###########################################################################
#
# MetadataEXIFPlugin.pm -- A plugin for EXIF
#
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright 2007 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.
#
###########################################################################


package MetadataEXIFPlugin;

use BasePlugin;

use Image::ExifTool qw(:Public);
use strict;

no strict 'refs'; # allow filehandles to be variables and viceversa


sub BEGIN
{
  @MetadataEXIFPlugin::ISA = ('BasePlugin');
}



my $arguments =
    [ ];


my $options = { 'name'     => "MetadataEXIFPlugin",
		'desc'     => "{MetadataBasPlug.desc}",
		'abstract' => "no",
		'inherits' => "yes",
		'args'     => $arguments };

sub new()
{
    my ($class) = shift (@_);
    my ($pluginlist,$inputargs,$hashArgOptLists) = @_;
    push(@$pluginlist, $class);

    if(defined $arguments){ push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});}
    if(defined $options) { push(@{$hashArgOptLists->{"OptList"}},$options)};

    my $self = new BasePlugin($pluginlist, $inputargs, $hashArgOptLists);


    # Create a new Image::ExifTool object
    my $exifTool = new Image::ExifTool;
    $exifTool->Options(Duplicates => 0);
    $exifTool->Options(PrintConv => 0);
    $exifTool->Options(Unknown => 1);
    $exifTool->Options('Verbose');
    $self->{'exiftool'} = $exifTool;


    return bless $self, $class;
}


# Need to think some more about this
sub get_default_process_exp()
{
    return q^(?i)\.(wma|wmv|jpe?g|gif)$^;
}


# This plugin doesn't block any files 
sub get_default_block_exp()
{
    return '';
}


sub extractEmbeddedMetadata()
{
    my $self = shift(@_);
    my ($file, $filename, $extrametadata, $extrametakeys) = @_;

    my %exif_metadata = ();

    my $verbosity = $self->{'verbosity'};
    my $outhandle = $self->{'outhandle'};

    my $metadata_count = 0;
    
    my @group_list = Image::ExifTool::GetAllGroups(0);
    foreach my $group (@group_list)
      {
##	  print STDERR "**** group = $group\n";

        # Extract meta information from an image
        $self->{'exiftool'}->Options(Group0 => [$group]);
        $self->{'exiftool'}->ExtractInfo($filename);

        # Get list of tags in the order they were found in the file
        my @tag_list = $self->{'exiftool'}->GetFoundTags('File');
        foreach my $tag (@tag_list)
          {
###	      print STDERR "**** tag = $tag\n";

            # Strip any numbering suffix
            $tag =~ s/^([^\s]+)\s.*$/$1/i;
            my $value = $self->{'exiftool'}->GetValue($tag);
            if (defined $value && $value =~ /[a-z0-9]+/i)
              {
                if (ref $value eq 'SCALAR')
                  {
                    if ($$value =~ /^Binary data/)
                      {
                        $value = "($$value)";
                      }
                    else
                      {
                        my $len = length($$value);
                        $value = "(Binary data $len bytes)";
                      }
                  }

		my $field = "$group.$tag";

		if (!defined $exif_metadata{$field})
		{
		    $exif_metadata{$field} = [];
		}
		push (@{$exif_metadata{$field}}, $self->gsSafe($value));
##		print STDERR "**** adding $field: $value\n";

		++$metadata_count;
              }
          }
      }


    if ($metadata_count > 0) {
	print $outhandle " Extracted $metadata_count pieces of metadata from $filename EXIF block\n";
    }
  
  # Associate the metadata now
##    print STDERR "**** file = $file\n";

  $extrametadata->{$file} = \%exif_metadata;
  push(@$extrametakeys, $file);

}


sub metadata_read()
{
  my $self = shift (@_);
  my ($pluginfo, $base_dir, $file, $block_hash, $extrametakeys, $extrametadata, $processor, $maxdocs, $gli) = @_;
  


  # See if we are looking at a PDF file... which may contain EXIF
  my $filename = &util::filename_cat($base_dir, $file);
#  if ($filename !~ /\.pdf$/i || !-f $filename)
#    {
#      return undef;
#    }

  print STDERR "\n<Processing n='$file' p='MetadataEXIFPlugin'>\n" if ($gli);
  print STDERR "MetadataEXIFPlugin: processing $file\n" if ($self->{'verbosity'}) > 1;


  $self->extractEmbeddedMetadata($file,$filename,
				 $extrametadata,$extrametakeys);

    
  return undef;
}


sub process()
{
    # not used
    return undef;
}

sub gsSafe()
  {
    my $self = shift(@_);
    my ($text) = @_;
    # Replace dangerous characters
    $text =~ s/\(/&#40;/g;
    $text =~ s/\)/&#41;/g;
    $text =~ s/,/&#44;/g;
    $text =~ s/\</&#60;/g;
    $text =~ s/\</&#62;/g;
    $text =~ s/\[/&#91;/g;
    $text =~ s/\]/&#93;/g;
    # Done
    return $text;
  }

1;