using System;

namespace TINK.Model
{
	public class Position : IPosition
	{
		private const double PRECISSION_LATITUDE_LONGITUDE = 0.000000000000001;

		internal Position(double latitude, double longitude)
		{
			if (!GetIsValid(latitude, longitude))
				throw new ArgumentNullException();

			Latitude = latitude;
			Longitude = longitude;
		}

		public double Latitude { get; private set; }

		public double Longitude { get; private set; }


		/// <summary>
		/// Compares position with a target position.
		/// </summary>
		/// <param name="target">Target position to compare with.</param>
		/// <returns>True if positions are equal.</returns>
		public override bool Equals(object target)
		{
			if (!(target is IPosition targetPosition))
				return false;

			return GetEquals(this, targetPosition);
		}

		public bool Equals(IPosition other)
			=> (other is Position position) && position.Equals(this as object);

		public override int GetHashCode()
		{
			var hashCode = -1416534245;
			hashCode = hashCode * -1521134295 + Latitude.GetHashCode();
			hashCode = hashCode * -1521134295 + Longitude.GetHashCode();
			return hashCode;
		}

		public bool IsValid => GetIsValid(Latitude, Longitude);

		public static bool GetEquals(IPosition source, IPosition target)
		{
			if (source == null || target == null)
				return source == null ^ target == null;

			if (!source.IsValid || !target.IsValid)
				return !source.IsValid ^ !target.IsValid;

			return Math.Abs(source.Latitude - target.Latitude) < PRECISSION_LATITUDE_LONGITUDE
				&& Math.Abs(source.Longitude - target.Longitude) < PRECISSION_LATITUDE_LONGITUDE;
		}

		public static bool GetIsValid(double latitude, double longitude)
			=> !double.IsNaN(latitude) && !double.IsNaN(longitude);
	}
}