###########################################################################
#
# AMCMetadataJSONPlugin.pm -- A plugin for JSON files resulting from page 
#                             scrape of artists on the Australian Music Centre
#                             website
#
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright 2016 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 AMCMetadataJSONPlugin;


use BaseImporter;
use MetadataRead;

use strict;
no strict 'refs';
use multiread;

use Encode;
use JSON;

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


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

];


my $options = { 'name'     => "AMCMetadataJSONPlugin",
		'desc'     => "{AMCMetadataJSONPlugin.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);

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

    return bless $self, $class;
}


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

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) = @_;

    # Read metadata from JSON files
    my $filename = &util::filename_cat($base_dir, $file);

    if (!-f $filename || !$self->can_process_this_file($filename)) {

	return undef;
    }
    print STDERR "\n<Processing n='$file' p='AMCMetadataJSONPlugin'>\n" if ($gli);
    print STDERR "AMCMetadataJSONPlugin: 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
    $self->block_filename($block_hash,$filename);


    # Read the JSON file to get the metadata
    my $json_file_content;
    open(JSON_FILE, "$filename");
    my $json_file_reader = new multiread();
    $json_file_reader->set_handle('AMCMetadataJSONPlugin::JSON_FILE');
    $json_file_reader->read_file(\$json_file_content);

    # Would be nice if AMCMetadataJSONPlugin was extended to support a minus
    # option to choose the character encoding the JSON file is in 
    # For now we will assume it is always in UTF8

    my $json_file_content_bytes = encode('UTF-8', $json_file_content);

    $json_file_content = decode("utf8",$json_file_content_bytes);

    close(JSON_FILE);

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

#    my $matching_file = $file;
#    $matching_filename =~ s/\.js/\.{ogg,mp3,wav}/;


#    my $json_metadata = {};

    print STDERR "**** json_metadata = $json_file_content\n";
    # my $json_metadata = decode_json $json_file_content;
    my $json_metadata = JSON->new->utf8->decode($json_file_content);

    # We can't associate any metadata without knowing the file to associate it with
    my $audio_url = $json_metadata->{"audio_url"};
    if (!defined $audio_url) {
	$self->print_error($outhandle, $failhandle, $gli, $filename, "No audio_url metadata in JSON file: $file");
	
	return -1;
    }

    my $local_audio_file = $audio_url;
    $local_audio_file =~ s/^http(s?):\/\/.*\///;
    my ($amc_id) = ($local_audio_file =~ m/^(.+)(?:\..+?)$/);

    ## print STDERR "***** local audio file = $local_audio_file\n";
 
    # Set up metadata table based on JSON file read in
    foreach my $k (keys %$json_metadata) {
	$json_metadata->{'amc.'.$k} = [ $json_metadata->{$k} ];
	delete $json_metadata->{$k};
    }
    $json_metadata->{'amc.id'} = [ $amc_id ];

#    my $json_filename = shift(@$json_trackurl_array);
#    $json_filename =~ s/\"//g; # strip off quotes
#    delete $json_metadata->{"track_url"};
    
    # Associate the metadata now
    $local_audio_file = &util::filename_to_regex($local_audio_file);

###  print STDERR "**** setting up mapping for: $json_filename\n";
    
    # Set up mapping from local_audio_file to the created JSON metadata table 
    # so it 'sticks' to the file
    $extrametadata->{$local_audio_file} = $json_metadata;
    push(@$extrametakeys, $local_audio_file);
    # record which file the metadata came from 
    if (!defined $extrametafile->{$local_audio_file}) {
	$extrametafile->{$local_audio_file} = {};
    }
    # maps the file to full path
    $extrametafile->{$local_audio_file}->{$file} = $filename;

    return 1; 
}

sub print_error
{

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

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