#!/usr/bin/perl
use Socket;
use URI::Escape;
use POSIX ":sys_wait_h";
use POSIX qw(strftime);
use File::Basename;
use File::Path;
use LWP::UserAgent;
use HTTP::Request::Common;
use Getopt::Long;
use Cwd;

my $port = 10000;
my $addr = '127.0.0.1';
my $DEBUG = 0;
my $workDir = dirname($0);
my $logClient = '-';
my $sleepDuration = 10;
my $logFileDir;
my $logFileName;
umask(0);

foreach $argnum (0 .. $#ARGV) {
    my $argument = $ARGV[$argnum];
    if ($argument eq '--help') {
        print "Background Job Server:\n";
        print "Version: 0.1\n\n";
        print "Command line arguments:\n";
        print "    --port=<port>    Set a custom port. Default value is $port\n";
        print "    --debug          Write debug information to sdtout\n";
        print "    --help           This page\n";
        exit;
    }
    if ($argument eq '--debug') {
        $DEBUG = 1;
        next;
    }
    ($name, $value) = split(/=/, $argument, 2);
    if ($value == '') {
        print "Invalid argument: $argument\n";
        exit;
    }
    if ($name eq '--port') {
        $port = $value;
    }
}

writeLog('Started Server. Listen ' . $addr . ':' . $port);

socket(SERVER, PF_INET, SOCK_STREAM, getprotobyname('tcp')) or die "socket:$!";
setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, pack("l", 1)) or die "setsockopt: $!";
bind(SERVER, sockaddr_in($port, inet_aton($addr))) or die "bind: $!";
listen(SERVER, SOMAXCONN) or die "listen: $!";

sub initLogPath
{
    my $date = strftime '%Y-%m-%d', localtime;
    $logFileName = "$workDir/tmp/background-job-server/$date/log.txt";
    $logFileDir = dirname($logFileName);
    mkpath($logFileDir, 0, 0717);
}

sub writeLog
{
    initLogPath();
    my $str = shift;
    my $time = strftime '%Y-%m-%d %H:%M:%S', localtime;
    my $message = "$time\t$logClient\t$str";
    open(my $hLog, '>>', $logFileName);
    print $hLog $message, "\n";
    close($hLog);
    if ($DEBUG == 1) {
        print $message, "\n";
    }
}

sub varDump
{
    print "=" x 80, "\n";
    print shift, "\n";
    print "=" x 80, "\n";
}

sub REAPER
{
    while ((my $waitedpid = waitpid(-1, WNOHANG)) > 0) { }
    $SIG{CHLD} = \&REAPER;
}
$SIG{CHLD} = \&REAPER;

while(1) {
    my $paddr;
    for(; $paddr = accept(CLIENT, SERVER); close CLIENT) {
        my $pid = fork();
        if (not defined $pid) {
            print "resources not avilable.\n";
        } elsif ($pid == 0) {
            # child process
            my($port, $iaddr) = sockaddr_in($paddr);
            my $ip = inet_ntoa($iaddr);
            $logClient = "$ip:$port";
            writeLog('connected');
            processClientRequest();
            writeLog('disconnected');
            $logClient = '-';
            exit(-1);
        } else {
            # parent process
        }
    }
}

sub processClientRequest
{
    local $SIG{ALRM} = sub { };
    my $line = <CLIENT>;
    my $url = '';
    chomp($line);
    ($name, $value) = split(/\s/, $line, 2);
    if ($name eq "START") {
        $url = $value;
        writeLog($line);
        do {
            my $res = `lwp-request "$url"`;
            @array = split(" ", $res);
            writeLog("$res sleep $sleepDuration seconds");
            sleep $sleepDuration;
            writeLog('wakeup');
        } while ($array[0] eq 'CONTINUE');
    }
}