/*
    Copyright (C) 1995-1997 AROS - The Amiga Replacement OS
    $Id: checkdate.c,v 1.4 1997/02/03 02:58:31 ldp Exp $

    Desc: CheckDate() - is a date valid ?
    Lang: english
*/
#include "utility_intern.h"

/*****************************************************************************

    NAME */
#include <utility/date.h>
#include <proto/utility.h>

        AROS_LH1(ULONG, CheckDate,

/*  SYNOPSIS */
        AROS_LHA(struct ClockData *, date, A0),

/*  LOCATION */
        struct Library *, UtilityBase, 22, Utility)

/*  FUNCTION
        Examine the date described in the ClockData structure and
        determine whether it is a valid date. In particular this
        checks whether the ranges of the fields are within normal
        limits.

        This function does not check whether the wday field of the
        ClockData structure is valid.

    INPUTS
        date        -   A ClockData structure desribing the date
                        to check.

    RESULT
        If the date is valid, the number of seconds from midnight
        1-Jan-1978 AD to the date, or 0 if the date is invalud.

    NOTES
        The date 01-Jan-78 00:00:00 is actually returned as invalid.

        This also assumes that the ClockDate refers to a date in the
        Gregorian calendar. (60 sec/min, 60 min/hour, 24 hr/day,
        12 months/year).

    EXAMPLE

    BUGS
        Does not check whether the 29/2 is valid outside of a leap year.

    SEE ALSO
        Amiga2Date(), Date2Amiga()

    INTERNALS
        Since all the values are unsigned, we don't have to check for < 0
        in fields which range from 0 ... n.

    HISTORY
        29-10-95    digulla automatically created from
                            utility_lib.fd and clib/utility_protos.h

*****************************************************************************/
{
    AROS_LIBFUNC_INIT

    /* Note: 60!!! This is in case of any future leap seconds... */
    if( date->sec > 60 )
        return 0;

    if( date->min > 59)
        return 0;

    if( date->hour > 23)
        return 0;

    /* XXX: When does the year become invalid? */
    if( date->year < 1978 )
        return 0;

    if( date->wday > 6)
        return 0;

    if( date->mday < 1 )
        return 0;

    switch( date->month )
    {
        /* 30 days hath April, September, June and November */
        case 4:
        case 6:
        case 9:
        case 11:
            if(date->mday > 30)
                return 0;
            break;

        /* And all the rest have 31 ... */
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            if(date->mday > 31)
                return 0;
            break;

        /*  Except February with has 28, or 29 on a leap year,
            should I check whether this is a leap year or not?
        */
        case 2:
            if(date->mday > 29)
                return 0;
            break;

        /* This also traps invalid month numbers */
        default:
            return 0;
    } /* switch(date->month) */

    return Date2Amiga(date);

    AROS_LIBFUNC_EXIT
} /* CheckDate */