import {
  Feature,
  LineString,
  Polygon,
  MultiPolygon,
  MultiLineString,
  featureReduce,
  lineIntersect,
  getCoords,
  booleanWithin,
  point,
  polygon,
  featureCollection,
  combine,
  polygonToLine,
  polygonize,
  booleanPointInPolygon,
  pointOnFeature,
} from "@turf/turf";
import * as jsts from "jsts/dist/jsts.es6.js";

function isValidSplitLine(polygon: Feature<Polygon>, line: Feature<LineString>) {
  const intersections = lineIntersect(polygon, line);
  const lineCoords = getCoords(line);
  // 两者不交叉
  if (intersections.features.length === 0) {
    return false;
  }
  // 截断线的起点或终点在封闭多边形的内部
  if (
    booleanWithin(point(lineCoords[0]), polygon) ||
    booleanWithin(point(lineCoords[lineCoords.length - 1]), polygon)
  ) {
    return false;
  }
  return true;
}

export function splitMultiPolygonByLine(feature: Feature<MultiPolygon>, line: Feature<LineString>) {
  const segmentPolygons: Feature<Polygon>[] = [];
  let hasIntersection = false;
  feature.geometry.coordinates.forEach((coordinate) => {
    const _polygon = polygon(coordinate);
    const subtraction = splitPolygonByLine(_polygon, line);
    // 被打断
    if (Array.isArray(subtraction)) {
      hasIntersection = true;
      segmentPolygons.push(...subtraction);
    } else {
      segmentPolygons.push(subtraction);
    }
  });
  const result = combine(featureCollection(segmentPolygons)).features[0] as Feature<MultiPolygon>;
  result.properties = feature.properties;
  console.log(result);
  return hasIntersection ? result : null;
}

export function splitPolygonByLine(
  polygon: Feature<Polygon>,
  line: Feature<LineString>
): Feature<Polygon> | Feature<Polygon>[] {
  const parser = new jsts.io.GeoJSONReader();
  const writer = new jsts.io.GeoJSONWriter();
  if (!isValidSplitLine(polygon, line)) {
    return polygon;
  }

  const polyLine = polygonToLine(polygon) as Feature<LineString>;
  const geom = parser.read(polyLine.geometry);
  const lineGeo = parser.read(line.geometry);
  const multiLine: Feature<MultiLineString> = {
    type: "Feature",
    geometry: writer.write(geom.union(lineGeo)) as MultiLineString,
    properties: {},
  };
  const polygonized = polygonize(multiLine).features.filter((ea) => {
    return booleanPointInPolygon(pointOnFeature(ea), polygon);
  });

  polygonized.forEach((feat) => (feat.properties = polygon.properties));
  return polygonized;
}