#!/usr/bin/perl

use Fcntl ':flock';
$QMAIL = "/var/qmail";
$CONTROL = "$QMAIL/control";

open LOG, ">>", "/tmp/qmail-remote-log";
{ my $ofh = select LOG; $|=1; select $ofh; }
Log("starting");

$msgs = 0;
$time = 0; 

load_policy();


while(1) {
  my @last = grep {$_ > time() - $time} read_log();
  Log("status " . @last . "/$msgs");

  if (@last >= $msgs) {
#    Log("sleeping");
  } else {
    last;
  }

  while (@last >= $msgs) {
    my $oldest = $last[0];
    my $age = time() - $oldest;
    # When will the oldest message expire off the queue?
    # The end of the queue is $time seconds ago
    # The age of the oldest message is now time() - $oldest 
    # The oldest message will expire in $time - $age seconds
    my $zzz = $time - $age + int(rand(3));
    $zzz = 1 if $zzz < 1;
#    Log("Sleeping for $zzz secs");
    sleep $zzz;
    shift @last while @last && $last[0] < time() - $time;
    load_policy();
  }
} 

append_log(time());

#if (open F, ">>", "/tmp/qmail-remote-log") {
#  print F time(), " @ARGV\n";
#}
Log("sending @ARGV");
exec "/var/qmail/bin/qmail-remote.real", @ARGV;
exit 0;


sub fail {
  my $msg = shift;
  Log("fail: $msg");
  print "Z$msg";
  exit 0;
}

my $last_policy_load ;
sub load_policy {
  my $POLICY = "$CONTROL/outratelimit";
  return if ((stat($POLICY))[9] <= $last_policy_load);
  if (open F, "<", $POLICY) {
    chomp(my $line = <F>);
    ($msgs, $time) = split m{/}, $line;
    if (defined $last_policy_load) {
      Log("Policy changed to $msgs/$time");
    }
    $last_policy_load = time();
    close F;
  }
}


sub read_log {
  lock_semaphore(LOCK_SH);

  my @last;
  if (open(F, "+<", "$CONTROL/outlog")) {
    chomp(@last = <F>);
    close F;
  }

  lock_semaphore(LOCK_UN);

  return @last;
}

sub append_log {
  lock_semaphore(LOCK_EX);

  if (open(F, "+<", "$CONTROL/outlog")) {
    my @last = grep {$_ > time() - $time} <F>;
    chomp(@last);
    truncate F, 0;
    seek F, 0, 0;
    print F join "\n", @last, @_, "";
    close F;
  }

  lock_semaphore(LOCK_UN);
}


sub lock_semaphore {
  if (open SEM, ">", "$CONTROL/qmail-remote-semaphore") {
    flock(SEM, $_[0]) or fail("Couldn't lock semaphore: $!");
  } else {
    fail("Couldn't open semaphore: $!");
  }
}

sub Log {
  my @args = @_;
  tr/\n//d for @args;
  print LOG time(), " $$ @args\n";
}