###########################################################################
#
# doc.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.
#
###########################################################################

# base class to hold documents

package doc;

BEGIN {
    die "GSDLHOME not set\n" unless defined $ENV{'GSDLHOME'};
    unshift (@INC, "$ENV{'GSDLHOME'}/perllib/dynamic/lib/site_perl/5.005/i686-linux");
}

use unicode;
use util;
use ghtml;
##use hashdoc;

# the document type may be indexed_doc, nonindexed_doc, or
# classification

sub new {
    my $class = shift (@_);
    my ($source_filename, $doc_type) = @_;

    my $self = bless {'associated_files'=>[],
		      'subsection_order'=>[],
		      'next_subsection'=>1,
		      'subsections'=>{},
		      'metadata'=>[],
		      'text'=>""}, $class;

    $self->set_source_filename ($source_filename) if defined $source_filename;
    $self->set_doc_type ($doc_type) if defined $doc_type;

    return $self;
}

# clone the $self object
sub duplicate {
    my $self = shift (@_);

    my $newobj = {};
    
    foreach $k (keys %$self) {
	$newobj->{$k} = &clone ($self->{$k});
    }

    bless $newobj, ref($self);
    return $newobj;
}

sub clone {
    my ($from) = @_;
    my $type = ref ($from);

    if ($type eq "HASH") {
	my $to = {};
	foreach $key (keys %$from) {
	    $to->{$key} = &clone ($from->{$key});
	}
	return $to;
    } elsif ($type eq "ARRAY") {
	my $to = [];
	foreach $v (@$from) {
	    push (@$to, &clone ($v));
	}
	return $to;
    } else {
	return $from;
    }
}


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

    $self->set_metadata_element ($self->get_top_section(), 
				 "gsdlsourcefilename", 
				 $source_filename);
}

# returns the source_filename as it was provided
sub get_source_filename {
    my $self = shift (@_);

    return $self->get_metadata_element ($self->get_top_section(), "gsdlsourcefilename");
}

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

    $self->set_metadata_element ($self->get_top_section(), 
				 "gsdldoctype", 
				 $doc_type);
}

# returns the source_filename as it was provided
# the default of "indexed_doc" is used if no document
# type was provided
sub get_doc_type {
    my $self = shift (@_);

    my $doc_type = $self->get_metadata_element ($self->get_top_section(), "gsdldoctype");
    return $doc_type if (defined $doc_type);
    return "indexed_doc";
}

sub _escape_text {
    my ($text) = @_;

    # special characters in the gml encoding
    $text =~ s/&/&/g; # this has to be first...
    $text =~ s/</&lt;/g;
    $text =~ s/>/&gt;/g;
    $text =~ s/\"/&quot;/g;

    return $text;
}


sub buffer_section {
    my $self = shift (@_);
    my ($section, $suppress_subject_info) = @_;

    $suppress_subject_info = 0 unless defined $suppress_subject_info;
    my ($all_text,$data, $subsection);
    
    my $section_ptr = $self->_lookup_section ($section);
    my ($section_num) = $section =~ /(\d+)$/;
    
    return "" unless defined $section_ptr;

    # output the section header (including the section number
    # and metadata)

    $all_text = "<gsdlsection";
    $all_text .= " gsdlnum=\"$section_num\"" if defined $section_num;
    foreach $data (@{$section_ptr->{'metadata'}}) {
	$all_text .= " $data->[0]=\"" . &_escape_text($data->[1]) . "\"" 
	    unless $suppress_subject_info && $data->[0] eq "Subject";
    }
    $all_text .= ">";

    # output the text
    $all_text .= &_escape_text($section_ptr->{'text'});

    # output all the subsections
    foreach $subsection (@{$section_ptr->{'subsection_order'}}) {
	$all_text .= $self->buffer_section("$section.$subsection", $suppress_subject_info);
    }
    
    # output the closing tag
    $all_text .=  "</gsdlsection>\n";

    return $all_text;
}

sub output_section {
    my $self = shift (@_);
    my ($handle, $section, $suppress_subject_info) = @_;

    my $all_text = $self->buffer_section($section, $suppress_subject_info);
    print $handle $all_text;
}

