#!/usr/bin/perl

use warnings;
use strict;

use feature qw(switch);
no if $] >= 5.018, warnings => "experimental::smartmatch";

use Pandoc::Filter 0.05;
use Pandoc::Elements;

use Text::BibTeX::Entry;
use Path::Tiny;
use List::Util qw(pairmap);
use DateTime::Format::Flexible;


my $bibfilename = $ENV{'PANDOC_CITEPROC_FILE'} || 'bibliography.bib';
my $bibfile = path($bibfilename);
my $bibdata = new Text::BibTeX::Entry;

my (@a, $i);

pandoc_filter sub {
	my $self = shift;
	return unless ($self->name eq 'RawInline' and $self->format eq 'mediawiki');

	given ($self->content) {
		when (/^\{\{cite\s+(\w+)\s*\|(.*)\}\}$/) {
			my $id = 'ref'.++$i;
			my @data = pairmap { $b =~ s/"/\\"/g; "$a=\"$b\"" }
				map { /^\s*(\w+)\s*=\s*"?(.*?)"?\s*$/ }
					split( /\|/, $2 );
			$bibdata->parse_s (join ",\n",
				'@'.$1.'{'.$id,
				@data,
				'}');
			if ( ! $bibdata->get('author') ) {
				my @authors;
				for ( my $i = 1;; $i++ ) {
					my ( $first, $last );
					if ( $i == 1 and $bibdata->get('first') ) {
						$first = $bibdata->get('first');
						$bibdata->delete('first');
					} elsif ( $bibdata->get("first$i") ) {
						$first = $bibdata->get("first$i");
						$bibdata->delete("first$i");
					}
					if ( $i == 1 and $bibdata->get('last') ) {
						$last = $bibdata->get('last');
						$bibdata->delete('last');
					} elsif ( $bibdata->get("last$i") ) {
						$last = $bibdata->get("last$i");
						$bibdata->delete("last$i");
					}
					if ( $first and $last ) {
						push @authors, "$first {$last}";
					} elsif ($first) {
						push @authors, $first;
					} elsif ($last) {
						push @authors, $last;
					} else {
						last;
					}
				}
				if ( @authors > 0 ) {
					$bibdata->set( 'author', join ( ' and ', @authors ) );
				};
			};
			if ( $bibdata->type =~ /web/i ) {
				$bibdata->set_type('online');
				if ( my $urldate = $bibdata->get('accessdate') ) {
					my $dt = DateTime::Format::Flexible->parse_datetime($urldate);
					$bibdata->set( 'urldate', $dt->format_cldr('yyyy-MM-dd') );
					$bibdata->delete('accessdate');
				};
			};
			$bibfile->spew( '' )
				if ( $i <= 1 );
			$bibfile->append( $bibdata->print_s );
			return Cite(
				[{
					'citationId' => $id,
					'citationPrefix' => [],
					'citationSuffix' => [],
					'citationMode' => {
						t => 'NormalCitation',
						c => [],
					},
					'citationNoteNum' => 0,
					'citationHash' => 0,
				 }],
				[ Str $id ],
			);
		}
		when (/^\{\{citation needed\}\}$/) {
			say STDERR "WARNING: Mediawiki citation needed.";
			return [
				Str "citation",
				Space,
				Str "needed",
			];
		}
		default {
			say STDERR "WARNING: Mediawiki unknown data skipped: "
				. '"' . $_ . '"';
			return Str "";
		}
	}
};