#!/usr/bin/python3

import argparse
import librouteros
import ssl
import os
import yaml
import re
import dns.resolver, dns.reversename
import ipaddress

# comment format:
#   hostname.example.com [aM flag1 flag2 key1=value1 key2=option3:value3,option4:value4] selector.example.com
#
# flags:
#   static - do not auto-enable or auto-disable this address (loopbacks, linknets)
#   home - this is the normal home-location of the IP
#   standby - this is an active interface, but not intended as primary route
#   teardown - being destroyed
#
# keys:
#   evacuated=router - this address has been moved from this host to router
#   evacuee=router - this is an evacuated address originally from router

aM1 = re.compile( r"\[aM ?([^]]*)\]" )
def parse_comment( comment ):
    bits = aM1.split( comment )
    if len( bits ) == 3:
        hostname = bits[ 0 ].strip()
        selector = bits[ 2 ].strip()
        if not selector:
            selector = hostname
        rval = {}
        for bit in bits[ 1 ].split():
            try:
                ( k, v ) = bit.split( "=", 1 )
            except ValueError:
                if bit:
                    rval[ bit ] = True
            else:
                if ':' in v:
                    rval[ k ] = {}
                    for subbit in v.split( "," ):
                        ( subk, subv ) = subbit.split( ":", 1 )
                        rval[ k ][ subk ] = subv
                else:
                    rval[ k ] = v
        return ( selector, rval, hostname )
    else:
        return ( None, None, comment )

def reverse_dns( address ):
    try:
        return str( dns.resolver.resolve( dns.reversename.from_address( address ), 'PTR' )[ 0 ] )
    except:
        return address

def make_comment( selector, rval, hostname ):
    rvalbits = [ "aM" ]
    for ( k, v ) in rval.items():
        if v is True:
            rvalbits.append( k )
        elif isinstance( v, dict ):
            rvalbits.append( "%s=%s" % ( k, ",".join( "%s:%s" % vi for vi in v.items() ) ) )
        elif v:
            rvalbits.append( "%s=%s" % ( k, v ) )
    if selector == hostname or selector is None:
        return "%s [%s]" % ( hostname, " ".join( rvalbits ) )
    else:
        return "%s [%s] %s" % ( hostname, " ".join( rvalbits ), selector )

def connection( host, username = None, password = None, port = 8729 ):
    if ':' in host:
        ( host, port ) = host.split( ":", 1 )
        port = int( port )
    kwargs = { 'username': username or os.environ.get( 'AUTOMONTY_USERNAME', None ),
               'password': password or os.environ.get( 'AUTOMONTY_PASSWORD', None ),
               'host': host,
               'port': port,
               }
    kwargs[ 'ssl' ] = True
    ssl_ctx = ssl.create_default_context()
    ssl_ctx.check_hostname = False # XXX figure out how
    ssl_option = 'CERT_REQUIRED'
    ssl_ctx.verify_mode = getattr( ssl, ssl_option, ssl.CERT_REQUIRED )
    ssl_ctx.set_ciphers( 'DHE-RSA-AES256-GCM-SHA384' )
    kwargs[ 'ssl_wrapper' ] = ssl_ctx.wrap_socket
    return librouteros.connect( **kwargs )

def router_in_groups( options, groups ):
    if not groups:
        return False
    for group in groups:
        if group in options.get( 'group', [] ):
            return True
    return False

def connect_routers( config, args ):
    routers = config.get( 'router', {} )
    rval = {}
    for ( name, options ) in routers.items():
        if ( not args.only_router and not args.only_group ) or ( name in args.only_router ) or router_in_groups( options, args.only_group ):
            kwargs = {}
            kwargs.update( options.get( 'connection', {} ) )
            if 'host' not in kwargs:
                kwargs[ 'host' ] = name
            rval[ name ] = connection( **kwargs )
    return rval

