#!/usr/bin/perl
#-------------------------------------------------------------------------------
# This file is part of the FLARM¨-Radar Project.
#   
#   Copyright 2013 Netzschmiede GmbH (http://www.netzschmiede.ch)
# 
# 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;
use constant {
	OPS => 0b001,
	DEBUG => 0b010,
	TRACE => 0b100
};
my %config;
my %options;
my $log;
my $log_initialized = 0;

# default values
my $log_ops = 1;
my $log_debug = 1;
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 debug information. The debug information is written to STDOUT
  		unless tracing (option -t) is turned on. With tracing switched on,
  		the debug information is written to the trace file (see below).  		
  		
  -f	Read the data from the specified data file. 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. A trace file is created in 
  		\$HOME/flarmclient.trace
  		WARNING: Do not use that in Production, the trace file is not truncated
  		and might fill up the file system.
  		
  -h	Print this help.

EOF
  exit 0;
}

# a very basic logger
sub logit {
	my ($aspect, $msg) = @_;
	
	if (!$log_initialized) {
		if (exists($config{"log"})) {
			open($log, ">> $log") || print "Failed to open trace file $log: $!";
		} 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);
}

# as the name says
sub exact_time {
	return strftime("%H:%M:%S", 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 $date = `date -u +%Y/%m/%d`;
	chomp($date);
	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 ("config file found") unless (-f "./flarmclient.conf");
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;

# create Flarm object
my $flarm = new Device::SerialPort ($config{'serial_device'});
$flarm->baudrate($config{'baud'});
$flarm->parity("none");
$flarm->databits(8);
$flarm->stopbits(1);
$flarm->are_match("\r\n");

my $buf;
my $i = 0;
while(1) {
	my $record = $flarm->lookfor();
	if ($record) {
		chomp($record);

		# send only n-th record to the server (option -s)
		if ($i % $skip == 0) {
			chomp($record);
			
			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) ;
				$buf = undef;
				sleep($interval * $skip) if (defined($options{'f'})); 
			}
		
			$i++;
		}
		
	} else {
		sleep(1);
	}
}
exit 0;

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