import Map from 'ol/Map';
import View from 'ol/View';
import GeoJSON from 'ol/format/GeoJSON';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {fromLonLat} from 'ol/proj';
import OSM from 'ol/source/OSM';
import VectorSource from 'ol/source/Vector';
import LinearRing from 'ol/geom/LinearRing';
import {Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon} from 'ol/geom';

const source = new VectorSource();
fetch('data/geojson/roads-seoul.geojson').then(function(response) {
  return response.json();
}).then(function(json) {
  const format = new GeoJSON();
  const features = format.readFeatures(json, {featureProjection: 'EPSG:3857'});

  const parser = new jsts.io.OL3Parser();
  parser.inject(Point, LineString, LinearRing, Polygon, MultiPoint, MultiLineString, MultiPolygon);

  for (let i = 0; i < features.length; i++) {
    const feature = features[i];
    // convert the OpenLayers geometry to a JSTS geometry
    const jstsGeom = parser.read(feature.getGeometry());

    // create a buffer of 40 meters around each line
    const buffered = jstsGeom.buffer(40);

    // convert back from JSTS and replace the geometry on the feature
    feature.setGeometry(parser.write(buffered));
  }

  source.addFeatures(features);
});
const vectorLayer = new VectorLayer({
  source: source
});

const rasterLayer = new TileLayer({
  source: new OSM()
});

const map = new Map({
  layers: [rasterLayer, vectorLayer],
  target: document.getElementById('map'),
  view: new View({
    center: fromLonLat([126.979293, 37.528787]),
    zoom: 15
  })
});