#!/usr/local/bin/perl

use Net::DHCP::Control::Failover 'failover_statename';
use MIME::Base64;
use Getopt::Std;
use Carp;


my %auth = (key_name => 'omkey',
	    key_type => 'hmac-md5',
	    key => MIME::Base64::decode_base64("K/E3ho1EbqGk1mYPNpiIcmpuR/rFG6T689HHGI78ekM="),
	   );


my %host = (
#	    primary => 'flotsam.net.isc.upenn.edu',
	    primary => 'noc-2003-ist.NET.ISC.UPENN.EDU',
#	    secondary => 'jetsam.net.isc.upenn.edu',
	    secondary => 'noc-2003-dmr.net.isc.upenn.edu',
	   );

getopts('a:t:n:') or usage();
$opt_a or usage();

if ($opt_a eq 'status') { 
  show_status();
} elsif ($opt_a eq 'change_state') { 
  usage() unless defined $opt_t && defined $opt_n; 
  usage() unless exists $host{$opt_t};
  usage() unless defined failover_statename($opt_n);
  change_state(auth => \%auth); 
} elsif ($opt_a eq 'ipstats') { 
  die "not implemented\n";
} else { 
  usage();
}

sub show_status {
  for my $what (keys %host) {
    printf "%9s: %12s\n", $what, get_state(host => $host{$what}, 
					   auth => \%auth,
					  );
  }
}

sub get_state {
  my (%opts) = @_;
  my $fo = $opts{handle} 
  || Net::DHCP::Control::Failover::State->new(host => $opts{host}, %{$opts{auth}},
				 attrs => { name => "dhcp.net.isc.upenn.edu" },
				 )
  || return failover_statename(0);
  my $state = $fo->get("local-state");
  defined($state)
    or die "Couldn't get failover local state: $Net::DHCP::Control::STATUS";
  failover_statename($state);
}

my %legal_transition;
BEGIN {
  $legal_transition{recover}  = {target => 'shutdown', 
				 peer => 'partner down',
				};
  $legal_transition{shutdown} = {target => 'normal',
				 peer => 'normal',
				};
  $legal_transition{'partner down'} = {target => 'communications interrupted', 
				       peer => 'unavailable',
				      };
}

sub change_state {
  my %opts = @_;
  my (%state, %handle);
  my $target = $opt_t;
  my $new_state = $opt_n;
  my %map;
  $map{target} = $target;
  $map{peer}   = $target eq 'primary' ? 'secondary' : 'primary';
  
  print "changing state\n";
  for my $what (qw(target peer)) {
    $handle{$what} =  Net::DHCP::Control::Failover::State->new(host => $host{$map{$what}},
						  %{$opts{auth}},
						  attrs => { name => "dhcp.net.isc.upenn.edu" },
						 );
    $state{$what} = get_state(handle => $handle{$what});
    printf "%9s: %12s\n", $what, $state{$what};
  }
  
  if ($state{target} eq $new_state) {
    warn "target is already in state '$new_state'
no change made\n";
    exit 0;
  }

  my $required_current_state = $legal_transition{$new_state}
    or die "invalid new state\n";
  for my $what (qw(target peer)) {
    unless ($state{$what} eq $required_current_state->{$what}) {
      die "To transit the target to state $new_state, 
the $what must be in state $required_current_state->{$what}.
But it is in state $state{$what} instead.\n";
    }
  }

 set_state(handle => $handle{target}, state => failover_statename($new_state));
}

sub set_state {
  my %opts = @_;
  my $fo = $opts{handle} 
    || Net::DHCP::Control::Failover::State->new(host => $opts{host}, 
						%{$opts{auth}},
						attrs => { name => "dhcp.net.isc.upenn.edu" },
						)
	|| die "Couldn't create failover-state object: $Net::DHCP::Control::STATUS";
  $fo->set("local-state", $opts{state}) 
    or die "Couldn't set local state: $Net::DHCP::Control::STATUS";
}


sub usage {
  warn <<EOM;
usage: $0 -a status
       $0 -a change_state -t primary|secondary -n recover|normal|'partner down'
EOM
  exit 1;
}