def monty_check( config, args, routers ):
    for addr in args.addr:
        for ( name, api ) in routers.items():
            ip_address = api.path( 'ip', 'address' )
            ipv6_address = api.path( 'ipv6', 'address' )
            for item in ip_address:
                ( sel, rval, hst ) = parse_comment( item.get( 'comment', '' ) )
                active = not item[ 'disabled' ] and not item[ 'invalid' ]
                if sel == addr or hst == addr:
                    print( name, ": v4", 'ENABLED' if active else 'disabled', item[ 'interface' ] )
            for item in ipv6_address:
                ( sel, rval, hst ) = parse_comment( item.get( 'comment', '' ) )
                active = not item[ 'disabled' ] and not item[ 'invalid' ]
                if sel == addr or hst == addr:
                    print( name, ": v6", 'ENABLED' if active else 'disabled', item[ 'interface' ] )

def monty_fixup( config, args, routers ):
    reverse = {}
    statics = {}
    for ( name, api ) in routers.items():
        ip_address = api.path( 'ip', 'address' )
        ipv6_address = api.path( 'ipv6', 'address' )
        for item in ip_address:
            ( sel, rval, hst ) = parse_comment( item.get( 'comment', '' ) )
            if sel is None:
                rval = {}
                active = not item[ 'disabled' ] and not item[ 'invalid' ]
                if item[ 'address' ] in config[ 'loopbacks' ]:
                    if active:
                        rval[ 'home' ] = True
                else:
                    rval[ 'static' ] = True
                    statics[ item[ 'interface' ] ] = True
                if not hst:
                    hst = reverse_dns( item[ 'network' ] )
                    while hst.endswith( "." ):
                        hst = hst[ :-1 ]
                if not sel:
                    if item[ 'interface' ] not in reverse:
                        rev = reverse_dns( item[ 'network' ] )
                        while rev.endswith( "." ):
                            rev = rev[ :-1 ]
                        reverse[ item[ 'interface' ] ] = rev
                    sel = reverse[ item[ 'interface' ] ]
                new_comment = make_comment( sel, rval, hst )
                if args.dry_run:
                    print( '/ip address set [find where interface="%s" and network="%s"] comment="%s"' % ( item[ 'interface' ], item[ 'network' ], new_comment ) )
                else:
                    print( name, ":", item[ 'interface' ], new_comment )
                    ip_address.update( **{ 'comment': new_comment, '.id': item[ '.id' ] } )
            addr = ipaddress.ip_interface( item[ 'address' ] )
            if item[ 'address' ] in config[ 'loopbacks' ]:
                addr = ipaddress.ip_interface( item[ 'network' ] )
            _adjust_filter( config, api, addr.network, hst, sel, home = rval.get( 'home', False ), standby = False, static = rval.get( 'static', False ), rval = rval )

        for item in ipv6_address:
            if item[ 'interface' ].startswith( "loop" ):
                continue
            if item[ 'dynamic' ]:
                continue
            ( sel, rval, hst ) = parse_comment( item.get( 'comment', '' ) )
            if sel is None:
                rval = {}
                active = not item[ 'disabled' ] and not item[ 'invalid' ]
                if statics.get( item[ 'interface' ], False ):
                    rval[ 'static' ] = True
                elif active:
                    rval[ 'home' ] = True
                if not sel:
                    sel = reverse.get( item[ 'interface' ], "XXX " + item[ 'interface' ] )
                if not hst:
                    hst = reverse.get( item[ 'interface' ], "XXX " + item[ 'interface' ] )
                new_comment = make_comment( sel, rval, hst )
                if args.dry_run:
                    print( '/ipv6 address set [find where interface="%s" and address="%s" ] comment="%s"' % ( item[ 'interface' ], item[ 'address' ], new_comment ) )
                else:
                    print( name, ":", item[ 'interface' ], new_comment )
                    ipv6_address.update( **{ 'comment': new_comment, '.id': item[ '.id' ] } )
            addr = ipaddress.ip_interface( item[ 'address' ] )
            _adjust_filter( config, api, addr.network, hst, sel, home = rval.get( 'home', False ), standby = False, static = rval.get( 'static', False ), rval = rval )

