# $Id$
#
# BioPerl module Bio::Biblio::IO::pubmedxml.pm
#
# Cared for by Martin Senger <senger@ebi.ac.uk>
# For copyright and disclaimer see below.

# POD documentation - main docs before the code

=head1 NAME

Bio::Biblio::IO::pubmedxml - A converter of XML files with PUBMED citations

=head1 SYNOPSIS

Do not use this object directly, it is recommended to access it and use
it through the I<Bio::Biblio::IO> module:

  use Bio::Biblio::IO;
  my $io = new Bio::Biblio::IO (-format => 'pubmedxml');

=head1 DESCRIPTION

This object reads bibliographic citations in XML/MEDLINE format and
converts them into I<Bio::Biblio::RefI> objects. It is an
implementation of methods defined in I<Bio::Biblio::IO>.

=head1 FEEDBACK

=head2 Mailing Lists

User feedback is an integral part of the evolution of this and other
Bioperl modules. Send your comments and suggestions preferably to
the Bioperl mailing list.  Your participation is much appreciated.

  bioperl-l@bioperl.org              - General discussion
  http://bioperl.org/MailList.shtml  - About the mailing lists

=head2 Reporting Bugs

Report bugs to the Bioperl bug tracking system to help us keep track
of the bugs and their resolution. Bug reports can be submitted via
email or the web:

  bioperl-bugs@bioperl.org
  http://bugzilla.bioperl.org/

=head1 AUTHOR

Martin Senger (senger@ebi.ac.uk)

=head1 COPYRIGHT

Copyright (c) 2002 European Bioinformatics Institute. All Rights Reserved.

This module is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

=head1 DISCLAIMER

This software is provided "as is" without warranty of any kind.

=head1 APPENDIX

The main documentation details are to be found in
L<Bio::Biblio::IO>.

Here is the rest of the object methods.  Internal methods are preceded
with an underscore _.

=cut


# Let the code begin...


package Bio::Biblio::IO::pubmedxml;
use vars qw(@ISA $VERSION $Revision);
use vars qw(%PCDATA_NAMES %SIMPLE_TREATMENT %POP_DATA_AND_PEEK_OBJ %POP_AND_ADD_DATA_ELEMENT);

use strict;

use Bio::Biblio::IO::medlinexml;

@ISA = qw(Bio::Biblio::IO::medlinexml);

BEGIN { 
    # set the version for version checking
    $VERSION = do { my @r = (q$Revision$ =~ /\d+/g); sprintf "%d.%-02d", @r };
    $Revision = q$Id$;
}

sub _initialize {
    my ($self, @args) = @_;
    
    # make a hashtable from @args
    my %param = @args;
    @param { map { lc $_ } keys %param } = values %param; # lowercase keys

    # copy all @args into this object (overwriting what may already be
    # there) - changing '-key' into '_key', and making keys lowercase
    my $new_key;
    foreach my $key (keys %param) {
	($new_key = $key) =~ s/^-/_/;
	$self->{ lc $new_key } = $param { $key };
    }

    # find the format for output - and put it into a global $Convert
    # because it will be used by the event handler who knows nothing
    # about this object
    my $result = $self->{'_result'} || 'pubmed2ref';
    $result = "\L$result";	# normalize capitalization to lower case

    # a special case is 'raw' when no converting module is loaded
    # and citations will be returned as a hashtable (the one which
    # is created during parsing XML file/stream)
    unless ($result eq 'raw') {

	# load module with output converter - as defined in $result
	if (defined &Bio::Biblio::IO::_load_format_module ($result)) {
	    $Bio::Biblio::IO::medlinexml::Convert = "Bio::Biblio::IO::$result"->new (@args);
	}
    }

    # create an instance of the XML parser
    # (unless it is already there...)
    $self->{'_xml_parser'} = new XML::Parser (Handlers => {Init  => \&Bio::Biblio::IO::medlinexml::handle_doc_start,
							   Start => \&handle_start,
							   End   => \&handle_end,
							   Char  => \&Bio::Biblio::IO::medlinexml::handle_char,
							   Final => \&Bio::Biblio::IO::medlinexml::handle_doc_end})
	unless $self->{'_xml_parser'};

    # if there is an argument '-callback' then start parsing at once -
    # the registered event handlers will use 'callback' to report
    # back after each citation
    #
    # we need to remember this situation also in a global variable
    # because the event handler subroutines know nothing about this
    # object (unfortunately)
    if ($SUPER::Callback = $self->{'_callback'}) {
	$self->_parse;
    }
}

# ---------------------------------------------------------------------
#
#   Here are the event handlers (they do the real job!)
#
# Note that these methods do not know anything about the object they
# are part of - they are called as subroutines. not as methods.
# It also means that they need to use global variables to store and
# exchnage intermediate results.
#
# ---------------------------------------------------------------------

#
# This is a list of #PCDATA elements.
#
%PCDATA_NAMES =
    (
     'PublicationStatus' => 1,
     'ProviderId' => 1,
     'ArticleId' => 1,
     'URL' => 1,
     );

