; 
;Function: 
; fnDateDiff() 
; 
;Author: 
; Christopher Shilt (gk_zone@hotmail.com) 
; 
;Contributors: 
; Jochen Polster (jochenDOTpolsterATgmxDOTnet)
; 
;Version: 
; 1.0 (October 3, 2006) 
; 
;Version History: 
; 
;Action: 
; Calculates a specified interval between two dates or returns the date/time difference
; of a specified interval.
; 
;Syntax: 
; fnLDAPQuery(DATE1, [DATE2|INTEGER], [INTERVAL], [FIX]) 
; 
;Parameters: 
; DATE1          : Required. Gregorian datetime in YYYY/M[M]/D[D] [HH:MM:SS] format.
;                  Note: Time is not required, if omitted 00:00:00 (midnight) will be
;                  used.
; 
; DATE2|INTERVAL : Optional. Gregorian datetime in YYYY/M[M]/D[D] [HH:MM:SS] format or
;                  positive or negative integer to add to DATE1.
; 
; INTERVAL       : Optional. Type of interval to add to DATE1. Supported formats are:
; 
;                  S : Seconds
;                  M : Minutes
;                  H : Hours
;                  D : Days
;                  W : Weeks
;
; FIX            : Optional. Removes the fractional part of number and returns the 
;                  resulting integer value.
; 
;Remarks:  
; 
; Based on date algorithms by Peter Baum (http://www.capecod.net/~pbaum/date/date0.htm)
; 
;Returns: 
; 
; A Datetime string or the difference (positive or negative) between two given datetimes.
; 
; Sets the value of @ERROR based on success/failure. 
;         
;Dependencies: 
;  
;  
;Example: 
; 
; "One second after midnight: " + fnDateDiff(@DATE,1,"s") ?
; "One second before midnight: " + fnDateDiff(@DATE,-1,"s") ?
; "Seconds between today and tomorrow: " + fnDateDiff(@DATE,fnDateDiff(@DATE,1,"d"),"s",0) ?
; "Weeks between today and six days from today: " + fnDateDiff(@DATE,fnDateDiff(@DATE,6,"d"),"w",0) ?
; "Weeks (fixed) between today and six days from today: " + fnDateDiff(@DATE,fnDateDiff(@DATE,6,"d"),"w",1) ?
; "Shopping days until my birthday: " + fnDateDiff(@DATE,"2006/04/20","d") ?
; "Seconds between 1/1/1601 and 1/1/1970: " + fnDateDiff("1601/01/01","1970/01/01","s") ?
; "Hours between NOW and 9/18/2005 13:00: " + fnDateDiff(@DATE+' '+@TIME,"2005/09/18 13:00:00","h") ?
; "Hours between 9/18/2005 13:00 and NOW: " + fnDateDiff("2005/09/18 13:00:00",@DATE+' '+@TIME,"h") ?
; "Yesterday's date: " + fnDateDiff(@DATE,-1,"d") ?
; "Seconds between midnight and 11:59:59 pm: " + fnDateDiff("00:00:00","23:59:59","s") ?
; "Seconds between 11:59:59 pm and midnight: " + fnDateDiff("23:59:59","00:00:00","s") ?
; "Add one minute to midnight: " + fnDateDiff("00:00:00",1,"m",0) ?
; "VarTypeName of fnDateDiff output: " + VarTypeName(fnDateDiff(@TIME,0,"s")) ?
; "VarTypeName of @@TIME: " + VarTypeName(@TIME) ?
; Get $
; 
 
