source: trunk/gsdl/perllib/classify/DateList.pm@ 4873

###########################################################################
#
# DateList.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 by date

# always sorts by 'Date' metadata

# date is assumed to be in the form yyyymmdd

# at present dates are split by year - this should change
# jrm21 - added option "bymonth", which splits by year and month.

# 12/05/02 Added usage datastructure - John Thompson

package DateList;

use BasClas;
use sorttools;

sub BEGIN {
    @ISA = ('BasClas');
}

my $arguments =
    [ { 'name' => "bymonth",
    'desc' => "{DateList.bymonth}",
    'type' => "flag",
    'reqd' => "no" } ];

my $options = { 'name'     => "DateList",
        'desc'     => "Classifier plugin for sorting by date. Always sorts by 'Date' metadata. Date is assumed to be in the form yyyymmdd.",
        'inherits' => "Yes",
        'args'     => $arguments };

#  sub print_usage {
#      print STDERR "
#    usage: classify DateList [options]
#    options:
#   -bymonth  [or bymonth=1]    Classify by year and month

#   Classifier plugin for sorting by date.
#   Always sorts by 'Date' metadata.
#   Date is assumed to be in the form yyyymmdd (all digits).
#   By default dates are split by year - this should change.

#   Any errors are Dana's problem.
#  ";
#  }

sub new {
    my $class = shift (@_);
    my $self = new BasClas($class, @_);

    # 14-05-02 To allow for proper inheritance of arguments - John Thompson
    my $option_list = $self->{'option_list'};
    push( @{$option_list}, $options );

    $self->{'list'} = {};
    if (!parsargv::parse(\@_, 
                         q^bymonth^, \$self->{'bymonth'},
                         "allow_extra_options")) {
    $self->print_txt_usage("");  # Use default resource bundle
    die "\n";
    }
    return bless $self, $class;
}

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

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

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

    my $doc_OID = $doc_obj->get_OID();
    my $date = $doc_obj->get_metadata_element ($doc_obj->get_top_section(), 'Date');

    # if this document doesn't contain Date element we won't 
    # include it in this classification
    if (defined $date && $date =~ /\d/) {
    if (defined $self->{'list'}->{$doc_OID}) {
        my $outhandle = $self->{'outhandle'};
        print $outhandle "WARNING: DateList::classify called multiple times for $doc_OID\n";
    } 
    $self->{'list'}->{$doc_OID} = $date;
    }
}


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

    my @classlist = sort {$self->{'list'}->{$a} cmp $self->{'list'}->{$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 sub-sections by date
sub splitlist {
    my $self = shift (@_);
    my ($classlistref) = @_;
    my $classhash = {};

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


    if ($self->{'bymonth'}) {
    # first split up the list into separate year+month classifications
    foreach $classification (@$classlistref) {
        my $date = $self->{'list'}->{$classification};
        $date =~ s/^(\d\d\d\d)(\d\d).*$/$1&nbsp;_textmonth$2_/;
        # sanity check if month is zero
        if ($date =~ /00_$/) {
        $date =~ s/^(\d\d\d\d).*$/$1/g;
        }
        $classhash->{$date} = [] unless defined $classhash->{$date};
        push (@{$classhash->{$date}}, $classification);
    }
    } else {
    # first split up the list into separate year classifications
    foreach $classification (@$classlistref) {
        my $date = $self->{'list'}->{$classification};
        $date =~ s/^(\d\d\d\d).*$/$1/;
        $classhash->{$date} = [] unless defined $classhash->{$date};
        push (@{$classhash->{$date}}, $classification);
    }
    }
    $classhash = $self->compactlist ($classhash);

    foreach $subclass (sort keys %$classhash) {
    my $tempclassify = $self->get_entry($subclass, "DateList");
    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 $currentfirstdate = "";
    my $currentlastdate = "";
    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 my $subsection (sort keys %$classhashref) {
    $currentfirstdate = $subsection if $currentfirstdate eq "";
    if ((scalar (@currentOIDs) < $min) ||
        ((scalar (@currentOIDs) + scalar (@{$classhashref->{$subsection}})) <= $max)) {
        push (@currentOIDs, @{$classhashref->{$subsection}});
        $currentlastdate = $subsection;
    } else {

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

    # add final OIDs to last sub-classification if there aren't many otherwise
    # add final sub-classification
    if ((scalar (@currentOIDs) < $min) && (scalar (@currentOIDs) > 0)) {
    # want every thing in previous up to the dash
    my ($newkey) = $lastkey =~ /^([^\-]+)/;
    @currentOIDs = (@{$compactedhash->{$lastkey}}, @currentOIDs);
    delete $compactedhash->{$lastkey};
    @{$compactedhash->{"$newkey-$currentlastdate"}} = @currentOIDs; 
    } else {
    if ($currentfirstdate eq $currentlastdate) {
        @{$compactedhash->{$currentfirstdate}} = @currentOIDs;
    } else {
        @{$compactedhash->{"$currentfirstdate-$currentlastdate"}} = @currentOIDs;
    } 
    }

    return $compactedhash;
}

1;