#!/usr/bin/perl -w

use strict;
use warnings;
use JSON;
use File::Which;
use Getopt::Long;

my $json       = {};
my $pool       = undef;
my $dataset    = undef;
my $sanoidsnap = undef;
my $pretty     = 0;

GetOptions(
  "zpool|pool=s" => \$pool,
  "dataset=s"    => \$dataset,
  "sanoidsnap"   => \$sanoidsnap,
  "pretty"       => \$pretty
);

my $zpool  = which('zpool');
my $zfs    = which('zfs');
my $sanoid = which('sanoid');

if (not $zpool or not $zfs){
  print 'ZBX_NOTSUPPOTED';
  exit 0;
}
if ($sanoidsnap and not $sanoid){
  die 'ZBX_NOTSUPPOTED';
}

if (not $pool and not $dataset and not $sanoidsnap){
  print <<_EOF;
Usage:
$0 [--zpool=<name>|--dataset=<fs zvol or snap>|--sanoidsnap]
_EOF
  exit 1;
}

# Value map. For Zabbix, we want 0 instead of none
# We also prefer on/off represented as 1/0 as it's more efficient
my $map = {
  18446744073709551615 => 0, # See https://github.com/zfsonlinux/zfs/issues/9306
  none                 => 0,
  on                   => 1,
  off                  => 0
};

if ($pool){
  foreach (qx($zpool get all $pool -p -H)){
    chomp;
    my @parse = split /\t+/, $_;
    $json->{$parse[1]} = (defined $map->{$parse[2]}) ? $map->{$parse[2]} : $parse[2];
    $json->{errors} = get_zpool_errors($pool);
    $json->{stats}  = get_zpool_stats($pool);
  }
} elsif ($dataset){
  # Convert %40 back to @ (we send them as %40 in the discovery because @ is not allowed in item keys
  $dataset =~ s/%40/\@/g;
  foreach (qx($zfs get all $dataset -p -H)){
    chomp;
    my @parse = split /\t+/, $_;
    $json->{$parse[1]} = (defined $map->{$parse[2]}) ? $map->{$parse[2]} : $parse[2];
  }
} elsif ($sanoidsnap){
  print qx($sanoid --monitor-snapshot);
  exit 0;
}

print to_json($json, { pretty => $pretty }) . "\n";
exit 0;

sub get_zpool_errors {
  my $pool = shift;
  my $errors = {
    read_errors  => 0,
    write_errors => 0,
    cksum_errors => 0
  };
  my $i = 0;
  my $index = {};
  foreach my $line (qx($zpool status -p $pool)){
    # Output looks like
    #   pool: rpool
    #  state: ONLINE
    # status: One or more devices has experienced an unrecoverable error.  An
    #         attempt was made to correct the error.  Applications are unaffected.
    # action: Determine if the device needs to be replaced, and clear the errors
    #         using 'zpool clear' or replace the device with 'zpool replace'.
    #    see: http://zfsonlinux.org/msg/ZFS-8000-9P
    #   scan: scrub repaired 0B in 0h5m with 0 errors on Tue May 29 10:04:31 2018
    # config:
    #
    #         NAME        STATE     READ WRITE CKSUM
    #          rpool       ONLINE       0     0     0
    #            mirror-0  ONLINE       0     0     0
    #              sda2    ONLINE       0     0     0
    #              sdb2    ONLINE       0     0   474
    #
    # errors: No known data errors

    # We want to save status, action, scan and errors
    if ($line =~ m/^\s*(scan|action|status|errors):\s+(\w+.*)/){
      $errors->{$1} = $2;
      $index->{$i} = $1;
    } elsif ($line !~ /:/ and defined $index->{$i-1}){
      # Here, we reconstitute multiline values (like status and action)
      chomp($line);
      $line =~ s/\s+/ /g;
      $errors->{$index->{$i-1}} .= $line;
    } elsif ($line =~ m/\s+[a-zA-Z0-9_\-]+\s+[A-Z]+\s+(?<read>\d+(\.\d+)?)\s+(?<write>\d+(\.\d+)?)\s+(?<cksum>\d+(\.\d+)?)/){
      # And here, we count the number of read, write and checksum errors
      $errors->{read_errors}  += $+{'read'};
      $errors->{write_errors} += $+{'write'};
      $errors->{cksum_errors} += $+{'cksum'};
    }
    $i++;
  }
  # Ensure evey item returns something
  $errors->{$_} ||= '' foreach (qw(scan action status errors));
  return $errors;
}

sub get_zpool_stats {
  my $pool = shift;
  my $stats = {};
  return $stats unless (-e "/proc/spl/kstat/zfs/$pool/io");
  open STAT, "</proc/spl/kstat/zfs/$pool/io";
  while (<STAT>){
    if (m/^(?<nread>\d+)\s+(?<nwritten>\d+)\s+(?<reads>\d+)\s+(?<writes>\d+)\s+(?<wtime>\d+)\s+(?<wlentime>\d+)\s+(?<wupdate>\d+)\s+(?<rtime>\d+)\s+(?<rlentime>\d+)\s+(?<rupdate>\d+)\s+(?<wcnt>\d+)\s+(?<rcnt>\d+)/){
      $stats->{$_} = $+{$_} foreach (keys %+);
    }
  }
  close STAT;
  return $stats;
}