using System;
using System.Collections.Generic;
using System.Text;

namespace SmartieLc
{
	public class LCDSmartie
	{
		protected const double LAT = [LAT];
		protected const double LON = [LON];
		protected const double ZENITH = 90.83333;

		public string function1(string a, string b)
		{
			DateTime sunset = Sunset(DateTime.Now);

			if (DateTime.Compare(sunset, DateTime.Now) < 0)
				sunset = Sunset(new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day + 1));

			//doing this subtraction returns a TimeSpan object, whose ToString method I call
			return (sunset - DateTime.Now).ToString();

		}

		public DateTime Sunset(DateTime date)
		{
			int dayOfYear = date.DayOfYear;

			double tApprox = dayOfYear + ((18 - LON / 15) / 24);

			double meanAnomaly = (0.9856 * tApprox) - 3.289;

			double sunTrueLon = meanAnomaly + (1.916 * Sin(meanAnomaly)) + (0.020 * Sin(2 * meanAnomaly)) + 282.634;

			if (sunTrueLon > 360) while (sunTrueLon > 360) sunTrueLon -= 360;
			if (sunTrueLon < 0) while (sunTrueLon < 0) sunTrueLon += 360;

			double rightAscension = Atan(0.91764 * Tan(sunTrueLon));

			if (rightAscension > 360) while (rightAscension > 360) rightAscension -= 360;
			if (rightAscension < 0) while (rightAscension < 0) rightAscension += 360;

			rightAscension = rightAscension + 90 * (Math.Floor(sunTrueLon / 90) - Math.Floor(rightAscension / 90));

			rightAscension = rightAscension / 15;

			double sinDec = .39782 * Sin(sunTrueLon);
			double cosDec = Cos(Asin(sinDec));

			double cosHour = (Cos(ZENITH) - sinDec * Sin(LAT)) / (cosDec * Cos(LAT));

			double hour = Acos(cosHour) / 15;

			double time = hour + rightAscension - (0.06571 * tApprox) - 6.622;

			time = time - LON / 15;
			time -= 7;

			while (time < 0) time += 24;
			while (time > 24) time -= 24;

			DateTime sunset = new DateTime(date.Year, date.Month, date.Day, (int)time, (int)((time - (int)time) * 60), 0);

			return sunset;
		}

		private double Sin(double degrees)
		{
			return Math.Sin(Math.PI / 180 * degrees);
		}

		private double Cos(double degrees)
		{
			return Math.Cos(Math.PI / 180 * degrees);
		}

		private double Tan(double degrees)
		{
			return Math.Tan(Math.PI / 180 * degrees);
		}

		private double Atan(double x)
		{
			return 180 / Math.PI * Math.Atan(x);
		}

		private double Acos(double x)
		{
			return 180 / Math.PI * Math.Acos(x);
		}

		private double Asin(double x)
		{
			return 180 / Math.PI * Math.Asin(x);
		}
	}
}