###########################################################################
#
# classify.pm --
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright (C) 1999 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.
#
###########################################################################

# functions to handle classifiers

package classify;

require util;


$next_classify_num = 1;

sub load_classifiers {
    my ($classify_list) = @_;
    my @classify_objects = ();
    
    foreach $classifyoption (@$classify_list) {

	# get the classifier name
	my $classname = shift @$classifyoption;
	next unless defined $classname;
    
	# find the classifier
	my $colclassname = &util::filename_cat($ENV{'GSDLCOLLECTDIR'},"perllib/classify", 
					       "${classname}.pm");
	my $mainclassname = &util::filename_cat($ENV{'GSDLHOME'},"perllib/classify", 
						"${classname}.pm");

	if (-e $colclassname) { require $colclassname; }
	elsif (-e $mainclassname) { require $mainclassname; }
	else { die "ERROR - couldn't find classifier \"$classname\"\n"; }

	# create the classify object
	my ($classobj);
	map { $_ = "\"$_\""; } @$classifyoption;
	my $options = join (",", @$classifyoption);
	eval ("\$classobj = new \$classname($options)");
	die "$@" if $@;
	
	# add this object to the list
	push (@classify_objects, $classobj);
    }

    return \@classify_objects;
}

# init_classifiers resets all the classifiers and readys them to process
# the documents.
sub init_classifiers {
    my ($classifiers) = @_;
    
    foreach $classobj (@$classifiers) {
	$classobj->init();
    }
}

# classify_doc lets each of the classifiers classify a document
sub classify_doc {
    my ($classifiers, $doc_obj) = @_;
    
    foreach $classobj (@$classifiers) {
	$classobj->classify($doc_obj);
    }
}

# output_classify_info outputs all the info needed for the classification
# to the gdbm
sub output_classify_info {
    my ($classifiers, $handle, $allclassifications) = @_;
#    $handle = "main::STDOUT";

    # create a classification containing all the info
    my $classifyinfo = {'classifyOID'=>'browse',
			'contains'=>[]};

    # get each of the classifications
    foreach $classobj (@$classifiers) {
	my $tempinfo = $classobj->get_classify_info();
	$tempinfo->{'classifyOID'} = "CL$next_classify_num";
	$next_classify_num++;
	push (@{$classifyinfo->{'contains'}}, $tempinfo);
    }

    &print_classify_info ($handle, $classifyinfo, "", $allclassifications);
}

sub print_classify_info {
    my ($handle, $classifyinfo, $OID, $allclassifications) = @_;

    $OID =~ s/^\.+//; # just for good luck

    # book information is printed elsewhere
    return if (defined ($classifyinfo->{'OID'}));
 
    # don't want empty classifications
    if ($allclassifications || &check_contents ($classifyinfo) > 0) {
   
	$OID = $classifyinfo->{'classifyOID'} if defined ($classifyinfo->{'classifyOID'});
	
	my $outputtext = "[$OID]\n";
	$outputtext .= "<doctype>classify\n";
	$outputtext .= "<hastxt>0\n";
	$outputtext .= "<childtype>$classifyinfo->{'childtype'}\n" 
	    if defined $classifyinfo->{'childtype'};
	$outputtext .= "<Title>$classifyinfo->{'Title'}\n" 
	    if defined $classifyinfo->{'Title'};
	$outputtext .= "<numleafdocs>$classifyinfo->{'numleafdocs'}\n" 
	    if defined $classifyinfo->{'numleafdocs'};
	$outputtext .= "<thistype>$classifyinfo->{'thistype'}\n" 
	    if defined $classifyinfo->{'thistype'};

	
	my $contains_text = "<contains>";
	my $mdoffset_text = "<mdoffset>";
	
	my $next_subOID = 1;
	my $first = 1;
	foreach $tempinfo (@{$classifyinfo->{'contains'}}) {
	    # empty contents were made undefined by clean_contents()
	    next unless defined $tempinfo;
	    
	    $contains_text .= ";" unless $first;
	    $mdoffset_text .= ";" unless $first;
	    $first = 0;
	    
	    if (defined ($tempinfo->{'classifyOID'})) {
		$contains_text .= $tempinfo->{'classifyOID'};
		&print_classify_info ($handle, $tempinfo, $tempinfo->{'classifyOID'},
				      $allclassifications);
	    } elsif (defined ($tempinfo->{'OID'})) {
		$contains_text .= $tempinfo->{'OID'};
		$mdoffset_text .= $tempinfo->{'offset'}
		  if (defined ($tempinfo->{'offset'}))
		# note: we don't want to print the contents of the books
	    } else {
		$contains_text .= "\".$next_subOID";
		&print_classify_info ($handle, $tempinfo, "$OID.$next_subOID",
				      $allclassifications);
		$next_subOID++;
	    }
	}
	
	$outputtext .= "$contains_text\n";
	$outputtext .= "<mdtype>$classifyinfo->{'mdtype'}\n" 
	    if defined $classifyinfo->{'mdtype'};
	$outputtext .= "$mdoffset_text\n"
	    if ($mdoffset_text !~ m/^<mdoffset>;+$/);
	
	$outputtext .= '-' x 70 . "\n";
	
	print $handle $outputtext;
    }
}

sub check_contents {
    my ($classifyinfo) = @_;
    my $num_leaf_docs = 0;
    my $sub_num_leaf_docs = 0;

    return $classifyinfo->{'numleafdocs'} if (defined $classifyinfo->{'numleafdocs'});

    foreach $content (@{$classifyinfo->{'contains'}}) {
	if (defined $content->{'OID'}) {
	    # found a book
	    $num_leaf_docs ++;
	} elsif (($sub_num_leaf_docs = &check_contents ($content)) > 0) {
	    # there's a book somewhere below
	    $num_leaf_docs += $sub_num_leaf_docs;
	} else {
	    # section contains no books so we want to remove 
	    # it from its parents contents
	    $content = undef;
	}
    }

    $classifyinfo->{'numleafdocs'} = $num_leaf_docs;
    return $num_leaf_docs;
}

1;