# TimeFormat convert UTC dates to seconds (date2sec) and
# seconds to UTC dates (sec2date) in a defined format. 
# Accepted input dates for &date2sec() are
#     2005-03-28 12:00:00.001
#     2005-03-28
#     2005-102 12:00:00
#     2005-102
#     2005102 12:00:00
#     2005102
#     2005,100,12:10:00
#     2005,100 12:10:00.001

package TimeFormat ;

use strict ;
use Time::Local qw(timegm_nocheck); 
use POSIX 'strftime'; # convert seconds to a formatted date

require Exporter ;


#our $SECONDS ; # set when date2sec is called
our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS, $Verbose, $FORMAT) ;

@ISA         = qw(Exporter);
@EXPORT      = ();
@EXPORT_OK   = qw( sec2date date2sec current2sec last_julian_day remove_time format ) ;
%EXPORT_TAGS = ( Default => [qw(&date2sec)], 
                 Both    => [qw(&date2sec &sec2date)],
                 All     => [qw(&date2sec &sec2date &current2sec &last_julian_day &remove_time &format)]);
$VERSION     = 1.0 ;
$Verbose     = 0 ;

# This variable is used for the conversion between dates
  $FORMAT    = "%Y-%m-%d %H:%M:%S.%q"  ; # should be set via format()
  # %Y - year including century or %y - year within century (00-99)
  # %m - month (1-12)
  # %d - day of month (1-31)
  # %j - julian day (000-366)
  # %H - hour (00-23) or %I - hour (01-12)
  # %M - minute (00-59)
  # %S - second (00-59)
  # %q - milli second (000-999) (not in the documentation)
  # %s - epoch time (xxxxxxxxxxx.xxx)

sub remove_time {
	my $sec = shift ;
	&date2sec( sec2date($sec,"%Y%j") ) ;
}

sub last_julian_day {
	my $year = shift ;
	&sec2date(date2sec("$year-12-31"),"%j") ;
}
sub current2sec {
	return &date2sec( localtime() ) ;	
}
# This function accepts epoch-seconds and returns a formatted date.
sub sec2date {
	my ($sec, $fmt) = @_;
	  $fmt = $FORMAT if ! $fmt ;	

	# check input format
	  if ( $sec !~ /^\d+(?:\.\d+)?$/ ) {
		$sec = &date2sec($sec) ;
	  }

	# is input format correct ?
	  return $sec if ($sec !~ /^\d+(?:\.\d+)?$/)  ;

    	## fractional part of $sec, rounded to 3 digits
    	  my $milli = sprintf "%03.0f", 1000 * ($sec - int $sec);
	# add mili-seconds (%q)
    	  $fmt =~ s/%q/$milli/g; # change output-format for milli-seconds
	
    	strftime $fmt, gmtime(int $sec);
    	#strftime $fmt, localtime(int $sec);
}

# converts a date to epoch seconds
sub date2sec {
    my $time = undef ;
    if ( @_ > 1 ) {
	$time = sprintf ("%d-%.3d %.2d:%.2d:%.2d",(1900 + $_[5]),($_[7]+1),$_[2],$_[1],$_[0]) ;
    }
    else { $time = shift ; }
      return undef if ! defined $time ;

    my $seconds ;

    # decl. of vars.
      my ( $year, $month, $day, $julian, $hour, $minute, $second, $mili) ;

    # convert year-only-date
    $time .= "-001" if ( length($time) == 4) ;

    # date is already in seconds 
      if ( length($time) != 7 && $time =~ /^      
                   \d+      # seconds
	           (?:      
		     \.\d+  # milli-seconds
	   	   )?
		  $/xg
	) { $seconds = $time ; }
      # split date ( with a julian day)
      # elsif ( $time =~ /\d{4}(?:[-,])?(\d{3})[\s{0,},](\d\d:\d\d:\d\d)?/ ) {
      elsif ( $time =~ /\d{4}(?:[-,])?(\d{3})\b/ ) {
	( $year, $julian, $hour, $minute, $second, $mili ) = ( $time =~ m/
        (\d{4})         # year
        (?:               # group the day - time portions
            (?:
	     [-,]       # year and julian day sep. with a , or -
	    )?
            (\d{1,3})   # julian day
            (?:         # group the time portions
                [\s+,]  # date and time sep. by  whitespaces or ,
                (\d\d)  # hour
                :
                (\d\d)  # minute
                :
                (\d\d)  # second + fractions
		(?:
	          (\.\d+)   
		)?
            )?           # time is optional
        )?               # day - time is optional
        /xg );
	$seconds  = &timegm_nocheck($second,$minute,$hour,$julian,0,$year-1900) + $mili ; 
      } # (date contains month and day)
      elsif   ( $time =~ /\d{4}-\d{2}-\d{2}\s{0,}?(\d\d:\d\d:\d\d)?(?:\.\d+)?/ ) {
	( $year, $month, $day, $hour, $minute, $second, $mili ) = ( $time =~ m/
        (\d{4})           # year
        -                 # 
        (\d{2})           # month 
        -                 # 
	(\d{2})	          # day
        (?:               # group the time portions
                \s+       # one or more whitespace
                (\d\d)    # hour
                :
                (\d\d)    # minute
                :
                (\d\d)    # second
		(?:
		    (\.\d+)
		)?
        )?                # time is optional
        /xg );
	print STDERR __PACKAGE__." Error: Month out of range: $month\n" if $month > 12;
        return undef unless $month < 13 && defined $year ; # only check month
      	$seconds = &timegm_nocheck($second,$minute,$hour,$day,$month-1,$year-1900) + $mili ; 
      } else { return undef ; } # input date could not be parsed 
      return $seconds ;
}

# predefine the output format
sub format {
	$FORMAT = shift ;
	return 1 ; # OK
}

1;

__END__