=head1 NAME

RDF::Query::Functions::Xpath - XPath functions

=head1 VERSION

This document describes RDF::Query::Functions::Xpath version 2.918.

=head1 DESCRIPTION

Defines the following function:

=over

=item * http://www.w3.org/2005/xpath-functions#matches

=item * http://www.w3.org/2005/xpath-functions#abs

=item * http://www.w3.org/2005/xpath-functions#ceiling

=item * http://www.w3.org/2005/xpath-functions#floor

=item * http://www.w3.org/2005/xpath-functions#round

=item * http://www.w3.org/2005/xpath-functions#round-half-to-even

=item * http://www.w3.org/2005/xpath-functions#compare

=item * http://www.w3.org/2005/xpath-functions#concat

=item * http://www.w3.org/2005/xpath-functions#substring

=item * http://www.w3.org/2005/xpath-functions#string-length

=item * http://www.w3.org/2005/xpath-functions#upper-case

=item * http://www.w3.org/2005/xpath-functions#lower-case

=item * http://www.w3.org/2005/xpath-functions#encode-for-uri

=item * http://www.w3.org/2005/xpath-functions#contains

=item * http://www.w3.org/2005/xpath-functions#starts-with

=item * http://www.w3.org/2005/xpath-functions#ends-with

=item * http://www.w3.org/2005/xpath-functions#year-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#month-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#day-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#hours-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#minutes-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#seconds-from-dateTime

=item * http://www.w3.org/2005/xpath-functions#timezone-from-dateTime


=back

=cut

package RDF::Query::Functions::Xpath;

use strict;
use warnings;
use Log::Log4perl;
use POSIX;
use URI::Escape;

use RDF::Trine::Namespace qw(xsd);

our ($VERSION, $l);
BEGIN {
	$l			= Log::Log4perl->get_logger("rdf.query.functions.xpath");
	$VERSION	= '2.918';
}

use Scalar::Util qw(blessed reftype refaddr looks_like_number);

=begin private

=item C<< install >>

Documented in L<RDF::Query::Functions>.

=end private

=cut

sub install {
	# # fn:compare
	# $RDF::Query::functions{"http://www.w3.org/2005/04/xpath-functionscompare"}	= sub {
	# 	my $query	= shift;
	# 	my $nodea	= shift;
	# 	my $nodeb	= shift;
	# 	my $cast	= 'sop:str';
	# 	return ($RDF::Query::functions{$cast}->($query, $nodea) cmp $RDF::Query::functions{$cast}->($query, $nodeb));
	# };
	# 
	# # fn:not
	# $RDF::Query::functions{"http://www.w3.org/2005/04/xpath-functionsnot"}	= sub {
	# 	my $query	= shift;
	# 	my $nodea	= shift;
	# 	my $nodeb	= shift;
	# 	my $cast	= 'sop:str';
	# 	return (0 != ($RDF::Query::functions{$cast}->($query, $nodea) cmp $RDF::Query::functions{$cast}->($query, $nodeb)));
	# };

	# fn:matches
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#matches",
		sub {
			my $query	= shift;
			my $node	= shift;
			my $match	= shift;
			my $f		= shift;
			
			my $string;
			if ($node->isa('RDF::Query::Node::Resource')) {
				$string	= $node->uri_value;
			} elsif ($node->isa('RDF::Query::Node::Literal')) {
				$string	= $node->literal_value;
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:matches called without a literal or resource";
			}
			
			my $pattern	= $match->literal_value;
			return undef if (index($pattern, '(?{') != -1);
			return undef if (index($pattern, '(??{') != -1);
			my $flags	= blessed($f) ? $f->literal_value : '';
			
			my $matches;
			if ($flags) {
				$pattern	= "(?${flags}:${pattern})";
				warn 'pattern: ' . $pattern;
				$matches	= $string =~ /$pattern/;
			} else {
				$matches	= ($string =~ /$pattern/) ? 1 : 0;
			}

			return ($matches)
				? RDF::Query::Node::Literal->new('true', undef, 'http://www.w3.org/2001/XMLSchema#boolean')
				: RDF::Query::Node::Literal->new('false', undef, 'http://www.w3.org/2001/XMLSchema#boolean');

