// utils.js - Utility functions for coordinate conversion

import * as THREE from 'three';

import { CONFIG } from './constants.js';

// Convert latitude/longitude to 3D vector
export function latLonToVector3(lat, lon, radius = CONFIG.earthRadius) {
  const phi = (90 - lat) * (Math.PI / 180);
  const theta = (lon + 180) * (Math.PI / 180);

  const x = -(radius * Math.sin(phi) * Math.cos(theta));
  const z = radius * Math.sin(phi) * Math.sin(theta);
  const y = radius * Math.cos(phi);

  return new THREE.Vector3(x, y, z);
}

// Convert 3D vector to latitude/longitude
export function vector3ToLatLon(vector) {
  const radius = Math.sqrt(vector.x * vector.x + vector.y * vector.y + vector.z * vector.z);
  const lat = 90 - (Math.acos(vector.y / radius) * 180 / Math.PI);
  const lon = (Math.atan2(vector.z, -vector.x) * 180 / Math.PI) - 180;

  return {
    lat: parseFloat(lat.toFixed(4)),
    lon: parseFloat(lon.toFixed(4)),
    alt: radius - CONFIG.earthRadius
  };
}

// Convert screen coordinates to Earth surface 3D coordinates
export function screenToEarthCoords(x, y, camera, earth) {
  const raycaster = new THREE.Raycaster();
  const mouse = new THREE.Vector2(
    (x / window.innerWidth) * 2 - 1,
    -(y / window.innerHeight) * 2 + 1
  );

  raycaster.setFromCamera(mouse, camera);
  const intersects = raycaster.intersectObject(earth);

  if (intersects.length > 0) {
    return intersects[0].point;
  }

  return null;
}

// Calculate simplified distance between two points
export function calculateDistance(lat1, lon1, lat2, lon2) {
  const dx = lon2 - lon1;
  const dy = lat2 - lat1;
  return Math.sqrt(dx * dx + dy * dy);
}