# look up the reference to the a particular section
sub _lookup_section {
    my $self = shift (@_);
    my ($section) = @_;

    my ($num);
    my $sectionref = $self;

    while (defined $section && $section ne "") {
	($num, $section) = $section =~ /^\.?(\d+)(.*)$/;
	$num =~ s/^0+(\d)/$1/; # remove leading 0s
	$section = "" unless defined $section;
	
	if (defined $num && defined $sectionref->{'subsections'}->{$num}) {
	    $sectionref = $sectionref->{'subsections'}->{$num};
	} else {
	    return undef;
	}
    }
    
    return $sectionref;
}

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

    my $osexe = &util::get_os_exe();

    my $hashfile_exe = &util::filename_cat($ENV{'GSDLHOME'},"bin",
					   $ENV{'GSDLOS'},"hashfile$osexe");
    my $result = "NULL";

    if (-e "$hashfile_exe") {
	$result = `$hashfile_exe \"$filename\"`;
	($result) = $result =~ /:\s*([0-9a-f]+)/i;

    } else {
	print STDERR "doc::_calc_OID $hashfile_exe could not be found\n";
    }

    return "HASH$result";
}

# methods dealing with OID, not groups of them.

# if $OID is not provided one is calculated from hashing the
# current contents of the document
# An OID are actually stored as metadata of the document
sub set_OID {
    my $self = shift (@_);
    my ($OID) = @_;

    # if an OID wasn't provided then feed this document to 
    # hashfile.exe
    if (!defined $OID) {
	$OID = "NULL";

	my $filename = $self->get_source_filename();
	if (defined($filename) && -e $filename) {

	    $OID = $self->_calc_OID ($filename);

	} else {
	    
	    print STDERR "doc::set_OID source filename undefined/non-existant (continuing)\n";
	    
	    $filename = &util::get_tmp_filename();
	    if (!open (OUTFILE, ">$filename")) {
		print STDERR "doc::set_OID could not write to $filename\n";
	    } else {
		$self->output_section('OUTFILE', $self->get_top_section(), 1);
		close (OUTFILE);
	    }
	    
	    $OID = $self->_calc_OID ($filename);
	    &util::rm ($filename);
	}
    }

    $self->set_metadata_element ($self->get_top_section(), "Identifier", $OID);
}

# this uses hashdoc (embedded c thingy) which is faster but still 
# needs a little work to be suffiently stable
sub ___set_OID {
    my $self = shift (@_);
    my ($OID) = @_;

    # if an OID wasn't provided then calculate hash value based on document
    if (!defined $OID) 
    {
	my $hash_text = $self->buffer_section($self->get_top_section(), 1);
	my $hash_len = length($hash_text);

        $OID = &hashdoc::buffer($hash_text,$hash_len);
    }

    $self->set_metadata_element ($self->get_top_section(), "Identifier", $OID);
}

# returns the OID for this document
sub get_OID {
    my $self = shift (@_);
    my $OID = $self->get_metadata_element ($self->get_top_section(), "Identifier");
    return $OID if (defined $OID);
    return "NULL";
}

sub delete_OID {
    my $self = shift (@_);
    
    $self->set_metadata_element ($self->get_top_section(), "Identifier", "NULL");
}


# methods for manipulating section names

# returns the name of the top-most section (the top
# level of the document
sub get_top_section {
    my $self = shift (@_);
    
    return "";
}

# returns a section
sub get_parent_section {
    my $self = shift (@_);
    my ($section) = @_;

    $section =~ s/(^|\.)\d+$//;

    return $section;
}

# returns the first child section (or the end child 
# if there isn't any)
sub get_begin_child {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section($section);
    return "" unless defined $section_ptr;

    if (defined $section_ptr->{'subsection_order'}->[0]) {
	return "$section.$section_ptr->{'subsection_order'}->[0]";
    }

    return $self->get_end_child ($section);
}

# returns the next child of a parent section
sub get_next_child {
    my $self = shift (@_);
    my ($section) = @_;
    
    my $parent_section = $self->get_parent_section($section);
    my $parent_section_ptr = $self->_lookup_section($parent_section);
    return undef unless defined $parent_section_ptr;

    my ($section_num) = $section =~ /(\d+)$/;
    return undef unless defined $section_num;

    my $i = 0;
    my $section_order = $parent_section_ptr->{'subsection_order'};
    while ($i < scalar(@$section_order)) {
	last if $section_order->[$i] eq $section_num;
	$i++;
    }

