'+---------------------------------------------------------------------------+
'|                                                                           |
'|  Date routines for PowerBASIC                                             |
'|  Copyright (c) 1995 by PowerBASIC, Inc.  All Rights Reserved.             |
'|                                                                           |
'|  Note:  All routines expect dates and times to be in U.S. format.         |
'|         For international support, all you need to do is modify the       |
'|         SplitDate(), SplitTime(), MakeDate$(), MakeTime[12]$()            |
'|         routines to support your specified format.  All other routines    |
'|         call these routines to get the component parts.                   |
'|                                                                           |
'|         All dates used must be between 01-01-1900 and 06-05-2079          |
'|                                                                           |
'|         If you pass a null (zero-length) string to a given routine,       |
'|         the current date/time is used.                                    |
'|                                                                           |
'+---------------------------------------------------------------------------+
'+---------------------------------------------------------------------------+
'|                                                                           |
'|  CDOW           -  Return the name for the Day of the Week of a date      |
'|  DOW            -  Return the day of the week for a given date            |
'|  DOY            -  Return the day of the year for a given date            |
'|  DateMath       -  Add/Subtract days to a given date                      |
'|  DateToDays     -  Convert a date into the number of days since 1900      |
'|  Days           -  Return the number of days between two dates            |
'|  DaysToDate     -  Convert the number of days since 1900 into a date      |
'|  Elapsed        -  Return the number of seconds between two time strings  |
'|  Leap           -  Check a year to see if it's a leap year                |
'|  MakeDate       -  Create a date string from month, day, and year         |
'|  MakeTime       -  Create a time string from hour, minutes, and seconds   |
'|  MakeTime12     -  Create a 12 hour time string from hour and minutes     |
'|  MonthName      -  Return the name of a given month                       |
'|  SecondsToTime  -  Convert number of seconds since midnight into a time   |
'|  SplitDate      -  Split a date into its component parts                  |
'|  SplitTime      -  Split a time into its component parts                  |
'|  TimeToSeconds  -  Convert a time string into seconds since midnight      |
'|  ValidDate      -  Check a date to see if it's valid                      |
'|                                                                           |
'+---------------------------------------------------------------------------+

$CPU      8086      ' Make compatible with XT systems
$LIB      ALL OFF   ' Turn off all PowerBASIC libraries
$ERROR    ALL OFF   ' Turn off all PowerBASIC error checking
$OPTIMIZE SIZE      ' Optimize for smaller code
$COMPILE  UNIT      ' Compile to a UNIT (.PBU)

DEFINT    A-Z       'Required for all numeric functions, forces PB to not
                    'include floating point in UNIT (makes it smaller)

'===========================================================================
' SplitDate - Split a date passed in a string to its Month, Day, and Year
'             components.
'
'             Note:  All other date routines call this routine to get the
'                    component parts.
'
' TempDate = Date string in U.S. format (MM-DD-YY, MM-DD-YYYY)
' Month    = Returns the month
' Day      = Returns the day of the month
' Year     = Returns the year
'
SUB SplitDate(BYVAL InDate AS STRING, Month AS INTEGER, _
              Day AS INTEGER, Year AS INTEGER) PUBLIC

  IF LEN(InDate) = 0 THEN
    InDate = DATE$
  END IF

  Month = VAL(MID$(InDate$,1,2))
  Day   = VAL(MID$(InDate$,4,2))
  Year  = VAL(MID$(InDate$,7))

  IF Year < 80 THEN        'assume we've rolled into the next century
    INCR Year, 2000
  ELSEIF Year < 100 THEN   'between 80 and 99, use this century
    INCR Year, 1900
  END IF

END SUB


'===========================================================================
' SplitTime - Split a time passed in a string to its Hour, Minute, and
'             Second components.
'
'             Note:  All other time routines call this routine to get the
'                    component parts.
'
' TempTime = Time string in U.S. format (HH:MM:SS, HH:MM, HH:MMx)
' Hour     = Returns the hour (in military time)
' Minute   = Returns the minute
' Second   = Returns the second
'
SUB SplitTime(BYVAL InTime AS STRING, Hour AS INTEGER, _
              Minute AS INTEGER, Second AS INTEGER) PUBLIC

