###########################################################################
#
# MetadataCSVPlugin.pm -- A plugin for metadata in comma-separated value format
#
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright 2006 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 MetadataCSVPlugin;


use BaseImporter;
use MetadataRead;
use CSVFieldSeparator;

use strict;
no strict 'refs';

use multiread;
use util;

use Encode;
use Text::CSV;

# methods with identical signatures take precedence in the order given in the ISA list.
sub BEGIN {
    @MetadataCSVPlugin::ISA = ('MetadataRead', 'BaseImporter', 'CSVFieldSeparator');
}



my $arguments = [
      { 'name' => "process_exp",
	'desc' => "{BaseImporter.process_exp}",
	'type' => "regexp",
	'reqd' => "no",
	'deft' => &get_default_process_exp() }

];


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


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

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

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

    return bless $self, $class;
}


sub get_default_process_exp
{
    return q^(?i)\.csv$^;
}

sub file_block_read {
    my $self = shift (@_);
    my ($pluginfo, $base_dir, $file, $block_hash, $metadata, $gli) = @_;

    my ($filename_full_path, $filename_no_path) = &util::get_full_filenames($base_dir, $file);

    if (!-f $filename_full_path || !$self->can_process_this_file($filename_full_path)) {
	return undef; # can't recognise
    }

    # set this so we know this is a metadata file - needed for incremental 
    # build
    # if this file changes, then we need to reimport everything
    $block_hash->{'metadata_files'}->{$filename_full_path} = 1;

    return 1;
}

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

    # can we process this file??
    my ($filename_full_path, $filename_no_path) = &util::get_full_filenames($base_dir, $file);
    return undef unless $self->can_process_this_file_for_metadata($filename_full_path);
    
    print STDERR "\n<Processing n='$file' p='MetadataCSVPlugin'>\n" if ($gli);
    print STDERR "MetadataCSVPlugin: processing $file\n" if ($self->{'verbosity'}) > 1;

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

    # add the file to the block list so that it won't be processed in read, as we will do all we can with it here
    $self->block_raw_filename($block_hash,$filename_full_path);


    # Read the CSV file to get the metadata
    my $csv_file_content;
    open(CSV_FILE, "$filename_full_path");
    my $csv_file_reader = new multiread();
    $csv_file_reader->set_handle('MetadataCSVPlugin::CSV_FILE');
    $csv_file_reader->read_file(\$csv_file_content);

    # Would be nice if MetadataCSVPlugin was extended to support a minus
    # option to choose the character encoding the CSV file is in 
    # For now we will assume it is always in UTF8
    $csv_file_content = decode("utf8",$csv_file_content);

    close(CSV_FILE);

    # Split the file into lines and read the first line (contains the metadata names)
    $csv_file_content =~ s/\r/\n/g;  # Handle non-Unix line endings
    $csv_file_content =~ s/\n+/\n/g;

    my $separate_char = $self->{'csv_field_separator'};

    my $md_val_sep = $self->{'metadata_value_separator'};
    undef $md_val_sep if ($md_val_sep eq "");

    my @csv_file_lines = split(/\n/, $csv_file_content);
    my $csv_file_field_line = shift(@csv_file_lines);

    if ($separate_char =~ m/^auto$/i) {
	$separate_char = $self->resolve_auto($csv_file_field_line,$self->{'plugin_type'});
    }

    my $csv = Text::CSV->new();
    $csv->sep_char($separate_char);
 
    my @csv_file_fields = undef;
    if ($csv->parse($csv_file_field_line)) {
	@csv_file_fields = $csv->fields;
    }
    else {
	$self->print_error($outhandle, $failhandle, $gli, $filename_full_path, "Error: Badly formatted CSV header line: $csv_file_field_line");
	return -1;
    }

    my $found_filename_field = 0;
    for (my $i = 0; $i < scalar(@csv_file_fields); $i++) {
	# Remove any spaces from the field names, and surrounding quotes too
	$csv_file_fields[$i] =~ s/ //g;
	$csv_file_fields[$i] =~ s/^"//;
	$csv_file_fields[$i] =~ s/"$//;

	if ($csv_file_fields[$i] eq "Filename") {
	    $found_filename_field = 1;
	}
    }

    if (!$found_filename_field) {
	$self->print_error($outhandle, $failhandle, $gli, $filename_full_path, "No Filename field in CSV file");
	return -1; # error
    }
    # Read each line of the file and assign the metadata appropriately
    foreach my $csv_line (@csv_file_lines) {
	# Ignore lines containing only whitespace
	next if ($csv_line =~ /^\s*$/);
	my $orig_csv_line = $csv_line;

