import { geoInterpolate } from 'd3-geo';
import type { ArcConfig, ControlPoints } from '../types/arc';
import { calculateVec3FromLatLon } from './threejs';

export default function calculateArcControlPoints(config: ArcConfig): ControlPoints {
  const startCoords = {
    lon: config.startLocation.geometry.coordinates[0],
    lat: config.startLocation.geometry.coordinates[1],
  };

  const endCoords = {
    lon: config.endLocation.geometry.coordinates[0],
    lat: config.endLocation.geometry.coordinates[1],
  };

  const startVec3 = calculateVec3FromLatLon(startCoords.lat, startCoords.lon, 600);
  const endVec3 = calculateVec3FromLatLon(endCoords.lat, endCoords.lon, 600);
  const arcHeight = startVec3.distanceTo(endVec3) * config.height! + 600;

  const interpolate = geoInterpolate(
    [startCoords.lon, startCoords.lat],
    [endCoords.lon, endCoords.lat],
  );

  const midCoords = {
    start: interpolate(0.25),
    end: interpolate(0.75),
  };

  const midStartVec3 = calculateVec3FromLatLon(
    midCoords.start[1],
    midCoords.start[0],
    arcHeight,
  );
  const midEndVec3 = calculateVec3FromLatLon(
    midCoords.end[1],
    midCoords.end[0],
    arcHeight,
  );

  return {
    start: startVec3,
    midStart: midStartVec3,
    midEnd: midEndVec3,
    end: endVec3,
  };
}