		}
	);

	# fn:abs
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#abs",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal') and $node->is_numeric_type) {
				my $value	= $node->numeric_value;
				return RDF::Query::Node::Literal->new( abs($value), undef, $node->literal_datatype );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:abs called without a numeric literal";
			}
		}
	);
	
	# fn:ceiling
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#ceiling",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal') and $node->is_numeric_type) {
				my $value	= $node->numeric_value;
				return RDF::Query::Node::Literal->new( ceil($value), undef, $node->literal_datatype );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:ceiling called without a numeric literal";
			}
		}
	);
	
	# fn:floor
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#floor",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal') and $node->is_numeric_type) {
				my $value	= $node->numeric_value;
				return RDF::Query::Node::Literal->new( floor($value), undef, $node->literal_datatype );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:floor called without a numeric literal";
			}
		}
	);
	
	# fn:round
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#round",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal') and $node->is_numeric_type) {
				my $value	= $node->numeric_value;
				my $mult	= 1;
				if ($value < 0) {
					$mult	= -1;
					$value	= -$value;
				}
				my $round	= $mult * POSIX::floor($value + 0.50000000000008);
				return RDF::Query::Node::Literal->new( $round, undef, $node->literal_datatype );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:round called without a numeric literal";
			}
		}
	);
	
	# fn:round-half-to-even
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#round-half-to-even",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal') and $node->is_numeric_type) {
				my $value	= $node->numeric_value;
				return RDF::Query::Node::Literal->new( sprintf('%.0f', $value), undef, $node->literal_datatype );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:round-half-to-even called without a numeric literal";
			}
		}
	);
	
	# fn:compare
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#compare",
		sub {
			my $query	= shift;
			my $nodea	= shift;
			my $nodeb	= shift;
			unless (blessed($nodea) and $nodea->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:compare called without a literal arg1 term";
			}
			unless (blessed($nodeb) and $nodeb->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:compare called without a literal arg2 term";
			}
			
			my $value	= ($nodea->literal_value cmp $nodeb->literal_value);
			return RDF::Query::Node::Literal->new( $value, undef, $xsd->integer );
		}
	);
	
	# fn:concat
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#concat",
		sub {
			my $query	= shift;
			my $model	= $query->model;
			my @nodes	= @_;
			my @strings	= map { $query->call_function($model, {}, 'sparql:str', $_) } @nodes;
			my $value	= join('', map { $_->literal_value } @strings);
			return RDF::Query::Node::Literal->new($value);
		}
	);
	
	# fn:substring
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#substring",
		sub {
			my $query	= shift;
			my $node	= shift;
			my @args	= @_;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:substring called without a literal arg1 term";
			}
			my $value	= $node->literal_value;
			my @nums;
			foreach my $i (0 .. $#args) {
				my $argnum	= $i + 2;
				my $arg		= $args[ $i ];
				unless (blessed($arg) and $arg->isa('RDF::Query::Node::Literal') and $arg->is_numeric_type) {
					throw RDF::Query::Error::TypeError -text => "xpath:substring called without a numeric literal arg${argnum} term";
				}
				push(@nums, $arg->numeric_value);
			}
			my $substring	= substr($value, @nums);
			return RDF::Query::Node::Literal->new($substring);
		}
	);
	
	# fn:string-length
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#string-length",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				my $value	= $node->literal_value;
				return RDF::Query::Node::Literal->new( length($value), undef, $xsd->integer );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:string-length called without a literal term";
			}
		}
	);
	
	# fn:upper-case
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#upper-case",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				my $value	= $node->literal_value;
				return RDF::Query::Node::Literal->new( uc($value) );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:upper-case called without a literal term";
			}
		}
	);
	
	# fn:lower-case
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#lower-case",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				my $value	= $node->literal_value;
				return RDF::Query::Node::Literal->new( lc($value) );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:lower-case called without a literal term";
			}
		}
	);
	
	# fn:encode-for-uri
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#encode-for-uri",
		sub {
			my $query	= shift;
			my $node	= shift;
			if (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				my $value	= $node->literal_value;
				return RDF::Query::Node::Literal->new( uri_escape($value) );
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:escape-for-uri called without a literal term";
			}
		}
	);
	