	# Build a hash of metadata name to metadata value for this line
	my %csv_line_metadata;

	if ($csv->parse($csv_line)) {
	    my @md_vals = $csv->fields;
	    my $md_vals_len = scalar(@md_vals);
	    
	    for (my $i=0; $i<$md_vals_len; $i++) {
		my $md_val = $md_vals[$i];
		# Only bother with non-empty values
		if ($md_val ne "" && defined($csv_file_fields[$i])) {

		    my $md_name = $csv_file_fields[$i];

		    if (!defined $md_name) {
			$csv_line_metadata{$md_name} = [];
		    }

		    if (defined $md_val_sep) {			
			
			my @within_md_vals = split(/${md_val_sep}/,$md_val);
			#push (@{$csv_line_metadata{$md_name}}, @within_md_vals);

			# protect square brackets in metadata values by hex entity encoding them
			# As unescaped square bracket chars in metadata
			# have special meaning in GS' Java runtime code
			my @escaped_within_md_vals = ();
			for my $meta_value (@within_md_vals) {
			    $meta_value =~ s/\[/&\#091;/g;
			    $meta_value =~ s/\]/&\#093;/g;
			    push(@escaped_within_md_vals, $meta_value);
			}
			push (@{$csv_line_metadata{$md_name}}, @escaped_within_md_vals);

#			foreach my $within_md_val (@within_md_vals) {
#			    push (@{$csv_line_metadata{$md_name}}, $within_md_val);
#			}
		    }
		    else {
			#push (@{$csv_line_metadata{$md_name}}, $md_val);
			# protect square brackets in metadata values by hex entity encoding them
			my $escaped_metadata_value = $md_val;
			$escaped_metadata_value =~ s/\[/&\#091;/g;
			$escaped_metadata_value =~ s/\]/&\#093;/g;
			push (@{$csv_line_metadata{$md_name}}, $escaped_metadata_value);
		    }
		}
	    }
	}
	else {
	    $self->print_error($outhandle, $failhandle, $gli, $filename_full_path, "Badly formatted CSV line: $csv_line");
	    last;
	}
    
	# We can't associate any metadata without knowing the file to associate it with
	my $csv_line_filename_array = $csv_line_metadata{"Filename"};
	if (!defined $csv_line_filename_array) {
	    $self->print_error($outhandle, $failhandle, $gli, $filename_full_path, "No Filename metadata in CSV line: $orig_csv_line");
	    next;
	}
	my $csv_line_filename = shift(@$csv_line_filename_array);
	delete $csv_line_metadata{"Filename"};

	my $csv_line_section_array = $csv_line_metadata{"Section"};
	my $section_suffix = "";
	if (defined $csv_line_section_array) {
		my $section_value = shift(@$csv_line_section_array);
		if ($section_value =~ /[\d.]+/m){
			my $section_suffix = "///Section/" . $section_value;
			foreach my $metaname (keys %csv_line_metadata) {
				my $new_name = $metaname . $section_suffix;
				$csv_line_metadata{$new_name} = delete $csv_line_metadata{$metaname};
			}
		} else{
			unshift(@$csv_line_section_array, $section_value);
		}
	}


 	# Associate the metadata now
	$self->store_meta_in_extrametadata($csv_line_filename, \%csv_line_metadata, $file, $filename_full_path, $extrametakeys, $extrametadata, $extrametafile);

    }
}

sub print_error
{

    my $self = shift(@_);
    my ($outhandle, $failhandle, $gli, $file, $error) = @_;

    print $outhandle "MetadataCSVPlugin Error: $file: $error\n";
    print $failhandle "MetadataCSVPlugin Error: $file: $error\n";
    print STDERR "<ProcessingError n='$file' r='$error'/>\n" if ($gli);
}
1;