    $i++; # the next child
    if ($i < scalar(@$section_order)) {
	return $section_order->[$i] if $parent_section eq "";
	return "$parent_section.$section_order->[$i]";
    }

    # no more sections in this level
    return undef;
}

# returns a reference to a list of children
sub get_children {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section($section);
    return [] unless defined $section_ptr;

    my @children = @{$section_ptr->{'subsection_order'}};

    map {$_ = "$section.$_"; $_ =~ s/^\.+//;} @children;
    return \@children;
}

# returns the child section one past the last one (which
# is coded as "0")
sub get_end_child {
    my $self = shift (@_);
    my ($section) = @_;

    return $section . ".0" unless $section eq "";
    return "0";
}

# returns the next section in book order
sub get_next_section {
    my $self = shift (@_);
    my ($section) = @_;

    return undef unless defined $section;

    my $section_ptr = $self->_lookup_section($section);
    return undef unless defined $section_ptr;

    # first try to find first child
    if (defined $section_ptr->{'subsection_order'}->[0]) {
	return $section_ptr->{'subsection_order'}->[0] if ($section eq "");
	return "$section.$section_ptr->{'subsection_order'}->[0]";
    }

    do {
	# try to find sibling
	my $next_child = $self->get_next_child ($section);
	return $next_child if (defined $next_child);

	# move up one level
	$section = $self->get_parent_section ($section);
    } while $section =~ /\d/;

    return undef;
}

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

    my $section_ptr = $self->_lookup_section($section);
    return 1 unless defined $section_ptr;

    return (scalar (@{$section_ptr->{'subsection_order'}}) == 0);
}

# methods for dealing with sections

# returns the name of the inserted section
sub insert_section {
    my $self = shift (@_);
    my ($before_section) = @_;

    # get the child to insert before and its parent section
    my $parent_section = "";
    my $before_child = "0";
    my @before_section = split (/\./, $before_section);
    if (scalar(@before_section) > 0) {
	$before_child = pop (@before_section);
	$parent_section = join (".", @before_section);
    }

    my $parent_section_ptr = $self->_lookup_section($parent_section);
    if (!defined $parent_section_ptr) {
	print STDERR "doc::insert_section couldn't find parent section " .
	    "$parent_section\n";
	return;
    }

    # get the next section number
    my $section_num = $parent_section_ptr->{'next_subsection'}++;

    my $i = 0;
    while ($i < scalar(@{$parent_section_ptr->{'subsection_order'}}) &&
	   $parent_section_ptr->{'subsection_order'}->[$i] ne $before_child) {
	$i++;
    }
    
    # insert the section number into the order list
    splice (@{$parent_section_ptr->{'subsection_order'}}, $i, 0, $section_num);

    # add this section to the parent section
    my $section_ptr = {'subsection_order'=>[],
		       'next_subsection'=>1,
		       'subsections'=>{},
		       'metadata'=>[],
		       'text'=>""};
    $parent_section_ptr->{'subsections'}->{$section_num} = $section_ptr;

    # work out the full section number
    my $section = $parent_section;
    $section .= "." unless $section eq "";
    $section .= $section_num;
    
    return $section;
}

# creates a pre-named section
sub create_named_section {
    my $self = shift (@_);
    my ($mastersection) = @_;

    my ($num);
    my $section = $mastersection;
    my $sectionref = $self;

####    print STDERR "*** mastersection = $mastersection\n";

    while ($section ne "") {
	($num, $section) = $section =~ /^\.?(\d+)(.*)$/;
	$num =~ s/^0+(\d)/$1/; # remove leading 0s
	$section = "" unless defined $section;
	
	if (defined $num) {
	    if (!defined $sectionref->{'subsections'}->{$num}) {
		push (@{$sectionref->{'subsection_order'}}, $num);
		$sectionref->{'subsections'}->{$num} = {'subsection_order'=>[],
							'next_subsection'=>1,
							'subsections'=>{},
							'metadata'=>[],
							'text'=>""};
		if ($num >= $sectionref->{'next_subsection'}) {
		    $sectionref->{'next_subsection'} = $num + 1;
		}
	    }
	    $sectionref = $sectionref->{'subsections'}->{$num};

