#!/usr/bin/perl -w

=encoding utf8

=head1 NAME

courier_mta_mailstats - Plugin to monitor the number of mails
delivered and rejected by courier-mta.

=head1 CONFIGURATION

The following environment variables are used:

 logdir  - Where to find logfiles (default "/var/log")
 logfile - What file to read in logdir (default "mail.log")
 courier - Path to "courier" (default "/usr/sbin/courier")

=head1 AUTHOR

Rune Nordbøe Skillingstad <runesk@linpro.no>

=head1 LICENSE

Unknown

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=cut

my $statefile = "$ENV{MUNIN_PLUGSTATE}/munin-plugin-courier_mta_mailstats.state";
my $pos   = undef;
my $delivered = 0;
my $rejects = {};
my $LOGDIR  = $ENV{'logdir'}  || '/var/log';
my $LOGFILE = $ENV{'logfile'} || 'mail.log';
my $COURIER = $ENV{'courier'} || '/usr/sbin/courier';

if ( $ARGV[0] and $ARGV[0] eq "autoconf" )
{
    my $logfile;
    if(-x $COURIER) {
	if(-d $LOGDIR) {
	    $logfile = "$LOGDIR/$LOGFILE";
	    if(-f $logfile) {
		if(-r "$logfile") {
		    print "yes\n";
		    exit 0;
		} else {
		    print "no (logfile not readable)\n";
		}
	    } else {
		print "no (logfile not found)\n";
	    }
	} else {
	    print "no (could not find logdir)\n";
	}
    } else {
	print "no (could not find executable)\n";
    }
    exit 0;
}

my $logfile = "$LOGDIR/$LOGFILE";
my $prevdate = get_prev_date();

if(-f "$logfile.$prevdate") {
    $rotlogfile = "$logfile.$prevdate";
} elsif (-f "$logfile.0") {
    $rotlogfile = $logfile . ".0";
} elsif (-f "$logfile.1") {
    $rotlogfile = $logfile . ".1";
} elsif (-f "$logfile.01") {
    $rotlogfile = $logfile . ".01";
} else {
    $rotlogfile = $logfile . ".0";
}

if(-f "$statefile") {
    open (IN, "$statefile") or exit 4;
    if(<IN> =~ /^(\d+):(\d+)/) {
	($pos, $delivered) = ($1, $2);
    }
    while (<IN>) {
    	if (/^(\d+):(\d+)$/) {
	    $rejects->{$1} = $2;
	}
    }
    close IN;
}

if(! -f $logfile and ! -f $rotlogfile) {
    print "delivered.value U\n";
    foreach my $i (keys %{$rejects}) {
    	print "r$i.value U\n";
    }
    exit 0;
}


$startsize = (stat $logfile)[7];

if(!defined $pos) {
    # Initial run.
    $pos = $startsize;
}

if($startsize < $pos) {
    # Log rotated
    parseLogfile ($rotlogfile, $pos, (stat $rotlogfile)[7]);
    $pos = 0;
}

parseLogfile ($logfile, $pos, $startsize);
$pos = $startsize;

if($ARGV[0] and $ARGV[0] eq "config") {
    print "graph_title Courier MTA mail throughput\n";
    print "graph_category mail\n";
    print "graph_args --base 1000 -l 0\n";
    print "graph_vlabel mails / \${graph_period}\n";
    print "graph_scale  no\n";
    print "graph_total  Total\n";
    print "delivered.label delivered\n";
    print "delivered.type DERIVE\n";
    print "delivered.draw AREA\n";
    print "delivered.min 0\n";
    foreach my $i (keys %{$rejects}) {
	    print "r$i.label reject $i\n";
	    print "r$i.type DERIVE\n";
	    print "r$i.draw STACK\n";
	    print "r$i.min 0\n";
    }
    exit 0;
}

print "delivered.value $delivered\n";
foreach my $i (keys %{$rejects}) {
	print "r$i.value ", $rejects->{$i}, "\n";
}

if(-l $statefile) {
    die("$statefile is a symbolic link, refusing to touch it.");
}
open (OUT, ">$statefile") or exit 4;
print OUT "$pos:$delivered\n";
foreach my $i (keys %{$rejects}) {
    print OUT "$i:", $rejects->{$i}, "\n";
}
close OUT;

sub parseLogfile {
    my ($fname, $start, $stop) = @_;
    open (LOGFILE, $fname) or exit 3;
    seek (LOGFILE, $start, 0) or exit 2;

    while (tell (LOGFILE) < $stop) {
	my $line =<LOGFILE>;
	chomp ($line);
	if($line =~ /(?:courierlocal|courieresmtp): id=.*,from=.*,addr=.*,size=\d+,success:.*delivered/) {
	    $delivered++;
	} elsif($line =~ /courieresmtpd: error,relay=.*(?:\d{1,3}\.){3}\d{1,3},from=[^:]+: (\d{3})/) {
	    $rejects->{$1} ++;
	}
    }
    close(LOGFILE);
}

sub get_prev_date {
	my @date = localtime (time - 86400);
	my $prevdate = $date[5]+1900 . $date[4]+1 . $date[3];
	return $prevdate;
}