#!/usr/bin/perl

use strict; use IPC::Open2; use IO::Socket::INET;
use Time::HiRes; use Getopt::Std;
use Socket qw(IPPROTO_TCP TCP_NODELAY);

my ($tex,$texfile,$debuglevel) = ("tex","main.tex",0);
my %args; getopts('d:lf:',\%args);
$debuglevel = $args{'d'} if defined $args{'d'};
$tex = "pdflatex" if defined $args{'l'};
$texfile = $args{'f'} if defined $args{'f'};

my $oldh = select(STDERR); $| = 1; select($oldh);

my $pid = open2 *TEXOUT, *TEXIN, "$tex $texfile"
  or die "cannot connect to TeX";
open TEXLOG, ">texlog";

my $host = shift or 'localhost'; my $port = shift or '17676';
my $socket = IO::Socket::INET->new(Proto => "tcp",
				   PeerAddr => $host,
				   PeerPort => $port,
				   Blocking => 0)
  or die "cannot connect to TCP server $host:$port";
$socket->setsockopt(IPPROTO_TCP,TCP_NODELAY,1);

my @lines = ('')x30; my $lasttics = 0; my $clockoffset=0;
my ($start,$startu)=Time::HiRes::gettimeofday();
my $initline = '';
my $noterr = 0; # TeX doesn't just stop for errors...

while (<TEXOUT>) {
    print if $debuglevel>6;
    if (/\! OK/) { $noterr++; }
    if (/WANT/) {
	print STDERR "." if $debuglevel>5;
	my $data = <$socket>;
	my ($time,$timeu)=Time::HiRes::gettimeofday();
	$time -= $start; $timeu -= $startu;
	my $tics = 1000*$time+int($timeu/1000)-$clockoffset;
	if ($data) {
	    $initline = $data if $data=~/I/;
	    if ($data=~/T 0/) { $clockoffset += $tics; $tics = 0 }
	    print STDERR "Transmitted packet: $data\n" if $debuglevel>3;
	    print TEXIN "t $tics ; $data\n";
	    print TEXLOG "t $tics ; $data\n";
	} else {
	    unless ($socket->connected) {
		print TEXIN "\\done\n";
		print STDERR "Server disconnected\n" if $debuglevel>-1;
		close TEXIN; close TEXOUT;
	    } else {
		if ($tics-$lasttics<10) {
		    Time::HiRes::usleep(1000*(10+$lasttics-$tics));
		    ($time,$timeu)=Time::HiRes::gettimeofday();
		    $time -= $start; $timeu -= $startu;
		    $tics = 1000*$time+int($timeu/1000)-$clockoffset;
		}
		print TEXIN "t $tics ;\n";
		print TEXLOG "t $tics ;\n";
	    }
	}
	$lasttics=$tics;
    } elsif (/HERE: (.*)$/) {
	print STDERR "Got message: $1\n" if $debuglevel>1;
	print $socket $1;
    } elsif (/DEBUG\((.*)\): (.*)$/) {
	print STDERR "$2\n" if $1<=$debuglevel;
    } elsif (/DONE/) {
	while (<TEXOUT>) { print STDERR $_ }
	close TEXIN; close TEXOUT; close $socket;
    } else { if (/\S+/) { shift @lines; push @lines,$_; } }
    if (/^l\./) {
	if ($noterr) { print TEXIN "\n"; $noterr--; }
	else {
	    print STDERR "TeX Error: $_\n" if $debuglevel>=0;
	    $"=''; print "@lines";
	    print TEXIN "x\nx\nx\nx\nx\n";
	    for (my $i=0;$i<20;++$i) { print <TEXOUT> }
	    close TEXIN; close TEXOUT; close TEXLOG; kill $pid;
	    system "cp main.log error.log";
	    system "cp texlog texlog.1"; print STDERR "log file copied\n";
	    $pid = open2 *TEXOUT, *TEXIN, "$tex $texfile"
	      or die "cannot connect to TeX";
	    my $data = ''; while ($data!~/E/) {
		last unless $socket->connected; 
		open TEXLOG, ">texlog"; $data = <$socket>
	    }
	    while (<TEXOUT>) { # wait till we're good to go
		print TEXIN "$initline\n" and last if /WANT/;
	    }
	}
    }
}

print STDERR "Remaining data:\n" if $debuglevel>-1;
while (<$socket>) { print STDERR "$_\n" if $debuglevel >-1 }
close $socket; close TEXLOG;