#! /usr/bin/perl
use strict;
#use warnings; # Had to turn off warnings as Device::SerialPort threw warnings after closing and re-using see re_initialise_serial_port
use Getopt::Std;
use Sys::Syslog qw(:standard :macros);
use Device::SerialPort;
use Proc::Daemon;

Proc::Daemon::Init;

#TODO add response  checking to write commands
#TODO turn into service running on boot after zoneminder, maybe from zoneminder init.d script


# boolean type variables
my $true           = 1;
my $false          = 0;
my $serviceRunning = $false;
my $switchStateOn  = $false;

# Service to control - Change these to zoneminder specific strings
my $serviceName          = "cups";
my $serviceStatusCommand = "status";
my $serviceStopCommand   = "stop";
my $serviceStartCommand  = "start";

# service command response strings
my $serviceStoppedResponse = "cupsd is not running";
my $serviceRunningResponse = "cupsd is running";

# commands to control switch box
my $ledGreenOn   = "ledgrnon";
my $ledGreenOff  = "ledgrnoff";
my $ledRedOn     = "ledredon";
my $ledRedOff    = "ledredoff";
my $ledPending   = "ledpending";
my $switchStatus = "swstatus";

# command response
my $respGreenOn = "greenon";
my $respGreenOff = "greenoff";
my $respRedOn = "redon";
my $respRedOff = "redoff";
my $respSwitchOn = "on";
my $respSwitchOff = "off";

# Set up the serial port for arduino serial communication
# 9600, 81N on the USB ftdi driver
my $portPath = "/dev/ttyUSB0";
my $baudRate = 9600;
my $dataBits = 8;
my $parity   = "none";
my $stopBits = 1;
my $waitConnect = 5; # How long to wait to retry connecting to serial port

# check for option -d to determin level of logging
my %options=();
getopts("d", \%options);


# set up logging to syslog
my $identity = "ZoneSwitchControl";
openlog ($identity, "ndelay,pid", LOG_DAEMON);
if ($options{d}){	#if program called with -d for debugging, allow debug info to go to log
	setlogmask( LOG_MASK(LOG_DEBUG) | LOG_MASK(LOG_ERR) | LOG_MASK(LOG_INFO) );
}else{
	setlogmask( LOG_MASK(LOG_ERR) | LOG_MASK(LOG_INFO) );
}

syslog(LOG_INFO, "Starting ZoneSwitch to control $serviceName service");


my $port = initialise_serial_port();



#TODO on first boot as part of service init, wait for zoneminder to start normally?

my $continue = 1;
$SIG{TERM} = sub { $continue = 0 };

while ($continue) {

	#Check to see if service running 
	check_service ();

	#turn on led's to show state
	maintain_led_status ($port);

	#check switch position on or off
	check_switch ($port);

	#act on switch state
	mantain_service();


}

sub mantain_service{
	
		my $message = "";
		if (($switchStateOn == $true) && ($serviceRunning == $false)){
			#start service
			my $return = start_service();			
			$message = "Starting service - $serviceName service ";
			$message = $message . "returning: $return";
		}
		if (($switchStateOn == $false) && ($serviceRunning == $true)){
			#stop service
			my $return = stop_service();
			$message = "Stopping service - $serviceName service ";
			$message = $message . "returning: $return";
		}
		$message eq "" || syslog(LOG_INFO, $message);

}

sub led_pending {
	my $port = shift;
	
	send_command($port, $ledPending );
	return ();
}

sub red_on {
	my $port = shift;

	send_command($port, $ledRedOn );
	send_command($port, $ledGreenOff );
	return ();
}

sub green_on {
	my $port = shift;

	send_command($port, $ledGreenOn );
	send_command($port, $ledRedOff );
	return ();
}

sub send_command{
	my $port = shift;
	my $command = shift;
	
	clear_input($port);
	$port->write($command);
	$port->write("\n");
	#not handling response yet
	#read and return response
	return();
}

sub check_service {

	#check service state using back ticks to run command in shell
	my $return = `service  $serviceName $serviceStatusCommand`;
	my $message = "";
	if ( $return =~ m/$serviceRunningResponse/ ) {
		$serviceRunning = $true;

		$message = "Service $serviceName is running";
		
	}
	elsif ( $return =~ m/$serviceStoppedResponse/ ) {
		$serviceRunning = $false;

		$message = "Service $serviceName is not running\n";
	}
	($message eq "") || syslog(LOG_DEBUG, $message);

