#!/usr/bin/perl

# emphasis + doublequote means technical or foreign term.
# doublequote + emphasis means title.
#
# Pandoc parses quotation marks in two ways (possibly concurrently):
#  * Leave as-is when parsing and serializing
#  * smart-converts to Quoted object and serializes to ``'' or `'
# Some quotation marks may still be left as-is in smart mode, depending
# on parser.  See e.g. https://github.com/jgm/pandoc/issues/2012
#
# This filter handles Quoted objects and (less reliably) Char quotes.

use Moops -strict;

use Pandoc::Filter 0.06;
use Pandoc::Elements 0.12;
use Scalar::Util qw(reftype);
use Clone qw(clone);

use Log::Any qw($log);
use Log::Any::Adapter ( 'Screen',
	use_color => ! -t *STDERR );

# TODO: add class Egg, and coercing roles Exotic and Noble

class Uterus with MooX::Role::Logger {
	lexical_has fetuses => (
		isa => ArrayRef[Object],
		default => sub { [] },
		reader => \( my $fetuses ),
		lazy => 1,
	);
	has is_monstrous => (
		is => 'rw',
		isa => Bool,
		default => sub { 0 },
	);
	# TODO: replace with method fertilize, with Egg coercions
	method implant ( Object $clone ) {
		push @{ $self->$fetuses }, $clone;
	}
	method create ( Object $monster ) {
		push @{ $self->$fetuses }, $monster;
		$self->is_monstrous(1);
	}
	method abort () {
		splice @{ $self->$fetuses };
		return;
	}
	method deliver () {
		my @babies = splice @{ $self->$fetuses };
		if ($self->_logger->is_debug()) {
#			$self->_logger->debugf( 'giving birth: %s',
#				\@babies );
			for my $baby ( @babies ) {
				$self->_logger->debugf( 'giving birth: %s',
					$baby->name );
			};
		};
		return [ @babies ];
	}
}

my $doublequote = qr/[\"\x{00AB}\x{00BB}\x{201C}-\x{201F}\x{300C}-\x{300F}\x{301D}-\x{301F}\x{FE41}-\x{FE44}\x{FF02}\x{FF62}\x{FF63}]/;
my $nodoublequote = qr/[^\"\x{00AB}\x{00BB}\x{201C}-\x{201F}\x{300C}-\x{300F}\x{301D}-\x{301F}\x{FE41}-\x{FE44}\x{FF02}\x{FF62}\x{FF63}]/;

my $womb = Uterus->new;

pandoc_filter(
	\&emphasis,
);

# FIXME: wrongly messes with "'''open'''": avoid strong emphasis
# FIXME: wrongly adds quotation mark to "'''''if''''' ...": maybe avoid emphasis not immediately followed by plain text?
# TODO: flatten only Str and Space as content of new children, else skip
sub emphasis {
	my $self = shift;
	# TODO: replace @children with $kids ref, and use at more places
	my (@children, $last_child, $kid);

	# we do our own walk of inline objects
	return unless $self->is_block;

	# skip known irrelevant block types
	return if ( $self->name =~
		/CodeBlock|RawBlock|Header|HorizontalRule|Null/ );

	# skip known irrelevant block types
	if ( $self->name =~
		/OrderedList|BulletList|DefinitionList|Table/
	) {
		$log->infof( 'emphasis: skipping unsupported block: %s',
			$self->name );
		return
	};

	# align coherently and walk direct descendants
	if ( reftype $self->content eq 'ARRAY') {
		@children = @{ $self->content };
		$last_child = scalar $self->content->[
			( keys @{ $self->content } ) -1 ];
	} elsif ( reftype $self->content eq 'HASH') {
		@children = [ $self->content ];
		$last_child = scalar $self->content;
	} else {
		$log->warnf( 'emphasis: skipping oddly structured block: %s',
			$self->name );
		return;
	}
	$kid = 0;
	$log->debugf( 'emphasis: processing block: %s',
		$self->name );
	while ($kid < keys @children ) {
		# title markup via Quoted
		# TODO: limit container to type DoubleQuote
		if ( $self->content->[$kid]->name eq 'Quoted'
			and $self->content->[$kid]->content->[0]->name eq 'Emph'
		) {
			my $new_content = $self->content->[$kid]->content->[0]->string;
			$log->infof( 'emphasis: Quoted+Emph→title: %s',
				$new_content );
			# FIXME: LaTeX-encode content
			$womb->create(
				Quoted( DoubleQuote,
				$new_content ));
			$kid++;
			next;
		}
		# title markup via quotation mark in Str
		if ( $self->content->[$kid]->name eq 'Str'
			and $self->content->[$kid]->content =~ /$doublequote/
			and $self->content->[$kid+1]->name eq 'Emph'
			and $self->content->[$kid+2]->name eq 'Str'
			and $self->content->[$kid+2]->content =~ /$doublequote/
		) {
			$log->infof( 'emphasis: %s+Emph→title: %s',
				$self->content->[$kid]->content,
				$self->content->[$kid+1]->content );
			$womb->create(
				Quoted( DoubleQuote,
				$self->content->[$kid+1]->content ));
			$kid += 3;
			next;
		};
		# foreign markup via Quoted
		# TODO: limit container to type DoubleQuote
		if ( $self->content->[$kid]->name eq 'Emph'
			and $self->content->[$kid]->content->[0]->name eq 'Quoted'
		) {
			my $new_content = $self->content->[$kid]->content->[0]->string;
			$log->infof( 'emphasis: Emph+Quoted→foreign: %s',
				$new_content );
			# FIXME: LaTeX-encode content
			$womb->create(
				RawInline( 'latex',
				sprintf( '\foreign{%s}',
					$new_content )));
			$kid++;
			next;
		}
		# foreign markup via quotation mark in Str
		if ( $self->content->[$kid]->name eq 'Emph'
			and $self->content->[$kid]->string
#			=~ /^(\")([^\"]+)\"$/
			=~ /^($doublequote)(^$nodoublequote+)$doublequote$/
		) {
			$log->infof( 'emphasis: Emph+%s→foreign: %s',
				$1, $2 );
			# FIXME: LaTeX-encode content
			$womb->create(
				RawInline( 'latex',
				sprintf( '\foreign{%s}',
					$2 )));
			$kid++;
			next;
		}

		# clone healthy kid, in case of monstrous siblings
		$womb->implant( $self->content->[$kid] );
		$kid++;
	}

	# cheaper to abort (i.e. return nothing) if no monsters created
	return $womb->abort unless ($womb->is_monstrous);

	my $kids = $womb->deliver;
	$log->debugf( 'delivered kids: %s', $kids );

	# dirty hack to preserve non-content block parts
	my $new_block = clone $self;
	$$new_block{c} = $kids;
	$log->debugf( 'block: %s', $new_block );

	return [ $new_block ];
}