demarches-normaliennes/app/javascript/components/shared/maplibre/utils.ts

import type { LngLat, LngLatLike, LngLatBoundsLike } from 'maplibre-gl';
import type { Geometry, FeatureCollection, Feature } from 'geojson';
import { LngLatBounds } from 'maplibre-gl';
import invariant from 'tiny-invariant';

export function getBounds(geometry: Geometry): LngLatBoundsLike {
  const bbox = new LngLatBounds();

  if (geometry.type === 'Point') {
    return [geometry.coordinates, geometry.coordinates] as [
      [number, number],
      [number, number]
    ];
  } else if (geometry.type === 'LineString') {
    for (const coordinate of geometry.coordinates) {
      bbox.extend(coordinate as [number, number]);
    }
  } else {
    invariant(
      geometry.type != 'GeometryCollection',
      'GeometryCollection not supported'
    );
    for (const coordinate of geometry.coordinates[0]) {
      bbox.extend(coordinate as [number, number]);
    }
  }
  return bbox;
}

export function findFeature<G extends Geometry>(
  featureCollection: FeatureCollection<G>,
  value: unknown,
  property = 'id'
): Feature<G> | null {
  return (
    featureCollection.features.find(
      (feature) => feature.properties && feature.properties[property] === value
    ) ?? null
  );
}

export function filterFeatureCollection<G extends Geometry>(
  featureCollection: FeatureCollection<G>,
  source: string
): FeatureCollection<G> {
  return {
    type: 'FeatureCollection',
    features: featureCollection.features.filter(
      (feature) => feature.properties?.source === source
    )
  };
}

export function filterFeatureCollectionByGeometryType<G extends Geometry>(
  featureCollection: FeatureCollection<G>,
  type: Geometry['type']
): FeatureCollection<G> {
  return {
    type: 'FeatureCollection',
    features: featureCollection.features.filter(
      (feature) => feature.geometry.type === type
    )
  };
}

export function generateId(): string {
  return Math.random().toString(20).substring(2, 6);
}

export function getCenter(geometry: Geometry, lngLat: LngLat): LngLatLike {
  const bbox = new LngLatBounds();

  invariant(
    geometry.type != 'GeometryCollection',
    'GeometryCollection not supported'
  );

  switch (geometry.type) {
    case 'Point':
      return [...geometry.coordinates] as [number, number];
    case 'LineString':
      return [lngLat.lng, lngLat.lat];
    default:
      for (const coordinate of geometry.coordinates[0]) {
        bbox.extend(coordinate as [number, number]);
      }
      return bbox.getCenter();
  }
}