Type Airport
    nombre As String
    location As String
    ICAO As String
    dist As Double
    bearing As Integer
End Type

#define MAX_AIRPORTS  21
#define PI  3.1415926535897932

Dim Shared db(MAX_AIRPORTS) As Airport
Dim Shared DME As Double, TOHDG As Double

Function DegToRad(degrees As Double) As Double
    Return degrees * PI / 180
End Function

Function RoundIt(theNum As Double, theDec As Integer) As Double
    Return Fix(theNum * (10 ^ theDec) + 0.5) / (10 ^ theDec)
End Function

Function DistanceGC(lat1 As Double, lon1 As Double, lat2 As Double, lon2 As Double) As Double
    Dim As Double Dm, ER, dLat, dLon, a, c

    ER = 6371.0 'Earth's mean radius in km
    dLat = DegToRad(lat2) - DegToRad(lat1)
    dLon = DegToRad(lon2) - DegToRad(lon1)
    a = Sin(dLat / 2) * Sin(dLat / 2) + Cos(DegToRad(lat1)) * Cos(DegToRad(lat2)) * Sin(dLon / 2) * Sin(dLon / 2)
    c = 2 * Atan2(Sqr(a), Sqr(1 - a))
    Dm = ER * c / 1.852

    Return Dm
End Function

Function Bearing(lat1 As Double, lon1 As Double, lat2 As Double, lon2 As Double) As Double
    Dim As Double lat1Rad = DegToRad(lat1)
    Dim As Double lat2Rad = DegToRad(lat2)
    Dim As Double dLon = DegToRad(lon2 - lon1)
    Dim As Double y = Sin(dLon) * Cos(lat2Rad)
    Dim As Double x = Cos(lat1Rad) * Sin(lat2Rad) - Sin(lat1Rad) * Cos(lat2Rad) * Cos(dLon)

    Return (Atan2(y, x) * 180/PI + 360) Mod 360
End Function

Sub Insert(ap As Airport)
    Dim n As Integer = MAX_AIRPORTS - 1
    If ap.dist >= db(n).dist Then Exit Sub
    While ap.dist < db(n).dist Andalso n > 0
        db(n + 1) = db(n)
        n -= 1
    Wend
    db(n + 1) = ap
End Sub

Sub Test(lat2 As Double, lon2 As Double)
    Static As Double lat1 = 51.514669, lon1 = 2.198581 'Rosetta coordinates
    DME = DistanceGC(lat1, lon1, lat2, lon2)
    DME = RoundIt(DME, 1)
    TOHDG = Bearing(lat1, lon1, lat2, lon2)
    TOHDG = RoundIt(TOHDG, 0)
End Sub

Function IsValidNumber(s As String) As Integer
    Return (Val(s) <> 0 Or s = "0")
End Function

Function ReadAirportFile() As Integer
    Dim As String linea, campo, c
    Dim As Airport ap
    Dim As Integer i, j, inQuotes

    Open "Airport-data.csv" For Input As #1
    If Err Then Print "Error opening file": Return 0

    While Not Eof(1)
        Line Input #1, linea
        If Len(linea) = 0 Then Continue While

        Dim fields(15) As String
        i = 0
        campo = ""
        inQuotes = 0

        For j = 1 To Len(linea)
            c = Mid(linea, j, 1)
            Select Case c
            Case """"
                inQuotes = Not inQuotes
            Case ","
                If Not inQuotes Then
                    If i < Ubound(fields) Then
                        fields(i) = campo
                        i += 1
                        campo = ""
                    End If
                Else
                    campo &= c
                End If
            Case Else
                If c <> """" Then campo &= c
            End Select
        Next

        If i <= Ubound(fields) Then fields(i) = campo

        If i >= 7 Then
            If IsValidNumber(fields(6)) And IsValidNumber(fields(7)) Then
                'Process the fields
                Test(Val(fields(6)), Val(fields(7)))
                ap.nombre = Trim(fields(1))
                ap.location = Trim(fields(2)) & ", " & Trim(fields(3))
                ap.ICAO = Trim(fields(5))
                ap.dist = DME
                ap.bearing = TOHDG
                Insert(ap)
            End If
        End If
    Wend

    Close #1
    Return 1
End Function

'Main program
Dim i As Integer

'Initialize distances
For i = 0 To MAX_AIRPORTS
    db(i).dist = 99999
Next

If ReadAirportFile() Then
    Print "AIRPORT/COUNTRY"; Tab(39); "ICAO"; Tab(46); "DISTANCE  BEARING"
    Print String(62, "-")

    For i = 1 To MAX_AIRPORTS - 1
        With db(i)
            Print Left(.nombre & Space(38), 38)
            Print Left(.location & Space(38), 38);
            Print Left(.ICAO & Space(5), 5); Spc(6);
            Print Using "##.#     ###"; .dist; .bearing;
            Print Chr(248); Chr(10)
        End With
    Next
End If

Sleep