  IF LEN(InTime) = 0 THEN
    InTime$ = TIME$
  END IF

  Hour   = VAL(InTime)
  Minute = VAL(MID$(InTime,4,2))
  IF LEN(InTime) > 6 THEN
    Second = VAL(MID$(InTime,7))
  ELSE
    Second = 0
  END IF

  IF INSTR(LEFT$(InTime,2), ANY "pP") THEN
    IF Hour < 12 THEN
      INCR Hour, 12
    END IF
  ELSEIF INSTR(LEFT$(InTime,2), ANY "aA") THEN
    IF Hour = 12 THEN
      Hour = 0
    END IF
  END IF

END SUB


'===========================================================================
' MakeDate - Combine the component parts of a date into a displayable
'            string in U.S. format.
'
'             Note:  All other date routines call this routine to combine
'                    the component parts.
'
' Month =
' Day   =
' Year  =
'
FUNCTION MakeDate(BYVAL Month AS INTEGER, BYVAL Day AS INTEGER, _
                   BYVAL Year AS INTEGER) PUBLIC AS STRING

  DIM Temp AS STRING

  IF Year < 80 THEN        'assume we've rolled into the next century
    INCR Year, 2000
  ELSEIF Year < 100 THEN   'between 1980 and 1999
    INCR Year, 1900
  END IF

  Temp  = RIGHT$(STR$(Month), 2) + "-" + _
          RIGHT$(STR$(Day), 2) + "-" + _
          RIGHT$(STR$(Year), 4)
  REPLACE " " WITH "0" IN Temp

  FUNCTION = Temp

END FUNCTION


'===========================================================================
' MakeTime12 - Combine the component parts of a time into a displayable
'              string in 12 hour U.S. format.
'
' Hour   =
' Minute =
'
FUNCTION MakeTime12(BYVAL Hour AS INTEGER, _
                     BYVAL Minute AS INTEGER) PUBLIC AS STRING

  DIM Pm AS INTEGER
  DIM H  AS STRING
  DIM M  AS STRING
  DIM T  AS STRING

  IF Hour > 12 THEN
    DECR Hour,12
    Pm  = -1
  END IF

  H$ = RIGHT$(STR$(Hour),2)
  M$ = RIGHT$(STR$(Minute),2)

  IF Pm THEN
    M$ = M$ + "p"
  ELSE
    M$ = M$ + "a"
  END IF

  T = H + ":" + M
  REPLACE " " WITH "0" IN T

  FUNCTION = T

END FUNCTION


'===========================================================================
' MakeTime - Combine the component parts of a time into a displayable
'            string in 24 hour U.S. format.
'
'             Note:  All other time routines call this routine to combine
'                    the component parts.
'
' Hour   =
' Minute =
' Second =
'
FUNCTION MakeTime(BYVAL Hour AS INTEGER, BYVAL Minute AS INTEGER, _
                   BYVAL Second AS INTEGER) PUBLIC AS STRING

  DIM H  AS STRING
  DIM M  AS STRING
  DIM S  AS STRING
  DIM T  AS STRING

  H = RIGHT$(STR$(Hour),2)
  M = RIGHT$(STR$(Minute),2)
  S = RIGHT$(STR$(Second),2)

  T = H + ":" + M + ":" + S
  REPLACE " " WITH "0" IN T

  FUNCTION = T

END FUNCTION


'===========================================================================
' Leap - Return a one (1) if specified year is a leap year.
'
' Year = year to check
'
FUNCTION Leap(BYVAL Year AS INTEGER) PUBLIC AS INTEGER

  IF (Year MOD 400) = 0 THEN
    FUNCTION = 1
  ELSEIF (Year MOD 100) = 0 THEN
    FUNCTION = 0
  ELSEIF (Year MOD 4) = 0 THEN
    FUNCTION = 1
  END IF

END FUNCTION


'===========================================================================
' DaysInMonth - Return the number of days in a given month.  It does not
'               account for leap years.
'
' Month = month to return number of days for
'
FUNCTION DaysInMonth(BYVAL Month AS INTEGER) PUBLIC AS INTEGER

   DIM Buff AS STRING

   Buff = "312831303130313130313031"

   IF Month > 0 AND Month < 13 THEN
     FUNCTION = VAL( MID$(Buff, (Month-1) * 2, 2) )
   END IF