	# fn:contains
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#contains",
		sub {
			my $query	= shift;
			my $node	= shift;
			my $pat		= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:contains called without a literal arg1 term";
			}
			unless (blessed($pat) and $pat->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:contains called without a literal arg2 term";
			}
			my $lit		= $node->literal_value;
			my $plit	= $pat->literal_value;
			my $pos		= index($lit, $plit);
			if ($pos >= 0) {
				return RDF::Query::Node::Literal->new('true', undef, $xsd->boolean);
			} else {
				return RDF::Query::Node::Literal->new('false', undef, $xsd->boolean);
			}
		}
	);
	
	# fn:starts-with
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#starts-with",
		sub {
			my $query	= shift;
			my $node	= shift;
			my $pat		= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:starts-with called without a literal arg1 term";
			}
			unless (blessed($pat) and $pat->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:starts-with called without a literal arg2 term";
			}
			if (index($node->literal_value, $pat->literal_value) == 0) {
				return RDF::Query::Node::Literal->new('true', undef, $xsd->boolean);
			} else {
				return RDF::Query::Node::Literal->new('false', undef, $xsd->boolean);
			}
		}
	);
	
	# fn:ends-with
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#ends-with",
		sub {
			my $query	= shift;
			my $node	= shift;
			my $pat		= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:ends-with called without a literal arg1 term";
			}
			unless (blessed($pat) and $pat->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:ends-with called without a literal arg2 term";
			}
			
			my $lit		= $node->literal_value;
			my $plit	= $pat->literal_value;
			my $pos	= length($lit) - length($plit);
			if (rindex($lit, $plit) == $pos) {
				return RDF::Query::Node::Literal->new('true', undef, $xsd->boolean);
			} else {
				return RDF::Query::Node::Literal->new('false', undef, $xsd->boolean);
			}
		}
	);
	
	# op:dateTime-equal
	# op:dateTime-less-than
	# op:dateTime-greater-than
	
	# fn:year-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#year-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:year-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->year);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:year-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:month-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#month-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:month-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->month);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:month-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:day-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#day-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:day-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->day);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:day-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:hours-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#hours-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:hours-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->hour);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:hours-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:minutes-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#minutes-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:minutes-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->minute);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:minutes-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:seconds-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#seconds-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:seconds-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				return RDF::Query::Node::Literal->new($dt->second);
			} else {
				throw RDF::Query::Error::TypeError -text => "xpath:seconds-from-dateTime called without a valid dateTime";
			}
		}
	);
	
	# fn:timezone-from-dateTime
	RDF::Query::Functions->install_function(
		"http://www.w3.org/2005/xpath-functions#timezone-from-dateTime",
		sub {
			my $query	= shift;
			my $node	= shift;
			unless (blessed($node) and $node->isa('RDF::Query::Node::Literal')) {
				throw RDF::Query::Error::TypeError -text => "xpath:timezone-from-dateTime called without a literal term";
			}
			my $dt		= $node->datetime;
			if ($dt) {
				my $tz		= $dt->time_zone;
				if ($tz) {
					my $offset	= $tz->offset_for_datetime( $dt );
					my $minus	= '';
					if ($offset < 0) {
						$minus	= '-';
						$offset	= -$offset;
					}

					my $duration	= "${minus}PT";
					if ($offset >= 60*60) {
						my $h	= int($offset / (60*60));
						$duration	.= "${h}H" if ($h > 0);
						$offset	= $offset % (60*60);
					}
					if ($offset >= 60) {
						my $m	= int($offset / 60);
						$duration	.= "${m}M" if ($m > 0);
						$offset	= $offset % 60;
					}
					my $s	= int($offset);
					$duration	.= "${s}S" if ($s > 0 or $duration eq 'PT');
					
					return RDF::Query::Node::Literal->new($duration);
				}
			}
			throw RDF::Query::Error::TypeError -text => "xpath:timezone-from-dateTime called without a valid dateTime";
		}
	);

}



1;

__END__

=head1 AUTHOR

 Gregory Williams <gwilliams@cpan.org>.

=cut