	} else {
	    print STDERR "doc::create_named_section couldn't create section ";
	    print STDERR "$mastersection\n";
	    last;
	}
    }
}

# returns a reference to a list of subsections
sub list_subsections {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section ($section);
    if (!defined $section_ptr) {
	print STDERR "doc::list_subsections couldn't find section $section\n";
	return [];
    }

    return [@{$section_ptr->{'subsection_order'}}];
}

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

#    my $section_ptr = {'subsection_order'=>[],
#		       'next_subsection'=>1,
#		       'subsections'=>{},
#		       'metadata'=>[],
#		       'text'=>""};

    # if this is the top section reset everything
    if ($section eq "") {
	$self->{'subsection_order'} = [];
	$self->{'subsections'} = {};
	$self->{'metadata'} = [];
	$self->{'text'} = "";
	return;
    }

    # find the parent of the section to delete
    my $parent_section = "";
    my $child = "0";
    my @section = split (/\./, $section);
    if (scalar(@section) > 0) {
	$child = pop (@section);
	$parent_section = join (".", @section);
    }

    my $parent_section_ptr = $self->_lookup_section($parent_section);
    if (!defined $parent_section_ptr) {
	print STDERR "doc::delete_section couldn't find parent section " .
	    "$parent_section\n";
	return;
    }

    # remove this section from the subsection_order list
    my $i = 0;
    while ($i < scalar (@{$parent_section_ptr->{'subsection_order'}})) {
	if ($parent_section_ptr->{'subsection_order'}->[$i] eq $child) {
	    splice (@{$parent_section_ptr->{'subsection_order'}}, $i, 1);
	    last;
	}
	$i++;
    }

    # remove this section from the subsection hash
    if (defined ($parent_section_ptr->{'subsections'}->{$child})) {
	undef $parent_section_ptr->{'subsections'}->{$child};
    }
}

#--
# methods for dealing with metadata

# set_metadata_element and get_metadata_element are for metadata
# which should only have one value. add_meta_data and get_metadata
# are for metadata which can have more than one value.

# returns the first metadata value which matches field
sub get_metadata_element {
    my $self = shift (@_);
    my ($section, $field) = @_;
    my ($data);

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::get_metadata_element couldn't find section " .
	    "$section\n";
	return;
    }

    foreach $data (@{$section_ptr->{'metadata'}}) {
	return $data->[1] if (scalar(@$data) >= 2 && $data->[0] eq $field);
    }
	
    return undef; # was not found
}


# returns a list of the form [value1, value2, ...]
sub get_metadata {
    my $self = shift (@_);
    my ($section, $field) = @_;
    my ($data);

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
        print STDERR "doc::get_metadata couldn't find section " .
            "$section\n";
        return;
    }

    my @metadata = ();
    foreach $data (@{$section_ptr->{'metadata'}}) {
        push (@metadata, $data->[1]) if ($data->[0] eq $field);
    }
        
    return \@metadata;
}

# returns a list of the form [[field,value],[field,value],...]
sub get_all_metadata {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::get_all_metadata couldn't find section " .
	    "$section\n";
	return;
    }
    
    return $section_ptr->{'metadata'};
}

# $value is optional
sub delete_metadata {
    my $self = shift (@_);
    my ($section, $field, $value) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::delete_metadata couldn't find section " .
	    "$section\n";
	return;
    }

    my $i = 0;
    while ($i < scalar (@{$section_ptr->{'metadata'}})) {
	if (($section_ptr->{'metadata'}->[$i]->[0] eq $field) &&
	    (!defined $value || $section_ptr->{'metadata'}->[$i]->[1] eq $value)) {
	    splice (@{$section_ptr->{'metadata'}}, $i, 1);
	} else {
	    $i++;
	}
    }
}

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

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::delete_all_metadata couldn't find section " .
	    "$section\n";
	return;
    }
    
    $section_ptr->{'metadata'} = [];
}

sub set_metadata_element {
    my $self = shift (@_);
    my ($section, $field, $value) = @_;