END FUNCTION


'===========================================================================
' DateToDays - Convert the specified date into the number of days since
'              01-01-1900.  Supports dates up to 06-05-2079.
'
' InDate = Date to convert
'
FUNCTION DateToDays(InDate AS STRING) PUBLIC AS WORD

  DIM Buffer AS STATIC STRING
  DIM Temp   AS WORD
  DIM z      AS INTEGER
  DIM Month  AS INTEGER
  DIM Day    AS INTEGER
  DIM Year   AS INTEGER

  Buffer = "000031059090120151181212243273304334366"

  SplitDate InDate, Month, Day, Year

  IF Year < 80 THEN
    INCR Year, 2000
  ELSEIF Year < 100 THEN
    INCR Year, 1900
  ELSEIF Year < 1900 THEN
    EXIT FUNCTION
  END IF

  IF Year > 1900 THEN
    FOR z = Year - 1 TO 1900 STEP -1
      INCR Temp, 365 + Leap(z)
    NEXT z
  END IF

  INCR Temp, VAL(MID$(Buffer, 1 + ((Month-1) * 3), 3))

  IF (Month > 2) THEN
    INCR Temp, Leap(Year)
  END IF

  INCR Temp, Day

  FUNCTION = Temp

END FUNCTION


'===========================================================================
' DaysToDate - Convert the number of days since 01-01-1900 to a date string.
'
' NumDays = number of days since 1900
'
FUNCTION DaysToDate(BYVAL NumDays AS WORD) PUBLIC AS STRING

  DIM Month        AS INTEGER
  DIM Year         AS INTEGER
  DIM DaysInMnth   AS INTEGER
  DIM DaysInYear   AS INTEGER
  DIM Temp         AS STRING

  Year       = 1900
  DaysInYear = 365 + Leap(Year)
  DO UNTIL NumDays < DaysInYear
    DECR NumDays, 365 + Leap(Year)
    INCR Year
    DaysInYear = 365 + Leap(Year)
  LOOP

  FOR Month = 1 TO 12
    DaysInMnth = DaysInMonth(Month)
    IF NumDays <= DaysInMnth THEN
      EXIT FOR
    END IF
    DECR NumDays, DaysInMnth
  NEXT

  IF NumDays = 0 THEN
    Month = 12
    NumDays = 31
    DECR Year
  END IF

  FUNCTION = MakeDate(Month, NumDays, Year)

END FUNCTION


'===========================================================================
' DateMath - Add the specified number of days the specified date.
'            To subtract days, use a negative value.
'
' InDate       = starting date
' NumberOfDays = number of days to add
'
FUNCTION DateMath(BYVAL InDate AS STRING, _
                  BYVAL NumberOfDays AS INTEGER) PUBLIC AS STRING

  FUNCTION = DaysToDate(DateToDays(InDate) + NumberOfDays)

END FUNCTION


'===========================================================================
' Days - Return the number of days between two dates.  If the first date
'        comes after the second date, a negative value is returned.
'
' Date1 = starting date
' Date2 = ending date
'
FUNCTION Days(BYVAL Date1 AS STRING, BYVAL Date2 AS STRING) PUBLIC AS INTEGER

  FUNCTION = DateToDays(Date1) - DateToDays(Date2)

END FUNCTION


'===========================================================================
' ValidDate - Returns true (-1) if the specified date is valid, or false (0)
'             if the date is invalid.
'
' InDate = date to check
'
FUNCTION ValidDate(BYVAL InDate AS STRING) PUBLIC AS INTEGER

  DIM Month     AS INTEGER
  DIM Day       AS INTEGER
  DIM Year      AS INTEGER
  DIM TotalDays AS INTEGER

  IF LEN(InDate) = 0 THEN
    EXIT FUNCTION
  END IF

  SplitDate InDate, Month, Day, Year

  IF (Month < 1) OR (Month > 12) THEN
    EXIT FUNCTION
  END IF

  TotalDays = DaysInMonth(Month)

