#!/usr/bin/perl
#-------------------------------------------------------------------------------
# This file is part of the FLARM®-Radar Project.
#   
#   Copyright 2012-2014 Simon Moser
#   Copyright 2013-2014 Dominic Spreitz
# 
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# 
#   http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# 
#   Project Website: www.flarmradar.ch
#   Email: info@flarmradar.ch
#-------------------------------------------------------------------------------

use strict;
use warnings;
use Getopt::Std;
use File::Basename;
use Time::HiRes qw(gettimeofday);
use POSIX qw(strftime);
use POSIX qw(setsid);
use LWP::UserAgent;
use Device::SerialPort;

# constants
use constant {
	OPS => 0b001,
	DEBUG => 0b010,
	TRACE => 0b100
};
# FIXME: increas that value
my $MAX_READ_OP = 10000;
my $MAX_CMD_WAIT = 3;

# variables
my %config;
my %options;
my $log;
my $log_initialized = 0;
my $flarm_initialized = 0;
my $read_cnt = 0;
my $flarm;

# defaults
my $log_ops = 1;
my $log_debug = 0;
my $log_trace = 0;
my $interval = 3;
my $skip = 1;

# signal handlers
# toggle $log_trace with 'kill -USR1 <pid>'
$SIG{USR1} = sub {
	if ($log_trace) {
		$log_trace = 0;
	} else {
		$log_trace = 1;
	}
};
$SIG{INT} = sub {
	die("terminate program");
};

# display a help page
sub usage {
  print <<EOF;
NAME
  $0 -- stream flarm records to server

SYNOPSIS
  $0 [-c config_file] [-d] [-f data_file] [-i n] [-j m] [-r] [-t] [-h]

DESCRIPTION
  The following options are available:
  
  -c	Use the specified configuration file. Use the default configuration
  		file as a starting point for customization.
  		
  -d	Write out debug information
  		WARNING: If your configuration is to write the out put to a file (see
  		option 'log') then this might fill up the file system.  		
  		
  -f	Read the data from the specified data file instead of the serial
  		device. This is mainly used for testing and development.

  -i	Bundle records, send a request to the server every i-th GPGGA record. 
  		Used for bandwidth optimization. Defaults to 3.
  		
  -j	Send every j-th record to the server. Used for bandwidth
  		optimization. Defaults to 1.
  		
  -t	Trace client operations, write out all data read from the flarm device
  		WARNING: If your configuration is to write the out put to a file (see
  		option 'log') then this might fill up the file system.
  		
  -h	Print this help.

EOF
  exit 0;
}

# a very basic logger
sub logit {
	my ($aspect, $msg) = @_;
	
	unless ($log_initialized) {
		if (exists($config{'log'})) {
			open($log, ">> $config{'log'}") || die("Failed to open log file $config{'log'}: $!");
			select($log);
			$| = 1;
		} else {
			$log = *STDOUT;
		}
		$log_initialized = 1;
	}
	print $log "$msg\n" if (($aspect & OPS) && $log_ops);
	print $log "$msg\n" if (($aspect & TRACE) && $log_trace);
	print $log "$msg\n" if (($aspect & DEBUG) && $log_debug);
}

# read config file
sub readconfig {
	my ($config_file) = @_;
	open(CONF, "< $config_file") || die("failed to open config file for reading: $!");
	while(my $line = <CONF>) {
		chomp($line);
		next if $line =~ /^\s*#/;
		next if $line =~ /^\s*$/;
		if ($line =~ /^\s*(\S*)\s*=\s*(\S*)\s*$/) {
			$config{$1} = $2;
		}
	}
	close(CONF);
}