%SIMPLE_TREATMENT =
    (
     'History' => 1,
     'PubMedArticle' => 1,
     'PubmedArticle' => 1,
     'PubmedData' => 1,
     );

%POP_DATA_AND_PEEK_OBJ =
    (
     'Year' => 1,
     'Month' => 1,
     'Day' => 1,
     'Hour' => 1,
     'Minute' => 1,
     'Second' => 1,
     'ProviderId' => 1,
     'PublicationStatus' => 1,
     );

%POP_AND_ADD_DATA_ELEMENT =
    (
     'PubMedPubDate' => 'pubDates',
     'History' => 'histories',
     );


=head2 VERSION and Revision

 Usage   : print $Bio::Biblio::IO::pubmedxml::VERSION;
           print $Bio::Biblio::IO::pubmedxml::Revision;

=cut


sub handle_start {
    my ($expat, $e, %attrs) = @_; 
#    &Bio::Biblio::IO::medlinexml::_debug_object_stack ("START", $e);

    #
    # The #PCDATA elements which have an attribute list must
    # be first here - because for them I create entries both on
    # the @PCDataStack _and_ on @ObjectStack.
    #
    if ($e eq 'ArticleId') {
	my %p = ();
	$p{'idType'} = (defined $attrs{'IdType'} ? $attrs{'IdType'} : 'pubmed');
	push (@Bio::Biblio::IO::medlinexml::ObjectStack, \%p);
    }

    if ($e eq 'URL') {
	my %p = ();
	$p{'type'} = $attrs{'type'} if $attrs{'type'};
	$p{'lang'} = $attrs{'lang'} if $attrs{'lang'};
	push (@Bio::Biblio::IO::medlinexml::ObjectStack, \%p);
    }

    #
    # Then we have #PCDATA elements without an attribute list.
    # For them I create an entry on @PCDataStack.
    #
    if (exists $PCDATA_NAMES{$e}) {
	push (@Bio::Biblio::IO::medlinexml::PCDataStack, '');

    #
    # And finally, all non-PCDATA elements go to the objectStack
    #
    } elsif (exists $SIMPLE_TREATMENT{$e}) {
	push (@Bio::Biblio::IO::medlinexml::ObjectStack, {});

    } elsif ($e eq 'ArticleIdList') {
	;

    } elsif ($e eq 'PubMedPubDate') {
	my %p = ();
	$p{'pubStatus'} = $attrs{'PubStatus'} if $attrs{'PubStatus'};
	push (@Bio::Biblio::IO::medlinexml::ObjectStack, \%p);

    } else {
	&Bio::Biblio::IO::medlinexml::handle_start ($expat, $e, %attrs);	
    }
}

sub handle_end {
    my ($expat, $e) = @_;

    #
    # First I have to deal with those elements which are both PCDATA
    # (and therefore they are on the pcdataStack) and which have an
    # attribute list (therefore they are also known as a separate
    # p-object on the objectStack.
    #
    if ($e eq 'ArticleId') {
	&Bio::Biblio::IO::medlinexml::_data2obj ('id');
	&Bio::Biblio::IO::medlinexml::_add_element ('pubmedArticleIds', pop @Bio::Biblio::IO::medlinexml::ObjectStack);
#	&Bio::Biblio::IO::medlinexml::_debug_object_stack ("END", $e);
	return;
    }

    if ($e eq 'URL') {
	&Bio::Biblio::IO::medlinexml::_data2obj ('URL');
	&Bio::Biblio::IO::medlinexml::_add_element ('pubmedURLs', pop @Bio::Biblio::IO::medlinexml::ObjectStack);
#	&Bio::Biblio::IO::medlinexml::_debug_object_stack ("END", $e);
	return;
    }


    #
    # both object and pcdata stacks elements mixed here together
    #

    if (exists $POP_DATA_AND_PEEK_OBJ{$e}) {
	&Bio::Biblio::IO::medlinexml::_data2obj ("\l$e");

    } elsif (exists $POP_AND_ADD_DATA_ELEMENT{$e}) {
	&Bio::Biblio::IO::medlinexml::_add_element ($POP_AND_ADD_DATA_ELEMENT{$e}, pop @Bio::Biblio::IO::medlinexml::ObjectStack);

    } elsif ($e eq 'MedlineCitation' ||
	     $e eq 'NCBIArticle') {
	&Bio::Biblio::IO::medlinexml::_obj2obj ('Citation');

    } elsif ($e eq 'PubmedData') {
	&Bio::Biblio::IO::medlinexml::_obj2obj ('PubmedData');

    } elsif ($e eq 'PubMedArticle' ||
	     $e eq 'PubmedArticle') {

	#
	# Here we finally have the whole citation ready.
	#
	&Bio::Biblio::IO::medlinexml::_process_citation (pop @Bio::Biblio::IO::medlinexml::ObjectStack);

    } else {
	&Bio::Biblio::IO::medlinexml::handle_end ($expat, $e);	
    }
    
#    &Bio::Biblio::IO::medlinexml::_debug_object_stack ("END", $e);

}

1;
__END__
