#!/usr/bin/perl

##############################################################################
#	$Id$
##############################################################################
#
#	lepresenced
#
#	checks for one or multiple bluetooth *low energy* devices for their
#	presence state and reports it to the 73_PRESENCE.pm module.
#
#	Copyright (C) 2015-2016 P. Reinhardt, pr-fhem (at) reinhardtweb (dot) de
#
#	This script free software; you can redistribute it and/or modify
#	it under the terms of the GNU General Public License as published by
#	the Free Software Foundation; either version 2 of the License, or
#	(at your option) any later version.
#
#	The GNU General Public License can be found at
#	http://www.gnu.org/copyleft/gpl.html.
#	A copy is found in the textfile GPL.txt and important notices to the
#	license from the author is found in LICENSE.txt distributed with these
#	scripts.
#
#	This script is distributed in the hope that it will be useful,
#	but WITHOUT ANY WARRANTY; without even the implied warranty of
#	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#	GNU General Public License for more details.
#
##############################################################################

use strict;
use warnings;

use threads;
use threads::shared;

use IO::Select;
use IO::Socket::INET;

use Getopt::Long;
use Sys::Syslog qw(:standard :macros);
use Time::HiRes qw(usleep);
use Net::Server::Daemonize qw(daemonize);

use constant RETRY_SLEEP						=> 1;
use constant INET_RECV_BUFFER					=> 1024;
use constant MAINLOOP_SLEEP_US					=> 100 * 1000;

use constant CLEANUP_INTERVAL					=> 15 * 60;
use constant CLEANUP_MAX_AGE					=> 30 * 60;
use constant STATS_INTERVAL						=>  5 * 60;

use constant ME									=> 'lepresenced';
use constant VERSION							=> '0.6';

use constant PIDFILE							=> '/var/run/' . ME . '.pid';

my %devices :shared;
my @clients = ();
my $syslog_level;

sub syslogw {
	return if (scalar(@_) < 2);
	if (scalar(@_)==2) {
		my ($priority, $message) = @_;
		syslog($priority, "[tid:%i] %s: $message", threads->self()->tid(), (caller(1))[3] // 'main') if ($syslog_level >= $priority);
	} else {
		my ($priority, $format, @args) = @_;
		syslog($priority, "[tid:%i] %s: $format", threads->self()->tid(), (caller(1))[3] // 'main', @args) if ($syslog_level >= $priority);
	}
}

sub error_exit {
	my $exit_code = shift();
	syslogw(LOG_ERR, @_);
	foreach my $thread (threads->list()) {
		$thread->exit(0);
	}
	exit ($exit_code);
}

sub usage_exit() {
	print("usage:\n");
	printf("\t%s --bluetoothdevice <bluetooth device> --listenaddress <listen address> --listenport <listen port> --loglevel <log level> --daemon\n", ME);
	printf("\t%s -b <bluetooth device> -a <listen address> -p <listen port> -l <log level> -d\n", ME);
	print("valid log levels:\n");
	print("\tLOG_CRIT, LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG. Default: LOG_INFO\n");
	print("examples:\n");
	printf("\t%s --bluetoothdevice hci0 --listenaddress 127.0.0.1 --listenport 5333 --daemon\n", ME);
	printf("\t%s --loglevel LOG_DEBUG --daemon\n", ME);
	closelog();
	exit(1);
}

sub parse_options() {
	my $device							= "hci0";
	my $daemonize						= 0;
	my $listen_address					= "0.0.0.0";
	my $listen_port						= "5333";
	my $syslog_level					= "LOG_INFO";

	GetOptions(
		'bluetoothdevice|device|b=s'	=> \$device,
		'daemon|daemonize|d!'			=> \$daemonize,
		'listenaddress|address|a=s'		=> \$listen_address,
		'listenport|port|p=i'			=> \$listen_port,
		'loglevel|l=s'					=> \$syslog_level
	) or usage_exit();
	$listen_address =~ m/^\d+\.\d+\.\d+\.\d+$/ or usage_exit();
	$syslog_level =~ m/^LOG_(EMERG|ALERT|CRIT|ERR|WARNING|NOTICE|INFO|DEBUG)$/ or usage_exit();
	$syslog_level = eval($syslog_level);
	