    $self->set_utf8_metadata_element ($section, $field, 
				      &unicode::ascii2utf8($value));
}

# set_utf8_metadata_element assumes the text has already been
# converted to the UTF-8 encoding.
sub set_utf8_metadata_element {
    my $self = shift (@_);
    my ($section, $field, $value) = @_;

    $self->delete_metadata ($section, $field);
    $self->add_utf8_metadata ($section, $field, $value);
}


# add_metadata assumes the text is in (extended) ascii form. For
# text which hash been already converted to the UTF-8 format use
# add_utf8_metadata.
sub add_metadata {
    my $self = shift (@_);
    my ($section, $field, $value) = @_;

    $self->add_utf8_metadata ($section, $field,
			      &unicode::ascii2utf8($value));
}

# add_utf8_metadata assumes the text has already been converted
# to the UTF-8 encoding.
sub add_utf8_metadata {
    my $self = shift (@_);
    my ($section, $field, $value) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::add_utf8_metadata couldn't find section " .
	    "$section\n";
	return;
    }
    
    push (@{$section_ptr->{'metadata'}}, [$field, $value]);
}


# methods for dealing with text

# returns the text for a section
sub get_text {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::get_text couldn't find section " .
	    "$section\n";
	return "";
    }

    return $section_ptr->{'text'};
}

# returns the (utf-8 encoded) length of the text for a section
sub get_text_length {
    my $self = shift (@_);
    my ($section) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::get_text_length couldn't find section " .
	    "$section\n";
	return 0;
    }

    return length ($section_ptr->{'text'});
}

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

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::delete_text couldn't find section " .
	    "$section\n";
	return;
    }

    $section_ptr->{'text'} = "";
}

# add_text assumes the text is in (extended) ascii form. For
# text which has been already converted to the UTF-8 format
# use add_utf8_text.
sub add_text {
    my $self = shift (@_);
    my ($section, $text) = @_;

    # convert the text to UTF-8 encoded unicode characters
    # and add the text
    $self->add_utf8_text($section, &unicode::ascii2utf8($text));
}


# add_utf8_text assumes the text to be added has already
# been converted to the UTF-8 encoding. For ascii text use
# add_text
sub add_utf8_text {
    my $self = shift (@_);
    my ($section, $text) = @_;

    my $section_ptr = $self->_lookup_section($section);
    if (!defined $section_ptr) {
	print STDERR "doc::add_utf8_text couldn't find section " .
	    "$section\n";
	return;
    }

    $section_ptr->{'text'} .= $text;
}


# methods for dealing with associated files

# a file is associated with a document, NOT a section.
# if section is defined it is noted in the data structure
# only so that files associated from a particular section
# may be removed later (using delete_section_assoc_files)
sub associate_file {
    my $self = shift (@_);
    my ($real_filename, $assoc_filename, $mime_type, $section) = @_;
    $mime_type = &ghtml::guess_mime_type ($real_filename) unless defined $mime_type;

    # remove all associated files with the same name
    $self->delete_assoc_file ($assoc_filename);

    push (@{$self->{'associated_files'}}, 
	  [$real_filename, $assoc_filename, $mime_type, $section]);
}

# returns a list of associated files in the form
#   [[real_filename, assoc_filename, mimetype], ...]
sub get_assoc_files {
    my $self = shift (@_);

    return $self->{'associated_files'};
}

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

    my $i=0;
    while ($i < scalar (@{$self->{'associated_files'}})) {
	if (defined $self->{'associated_files'}->[$i]->[3] &&
	    $self->{'associated_files'}->[$i]->[3] eq $section) {
	    splice (@{$self->{'associated_files'}}, $i, 1);
	} else {
	    $i++;
	}
    }
}

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

    my $i=0;
    while ($i < scalar (@{$self->{'associated_files'}})) {
	if ($self->{'associated_files'}->[$i]->[1] eq $assoc_filename) {
	    splice (@{$self->{'associated_files'}}, $i, 1);
	} else {
	    $i++;
	}
    }
}

sub reset_nextsection_ptr {
    my $self = shift (@_);
    my ($section) = @_;
    
    my $section_ptr = $self->_lookup_section($section);
    $section_ptr->{'next_subsection'} = 1;
}

1;