# send a command to the flarm, optionally wait for the expected answer
sub send_flarm_cmd {
	my ($cmd, $expected_answer) = @_;
	if (defined($flarm)) {
		logit(OPS, "write to flarm cmd=" . $cmd);
		my $count_out = $flarm->write($cmd . "\r\n");
	    warn "write failed\n" unless ($count_out);
	    
		my $read_start = exact_time("%s");
		my $record;
		
		if (defined $expected_answer) {
			while (1) {
				until($record = $flarm->lookfor()) {
					logit(DEBUG, exact_time() . " wait for data from flarm device");
					sleep(1);
				}
				
				logit(DEBUG, "read from flarm=" . $record);
				if ($record =~ /$expected_answer/) {
					logit(OPS, "command accepted: " . $expected_answer);
					last;
				}
	
				my $elapsed = exact_time("%s") - $read_start;
				if ($elapsed > $MAX_CMD_WAIT) {
					logit(OPS, "WARN: did not receive expected answer in time (" . $MAX_CMD_WAIT . " s)");
					last;
				}
			}
		}
	}
}

# intialize the flarm device
sub initialize_flarm_device {
	logit(OPS, "initialize flarm device");
	
	# ACFT: type of aircraft, default 'unknown'
	if (defined($config{'acft_type'})) {
		send_flarm_cmd("\$PFLAC,S,ACFT," . $config{'acft_type'}, "PFLAC,A,ACFT");
	}
	
	# NMEAOUT: which sentences are sent to the data port, default '1', all incl. propriatery
	if (defined($config{'nmeaout'})) {
		send_flarm_cmd("\$PFLAC,S,NMEAOUT," . $config{'nmeaout'}, "PFLAC,A,NMEAOUT");
	}

	# RANGE_ detection range of aircraft, default 25500, max value 25500
	if (defined($config{'range'})) {
		send_flarm_cmd("\$PFLAC,S,RANGE," . $config{'range'}, "PFLAC,A,RANGE");
	}

	# THRE: threshold for aircraft on ground, default '2'
	if (defined($config{'threshold'})) {
		send_flarm_cmd("\$PFLAC,S,THRE," . $config{'threshold'}, "PFLAC,A,THRE");
	}
	
	# UI: visual and output, default '3' (disable buzzer, enable led warnings)
	if (defined($config{'visual'})) {
		send_flarm_cmd("\$PFLAC,S,UI," . $config{'visual'}, "PFLAC,A,UI");
	}
	
	# no idea how it would behave if it was set to stealth, better switch off
	send_flarm_cmd("\$PFLAC,S,PRIV,0", "PFLAC,A,PRIV");
	
	# not documented but this removes the vertical restriction
	send_flarm_cmd("\$PFLAC,S,DEBUG,9", "PFLAC,S,DEBUG,9");
	
	$flarm_initialized = 1;
	logit(OPS, "device initialization completed");
}

# abstraction for reading data (from flarm device or from file)
sub readdata {
	unless (defined($flarm)) {
		# initialize our flarm object
		if (defined($options{'f'})) {
			logit(OPS, "read flarm data from file " . $options{'f'});
			open($flarm, "< $options{'f'}") || die("failed to open flarm data file for reading: $!");
		} else {
			# check that we have the required configuration options
			die("missing option 'serial_device' in configuration file") unless (defined($config{'serial_device'}));
			die("device does not exist: " . $config{'serial_device'}) unless (-c $config{'serial_device'});
			die("missing option 'baud' in configuration file") unless (defined($config{'baud'}));
			
			# create serial device object
			logit(OPS, "initialize serial port reader on device=" . $config{'serial_device'} . " with baud=" . $config{'baud'});
			$flarm = new Device::SerialPort ($config{'serial_device'}) || die "Can't open $config{'serial_device'}!\n";
			$flarm->baudrate($config{'baud'});
			$flarm->parity("none");
			$flarm->databits(8);
			$flarm->stopbits(1);
			$flarm->are_match("\r\n");
			
			if ($config{'do_device_config'}) {
				initialize_flarm_device() unless ($flarm_initialized);
			}
		}
	}
	
	# read data
	my $record = undef;
	if (defined($options{'f'})) {
		$record = <$flarm>;
	} else {
		my $read_start = exact_time("%s");
		until($record = $flarm->lookfor()) {
			logit(DEBUG, exact_time() . " wait for data from flarm device");
			sleep(1);
			$read_start = exact_time("%s");
		}
		my $read_duration = exact_time("%s") - $read_start;
		if ($read_duration > 0.8) {
			logit(OPS, "trigger re-initialization of serial port, long read duration=" . $read_duration);
			$flarm = undef; 
		}
		