  IF Month = 2 THEN
    INCR TotalDays, Leap(Year)
  END IF

  IF (Day < 1) OR (Day > TotalDays) THEN
    EXIT FUNCTION
  END IF

  IF Year < 1900 THEN
    EXIT FUNCTION
  END IF

  FUNCTION = -1

END FUNCTION


'===========================================================================
' TimeToSeconds - Returns the number of seconds since midnight for a given
'                 time string.
'
' InTime = Time to convert into seconds
'
FUNCTION TimeToSeconds(BYVAL InTime AS STRING) PUBLIC AS LONG

  DIM Hour   AS INTEGER
  DIM Minute AS INTEGER
  DIM Second AS INTEGER

  SplitTime InTime, Hour, Minute, Second

  FUNCTION = (Hour * 3600) + (Minute * 60) + Second

END FUNCTION


'===========================================================================
' SecondsToTime$ - Return a time string for a given number of seconds since
'                  midnight.
'
' Secs = seconds to convert into a time string
'
FUNCTION SecondsToTime(BYVAL Secs AS LONG) PUBLIC AS STRING

  DIM Hour   AS INTEGER
  DIM Minute AS INTEGER
  DIM Second AS INTEGER

  Hour   = Secs \ 3600
  Minute = (Secs MOD 3600) \ 60
  Second = ((Secs MOD 3600) \ 60) MOD 60

  FUNCTION = MakeTime(Hour, Minute, Second)

END FUNCTION


'===========================================================================
' Elapsed - Return the number of seconds elapsed between two time strings.
'           If the second time is earlier than the first, a midnight rollover
'           is assumed.
'
' Time1 = start time
' Time2 = end time
'
FUNCTION Elapsed(BYVAL Time1 AS STRING, BYVAL Time2 AS STRING) PUBLIC AS LONG

  DIM Temp1 AS LONG
  DIM Temp2 AS LONG

  Temp1 = TimeToSeconds(Time1)
  Temp2 = TimeToSeconds(Time2)

  IF Temp2 < Temp1 THEN  'account for midnight rollover
    INCR Temp2, 86400
  END IF

  FUNCTION = Temp2 - Temp1

END FUNCTION


'===========================================================================
' DOW - Return the Day of the Week as an integer.
'
' InDate = date to convert into the day of the week
'
FUNCTION DOW(InDate AS STRING) PUBLIC AS INTEGER

  FUNCTION = 1 + DateToDays(InDate) MOD 7

END FUNCTION


'===========================================================================
' DOY - Return the Day of the Year
'
' InDate = date to convert into day of the year
'
FUNCTION DOY(InDate AS STRING) PUBLIC AS INTEGER

  DIM Month  AS INTEGER
  DIM Day    AS INTEGER
  DIM Year   AS INTEGER
  DIM Buffer AS STATIC STRING
  DIM Temp   AS INTEGER

  Buffer = "000031059090120151181212243273304334366"

  SplitDate InDate, Month, Day, Year

  Temp = VAL(MID$(Buffer, 1 + ((Month-1) * 3), 3)) + Day

  IF Month > 2 THEN
    INCR Temp, Leap(Year)
  END IF

  FUNCTION = Temp

END FUNCTION


'===========================================================================
' CDOW - Return the name for the Day of the Week for the specified date.
'
' InDate = Date to return day of week name for
'
FUNCTION CDOW(InDate AS STRING) PUBLIC AS STRING

  DIM Names AS STATIC STRING
  DIM DW    AS INTEGER

  Names = "Sunday   " + _
          "Monday   " + _
          "Tuesday  " + _
          "Wednesday" + _
          "Thursday " + _
          "Friday   " + _
          "Saturday "

  DW = DateToDays(InDate) MOD 7

  FUNCTION = RTRIM$( MID$(names, 1 + DW * 9, 9) )

END FUNCTION


'===========================================================================
' MonthName$ - Return the name for a specified month.
'
' Month = month to return name for
'
FUNCTION MonthName(BYVAL Month AS INTEGER) PUBLIC AS STRING

  DIM Names AS STATIC STRING

  Names = "January  " + _
          "February " + _
          "March    " + _
          "April    " + _
          "May      " + _
          "June     " + _
          "July     " + _
          "August   " + _
          "September" + _
          "October  " + _
          "November " + _
          "December "

  IF Month < 1 OR Month > 12 THEN
    EXIT FUNCTION
  END IF

  FUNCTION = RTRIM$( MID$( Names, 1 + (Month - 1) * 9, 9) )

END FUNCTION