###########################################################################
# Net::SIP::Util
# various functions for helping in SIP programs
###########################################################################

use strict;
use warnings;

package Net::SIP::Util;

use Digest::MD5 'md5_hex';
use IO::Socket;
use Net::SIP::Debug;
use Carp qw(confess croak);
use base 'Exporter';

our @EXPORT_OK = qw(
	sip_hdrval2parts
	sip_parts2hdrval
	sip_uri2parts
	create_socket_to
	create_rtp_sockets
	invoke_callback
);
our %EXPORT_TAGS = ( all => \@EXPORT_OK );

###########################################################################
# creates hash from header val, e.g.
# 'Digest method="md5",qop="auth",...','www-authenticate' will result in
# ( 'Digest', { method => md5, qop => auth,... } )
# Args: ($key,$val)
#   $key: normalized key (lowercase, long)
#   $val: value
# Returns: ( $data,\%parameter )
#   $data: initial data
#   %parameter: additional parameter
###########################################################################
sub sip_hdrval2parts {
	croak( "usage: sip_hdrval2parts( key => val )" ) if @_!=2;
	my ($key,$v) = @_;
	return if !defined($v);
	my $delim = ';';
	if ( $key eq 'www-authenticate' || $key eq 'proxy-authenticate'
		|| $key eq 'authorization' || $key eq 'proxy-authorization' ) {
		# these keys have ',' instead of ';' as delimiter
		$delim = ',';
	}

	# split on delimiter (but not if quoted)
	my @v = ('');
	my $quoted = 0;
	my $bracket = 0;
	while (1) {
		if ( $v =~m{\G(.*?)([\\"<>$delim])}gc ) {
			if ( $2 eq "\\" ) {
				$v[-1].=$1.$2.substr( $v,pos($v),1 );
				pos($v)++;
			} elsif ( $2 eq '"' ) {
				$v[-1].=$1.$2;
				$quoted = !$quoted if ! $bracket;
			} elsif ( $2 eq '<' ) {
				$v[-1].=$1.$2;
				$bracket = 1 if ! $bracket && ! $quoted;
			} elsif ( $2 eq '>' ) {
				$v[-1].=$1.$2;
				$bracket = 0 if $bracket && ! $quoted;
			} elsif ( $2 eq $delim ) {
				# next item if not quoted
				if ( ! $quoted && ! $bracket ) {
					( $v[-1].=$1 ) =~s{\s+$}{}; # strip trailing space
					push @v,'' ;
					$v =~m{\G\s+}gc; # skip space after $delim
				} else {
					$v[-1].=$1.$2
				}
			}
		} else {
			# add rest to last from @v
			$v[-1].= substr($v,pos($v)||0 );
			last;
		}
	}

	# with delimiter ',' it starts 'Digest realm=...' so $v[0]
	# contains method and first parameter
	my $data = shift(@v);
	if ( $delim eq ',' ) {
		$data =~s{^(\S+)\s*(.*)}{$1};
		unshift @v,$2;
	}
	# rest will be interpreted as parameters with key|key=value
	my %hash;
	foreach my $vv (@v) {
		my ($key,$value) = split( m{\s*=\s*},$vv,2 );
		if ( defined($value) ) {
			$value =~s{^"(.*)"$}{$1};  # unquote
			# TODO Q: what's the meaning of "\%04", e.g. is it
			# '%04' or "\\\004" ??
			$value =~s{\\(.)}{$1}sg;   # unescape backslashes
			$value =~s{%([a-fA-F][a-fA-F])}{ chr(hex($1)) }esg; # resolve uri encoding
		}
		$hash{lc($key)} = $value;
	}
	return ($data,\%hash);
}


###########################################################################
# reverse to sip_hdrval2parts
# Args: ($key,$data,\%parameter)
#   $key: normalized key (lowercase, long)
#   $data: initial data
#   %parameter: additional parameter
# Returns: $val
#   $val: value
###########################################################################
sub sip_parts2hdrval {
	my ($key,$data,$param) = @_;

	my $delim = ';';
	if ( $key eq 'www-authenticate' || $key eq 'proxy-authenticate'
		|| $key eq 'authorization' || $key eq 'proxy-authorization' ) {
		# these keys have ',' instead of ';' as delimiter
		$delim = ',';
	}

	my $val = $data; # FIXME: need to escape $data?
	while ( my ($k,$v) = each %$param ) {
		$val .= $delim.$k;
		if ( defined $v ) {
			# escape special chars
			$v =~s{([%\r\n\t"[:^print:]])}{ sprintf "%%%02x",ord($1) }sg;
			$v = '"'.$v.'"' if $v =~m{\s|$delim};
			$val .= '='.$v
		}
	}
	return $val;
}


###########################################################################
# extract parts from SIP URI
# Args: $uri
# Returns: $domain || ($domain,$user,$proto,$data,$param)
#  $domain: SIP domain maybe with port
#  $user:   user part
#  $proto:  'sip'|'sips'
#  $data:   full part before any params
#  $param:  hashref with params, e.g { transport => 'udp',... }
###########################################################################
sub sip_uri2parts {
	my $uri = shift;
	$uri = $1 if $uri =~m{<([^>]+)>\s*$}i;
	my ($data,$param) = sip_hdrval2parts( uri => $uri );
	if ( $data =~m{^(?:(sips?):)?(?:([^\s\@]*)\@)?([\w\-\.:]+)}i ) {
		my ($proto,$user,$domain) = ($1,$2,$3);
		$proto ||= 'sip';
		return wantarray
			? ($domain,$user,lc($proto),$data,$param)
			: $domain
	} else {
		return;
	}
}

