#!/usr/bin/perl
use strict;
use DBI;
use Getopt::Long;

my $dbname    = "schwartz";
my $user      = "root";
my $pass      = "";
my $job       = "";
my $max_age   = 0;
my $max_count = 0;

=head1 NAME

schwartzmon - monitor The Schwartz

=head1 USAGE

Type

    schwartzmon --help

to get full usage.

=cut

sub usage {
    die <<USAGE;
Usage: schwartzmon <command> [OPTS]

Possible commands:
     queues           View past-due job queue depths.  (default cmd)
     errors           View errors.

Global options:
   --job=<JOBNAME>    Only look at one specific job name.  Else all are considered.
   --user=<user>      Connect to the database as this user
   --pass=<pass>      Connect to the database with this password
   --database=<db>    Connect to this database
   --dsn=<dsn>        Connect to the database using this DSN

Options for 'queues' command:
   --maxage=<n>       Don't complain if age of overdue job queue is <= 'n'
   --maxcount=<n>     Don't complain if depth of overdue job queue is <= 'n'

Options for 'errors' command:
   --follow | -f      Like 'tail -f' for tracking the error log
   --last=n           Show last 'n' errors from log
   --inlast=n         Show errors in last 'n' seconds

Verbosity:
   if no alerts, nothing is printed, and exit status is 0.

Exit status:
   0 if no alerts,
   non-zero if there are alerts, in which case the alerts are printed.

USAGE

}

my $opt_help = 0;
my ( $opt_follow, $opt_last, $opt_inlast, $opt_func, $dsn );
usage()
    unless GetOptions(
    "job=s"      => \$job,
    "maxage=i"   => \$max_age,
    "maxcount=i" => \$max_count,
    "help"       => \$opt_help,
    "follow|f"   => \$opt_follow,
    "last=i"     => \$opt_last,
    "inlast=i"   => \$opt_inlast,
    "user=s"     => \$user,
    "pass=s"     => \$pass,
    "dsn=s"      => \$dsn,
    "database=s" => \$dbname,
    "func=s"     => \$opt_func,
    );
usage() if $opt_help;

my $cmd = shift || "queues";
usage() unless $cmd =~ /^queues|errors$/;

my $dbset = DBSet->new;

$dsn ||= "DBI:mysql:$dbname";

$dbset->add( DBHandle->new( { dsn => $dsn, user => $user, pass => $pass } ) );

if ( $cmd eq "queues" ) { queues($dbset); }
if ( $cmd eq "errors" ) { errors($dbset); }
exit 0;

#################

sub queues {
    my $dbs        = shift;
    my $some_alert = 0;
    $dbs->foreach(
        sub {
            my $db = shift;
            my $dbh = $db->dbh or next;

            my $funcmap = $dbh->selectall_hashref(
                "SELECT funcid, funcname FROM funcmap", "funcid" );

            foreach my $funcid (
                sort { $funcmap->{$a}{funcname} cmp $funcmap->{$b}{funcname} }
                keys %$funcmap
                )
            {
                my $funcname = $funcmap->{$funcid}{funcname};
                next if $job && $funcname ne $job;

                my $now = time();
                my $inf = $dbh->selectrow_hashref(
                    "SELECT COUNT(*) as 'ct', MIN(run_after) 'oldest' FROM job WHERE funcid=? AND run_after <= $now",
                    undef, $funcid
                );
                my $behind = $inf->{ct} ? ( $now - $inf->{oldest} ) : 0;

                # okay by default, then we apply rules:
                my $okay = 1;
                $okay = 0 if $behind > $max_age;
                $okay = 0 if $inf->{ct} > $max_count;
                next if $okay;
                $some_alert = 1;

                print "$funcname\n";
                print "  outstanding: $inf->{ct}\n";
                print "  behind_secs: $behind\n";
            }
        }
    );
    exit( $some_alert ? 1 : 0 );
}

sub errors {
    my $dbs = shift;

    if ($opt_follow) {
        follow_errors($dbs);
    }

    $opt_last = 100 unless $opt_last || $opt_inlast;

    my @rows;
    $dbs->foreach(
        sub {
            my $db  = shift;
            my $dbh = $db->dbh
                or next;

