source: main/trunk/greenstone2/perllib/metadatautil.pm@ 22431

###########################################################################
#
# metadatautil.pm -- various useful utilities for dealing with metadata
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright (C) 2006 New Zealand Digital Library Project
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
###########################################################################

package metadatautil;

use strict;

sub combine_metadata_structures { 
    my ($mdref1, $mdref2) = @_;
    my ($key, $value1, $value2);

    foreach $key (keys %$mdref2) {

    $value1 = $mdref1->{$key};
    $value2 = $mdref2->{$key};
    
    # If there is no existing value for this metadata field in 
    # $mdref1, so we simply copy the value from $mdref2 over.
    if (!defined $value1) {
        $mdref1->{$key} = &clonedata($value2);
    } 
    # Otherwise we have to add the new values to the existing ones.
    # If the second structure is accumulated, then acculate all the
    # values into the first structure
    elsif ((ref $value2) eq "ARRAY") {
        # If the first metadata element is a scalar we have to 
        # convert it into an array before we add anything more.
        if ((ref $value1) ne 'ARRAY') {
        $mdref1->{$key} = [$value1];
        $value1 = $mdref1->{$key};
        }
        # Now add the value(s) from the second array to the first
        $value2 = &clonedata($value2);
        push @$value1, @$value2;
    } 
    # Finally, If the second structure is not an array reference, we
    # know it is in override mode, so override the first structure.
    else {
        $mdref1->{$key} = &clonedata($value2);
    }
    }
}


# Make a "cloned" copy of a metadata value.  
# This is trivial for a simple scalar value,
# but not for an array reference.

sub clonedata {
    my ($value) = @_;
    my $result;

    if ((ref $value) eq 'ARRAY') {
    $result = [];
    foreach my $item (@$value) {
        push @$result, $item;
    }
    } else {
    $result = $value;
    }
    return $result;
}

sub format_metadata_as_table {
    my ($metadata, $remove_namespace) = @_;
    
    my $text = "<table cellpadding=\"4\" cellspacing=\"0\">\n";
    
    foreach my $field (sort keys(%$metadata)) {
    # $metadata->{$field} may be an array reference
    if ($field eq "gsdlassocfile_tobe") {
        # ignore
    } else {
        my $no_ns = $field;
        if ($remove_namespace) {
        $no_ns =~ s/^\w+\.//;
        }
        if (ref ($metadata->{$field}) eq "ARRAY") {
        map { 
            $text .= "<tr><td valign=top><nobr><b>$no_ns</b></nobr></td><td>".$_."</td></tr>";
        } @{$metadata->{$field}};
        } else {
        $text .= "<tr><td valign=top><nobr><b>$no_ns</b></nobr></td><td valign=top>$metadata->{$field}</td></tr>\n";
        }
    }

    }
    $text .= "</table>\n";
    return $text;
}


sub store_saved_metadata
{
    my ($plug,$mname,$mvalue,$md_accumulate) = @_;

    if (defined $plug->{'saved_metadata'}->{$mname}) {
    if ($md_accumulate) {
        # accumulate mode - add value to existing value(s)
        if (ref ($plug->{'saved_metadata'}->{$mname}) eq "ARRAY") {
        push (@{$plug->{'saved_metadata'}->{$mname}}, $mvalue);
        } else {
        $plug->{'saved_metadata'}->{$mname} = 
            [$plug->{'saved_metadata'}->{$mname}, $mvalue];
        }
    } else {
        # override mode
        $plug->{'saved_metadata'}->{$mname} = $mvalue;
    }
    } else {
    if ($md_accumulate) {
        # accumulate mode - add value into (currently empty) array
        $plug->{'saved_metadata'}->{$mname} = [$mvalue];
    } else {
        # override mode
        $plug->{'saved_metadata'}->{$mname} = $mvalue;
    }
    }
}


1;