###############################################################################
#
# Example of how to add a user defined data handler to the Spreadsheet::
# WriteExcel write() method.
#
# The following example shows how to add a handler for dates in a specific
# format.
#
# This is a more rigorous version of write_handler3.pl.
#
# reverse('�'), September 2004, John McNamara, [email protected]
#

use strict;
use Spreadsheet::WriteExcel;


my $workbook    = Spreadsheet::WriteExcel->new("write_handler4.xls");
my $worksheet   = $workbook->add_worksheet();
my $date_format = $workbook->add_format(num_format => 'dd/mm/yy');


###############################################################################
#
# Add a handler to match dates in the following formats: d/m/yy, d/m/yyyy
#
# The day and month can be single or double digits and the year can be  2 or 4
# digits.
#
$worksheet->add_write_handler(qr[^\d{1,2}/\d{1,2}/\d{2,4}$], \&write_my_date);


###############################################################################
#
# The following function processes the data when a match is found.
#
sub write_my_date {

    my $worksheet = shift;
    my @args      = @_;

    my $token     = $args[2];

    if ($token =~  qr[^(\d{1,2})/(\d{1,2})/(\d{2,4})$]) {

        my $day  = $1;
        my $mon  = $2;
        my $year = $3;

        # Use a window for 2 digit dates. This will keep some ragged Perl
        # programmer employed in thirty years time. :-)
        if (length $year == 2) {
            if ($year < 50) {
                $year += 2000;
            }
            else {
                $year += 1900;
            }
        }

        my $date = sprintf "%4d-%02d-%02dT", $year, $mon, $day;

        # Convert the ISO ISO8601 style string to an Excel date
        $date = $worksheet->convert_date_time($date);

        if (defined $date) {
            # Date was valid
            $args[2] = $date;
            return $worksheet->write_number(@args);
        }
        else {
            # Not a valid date therefore write as a string
            return $worksheet->write_string(@args);
        }
    }
    else {
        # Shouldn't happen if the same match is used in the re and sub.
        return undef;
    }
}


# Write some dates in the user defined format
$worksheet->write('A1', '22/12/2004', $date_format);
$worksheet->write('A2', '22/12/04',   $date_format);
$worksheet->write('A3', '2/12/04',    $date_format);
$worksheet->write('A4', '2/5/04',     $date_format);
$worksheet->write('A5', '2/5/95',     $date_format);
$worksheet->write('A6', '2/5/1995',   $date_format);

# Some erroneous dates
$worksheet->write('A8', '2/5/1895',   $date_format); # Date out of Excel range
$worksheet->write('A9', '29/2/2003',  $date_format); # Invalid leap day
$worksheet->write('A10','50/50/50',   $date_format); # Matches but isn't a date


__END__