param {import("../proj/Projection.js").default} projection Projection.
     */
    loadFeatures(extent, resolution, projection) {
      this.source.loadFeatures(extent, resolution, projection);
      if (resolution !== this.resolution) {
        this.resolution = resolution;
        this.refresh();
      }
    }
  
    /**
     * Set the distance within which features will be clusterd together.
     * @param {number} distance The distance in pixels.
     * @api
     */
    setDistance(distance) {
      this.updateDistance(distance, this.minDistance);
    }
  
    /**
     * Set the minimum distance between clusters. Will be capped at the
     * configured distance.
     * @param {number} minDistance The minimum distance in pixels.
     * @api
     */
    setMinDistance(minDistance) {
      this.updateDistance(this.distance, minDistance);
    }
  
    /**
     * The configured minimum distance between clusters.
     * @return {number} The minimum distance in pixels.
     * @api
     */
    getMinDistance() {
      return this.minDistance;
    }
  
    /**
     * Replace the wrapped source.
     * @param {VectorSource} source The new source for this instance.
     * @api
     */
    setSource(source) {
      if (this.source) {
        this.source.removeEventListener(EventType.CHANGE, this.boundRefresh_);
      }
      this.source = source;
      if (source) {
        source.addEventListener(EventType.CHANGE, this.boundRefresh_);
      }
      this.refresh();
    }
  
    /**
     * Handle the source changing.
     */
    refresh() {
      this.clear();
      this.cluster();
      this.addFeatures(this.features);
    }
  
    /**
     * Update the distances and refresh the source if necessary.
     * @param {number} distance The new distance.
     * @param {number} minDistance The new minimum distance.
     */
    updateDistance(distance, minDistance) {
      const ratio =
        distance === 0 ? 0 : Math.min(minDistance, distance) / distance;
      const changed =
        distance !== this.distance || this.interpolationRatio !== ratio;
      this.distance = distance;
      this.minDistance = minDistance;
      this.interpolationRatio = ratio;
      if (changed) {
        this.refresh();
      }
    }
  
    /**
     * @protected
     */
    cluster() {
      if (this.resolution === undefined || !this.source) {
        return;
      }
      const extent = createEmpty();
      const mapDistance = this.distance * this.resolution;
      const features = this.source.getFeatures();
  
      /** @type {Object<string, true>} */
      const clustered = {};
  
      for (let i = 0, ii = features.length; i < ii; i++) {
        const feature = features[i];
        if (!(getUid(feature) in clustered)) {
          const geometry = this.geometryFunction(feature);
          if (geometry) {
            const coordinates = geometry.getCoordinates();
            createOrUpdateFromCoordinate(coordinates, extent);
            buffer(extent, mapDistance, extent);
  
            const neighbors = this.source
              .getFeaturesInExtent(extent)
              .filter(function (neighbor) {
                const uid = getUid(neighbor);
                if (uid in clustered) {
                  return false;
                }
                clustered[uid] = true;
                return true;
              });
            this.features.push(this.createCluster(neighbors, extent));
          }
        }
      }
    }
  
    /**
     * @param {Array<Feature>} features Features
     * @param {import("../extent.js").Extent} extent The searched extent for these features.
     * @return {Feature} The cluster feature.
     * @protected
     */
    createCluster(features, extent) {
      const centroid = [0, 0];
      for (let i = features.length - 1; i >= 0; --i) {
        const geometry = this.geometryFunction(features[i]);
        if (geometry) {
          addCoordinate(centroid, geometry.getCoordinates());
        } else {
          features.splice(i, 1);
        }
      }
      scaleCoordinate(centroid, 1 / features.length);
      const searchCenter = getCenter(extent);
      const ratio = this.interpolationRatio;
      const geometry = new Point([
        centroid[0] * (1 - ratio) + searchCenter[0] * ratio,
        centroid[1] * (1 - ratio) + searchCenter[1] * ratio,
      ]);
      if (this.createCustomCluster_) {
        return this.createCustomCluster_(geometry, features);
      } else {
        return new Feature({
          geometry,
          features,
        });
      }
    }
  }
  
  export default Cluster;
  