map-tools.js

const polygonEvents = ['set_at', 'insert_at', 'remove_at'];
const circleEvents = ['center_changed', 'radius_changed'];
import turfCircle from '@turf/circle';
import { polygon as turfPolygon } from '@turf/helpers';
import { featureToWKT } from './map-utilities';
import { cond, has, hasIn, pipe, path } from 'ramda';

export const setShapeEventListener = (shape, action) => {
  if (shape.radius) {
    circleEvents.forEach(event => {
      shape.addListener(event, action);
    });
  }
  if (shape.getPath) {
    polygonEvents.forEach(event => {
      shape.getPath().addListener(event, action);
    });
  }
  return shape;
};

const closeRing = points => [...points, points[0]];

const pointToArray = point => [point.lng(), point.lat()];

// google polygons are not closed so we use closeRing to make it a proper geoJson feature
const mapsPolygonToFeature = polygon => turfPolygon([closeRing(polygon
  .getPath()
  .getArray()
  .map(pointToArray)
)]);

const mapsCircleToFeature = circle => turfCircle(pointToArray(circle.getCenter()), circle.radius, null, 'meters');

const getFeatureFromGoogleMapsShape = cond([[has('radius'), mapsCircleToFeature], [hasIn('getPath'), mapsPolygonToFeature]]);

export const convertFromGoogleMapsShape = pipe(getFeatureFromGoogleMapsShape, path(['geometry']));

export const getFiltersFromGoogleMapsShape = pipe(getFeatureFromGoogleMapsShape, featureToWKT);

const metersToSquareMiles = meters => (meters / 2589988.11).toPrecision(3);

const getCircleArea = ({ radius }) => metersToSquareMiles(Math.PI * radius * radius);

const getPolygonArea = polygon => metersToSquareMiles(google.maps.geometry.spherical.computeArea(polygon.getPath())); // eslint-disable-line no-undef

export const getShapeArea = cond([[has('radius'), getCircleArea], [hasIn('getPath'), getPolygonArea]]);