            my $extra_where = '';
            if ($opt_func) {
                my $funcid = $db->funcid_of_func($opt_func) || 0;
                $extra_where = "AND funcid=$funcid";
            }

            my $sql;
            if ($opt_last) {
                $sql
                    = "SELECT error_time, jobid, message FROM error WHERE 1=1 $extra_where "
                    . "ORDER BY error_time DESC LIMIT $opt_last";
            }
            elsif ($opt_inlast) {
                my $since = time() - $opt_inlast;
                $sql
                    = "SELECT error_time, jobid, message FROM error WHERE error_time >= $since $extra_where "
                    . "ORDER BY error_time LIMIT 50000";
            }

            my $sth = $dbh->prepare($sql);
            $sth->execute;
            push @rows, $_ while $_ = $sth->fetchrow_hashref;
        }
    );

    @rows = sort { $a->{error_time} <=> $b->{error_time} } @rows;
    if ( $opt_last && @rows > $opt_last ) {
        shift @rows while @rows > $opt_last;
    }

    foreach my $r (@rows) {
        print_error($r);
    }

}

sub follow_errors {
    my $dbs = shift;

    while (1) {
        $dbs->foreach(
            sub {
                my $db  = shift;
                my $dbh = $db->dbh
                    or next;
                my $notes = $db->notes;

                my $lastmax = $notes->{lastmax} || time();
                my $seen = $notes->{seen} ||= {};

                my $extra_where = '';
                if ($opt_func) {
                    my $funcid = $db->funcid_of_func($opt_func) || 0;
                    $extra_where = "AND funcid=$funcid";
                }

                my $sth
                    = $dbh->prepare(
                    "SELECT error_time, jobid, message FROM error WHERE error_time >= ? $extra_where ORDER BY error_time"
                    );
                $sth->execute($lastmax);
                my @errors;
                push @errors, $_ while $_ = $sth->fetchrow_hashref;

                my $newmax = $lastmax;
                foreach my $r (@errors) {
                    my $sig = join( ",", map { $_, $r->{$_} } sort keys %$r );
                    next if $seen->{$sig};
                    $seen->{$sig} = $r->{error_time};
                    print_error($r);
                    $newmax = $r->{error_time} if $r->{error_time} > $newmax;
                }

                $notes->{lastmax} = $newmax;

                foreach my $sig ( keys %$seen ) {
                    my $time = $seen->{$sig};
                    delete $seen->{$sig} if $time < $newmax;
                }

            }
        );
        sleep 1;
    }
}

sub print_error {
    my $r   = shift;
    my $msg = $r->{message};
    $msg =~ s/\s+$//g;
    printf scalar( localtime( $r->{error_time} ) ) . " [$r->{jobid}]: $msg\n";
}

package DBSet;

sub new {
    my ( $this, $args ) = @_;
    my $class = ref($this) || $this;
    return bless [], $class;
}

sub add {
    my ( $self, $db ) = @_;
    push @$self, $db;
}

sub foreach {
    my ( $self, $cb ) = @_;
    foreach my $dbh (@$self) {
        $cb->($dbh);
    }
}

package DBHandle;

sub new {
    my ( $class, $dbinf ) = @_;
    return bless $dbinf, $class;
}

sub notes {
    my $self = shift;
    return $self->{notes} ||= {};
}

# returns DBI handle
sub dbh {
    my $self = shift;
    return $self->{_dbh}
        ||= DBI->connect( $self->{dsn}, $self->{user}, $self->{pass} )

}

sub funcid_of_func {
    my ( $self, $func ) = @_;
    my $notes = $self->notes;
    return $notes->{"funcid_of_$func"} if exists $notes->{"funcid_of_$func"};

    my $dbh = $self->dbh;
    return $notes->{"funcid_of_$func"}
        = $dbh->selectrow_array(
        "SELECT funcid FROM funcmap WHERE funcname=?",
        undef, $func );
}

=head1 COPYRIGHT, LICENSE & WARRANTY

This software is Copyright 2007, 2008 Six Apart Ltd, cpan@sixapart.com. All
rights reserved.

TheSchwartz is free software; you may redistribute it and/or modify it
under the same terms as Perl itself.

TheSchwartz comes with no warranty of any kind.

=cut