###########################################################################
# create socket preferable on port 5060 from which one might reach the given IP
# Args: ($dst_addr;$proto)
#  $dst_addr: the adress which must be reachable from this socket
#  $proto: tcp|udp, default udp
# Returns: ($sock,$ip_port) || $sock || ()
#  $sock: the created socket
#  $ip_port: ip:port of socket, only given if called in array context
# Comment: the IP it needs to come from works by creating a udp socket
#  to this host and figuring out it's IP by calling getsockname. Then it
#  tries to create a socket on this IP using port 5060 and if this does
#  not work it tries the port 5062..5100 and if this does not work too
#  it let the system use a random port
#  If creating of socket fails it returns () and $! is set
###########################################################################
sub create_socket_to {
	my ($dst_addr,$proto) = @_;
	$proto ||= 'udp';

	my $laddr = do {
		$dst_addr =~s{:.*}{}; # in case ip:port was given
		my $sock = IO::Socket::INET->new(
			PeerAddr => $dst_addr,
			PeerPort => 5060,
			Proto => 'udp'
		) || return; # No route?
		my $x = getsockname($sock) or return;
		my (undef,$addr) = unpack_sockaddr_in( $x );
		inet_ntoa( $addr );
	};
	DEBUG( "Local IP is $laddr" );

	# Bind to this IP
	# First try port 5060..5100, if they are all used use any port
	# I get from the system
	my ($sock,$port);
	for my $p ( 5060,5062..5100 ) {
		DEBUG( "try to listen on $laddr:$p" );
		$sock = IO::Socket::INET->new(
			LocalAddr => $laddr,
			LocalPort => $p,
			Proto => $proto,
		);
		if ( $sock ) {
			$port = $p;
			last
		}
	}
	if ( ! $sock ) {
		$sock = IO::Socket::INET->new(
			LocalAddr => $laddr, # use any port
			Proto => $proto,
		) || return;
		$port = (unpack_sockaddr_in( getsockname($sock)))[0];
	}
	DEBUG( "listen on $laddr:$port" );

	return wantarray ? ($sock,"$laddr:$port" ) : $sock;
}

###########################################################################
# create RTP/RTCP sockets
# Args: ($laddr;$range,$min,$max,$tries)
#   $laddr: local addr
#   $range: how many sockets, 2 if not defined
#   $min: minimal port number, default 2000
#   $max: maximal port number, default 10000 more than $min
#   $tries: how many tries, default 100
# Returns: ($port,$rtp_sock,$rtcp_sock,@more_socks)
#   $port:      port of RTP socket, port for RTCP is port+1
#   $rtp_sock:  socket for RTP data
#   $rtcp_sock: socket for RTCP data
#   @more_socks: more sockets (if range >2)
###########################################################################
sub create_rtp_sockets {
	my ($laddr,$range,$min,$max,$tries) = @_;
	$range ||= 2;
	$min ||= 2000;
	$min += $min%2; # make even
	$max ||= $min+10000;
	$tries ||= 1000;

	my $diff2 = int(($max-$min)/2) - $range +1;

	my (@socks,$port);
	while ( $tries-- >0 ) {

		last if @socks == $range;
		map { close($_) } @socks;
		@socks = ();

		$port = 2*int(rand($diff2)) + $min;
		for( my $i=0;$i<$range;$i++ ) {
			push @socks, IO::Socket::INET->new(
				Proto => 'udp',
				LocalAddr => $laddr,
				LocalPort => $port + $i,
			) || last;
		}
	}
	return if @socks != $range; # failed
	return ($port,@socks);
}

###########################################################################
# helper to call callback, set variable..
# Args: ($cb;@args)
#  $cb:  callback
#  @args: additional args for callback
# Returns: $rv
#  $rv: return value of callback
# Comment:
# callback can be
# - code ref: will be called with $cb->(@args)
# - object with method run, will be called with $cb->run(@args)
# - array-ref with [ \&sub,@myarg ], will be called with $sub->(@myarg,@args)
# - scalar ref: the scalar will be set to $args[0] if @args, otherwise true
# - regex: returns true if anything in @args matches regex
###########################################################################
sub invoke_callback {
	my ($cb,@more_args) = @_;
	if ( UNIVERSAL::isa( $cb,'CODE' )) {
		# anon sub
		return $cb->(@more_args)
	} elsif ( my $sub = UNIVERSAL::can( $cb,'run' )) {
		# Callback object
		return $sub->( @more_args );
	} elsif ( UNIVERSAL::isa( $cb,'ARRAY' )) {
		my ($sub,@args) = @$cb;
		# [ \&sub,@arg ]
		return $sub->( @args,@more_args );
	} elsif ( UNIVERSAL::isa( $cb,'Regexp' )) {
		@more_args or return;
		for(@more_args) {
			return 1 if m{$cb}
		}
		return 0;
	} elsif ( UNIVERSAL::isa( $cb,'SCALAR' ) || UNIVERSAL::isa( $cb,'REF' )) {
		# scalar ref, set to true
		$$cb = @more_args ? shift(@more_args) : 1;
		return $$cb;
	} elsif ( $cb ) {
		confess "unknown handler $cb";
	}
}


1;