###########################################################################
#
# AZList.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.
#
###########################################################################

# classifier plugin for sorting alphabetically
# options are:
# metadata=Metaname -- all documents with Metaname metadata
#                      will be included in list, list will be sorted
#                      by this element.
# title=Title       -- (optional) the title field for this classification.
#                      if not included title field will be Metaname. 

package AZList;

use sorttools;

sub new {
    my ($class, @options) = @_;

    my ($metaname, $title);

    foreach $option (@options) {
	if ($option =~ /^metadata=(.*)$/i) {
	    $metaname = $1;
	} elsif ($option =~ /^title=(.*)$/i) {
	    $title = $1;
	}
    }

    die "AZList used with no metadata name to classify by\n"
	unless defined $metaname;
    $title = $metaname unless defined $title;

    return bless {
	'list'=>{},
	'metaname' => $metaname,
	'title' => $title
	}, $class;
}

sub init {
    my $self = shift (@_);

    $self->{'list'} = {};
}

sub classify {
    my $self = shift (@_);
    my ($doc_obj) = @_;

    my $doc_OID = $doc_obj->get_OID();
    my $metavalue = $doc_obj->get_metadata_element ($doc_obj->get_top_section(),
						    $self->{'metaname'});

    # if this document doesn't contain the metadata element we're
    # sorting by we won't include it in this classification
    if (defined $metavalue && $metavalue ne "") {
	if ($self->{'metaname'} eq 'Creator') {
	    &sorttools::format_string_name_english (\$metavalue);
	} else {
	    &sorttools::format_string_english (\$metavalue);
	}
	if (defined $self->{'list'}->{$doc_OID}) {
	    print STDERR "WARNING: AZList::classify called multiple times for $doc_OID\n";
	} 
	$self->{'list'}->{$doc_OID} = $metavalue;
    }
}

sub alpha_numeric_cmp
{
    my ($self,$a,$b) = @_;

    my $title_a = $self->{'list'}->{$a};
    my $title_b = $self->{'list'}->{$b};

    if ($title_a =~ m/^(\d+(\.\d+)?)/)
    {
	my $val_a = $1;
	if ($title_b =~ m/^(\d+(\.\d+)?)/)
	{
	    my $val_b = $1;
	    if ($val_a != $val_b)
	    {
		return ($val_a <=> $val_b);
	    }
	}
    }
    
    return ($title_a cmp $title_b);
}

sub get_classify_info {
    my $self = shift (@_);

    my @classlist 
	= sort { $self->alpha_numeric_cmp($a,$b) } keys %{$self->{'list'}};

    return $self->splitlist (\@classlist);
}

sub get_entry {
    my $self = shift (@_);
    my ($title, $childtype, $thistype) = @_;
    
    # organise into classification structure
    my %classifyinfo = ('childtype'=>$childtype,
			'Title'=>$title,
			'contains'=>[]);
    $classifyinfo{'thistype'} = $thistype 
	if defined $thistype && $thistype =~ /\w/;

    return \%classifyinfo;
}

# splitlist takes an ordered list of classifications (@$classlistref) and splits it
# up into alphabetical sub-sections.
sub splitlist {
    my $self = shift (@_);
    my ($classlistref) = @_;
    my $classhash = {};

    # top level
    my $childtype = "HList";
    if (scalar (@$classlistref) <= 39) {$childtype = "VList";}
    my $classifyinfo = $self->get_entry ($self->{'title'}, $childtype, "Invisible");

    # don't need to do any splitting if there are less than 39 (max + min -1) classifications
    if ((scalar @$classlistref) <= 39) {
	foreach $subOID (@$classlistref) {
	    push (@{$classifyinfo->{'contains'}}, {'OID'=>$subOID});
	}
	return $classifyinfo;
    }
	
    # first split up the list into separate A-Z and 0-9 classifications
    foreach $classification (@$classlistref) {
	my $title = $self->{'list'}->{$classification};

