LOCAL'DAYS=30
TODAY=231221
LOCAL'PURGE'DATE=FN'INCREASE'DECREASE'DATE$(TODAY,-LOCAL'DAYS)

!
!==============================================================================
!{Increase/Decrease dates}						![035]
!==============================================================================
FUNCTION FN'INCREASE'DECREASE'DATE$(FN'DATE AS S6, FN'DAYS AS F6) AS S6
! IN:  Date in the format of YYMMDD
! IN:  Number of days.
! OUT: New Date (YYMMDD)
ON ERROR GOTO LOCAL'TRAP
++PRAGMA AUTO_EXTERN "TRUE"
MAP1 LOCAL'RESULT,F,6
MAP1 LOCAL'DATE,S,8
MAP1 LOCAL'NEW'DATE,S,8
	FN'INCREASE'DECREASE'DATE$=FN'DATE
	IF FN'DATE<>"" THEN
	   LOCAL'DATE=FN'FORMAT'DATE$(FN'DATE)
	   XCALL DATES,2,LOCAL'RESULT,LOCAL'DATE,LOCAL'NEW'DATE,FN'DAYS
	   IF LOCAL'RESULT<>0 THEN
	      XCALL MESAG,"DATE COMPUTE ERROR "+LOCAL'RESULT+" FOR DATE "+FN'DATE,2
	     ELSE
	      FN'INCREASE'DECREASE'DATE$=LOCAL'NEW'DATE[7;2]+LOCAL'NEW'DATE[4;2]+LOCAL'NEW'DATE[1;2]
	   ENDIF
	ENDIF
	EXITFUNCTION
LOCAL'TRAP:
 	XCALL MESAG,"Function Error "+STR(ERR(0))+" in FN'INCREASE'DECREASE'DATE$",2
	RESUME ENDFUNCTION WITH_ERROR 99
ENDFUNCTION

Function Fn'Date'Plus'Days'To'MM'DD'YY$(flexdate$ as T_FLEX_DATE:inputonly, &
                     days as i2:inputonly) as T_MM'DD'YY

    map1 locals
        map2 mm'dd'yy$,s,8
        map2 result,f
        map2 status,f
        map2 idate,b,4
        
    ! first convert all supported formats to mm/dd/yy    
    mm'dd'yy$ = Fn'Date'To'MM'DD'YY$(flexdate$)
    
    XCALL IDTIM,mm'dd'yy$,idate,0,2,status  ! check if valid
    if status # 0 then
        .fn = "?"
    else    
        xcall DATES,DTOP_DATEAFTER,result,mm'dd'yy$,.fn,days
        debug.print (99,"fndatetime") flexdate$,mm'dd'yy$,days,.fn
        if result then
            .fn = "?"
        endif
    endif
EndFunction

MAP1 TODAY,S,6,231221
PRINT FN'INCREASE'DECREASE'DATE$(TODAY,-30)
END

FUNCTION FN'INCREASE'DECREASE'DATE$(FN'DATE AS S6, FN'DAYS AS F6) AS S6
! IN:  Date in the format of YYMMDD
! IN:  Number of days.
! OUT: New Date (YYMMDD)
ON ERROR GOTO LOCAL'TRAP
++PRAGMA AUTO_EXTERN "TRUE"
MAP1 LOCAL'RESULT,F,6
MAP1 LOCAL'DATE,S,8
MAP1 LOCAL'NEW'DATE,S,8
        FN'INCREASE'DECREASE'DATE$=FN'DATE
        IF FN'DATE<>"" THEN
           LOCAL'DATE=FN'DATE[5;2]+"/"+FN'DATE[3;2]+"/"+FN'DATE[1;2]
           XCALL DATES,2,LOCAL'RESULT,LOCAL'DATE,LOCAL'NEW'DATE,FN'DAYS
           IF LOCAL'RESULT<>0 THEN
              XCALL MESAG,"DATE COMPUTE ERROR "+LOCAL'RESULT+" FOR DATE "+FN'DATE,2
             ELSE
              FN'INCREASE'DECREASE'DATE$=LOCAL'NEW'DATE[7;2]+LOCAL'NEW'DATE[4;2]+LOCAL'NEW'DATE[1
           ENDIF
        ENDIF
        EXITFUNCTION
LOCAL'TRAP:
        XCALL MESAG,"Function Error "+STR(ERR(0))+" in FN'INCREASE'DECREASE'DATE$",2
        RESUME ENDFUNCTION WITH_ERROR 99
ENDFUNCTION

++include'once ashinc:ashell.def
++include'once ashinc:ashell.sdf    ! [114]
++include'once ashinc:types.def     ! [107
++include'once ashinc:regex.def
++include'once ashinc:gtlang.sdf    ! [113]
++include'once sosfunc:fnistype.bsi
++include'once sosfunc:fndec2hex.bsi
++include'once sosfunc:fnfileage.bsi    ! [121]
++include'once sosfunc:fnextch.bsi      ! [121]
++include'once sosfunc:fndtoffset.bsi   ! [164]

deftype T_FLEX_DATE = s,50       ! [116] (see Date Format Notes above)
deftype T_FLEX_TIME = s,12       ! [121] various time formats, including "now"