Program Sunday;
{Jarmo Lammi 13.1.94
 Sunrise and Sunset timest}

USES CRT,DOS;
CONST tz = 2;

wocht: array[0..6] of string =
('Sunday','Monday', 'Tuesday','Wednesday','Thursday','Friday','Saturday');

DayTime: Array[0..3] of String =
('Morning','Day','Evening','Night');

VAR dgr:    CHAR;
vv,kk,pp,vd:      WORD;
hr,mn,sc,tc:      Word;
inlat,inlon,tzone: Real;

FUNCTION TAN(x:real):real;

BEGIN TAN:=SIN(x)/COS(x) END;

FUNCTION hhmm(h:real):string;

{Converting decimal hours HH.HH to string HH:MM}

VAR frac: REAL;
hr,mn: INTEGER;
hrs,mns: STRING[2];
BEGIN
hr:=TRUNC(h) ; frac:=h-hr;
mn:=TRUNC(60*frac+0.5);
STR(hr,hrs) ; IF hr<10 THEN hrs:='0'+hrs;
STR(mn,mns) ; IF mn<10 THEN mns:='0'+mns;
hhmm:=hrs+':'+mns;
END;              {hhmm}

PROCEDURE SunUpDown(lat:real;lon:real);
{Sunrise and Sunset times}
CONST DayOffs = 10.0;
      HoCor   = 0.033;
MDays: array[1..12] of Integer =
(31,28,31,30,31,30,31,31,30,31,30,12);

VAR dekl,fo,Nousu,Lasku:real;
    DayNr,j:              Integer;

BEGIN
     lon:=-lon; lat:=pi*lat/180;
     DayNr:=0;

for j:= 1 to kk-1 do DayNr:=DayNr+MDays[j];

    DayNr:= DayNr+pp;

dekl:=-23.5*COS(pi/180*(DayOffs+0.988*DayNr));
fo:=TAN(pi/180*dekl)*TAN(lat-HoCor);
IF fo>1 THEN Writeln('Sun will not set today !');
IF fo<-1 THEN Writeln('Sun will not rise today!');
fo:=pi/2-ARCTAN(fo/SQRT(1-fo*fo));
fo:=fo/(pi/180);

Nousu:=(lon/15)+(fo/15)+tzone;
IF Nousu>24 THEN Nousu:=Nousu-24;
IF Nousu<0  THEN Nousu:=Nousu+24;

Lasku:=(lon/15)-(fo/15)+tzone;
IF Lasku>24 THEN Lasku:=Lasku-24;
IF Lasku<0  THEN Lasku:=Lasku+24;
GoToXY(15,7);
Write('Sunrise:  ',hhmm(Nousu));
GoToXY(15,8);
Write('Sunset:   ',hhmm(Lasku));
GoToXY(15,10);
Write('Day number:   ',DayNr);
End; {SunUpDown}

Procedure TellCoord(lat:Real; Lon:Real);
Begin
     GoToXY(15,4);
     Write('Latitude:  ',lat:6:2,dgr);
     GoToXY(15, 5);
     Write('Longitude: ',lon:6:2,dgr);
     SunUpDown(lat,lon);
END;      {TellCoord}

Procedure Kehys;
VAR j: Word;
Begin
     ClrScr;
     Write(#201);
     For j:= 2 to 40 do
         Write(#205);
     Write(#187);
     GoToXY(1,15);
     Write(#200);
     For j:= 2 to 40 do
         Write(#205);
     Write(#188);
End;

Begin   {MAIN}
        dgr:=CHR(248);      {degree character}
        TextBackGround(Blue); TextColor(White); ClrScr;
        write('Input Latitude  [S  -90 ... 0 ...  +90 N ] ');
        readln(inlat);
        write('Input longitude [W -180 ... 0 ... +180 E ] ');
        readln(inlon);
        write('Input timezone  [ -12 h ... GMT 0 ... +12 h] ');
        readln(tzone);
        ClrScr;
        Window(10,5,51,19);
        TextBackGround(White);
        TextColor(Black);
        ClrScr; Kehys;
        GetDate(VV,KK,PP,VD);
        TellCoord(inlat,inlon);
        GoToXY(15,11);
        Write('Date: ',pp,'.',kk,'. ',vv);
        GoToXY(15,12);
        Write(wocht[vd]);
        GetTime(hr,mn,sc,tc);
        GoToXY(15,2);
        Write('Good ',DayTime[hr div 6],' !');
        GoToXY(15,14);
        Write('Time ',hr,':',mn,':',sc);
End.