	return ($device, $daemonize, $listen_address, $listen_port, $syslog_level);
}

sub update_device($$) {
	my ($mac, $name) = @_;
	$mac = lc($mac);
	{
		lock(%devices);
		unless (exists $devices{$mac}) {
			my %device :shared;
			$devices{$mac} = \%device;
		}
		$devices{$mac}{'name'} = $name unless ($name eq '(unknown)' && defined($devices{$mac}{'name'}));
		$devices{$mac}{'timestamp'} = time();
	}
}

sub bluetooth_thread($) {
	my ($device) = @_;
	my $hcitool;
	for(;;) {
		my $pid = open($hcitool, "-|", "stdbuf -oL hcitool -i " . $device . " lescan --duplicates 2>&1") || die('Unable to start scanning. Please make sure hcitool and stdbuf are installed!');
		while (<$hcitool>) {
			chomp($_);
			if ($_ eq 'LE Scan ...') {
				syslogw(LOG_INFO, "Received '%s'.", $_);
			} elsif (my ($fbmac, $fbname) = $_ =~ /^([\da-f]{2}:[\da-f]{2}:[\da-f]{2}:[\da-f]{2}:[\da-f]{2}:[\da-f]{2})\s(.*)$/i) {
				#syslogw(LOG_DEBUG, "Received advertisement from bluetooth mac address '%s' with name '%s'.", $fbmac, $fbname);
				update_device($fbmac, $fbname);
			} elsif (
					$_ =~ m/^Set scan parameters failed: Input\/output error$/ ||
					$_ =~ m/^Invalid device: Network is down$/
				) {
				syslogw(LOG_WARNING, "Received '%s', resetting...", $_);
				system(sprintf('hciconfig %s reset', $device));
			} else {
				syslogw(LOG_WARNING, "Received unknown output: '%s'!", $_);
			}
		}
		syslogw(LOG_WARNING, "hcitool exited, retrying...");
		close($hcitool);
		sleep(RETRY_SLEEP);
	}
}

sub handle_command($$) {
	my ($buf, $current_client) = @_;
	if (my ($mac, undef, $interval) = $buf =~ m/^\s*(([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2})\s*\|\s*(\d+)\s*$/) {
		$mac = lc($mac);
		if (my ($client) = grep { $current_client == $_->{'handle'} } @clients) {
			syslogw(LOG_INFO, "Received query update for mac address %s, interval: %i by client %s:%i.", $mac, $interval, $current_client->peerhost(), $current_client->peerport());
			$client->{'mac'} = $mac;
			$client->{'interval'} = $interval;
			$client->{'next_check'} = 0; #now
		} else {
			syslogw(LOG_INFO, "Received query for mac address %s, interval: %i. Adding client %s:%i to clients list.", $mac, $interval, $current_client->peerhost(), $current_client->peerport());
			my %new_client;
			$new_client{'handle'} = $current_client;
			$new_client{'mac'} = $mac;
			$new_client{'interval'} = $interval;
			$new_client{'next_check'} = 0; #now
			push(@clients, \%new_client);
		}
		print $current_client "command accepted\n"
	} elsif ($buf =~ m/^\s*now\s*$/) {
		syslogw(LOG_DEBUG, "Received now command from client %s:%i. Scheduling update...", $current_client->peerhost(), $current_client->peerport());
		foreach my $client (grep { $_->{'handle'} == $current_client } @clients) {
			$client->{'next_check'} = 0; #now
		}
		print $current_client "command accepted\n"
	} elsif ($buf =~ m/^\s*stop\s*$/) {
		# Stop does not make sense when scanning permanently
		syslogw(LOG_DEBUG, "Received stop command from client %s:%i. Pretending to care and ignoring...", $current_client->peerhost(), $current_client->peerport());
		print $current_client "no command running\n" # ToDo: Does the FHEM module even care?
	} else {
		syslogw(LOG_WARNING, "Received unknown command: '%s'.", $buf);
	}
}

sub stats_task() {
	my ($min_age, $max_age, $devices);
	{
		lock(%devices);
		$devices = scalar(keys(%devices));
		foreach my $mac (keys(%devices)) {
			my $age = time() - $devices{$mac}{'timestamp'};
			$min_age = $age if (!defined($min_age) || $age < $min_age);
			$max_age = $age if (!defined($max_age) || $age > $max_age);
		}
	}
	syslogw(LOG_INFO, "Active clients: %i, known devices: %i (min/max age: %s/%s)", scalar(@clients), $devices, $min_age // '%', $max_age // '%');
}

