#!/usr/bin/perl -w

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

my $opt = {
  shutdown  => 'all',
  snap_size => '5G',
  snapshot  => 1,
  mount     => '/home/lbkp/zimbra/mount',
  pre       => 1,
  post      => 0,
  quiet     => 0,
  verbose   => 0
};

GetOptions (
  'shutdown=s'  => \$opt->{shutdown},
  'snap-size=s' => \$opt->{snap_size},
  'snapshot!'   => \$opt->{snapshot},
  'mount=s'     => \$opt->{mount},
  'pre'         => \$opt->{pre},
  'post'        => \$opt->{post},
  'quiet'       => \$opt->{quiet},
  'verbose'     => \$opt->{verbose}
);

if ( not -d $opt->{mount} ) {
  die $opt->{mount} . " must exist\n";
}

$opt->{pre} = 0 if $opt->{post};

# Start by assuming we can run snapshots
my $can_snapshot = 1;

my $lvs = which('lvs');

if (not $lvs) {
  log_info("lvs not found, no snapshot will be attempted");
  $can_snapshot = 0;
}

my $lv_info = {};

my ($dev, $fs, undef, undef, undef, undef, $mp) = split /\s+/, ( qx( df -PTl /opt/zimbra ) )[1];
log_verbose("Found device $dev mounted on $mp with an $fs filesystem");

if ( $can_snapshot ) {
  log_verbose("Trying to detect if $dev is an LVM volume");
  $lv_info = from_json(qx( $lvs --reportformat=json -o vg_name,lv_name,pool_lv $dev 2>/dev/null));
  if (defined $lv_info->{report}->[0]->{lv}->[0] ){
    $lv_info = $lv_info->{report}->[0]->{lv}->[0];
  }
}

if ( $opt->{pre} ) {
  if ($opt->{shutdown} =~ m/^no(ne)?/){
    log_info("Not shutting down any service");
  } elsif ($opt->{shutdown} eq 'ldap' and -e '/opt/zimbra/bin/ldap'){
    log_info("Stoping Zimbra LDAP service");
    system("/opt/zimbra/bin/ldap stop");
  } else {
    log_info("Stoping Zimbra services");
    system('systemctl stop zimbra');
  }
  if ( not $lv_info->{vg_name} or not $lv_info->{lv_name} or $lv_info->{vg_name} eq '' or $lv_info->{lv_name} eq '' ) {
    # We cannot take a snapshot. Zimbra will just be kept shut down until the end of the backup (unless you choose not to shut down services)
    # Just bind mount /opt/zimbra on the backup dir
    log_info("Can't create a snapshot of $dev");
    if ( system('mount -o bind,ro /opt/zimbra ' . $opt->{mount} ) ) {
      die "Can't mount /opt/zimbra on $opt->{mount}\n";
    }
  } else {
    log_info("Trying to create a snapshot of device $dev");
    my $snap_args = '-s -n ' . $lv_info->{lv_name} . '_bkp';
    # Detect if thin pool or standard LVM
    if ( defined $lv_info->{pool_lv} and $lv_info->{pool_lv} ne '' ) {
      # Thin LVM
      log_verbose("$dev is a thin LVM volume");
      $snap_args .= ' -kn';
    } else {
      # Standard LVM
      log_verbose("$dev is a standard LVM volume");
      $snap_args .= ' -L' . $opt->{snap_size};
    }

    # Take the snapshot
    if ( system( "lvcreate $snap_args $dev") != 0 ) {
      die "Failed to create snapshot\n";
    }

    log_info("snapshot created as $dev" . '_bkp');

    # Restart Zimbra now to minimize down time
    if ($opt->{shutdown} =~ m/^no(ne)?/){
      log_info("No service were shutted down");
    } elsif ($opt->{shutdown} eq 'ldap' and -e '/opt/zimbra/bin/ldap'){
      log_info("Starting Zimbra LDAP service");
      system("/opt/zimbra/bin/ldap start");
    } else {
      log_info("Starting Zimbra services");
      system('systemctl start zimbra');
    }

    # Now mount the snapshot RO
    my $mount_args = "-o ro -t $fs";
    if ( $fs eq 'xfs' ) {
      $mount_args .= ' -o nouuid';
    }


    log_verbose("Mounting the snapshot readonly on $opt->{mount}");
    if ( system("mount $mount_args /dev/mapper/" . $lv_info->{vg_name} . '-' . $lv_info->{lv_name} . '_bkp ' . $opt->{mount}) != 0 ) {
      die "Can't mount " . $lv_info->{lv_name} . '_bkp on ' . $opt->{mount} . "\n";
    }

    # The snapshot is mounted, but we might need an additional bind mount if the volume hosts / or /opt
    my $level = grep { $_ ne '' } split( /\//, $mp);
    my $level2subdir = {
      0 => '/opt/zimbra',
      1 => '/zimbra'
    };
    if ( defined $level2subdir->{$level} ) {
      if ( system('mount -o bind,ro ' . $opt->{mount} . $level2subdir->{$level} . ' ' . $opt->{mount} ) ) {
        die "Can't mount $opt->{mount}$level2subdir->{$level} on $opt->{mount}\n";
      }
    }
  }
} elsif ( $opt->{post} ) {
  log_info("unmounting $opt->{mount}");
  while (is_mounted($opt->{mount})){
    # We need to loop as we can have a stacked bind mount over the standard FS
    system( "umount $opt->{mount}" );
  }

  if ( not $lv_info->{vg_name} or not $lv_info->{lv_name} or $lv_info->{vg_name} eq '' or $lv_info->{lv_name} eq '' ) {
    # No backup snapshot, zimbra should just be started again
    log_info("Restating Zimbra services");
    system('systemctl start zimbra');
  } else {
    log_verbose("Removing LVM snapshot");
    if ( system( "lvremove -y $lv_info->{vg_name}/$lv_info->{lv_name}" . '_bkp' ) != 0 ) {
      die "Failed to remove LVM snapshot\n";
    }
  }
}
# Print messages only if the verbose flag was given
sub log_verbose {
  my $msg = shift;
  print $msg . "\n" if ( $opt->{verbose} );
}

# Print info messages unless the quiet flag was given
sub log_info {
  my $msg = shift;
  print $msg . "\n" if ( not $opt->{quiet} );
}

# Print errors
sub log_error {
  my $msg = shift;
  print $msg . "\n";
}

# Check if something is mounted on a dir
sub is_mounted {
  my $dir = shift;
  $dir =~ s/\/$//;
  my $is_mounted = 0;
  open MOUNTS, '</proc/mounts';
  while (<MOUNTS>){
    my ($what, $where, $type, $options) = split(/\s+/, $_);
    if ($where eq $dir){
      $is_mounted = 1;
      last;
    }
  }
  close MOUNTS;
  return $is_mounted;
}