fieldcalc-frontend/src/app/calculator/field.service.ts

import {Injectable} from '@angular/core';

import {GeoJSON} from 'ol/format';
import {Geometry, Polygon} from 'ol/geom';
import {Vector as VectorSource} from 'ol/source';
import {getCenter} from 'ol/extent';
import {transform} from 'ol/proj';

import {HsEventBusService, HsMapService} from 'hslayers-ng';

@Injectable({providedIn: 'root'})
export class FieldService {
  fields: VectorSource<Geometry>;
  //TODO: temporarry hard-coded hack
  field1GeoJSON = {
    type: 'Polygon',
    coordinates: [
      [
        [17.008032903697003, 49.259378350222214],
        [17.012346093160815, 49.26055145480218],
        [17.01341275235608, 49.25661998865008],
        [17.01578237120672, 49.251834177355896],
        [17.01243531034079, 49.24966645404407],
        [17.009126895621744, 49.24897297823598],
        [17.003117114964958, 49.253454830509305],
        [17.008032903697003, 49.259378350222214],
      ],
    ],
  };
  //TODO: temporarry hard-coded hack
  field2GeoJSON = {
    type: 'Polygon',
    coordinates: [
      [
        [17.002437217427214, 49.25406053771264],
        [17.007010834533514, 49.25949599987935],
        [17.00652649276053, 49.26616621617807],
        [16.994875655608688, 49.25981844649525],
        [16.995730316423206, 49.257965703041684],
        [17.002437217427214, 49.25406053771264],
      ],
    ],
  };
  //TODO: temporarry hard-coded hack
  field3GeoJSON = {
    type: 'Polygon',
    coordinates: [
      [
        [16.993895078820575, 49.259216136348286],
        [16.994671522235812, 49.257860846173166],
        [17.00155277758227, 49.25349827686348],
        [16.99702124804218, 49.246825312276215],
        [16.993862809154038, 49.243797217302074],
        [16.97947178114977, 49.24513873718192],
        [16.980782403841776, 49.246567855409126],
        [16.980234692917616, 49.251993865297734],
        [16.982332050970445, 49.25428043019449],
        [16.98326065796653, 49.25618643740068],
        [16.99037376067523, 49.25783927642802],
        [16.993895078820575, 49.259216136348286],
      ],
    ],
  };
  selectableLayers = ['Farma'];
  selectedField;

  constructor(
    private hsEventBus: HsEventBusService,
    private hsMapService: HsMapService
  ) {
    this.hsEventBus.vectorQueryFeatureSelection.subscribe((data) => {
      if (
        !this.isValidGeometry(data.feature) ||
        !this.isValidLayer(data.feature)
      ) {
        return;
      }
      this.selectedField = data.feature.getGeometry() as Polygon;
    });
    //TODO: temporary hard-coded hack
    this.fields = new VectorSource({
      features: [
        new GeoJSON().readFeature(this.field1GeoJSON, {
          dataProjection: 'EPSG:4326',
          featureProjection: 'EPSG:5514',
        }),
      ],
    });
    this.fields.addFeatures([
      new GeoJSON().readFeature(this.field2GeoJSON, {
        dataProjection: 'EPSG:4326',
        featureProjection: 'EPSG:5514',
      }),
    ]);
    this.fields.addFeatures([
      new GeoJSON().readFeature(this.field3GeoJSON, {
        dataProjection: 'EPSG:4326',
        featureProjection: 'EPSG:5514',
      }),
    ]);
  }

  noFieldSelected(): boolean {
    return this.selectedField === undefined;
  }

  getCentroidOfField(field: Geometry) {
    return {
      type: 'Point',
      coordinates: transform(
        getCenter(field.getExtent()),
        'EPSG:5514',
        'EPSG:4326'
      ),
    };
  }

  getSelectedFieldCentroid() {
    return this.getCentroidOfField(this.selectedField);
  }

  getSelectedFieldGeoJSON() {
    return {
      type: 'Polygon',
      coordinates: this.selectedField
        .clone()
        .transform('EPSG:5514', 'EPSG:4326')
        .getCoordinates(),
    };
  }

  /**
   * Check whether selected feature geometry type is valid
   * (API expects polygon only)
   */
  isValidGeometry(feature) {
    if (!feature) {
      return false;
    }
    return feature.getGeometry().getType() == 'Polygon';
  }

  /**
   * Check whether user clicked into one of selectable layers
   */
  isValidLayer(feature) {
    const layer = this.hsMapService.getLayerForFeature(feature);
    return this.selectableLayers.includes(layer.get('title'));
  }
}