#!/usr/bin/perl
#
# Open an SSH tunnel using the Net::OpenSSH module and keep it opened with an infinite loop.
#

use strict;
use warnings;
use Anvil::Tools;
use Net::OpenSSH;

$| = 1;

my $THIS_FILE           =  ($0 =~ /^.*\/(.*)$/)[0];
my $running_directory   =  ($0 =~ /^(.*?)\/$THIS_FILE$/)[0];
if (($running_directory =~ /^\./) && ($ENV{PWD}))
{
	$running_directory =~ s/^\./$ENV{PWD}/;
}

my $anvil = Anvil::Tools->new({ on_sig_int => \&close_ssh_tunnel, on_sig_term => \&close_ssh_tunnel });

$anvil->Get->switches;

$anvil->Database->connect;
$anvil->Log->entry({ source => $THIS_FILE, line => __LINE__, level => 2, secure => 0, key => "log_0132" });
if (not $anvil->data->{sys}{database}{connections})
{
	# No databases, exit.
	$anvil->Log->entry({ source => $THIS_FILE, line => __LINE__, level => 0, 'print' => 1, priority => "err", key => "error_0003" });
	$anvil->nice_exit({ exit_code => 1 });
}

my $ssh_forward_local_port  = $anvil->data->{switches}{'forward-local-port'};
my $ssh_forward_remote_port = $anvil->data->{switches}{'forward-remote-port'};
my $ssh_remote_forward      = $anvil->data->{switches}{'remote'};
my $ssh_port                = $anvil->data->{switches}{'port'};
my $ssh_target              = $anvil->data->{switches}{'target'};
my $ssh_user                = $anvil->data->{switches}{'user'};

my $ssh_fh;

my ($open_rcode) = open_ssh_tunnel({
	forward_local_port  => $ssh_forward_local_port,
	forward_remote_port => $ssh_forward_remote_port,
	port                => $ssh_port,
	remote              => $ssh_remote_forward,
	target              => $ssh_target,
	user                => $ssh_user,
});

$anvil->nice_exit({ exit_code => 1 }) if ($open_rcode > 0);

my $is_ssh_tunnel_alive = 1;

while ($is_ssh_tunnel_alive)
{
	$is_ssh_tunnel_alive = $ssh_fh->test('echo');

	sleep(60);
}

close_ssh_tunnel();

$anvil->nice_exit({ exit_code => 0 });

#
# Functions
#

sub open_ssh_tunnel
{
	my $parameters          = shift;

	# Required parameters:
	my $forward_local_port  = $parameters->{forward_local_port};
	my $forward_remote_port = $parameters->{forward_remote_port};
	my $target              = $parameters->{target};
	# Optional parameters:
	my $debug               = $parameters->{debug} // 3;
	my $port                = $parameters->{port} // 22;
	my $remote              = $parameters->{remote} ? 1 : 0;
	my $user                = $parameters->{user} // "admin";

	$anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => $debug, list => $parameters });

	return (1) if ( (not defined $user)
		or (not defined $target)
		or (not defined $forward_local_port)
		or (not defined $forward_remote_port) );

	my $ssh_fh_key          = "${user}\@${target}:${port}";

	my ($output, $error, $return_code) = $anvil->Remote->call({
		no_cache    => 1,
		remote_user => $user,
		shell_call  => $anvil->data->{path}{exe}{echo}." 1",
		target      => $target,
	});

	$anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => $debug, list => {
		output      => $output,
		error       => $error,
		return_code => $return_code
	} });

	return (1) if ($output ne "1");

	$ssh_fh = $anvil->data->{cache}{ssh_fh}{$ssh_fh_key};

	delete $anvil->data->{cache}{ssh_fh}{$ssh_fh_key};

	$anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => $debug, list => {
		is_ssh_fh_defined => defined $ssh_fh ? 1 : 0
	} });

	my $forward_option = "L";
	my $port_a         = $forward_local_port;
	my $port_b         = $forward_remote_port;

	# When remote forward, change the option and reverse the ports.
	if ($remote)
	{
		$forward_option = "R";
		$port_a         = $forward_remote_port;
		$port_b         = $forward_local_port;
	}

	$ssh_fh->system({ ssh_opts => [ "-O", "forward", "-${forward_option} 0.0.0.0:${port_a}:0.0.0.0:${port_b}" ] });

	return (0);
}

sub close_ssh_tunnel
{
	my $parameters = shift;
	my $debug      = $parameters->{debug} // 3;

	if (defined $ssh_fh->disconnect)
	{
		$ssh_fh->disconnect();

		$anvil->Log->variables({ source => $THIS_FILE, line => __LINE__, level => $debug, list => {
			message => "SSH tunnel disconnected."
		} });
	}
}