import type { Coordinates, Kilometer } from "@thorium/utils/unitTypes";
import { Vector3 } from "three";

const dirVector1 = new Vector3();
const dirVector2 = new Vector3();
const HELIOPAUSE_DISTANCE_KM: Kilometer = 20_000_000_000;

export function getWaypointRelativePosition(
	entityPosition: Coordinates<number>,
	entitySystem: number | null,
	entitySystemPosition: Coordinates<number> | null,
	playerSystemPosition: Coordinates<number> | null,
	playerSystem: number | null,
	waypointVector: Vector3,
) {
	if (entitySystem === playerSystem && entityPosition) {
		// They are in the same system, or they are both in interstellar space
		waypointVector.set(entityPosition.x, entityPosition.y, entityPosition.z);
	} else {
		// Either the ship is in interstellar space, the waypoint is in interstellar space, or the waypoint is in a different system.
		if (playerSystem === null && entitySystemPosition) {
			// The ship is in interstellar space
			// Just use the waypoint's interstellar position
			waypointVector.set(entitySystemPosition.x, entitySystemPosition.y, entitySystemPosition.z);
		} else if (entitySystemPosition && playerSystemPosition) {
			// The waypoint is in a different system or
			// The waypoint is in interstellar space
			// Position the waypoint such that it is at a distant point along the vector
			// from this system's position to the waypoint's interstellar position
			dirVector1.set(playerSystemPosition.x, playerSystemPosition.y, playerSystemPosition.z);
			dirVector2.set(entitySystemPosition.x, entitySystemPosition.y, entitySystemPosition.z);
			waypointVector
				.subVectors(dirVector2, dirVector1)
				.normalize()
				.multiplyScalar(HELIOPAUSE_DISTANCE_KM);
		} else {
			console.error("For some reason, we do not have positions for placing a waypoint");
		}
	}
}