import * as geolib from "geolib";
import { computeSpeed } from "../utils/computeSpeed.ts";
import { generatePerformanceArc } from "../pathGenerators/generatePerformanceArc.ts";

export const TerminatorsDF = (
  leg: DFTerminalEntry,
  previousFix: NavFix,
  lastCourse: number,
  waypoint?: Waypoint
): [NavFix?, LineSegment[]?] => {
  const speed = computeSpeed(leg, previousFix);

  const targetFix: NavFix = {
    latitude: leg.WptLat,
    longitude: leg.WptLon,
    name: waypoint?.Ident ?? undefined,
    isFlyOver: leg.IsFlyOver,
    altitude: leg.Alt ? leg.Alt.parseAltitude() : previousFix.altitude,
    speed: speed,
    speedConstraint: leg.SpeedLimit,
    altitudeConstraint: leg.Alt,
  };

  let line: LineSegment[] = [];

  if (previousFix.isFlyOver) {
    const crsIntoEndpoint = geolib.getGreatCircleBearing(
      previousFix,
      targetFix
    );

    line = generatePerformanceArc(
      crsIntoEndpoint,
      lastCourse,
      previousFix,
      speed,
      leg.TurnDir,
      previousFix.latitude.equal(targetFix.latitude) &&
        previousFix.longitude.equal(targetFix.longitude)
    );
  } else {
    line.push([previousFix.longitude, previousFix.latitude]);
  }

  line.push([targetFix.longitude, targetFix.latitude]);

  return [targetFix, line];
};