		# pro-active workaround to prevent failures during continuous operation
		$read_cnt++;
		if ($read_cnt >= $MAX_READ_OP) {
			logit(DEBUG, exact_time() . " reset serial port reader");
			$flarm = undef;
			$read_cnt = 0;
		}
	}
	chomp($record);
	return $record;
}

# as the name says
sub exact_time {
	my ($format) = @_;
	$format = "%H:%M:%S" unless defined($format);
	return strftime($format, localtime()) . "." . (gettimeofday())[1];
}

# send the records to the server. We don't make a request for each record for
# performance reasons.
sub flush {
	my ($records, $url, $ua) = @_;
	logit(DEBUG, exact_time() . " start flushing data to server");
	
	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
    my $date= sprintf("%04d", ($year + 1900))."/".sprintf("%02d", ($mon + 1))."/".sprintf("%02d", $mday);
	my $resturl = $url . "/" . $date;
	logit(DEBUG, exact_time() . " request resource: " . $resturl);
	
	# compose the request
	my $request = HTTP::Request->new('PUT');
	$request->url($resturl);
	$request->header('stationKey'=>$config{'key'});
	my $content = compress($records);
	logit(DEBUG, exact_time() . " put on wire: " . $content);
	$request->content($content);
	
	# run the request
	logit(DEBUG, exact_time() . " start server push");
	my $response = $ua->request($request);
	logit(DEBUG, exact_time() . " end server push");
	
	# analyze the response
	my $code = $response->code;
	$response->code == 200 || logit(DEBUG, "error processing records (" . $response->code . ") records=[" . $records . "]");
	logit(DEBUG, exact_time() . " end flushing data");
}

# remove all unused records, debug information, etc.
sub compress {
	my ($records) = @_;
	my $on_wire;
	foreach my $record (split(';', $records)) {
		if ($record =~ /^\$GPGGA,/ || $record =~ /^\$PFLAA,/) {
			$on_wire = (defined($on_wire)) ? $on_wire . ";" . $record : $record;
		}		
	}
	return $on_wire;
}

#
# here starts our main program
#

# parse options
getopts('c:di:j:f:th', \%options);

my $cfile;
if (defined($options{'c'})) {
	$cfile = $options{'c'};
} elsif (-f "/etc/flarmclient.conf") {
	$cfile = "/etc/flarmclient.conf";
} else {
	# last resort, search for a config file in the local directory
	$cfile = "./flarmclient.conf";
}

# read config file
die ("no config file found") unless (-f "$cfile");
readconfig($cfile);

if (defined($options{'d'})) {
	$log_debug = 1;
}
if (defined($options{'i'})) {
	$interval = $options{'i'};
}
if (defined($options{'j'})) {
	$skip = $options{'j'}
}
if (defined($options{'h'})) {
	usage();
}
if (defined($options{'t'})) {
	$log_trace = 1;
}

# validation: key must be present in config file
die("no key found in config file " . $cfile . " (option: key)") unless defined($config{'key'});

# force a flush right away and after every write or print
local $| = 1;

# ok, everything is setup
logit(OPS, "start client, connect to " . $config{'url'});

# create UserAgent object
my $ua = new LWP::UserAgent;

my $buf;
my $i = 0;

while(my $record = readdata()) {
	
	# send only n-th sequence to the server (option -s). A sequence is terminated with a GPGGA-record
	if ($i % $skip == 0) {
			
		logit(TRACE, $record);
		$buf = (defined($buf)) ? "$buf;$record" : $record;
	}
		
	# a GPGGA record terminates the sequence
	if ($record =~ /^\$GPGGA,/) {
		if ($i % ($interval * $skip) == 0) {
			flush($buf, $config{'url'}, $ua) ;
			$buf = undef;
			if (defined($options{'f'})) {
				sleep($interval * $skip) 
			} elsif ($i > $MAX_READ_OP) {
				# force a re-initialization
				$i = 0;
				$flarm = undef;
			}
		} else {
			$i++;
		}		
	}
}
exit 0;

END {
	logit(OPS, "client is shutting down");
	if (exists($config{"log"})) {
		close($log);
	}
	undef $ua;
	undef $flarm;
}