Function fnDateDiff($DateTime,Optional $DateOrInterval,$Interval,$Fix)
   Dim $DATE1,$Date2,$jDate[2],$jTime[2],$y,$m,$d,$ss,$mm,$hh,$i
   $DATE1=Split($DateTime," ")
   If UBound($DATE1)>1 Exit 1901 EndIf
   If UBound($DATE1)=0
      Select
      Case InStr($DATE1[0],"/") $jDate=Split($DATE1[0],"/")
      Case InStr($DATE1[0],":")
         $jDate=Split("1899/12/30","/")
         $jTime=Split($DATE1[0],":")
      Case 1 Exit 1901
      EndSelect
   Else
      If InStr($DATE1[0],"/") and InStr($DATE1[1],":")
         $jDate=Split($DATE1[0],"/") 
         $jTime=Split($DATE1[1],":")
      Else
         Exit 1901
      EndIf
   EndIf
   $y=Val($jDate[0]) If $y=0 Exit 1901 EndIf
   $m=Val($jDate[1]) If $m<1 or $m>12 Exit 1901 EndIf
   $d=Val($jDate[2]) If $d<1 or $d>31 Exit 1901 EndIf
   If $m < 3 $m=$m+12 $y=$y-1 EndIf
   $jDate = CDbl($d+(153*$m-457)/5+365*$y+$y/4-$y/100+$y/400-306)
   $jTime = CDbl((Val($jTime[0])*3600)+(Val($jTime[1])*60)+Val($jTime[2]))/86400
   If $jTime=>1 Exit 1901 EndIf
   $DATE1=CDbl($jDate+$jTime)*86400
   
   If VarType($DateOrInterval)
      If InStr($DateOrInterval,"/") or InStr($DateOrInterval,":")
         $Date2=fnDateDiff($DateOrInterval)
         $fnDateDiff=$Date2-$DATE1
         Select
         Case $Interval="s"
         Case $Interval="m" $fnDateDiff=$fnDateDiff/60
         Case $Interval="h" $fnDateDiff=$fnDateDiff/3600
         Case $Interval="d" $fnDateDiff=$fnDateDiff/86400
         Case $Interval="w" $fnDateDiff=$fnDateDiff/604800
         Case 1 Exit 87
         EndSelect
         If $Interval="s" $fnDateDiff=CInt($fnDateDiff) EndIf
         If $Fix $fnDateDiff=Fix($fnDateDiff) EndIf
      Else
         If VarType($DateOrInterval)>5 Exit 87 EndIf
         Select
         Case $Interval="s" If VarType($DateOrInterval)>3 Exit 87 EndIf
         Case $Interval="m" $DateOrInterval=$DateOrInterval*60
         Case $Interval="h" $DateOrInterval=$DateOrInterval*3600
         Case $Interval="d" $DateOrInterval=$DateOrInterval*86400
         Case $Interval="w" $DateOrInterval=$DateOrInterval*604800
         Case 1 Exit 87
         EndSelect
         
         $fnDateDiff=($DATE1+$DateOrInterval)/86400
         $jTime=$fnDateDiff-Fix($fnDateDiff)
         $jDate=Fix($fnDateDiff)
         
         $y = (100*(((100*($jDate+306)-25)/3652425)-(((100*($jDate+306)-25)/3652425)/4))+
            (100*($jDate+306)-25))/36525 
         $m = (5*(((100*($jDate+306)-25)/3652425)-(((100*($jDate+306)-25)/3652425)/4)+
            ($jDate+306)-365*$y-$y/4)+456)/153 
         $d = (((100*($jDate+306)-25)/3652425)-(((100*($jDate+306)-25)/3652425)/4)+
            ($jDate+306)-365*$y-$y/4)-(153*$m-457)/5 
         If $m>12 $y=$y+1 $m=$m-12 EndIf
         If $y<0 $y=$y*-1 $y=Right("-000"+$y,5) Else $y = Right("000"+$y,4) EndIf
         $m = Right("0"+$m,2) 
         $d = Right("0"+$d,2)
         
         $ss = CInt(86400.0*$jTime)
         $mm=$ss/60 $ss=$ss mod 60 $hh=$mm/60 $mm=$mm mod 60
         
         $jDate=Iif($y,''+$y+'/'+$m+'/'+$d,'')
         $jDate=Iif($y=1899 & $m=12 & $d=30,'',$jDate)
         $jTime=Iif($jTime,Right("0"+$hh,2)+':'+Right("0"+$mm,2)+':'+Right("0"+$ss,2),'')
         
         $fnDateDiff=Iif($jDate & $jTime,$jDate+" "+$jTime,$jDate+$jTime)
      EndIf
   Else
      $fnDateDiff=$DATE1
   EndIf
EndFunction