}

sub maintain_led_status {
	my $port           = shift;

	
	if ( $serviceRunning == $false ) {
		red_on($port);

		#clear any response for now
	}
	else {
		green_on($port);

		#clear any response for now

	}
	return ();
}

sub clear_input{	#by reading anything that may be waiting
	my $port           = shift;

	my $STALL_DEFAULT = 1;    # how many seconds to wait for new input
	my $timeout = $STALL_DEFAULT;
	$port->read_char_time(0);        # don't wait for each character
	$port->read_const_time(1000);    # 1 second per unfulfilled "read" call

	eval {
		my $chars  = 0;
		my $buffer = "";
		while ( $timeout > 0 ) {

			my ( $count, $saw ) = $port->read(255)       # will read _up to_ 255 chars
				or die "Cant connect to serial port";
			if ( $count > 0 ) {
				$chars += $count;
				$buffer .= $saw;
			}
			else {
				$timeout--;
			}
		}
	};
	if ($@) {
			
		syslog(LOG_ERR, "Cant get response from ZoneSwitch device ");
		re_initialise_serial_port(); # Then try reconnecting port to device
	
	}
	
}

sub check_switch {
	my $port           = shift;

	my $message = "";
	my $STALL_DEFAULT = 1;    # how many seconds to wait for new input
	my $timeout = $STALL_DEFAULT;

	$port->read_char_time(0);        # don't wait for each character
	$port->read_const_time(1000);    # 1 second per unfulfilled "read" call

	send_command($port, $switchStatus ); # send command to request switch status
	
	eval {
		my $chars  = 0;
		my $buffer = "";
		while ( $timeout > 0 ) {

				my ( $count, $saw ) = $port->read(255)    # will read _up to_ 255 chars
					or die "Cant connect to serial port"; # if the port has been disconnected or we cant read the port
				if ( $count > 0 ) {
					$chars += $count;
					$buffer .= $saw;
		
					# Check here to see if what we want is in the $buffer
					# say "last" if we find it
					if ( $buffer =~ m/\n/ ) {
						#print "Switch status returned \"$buffer\"\n";
						$timeout = 1;
					}
				}
				else {
					$timeout--;
				}
		}
	
		if ( $buffer =~ m/on/ )
		{    
			$message = "Switch found to be ON";
			$switchStateOn = $true;
		}
		else {
			$message = "Switch found to be OFF";
			$switchStateOn = $false;
		}
		$message eq "" || syslog(LOG_DEBUG, $message);
		
		if ( $timeout == 0 ) {
			# havnt decided about this yet, it was in the example code
			#die "Waited $STALL_DEFAULT seconds and never saw what I wanted\n";
		}
		
	};
	if ($@) {
		syslog(LOG_ERR, "Cant get response from ZoneSwitch device ");
		re_initialise_serial_port(); # Then try reconnecting port to device
	}
	
}

sub re_initialise_serial_port{
	
	my $return = start_service(); # Assume someone maybe fiddling with switchbox and start service
	$switchStateOn = $true;
	syslog(LOG_ERR, "Started service $serviceName in case this is deliberate damage");

	# Getting errors from SerialPort.pm when disconnecting and connecting usb lead from switch box
	# close and undef then re-connecting serial port threw 
	# Use of uninitialized value in subroutine entry at /usr/lib/perl5/Device/SerialPort.pm line 1732.
	#
	# couldnt cleanly destoy original serial connection had to turn off warnings at head of script
	$port->close;
	undef $port;
	syslog(LOG_ERR, "Trying to re-initialise connection");
	$port = initialise_serial_port();

}

sub initialise_serial_port {
	my $port;

	while (){
		$port = Device::SerialPort->new($portPath);
		last if ($port);
		syslog(LOG_ERR, "Serial port not ready waiting $waitConnect seconds to try reconnect");
		sleep($waitConnect);
	}
	syslog(LOG_DEBUG, "Serial port connected");
	sleep(2); # allow microcontroller in switch box to initialise
	
	$port->databits($dataBits);
	$port->baudrate($baudRate);
	$port->parity($parity);
	$port->stopbits($stopBits);
	
	return $port;
}

sub start_service {
	my $return = `service  $serviceName $serviceStartCommand`;
	return $return;
}

sub stop_service {
	my $return = `service  $serviceName $serviceStopCommand`;
	return $return;
}