map.utils.ts

import * as geojson from 'geojson';
import * as L from 'leaflet';

import {Location} from '../nshmp-lib/geo';
import {MapBaseLayer} from './map-baselayer.model';

/** Location transform */
export type LocationTransform = (location: Location) => Location;

/**
 * Esri raster base layers for Leaflet.
 *
 * https://doc.arcgis.com/en/data-appliance/latest/maps/directory-maps-data.htm
 */
export function baseLayers(): Record<MapBaseLayer, L.TileLayer> {
  const baseLayers: Record<MapBaseLayer, L.TileLayer> = {
    /* Esri world hillshade */
    [MapBaseLayer.HILLSHADE]: L.tileLayer(
      `${ARCGIS_URL_START}Elevation/World_Hillshade${ARCGIS_URL_END}`,
      {
        ...OPTIONS,
        attribution:
          'Esri, USGS, NGA, NASA, CGIAR, N Robinson, NCEAS, NLS, OS, NMA, ' +
          'Geodatastyrelsen, Rijkswaterstaat, GSA, Geoland, FEMA, Intermap, ' +
          'and the GIS user community',
        id: MapBaseLayer.HILLSHADE,
      }
    ),
    /* Esri world hillshade */
    [MapBaseLayer.HILLSHADE_DARK]: L.tileLayer(
      `${ARCGIS_URL_START}Elevation/World_Hillshade_Dark${ARCGIS_URL_END}`,
      {
        ...OPTIONS,
        attribution:
          'Esri, USGS, NGA, NASA, CGIAR, N Robinson, NCEAS, NLS, OS, NMA, ' +
          'Geodatastyrelsen, Rijkswaterstaat, GSA, Geoland, FEMA, Intermap, ' +
          'and the GIS user community',
        id: MapBaseLayer.HILLSHADE_DARK,
      }
    ),
    /* Esri world ocean */
    [MapBaseLayer.OCEAN]: L.tileLayer(
      `${ARCGIS_URL_START}Ocean/World_Ocean_Base${ARCGIS_URL_END}`,
      {
        ...OPTIONS,
        attribution: 'Esri, Garmin, GEBCO, NOAA NGDC, and other contributors',
        id: MapBaseLayer.OCEAN,
        maxZoom: 10,
      }
    ),
    /* Esri world physical map */
    [MapBaseLayer.PHYSICAL]: L.tileLayer(
      `${ARCGIS_URL_START}World_Physical_Map${ARCGIS_URL_END}`,
      {
        ...OPTIONS,
        attribution: 'U.S. National Park Service',
        id: MapBaseLayer.PHYSICAL,
        maxZoom: 8,
      }
    ),
    [MapBaseLayer.SATELLITE]: L.tileLayer(
      `${ARCGIS_URL_START}World_Imagery${ARCGIS_URL_END}`,
      {
        ...OPTIONS,
        attribution:
          'Esri, Maxar, Earthstar Geographics, and the GIS User Community',
        id: MapBaseLayer.SATELLITE,
      }
    ),
    [MapBaseLayer.USGS_TOPO]: L.tileLayer(
      'https://basemap.nationalmap.gov/arcgis/rest/services/USGSTopo/MapServer/tile/{z}/{y}/{x}',
      {
        ...OPTIONS,
        attribution: `Esri, USGS | Esri, TomTom, FAO, NOAA, USGS | USGS The National Map: National Boundaries
       Dataset, 3DEP Elevation Program, Geographic Names Information System, National Hydrography
       Dataset, National Land Cover Database, National Structures Dataset, and National
       Transportation Dataset; USGS Global Ecosystems; U.S. Census Bureau TIGER/Line data;
       USFS Road data; Natural Earth Data; U.S. Department of State HIU; NOAA National
       Centers for Environmental Information. Data refreshed February, 2025.`,
        id: MapBaseLayer.USGS_TOPO,
      }
    ),
  };

  return baseLayers;
}

/**
 * Returns a specific Esri raster base layer.
 */
export function baseLayer(baseLayer: MapBaseLayer): L.TileLayer {
  return baseLayers()[baseLayer];
}

/**
 * Transform coordinates in a Feature Collection.
 *
 * @param featureCollection The feature collection
 * @param transform The transform function to use
 */
export function transformCoordinates(
  featureCollection: geojson.FeatureCollection,
  transform: LocationTransform = loc => loc
): geojson.FeatureCollection {
  for (const feature of featureCollection.features) {
    const geometry = feature.geometry;

    switch (geometry.type) {
      case 'LineString': {
        geometry.coordinates = geometry.coordinates.map(coord =>
          transformCoordinate(coord, transform)
        );
        break;
      }
      case 'MultiLineString': {
        geometry.coordinates = geometry.coordinates.map(position =>
          position.map(coord => transformCoordinate(coord, transform))
        );
        break;
      }
      case 'MultiPoint': {
        geometry.coordinates = geometry.coordinates.map(coord =>
          transformCoordinate(coord, transform)
        );
        break;
      }
      case 'MultiPolygon': {
        geometry.coordinates = geometry.coordinates.map(positions =>
          positions.map(position =>
            position.map(coord => transformCoordinate(coord, transform))
          )
        );
        break;
      }
      case 'Point': {
        geometry.coordinates = transformCoordinate(
          geometry.coordinates,
          transform
        );
        break;
      }
      case 'Polygon': {
        geometry.coordinates = geometry.coordinates.map(position =>
          position.map(coord => transformCoordinate(coord, transform))
        );
        break;
      }
    }
  }

  return featureCollection;
}

const ARCGIS_URL_START =
  'https://services.arcgisonline.com/arcgis/rest/services/';
const ARCGIS_URL_END = '/MapServer/tile/{z}/{y}/{x}';
const OPTIONS: L.MapOptions = {
  maxZoom: 16,
};

function transformCoordinate(
  coordinates: number[],
  transform: LocationTransform
): number[] {
  const longitude = coordinates[0];
  const latitude = coordinates[1];

  const location = transform({
    latitude,
    longitude,
  });

  return [location.longitude, location.latitude];
}