	$title =~ s/^(&.{1,6};|<[^>]>|[^a-zA-Z0-9])//g; # remove any unwanted stuff
	$title =~ s/^(.).*$/$1/;
	$title =~ tr/[a-z]/[A-Z]/;
	if ($title =~ /^[0-9]$/) {$title = '0-9';}
	elsif ($title !~ /^[A-Z]$/) {
	    print STDERR "AZList: WARNING $classification has badly formatted title ($title)\n";
	}
	$classhash->{$title} = [] unless defined $classhash->{$title};
	push (@{$classhash->{$title}}, $classification);
    }
    $classhash = $self->compactlist ($classhash);

    my @tmparr = ();
    foreach $subsection (sort keys (%$classhash)) {
	push (@tmparr, $subsection);
    }
    
    # if there's a 0-9 section it will have been sorted to the beginning
    # but we want it at the end
    if ($tmparr[0] eq '0-9') {
	shift @tmparr;
	push (@tmparr, '0-9');
    }

    foreach $subclass (@tmparr) {
	my $tempclassify = $self->get_entry($subclass, "VList");
	foreach $subsubOID (@{$classhash->{$subclass}}) {
	    push (@{$tempclassify->{'contains'}}, {'OID'=>$subsubOID});
	}
	push (@{$classifyinfo->{'contains'}}, $tempclassify);
    }

    return $classifyinfo;
}

sub compactlist {
    my $self = shift (@_);
    my ($classhashref) = @_;
    my $compactedhash = {};
    my @currentOIDs = ();
    my $currentfirstletter = "";
    my $currentlastletter = "";
    my $lastkey = "";

    # minimum and maximum documents to be displayed per page.
    # the actual maximum will be max + (min-1).
    # the smallest sub-section is a single letter at present
    # so in this case there may be many times max documents
    # displayed on a page.
    my $min = 10; 
    my $max = 30;

    foreach $subsection (sort keys %$classhashref) {
	if ($subsection eq '0-9') {
	    @{$compactedhash->{$subsection}} = @{$classhashref->{$subsection}};
	    next;
	}
	$currentfirstletter = $subsection if $currentfirstletter eq "";
	if ((scalar (@currentOIDs) < $min) ||
	    ((scalar (@currentOIDs) + scalar (@{$classhashref->{$subsection}})) <= $max)) {
	    push (@currentOIDs, @{$classhashref->{$subsection}});
	    $currentlastletter = $subsection;
	} else {

	    if ($currentfirstletter eq $currentlastletter) {
		@{$compactedhash->{$currentfirstletter}} = @currentOIDs;
		$lastkey = $currentfirstletter;
	    } else {
		@{$compactedhash->{"$currentfirstletter-$currentlastletter"}} = @currentOIDs;
		$lastkey = "$currentfirstletter-$currentlastletter";
	    } 
	    if (scalar (@{$classhashref->{$subsection}}) >= $max) {
		$compactedhash->{$subsection} = $classhashref->{$subsection};
		@currentOIDs = ();
		$currentfirstletter = "";
		$lastkey = $subsection;
	    } else {
		@currentOIDs = @{$classhashref->{$subsection}};
		$currentfirstletter = $subsection;
		$currentlastletter = $subsection;
	    }
	}
    }

    # add final OIDs to last sub-classification if there aren't many otherwise
    # add final sub-classification
    if (scalar (@currentOIDs) < $min) {
	my ($newkey) = $lastkey =~ /^(.)/;
	@currentOIDs = (@{$compactedhash->{$lastkey}}, @currentOIDs);
	delete $compactedhash->{$lastkey};
	@{$compactedhash->{"$newkey-$currentlastletter"}} = @currentOIDs;	
    } else {
	if ($currentfirstletter eq $currentlastletter) {
	    @{$compactedhash->{$currentfirstletter}} = @currentOIDs;
	} else {
	    @{$compactedhash->{"$currentfirstletter-$currentlastletter"}} = @currentOIDs;
	} 
    }

    return $compactedhash;
}

1;