/**
 * Coordinate validation and utility functions
 * Ensures coordinates are within valid ranges and handles edge cases
 */

/**
 * Validates if a latitude is within valid range [-90, 90]
 */
export function isValidLatitude(lat: number): boolean {
  return typeof lat === 'number' && !isNaN(lat) && lat >= -90 && lat <= 90;
}

/**
 * Validates if a longitude is within valid range [-180, 180]
 */
export function isValidLongitude(lng: number): boolean {
  return typeof lng === 'number' && !isNaN(lng) && lng >= -180 && lng <= 180;
}

/**
 * Validates if a coordinate pair [lat, lng] is valid
 */
export function isValidCoordinate(lat: number, lng: number): boolean {
  return isValidLatitude(lat) && isValidLongitude(lng);
}

/**
 * Validates and normalizes a coordinate pair
 * Returns null if invalid, otherwise returns normalized [lat, lng]
 */
export function normalizeCoordinate(lat: number, lng: number): [number, number] | null {
  if (!isValidCoordinate(lat, lng)) {
    return null;
  }
  return [lat, lng];
}

/**
 * Checks if a coordinate is within viewport bounds
 */
export function isCoordinateInBounds(
  lat: number,
  lng: number,
  bounds: { north: number; south: number; east: number; west: number }
): boolean {
  if (!isValidCoordinate(lat, lng)) return false;

  // Handle longitude wrapping (e.g., -180 to 180 crossing)
  const lngInBounds =
    (bounds.west <= bounds.east && lng >= bounds.west && lng <= bounds.east) ||
    (bounds.west > bounds.east && (lng >= bounds.west || lng <= bounds.east));

  return lat >= bounds.south && lat <= bounds.north && lngInBounds;
}

/**
 * Calculates distance between two coordinates using Haversine formula
 * Returns distance in kilometers
 */
export function calculateDistance(lat1: number, lng1: number, lat2: number, lng2: number): number {
  if (!isValidCoordinate(lat1, lng1) || !isValidCoordinate(lat2, lng2)) {
    return Infinity;
  }

  const R = 6371; // Earth's radius in km
  const dLat = ((lat2 - lat1) * Math.PI) / 180;
  const dLng = ((lng2 - lng1) * Math.PI) / 180;
  const a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos((lat1 * Math.PI) / 180) *
      Math.cos((lat2 * Math.PI) / 180) *
      Math.sin(dLng / 2) *
      Math.sin(dLng / 2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  return R * c;
}