#!/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;

my %config;
my %options;
my $ua;
my $debug = 0;
my $trace = 0;
my $interval = 3;
my $skip = 1;

# default values
my $cfile = "/etc/flarmclient.conf";
my $log = "$ENV{'HOME'}/flarmclient.trace";
my $fifo = "$ENV{'HOME'}/fifo";

# functions
sub usage {
  print <<EOF;
NAME
  $0 -- stream flarm data to server

SYNOPSIS
  $0 [-c config_file] [-d] [-f data_file] [-i n] [-j m] [-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;
}

# print statistic information to logfile
$SIG{USR1} = sub {
	if ($trace) {
		$trace = 0;
	} else {
		$trace = 1;
	}
};


sub openlog {
	if (tell(LOG) == -1) {
		open(LOG, ">> $log") || print "Failed to open trace file $log: $!";
	}
	return 1;
}

sub logit {
	my ($target, $msg) = @_;
	if ($trace && $target eq "TRACE") {
		openlog() && print LOG "$msg\n";
	}
	if ($debug && $target eq "DEBUG") {
		print "$msg\n";
		# if tracing is turned on, write debug messages also to the trace file 
		if ($trace) {
			openlog() && print LOG "$msg\n";
		} 
	}
	if ($target eq "ALL") {
		print "$msg\n";
		# if tracing is turned on, write debug messages also to the trace file 
		if ($trace) {
			openlog() && print LOG "$msg\n";
		} 
	}
}

sub cleanup {
	if (-e "$fifo") {
		unlink($fifo) || die("unable to remove $fifo: $!");
	}
	close(LOG);
}

sub readconfig {
	open(CONF, "< $cfile") || 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);
}

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) = @_;
	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;
}

# remove old leftovers
cleanup();

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

# read config file
if (defined($options{'c'})) {
	$cfile = $options{'c'};
}
if (defined($options{'d'})) {
	$debug = 1;
}
if (defined($options{'i'})) {
	$interval = $options{'i'};
}
if (defined($options{'j'})) {
	$skip = $options{'j'}
}
if (defined($options{'h'})) {
	usage();
}
if (defined($options{'t'})) {
	$trace = 1;
}

# read config file
readconfig();

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

logit("ALL", "Start client, connect to " . $config{'url'});

# create pipe
die("no fifo found in config file (option: fifo)") unless defined($fifo);
if (! -d dirname($fifo)) {
	system("mkdir", "-p", dirname($fifo)) == 0 || die("failed to create fifo directory " . dirname($fifo) . ": $!")
}
system("mkfifo", $fifo) == 0 || die("failed to create fifo: $!");

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

# let the kernel raper dead childs
$SIG{CHLD} = 'IGNORE';

# fork minicom and write to pipe
defined( my $pid = fork() ) or die "can't fork: $!";
unless ($pid) {
	# we're the child
	# detach from session
    setsid() or die "can't start a new session: $!";
    close(STDIN);
	close(STDOUT);
	close(STDERR);
	
	if (defined($options{'f'})) {
		open(DATA, "< $options{'f'}") || die("failed to open data file $options{'f'}: $!");
		open(FIFO, "> $fifo") || die("failed to open fifo for writing: $!");
		while(my $line = <DATA>) {
			chomp($line);
			next if ($line =~ /^\s*$/);
			print FIFO $line, "\n" || die("failed to execute child command: $!");
		}
		close(DATA);
		close(FIFO);
	} else {
		exec("exec minicom -t xterm-color -C $fifo> /dev/null 2>&1") == 0 || die("failed to run minicom: $!");
	}
	exit 0;
}

# create UserAgent object
$ua = new LWP::UserAgent;
my $buf;
# read data from pipe
open(FIFO, "< $fifo") || die("failed to open fifo for reading: $!");
my $i = 0;
while(my $record = <FIFO>) {
	# send only n-th record to the server (option -s)
	if ($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'}) ;
			$buf = undef;
			sleep($interval * $skip) if (defined($options{'f'})); 
		}
		
		$i++;
	}
}
close(FIFO);

cleanup();
exit 0;