Mini Kabibi Habibi

Imports Microsoft.VisualBasic
Imports System

Namespace ControlsDemo
	Public NotInheritable Class SunCalculatior
		' Algorithm source:
		' Almanac for Computers, 1990
		' published by Nautical Almanac Office
		' United States Naval Observatory
		' Washington, DC 20392

		Private Const Zenith As Double = 90.83

		Private Sub New()
		End Sub
		Public Shared Function SunRise(ByVal [date] As DateTime, ByVal utcOffset As Double, ByVal lat As Double, ByVal lon As Double) As DateTime?
			Return Calculate([date], utcOffset, lat, lon, True)
		End Function
		Public Shared Function SunSet(ByVal [date] As DateTime, ByVal utcOffset As Double, ByVal lat As Double, ByVal lon As Double) As DateTime?
			Return Calculate([date], utcOffset, lat, lon, False)
		End Function
		Private Shared Function Calculate(ByVal [date] As DateTime, ByVal utcOffset As Double, ByVal lat As Double, ByVal lon As Double, ByVal rise As Boolean) As DateTime?
			Dim N As Integer = [date].DayOfYear

			Dim lonHour As Double = lon / 15.0

			Dim t As Double = If(rise, N + ((6.0 - lonHour) / 24.0), N + ((18.0 - lonHour) / 24.0))

			Dim M As Double = (0.9856 * t) - 3.289

			Dim L As Double = M + (1.916 * Math.Sin(DegToRad(M))) + (0.020 * Math.Sin(DegToRad(2.0 * M))) + 282.634
			L = ToRange(L, 0, 360)

			Dim RA As Double = RadToDeg(Math.Atan(0.91764 * Math.Tan(DegToRad(L))))
			RA = ToRange(RA, 0, 360)

			Dim Lquadrant As Double = (Math.Floor(L / 90.0)) * 90.0
			Dim RAquadrant As Double = (Math.Floor(RA / 90.0)) * 90.0
			RA = RA + (Lquadrant - RAquadrant)

			RA = RA / 15.0

			Dim sinDec As Double = 0.39782 * Math.Sin(DegToRad(L))
			Dim cosDec As Double = Math.Cos(Math.Asin(sinDec))

			Dim cosH As Double = (Math.Cos(DegToRad(Zenith)) - (sinDec * Math.Sin(DegToRad(lat)))) / (cosDec * Math.Cos(DegToRad(lat)))

			If cosH > 1.0 OrElse cosH < -1.0 Then
				Return Nothing
			End If

			Dim H As Double = If(rise, 360.0 - RadToDeg(Math.Acos(cosH)), RadToDeg(Math.Acos(cosH)))

			H = H / 15.0

			Dim T_Renamed As Double = H + RA - (0.06571 * t) - 6.622

			Dim UT As Double = T_Renamed - lonHour

			UT += utcOffset

			UT = ToRange(UT, 0, 24)

			Return [date].Date.AddSeconds(Math.Round(UT * 3600.0))
		End Function
		Private Shared Function DegToRad(ByVal angle As Double) As Double
			Return angle * Math.PI / 180.0
		End Function
		Private Shared Function RadToDeg(ByVal angle As Double) As Double
			Return angle * 180.0 / Math.PI
		End Function
		Private Shared Function ToRange(ByVal value As Double, ByVal min As Double, ByVal max As Double) As Double
			Dim range As Double = max - min
			Do While value < min
				value += range
			Loop
			Do While value >= max
				value -= range
			Loop
			Return value
		End Function
	End Class
End Namespace