sub cleanup_task() {
	my $start_time = time();
	my $deleted_items = 0;
	{
		lock(%devices);
		foreach my $mac (keys(%devices)) {
			my $age = time() - $devices{$mac}{'timestamp'};
			if ($age > CLEANUP_MAX_AGE) {
				$deleted_items++;
				syslogw(LOG_DEBUG, "Deleting device %s.", $mac);
				delete($devices{$mac});
			}
		}
	}
	syslogw(LOG_INFO, "Cleanup finished, deleted %i devices in %i seconds.", $deleted_items, time() - $start_time);
}

openlog(ME, 'pid', LOG_USER);
(my $device, my $daemonize, my $listen_address, my $listen_port, $syslog_level) = parse_options();

	local $SIG{INT} = local $SIG{TERM} = local $SIG{HUP} = sub {
		syslogw(LOG_NOTICE, "Caught signal, cleaning up and exiting...");
		unlink(PIDFILE) if (-e PIDFILE);
		closelog();
		exit(1);
	};

syslogw(LOG_NOTICE, "Version %s started (device: %s, listen addr: %s, listen port: %s, daemonize: %i, log level: %i).",
		VERSION, $device, $listen_address, $listen_port, $daemonize, $syslog_level);

daemonize('root', 'root', PIDFILE) if $daemonize;

my $bluetooth_thread = threads->new(\&bluetooth_thread, $device)->detach();

my $current_client;
$| = 1;
my $server_socket = new IO::Socket::INET (
	LocalHost => $listen_address,
	LocalPort => $listen_port,
	Proto => 'tcp',
	Listen => 5,
	ReuseAddr => 1,
);
$server_socket or error_exit(1, "ERROR: Unable to create TCP server: $!, Exiting.");
my $select = IO::Select->new($server_socket) or error_exit(1, "ERROR: Unable to select: $!, Exiting.");

my $next_stats_time = 0;
my $next_cleanup_time = 0;

for(;;) {
	# Process INET socket
	foreach my $current_client ($select->can_read(0)) {
		if($current_client == $server_socket) {
			my $client_socket = $server_socket->accept();
			$select->add($client_socket);
			syslogw(LOG_INFO, "Connection from %s:%s. Connected clients: %i.", $client_socket->peerhost(), $client_socket->peerport(), $select->count()-1);
		} else {
			sysread ($current_client, my $buf, INET_RECV_BUFFER);
			if ($buf) {
				chomp($buf);
				handle_command($buf, $current_client);
			} else {
				$select->remove($current_client);
				@clients = grep {$_->{'handle'} != $current_client} @clients;
				syslogw(LOG_INFO, "Client %s:%s disconnected. Connected clients: %i.", $current_client->peerhost(), $current_client->peerport(), $select->count()-1);
				$current_client->close();
			}
		}
	}

	# Check for due client updates, cleanup, stats
	# For performance reasons, a maximum of one task is performed per loop
	if (my @due_clients = grep { time() >= $_->{'next_check'} } @clients) {
		foreach my $client (@due_clients) {
			if (
				defined($devices{$client->{'mac'}}) &&
				time()-$devices{$client->{'mac'}}{timestamp} <= $client->{'interval'}
			) {
				syslogw(LOG_DEBUG, "Sending update for mac address %s, age: %i, max age: %i, result: present.", $client->{'mac'}, time()-$devices{$client->{'mac'}}{timestamp}, $client->{'interval'});
				printf {$client->{'handle'}} "present;%s\n", $devices{$client->{'mac'}}{name}
			} else {
				syslogw(LOG_DEBUG, "Sending update for mac address %s, max age: %i, result: absence.", $client->{'mac'}, $client->{'interval'});
				print {$client->{'handle'}} "absence\n"
			}
			$client->{'next_check'} = time() + $client->{'interval'};
		}
	} elsif (time() > $next_cleanup_time) {
		cleanup_task();
		$next_cleanup_time = time() + CLEANUP_INTERVAL;
	} elsif (time() > $next_stats_time) {
		stats_task();
		$next_stats_time = time() + STATS_INTERVAL;
	}

	usleep(MAINLOOP_SLEEP_US);
}
$server_socket->close();