def _adjust_filter( config, api, network, hostname, selector = None, home = None, standby = None, static = None, delete = False, rval = None, disabled = False ):

    def _make_filter_attrs( comment, disabled, home, static, standby ):
        attrs = { 'action': 'accept',
                  'comment': comment,
                  'disabled': 'yes' if disabled else 'no',
                  }
        if home or static:
            attrs[ '!set-bgp-prepend' ] = ''
            attrs[ 'set-bgp-local-pref' ] = 980
        elif standby:
            attrs[ 'set-bgp-prepend' ] = 1
            attrs[ 'set-bgp-local-pref' ] = 970
        else:
            attrs[ 'set-bgp-prepend' ] = 2
            attrs[ 'set-bgp-local-pref' ] = 960
        return attrs

    if isinstance( network, ( ipaddress.IPv4Interface, ipaddress.IPv6Interface ) ):
        network = network.network

    filters = api.path( 'routing', 'filter' )
    found = False
    if rval is None:
        rval = {}
    else:
        _rval = rval
        rval = {}
        rval.update( _rval )
    if home is not None:
        rval[ 'home' ] = home
    if standby is not None:
        rval[ 'standby' ] = standby
    if static is not None:
        rval[ 'static' ] = static
    comment = make_comment( selector, rval, hostname )
    for f in filters:
        if f[ 'chain' ] == config[ 'routing_filter_chain' ]:
            match = str( network )
            if isinstance( network, ipaddress.IPv4Network ) and network.prefixlen == 32:
                match = match.split( "/", 1 )[ 0 ]
            elif isinstance( network, ipaddress.IPv6Network ) and network.prefixlen == 128:
                match = match.split( "/", 1 )[ 0 ]
            if f[ 'prefix' ] == match:
                if delete:
                    filters.delete( f[ '.id' ] )
                else:
                    update = _make_filter_attrs( comment, disabled, home, static, standby )
                    update[ '.id' ] = f[ '.id' ]
                    filters.update( **update )
                    found = True
    if not found and not delete:
        create = _make_filter_attrs( comment, disabled, home, static, standby )
        create[ 'chain' ] = config[ 'routing_filter_chain' ]
        create[ 'prefix' ] = str( network )
        filters.add( **create )
    return rval

def monty_provision( config, args, routers ):
    reverse = {}
    statics = {}
    if args.dry_run:
        print()
    for ( name, api ) in routers.items():
        if args.dry_run:
            print( '#' * ( len( name ) + 2 ) )
            print( '#', name )
            print()
        vlans = api.path( 'interface', 'vlan' )
        ip_address = api.path( 'ip', 'address' )
        ipv6_address = api.path( 'ipv6', 'address' )
        for vlan in vlans:
            if vlan[ 'vlan-id' ] == args.vlan:
                rval = {}
                if args.static:
                    rval[ 'static' ] = True
                    disabled = 'no'
                elif name in args.home:
                    rval[ 'home' ] = True
                    disabled = 'no'
                elif name in args.standby:
                    rval[ 'standby' ] = True
                    disabled = 'no'
                else:
                    disabled = 'yes'
                comment = make_comment( args.selector, rval, args.hostname )

                for addr in args.address:
                    if args.dry_run:
                        if isinstance( addr, ipaddress.IPv4Interface ):
                            if addr.network.prefixlen == 32:
                                print( '/ip address add interface="%s" address="%s" network="%s" disabled=%s comment="%s"' % ( vlan[ 'name' ], config[ 'default_ipv4_loopback' ], addr.network.network_address, disabled, comment ) )
                            else:
                                print( '/ip address add interface="%s" address="%s" disabled=%s comment="%s"' % ( vlan[ 'name' ], addr, disabled, comment ) )
                        elif isinstance( addr, ipaddress.IPv6Interface ):
                            if args.static:
                                print( '/ipv6 address add interface="%s" address="%s" disabled=%s comment="%s" advertise=no' % ( vlan[ 'name' ], addr, disabled, comment ) )
                            else:
                                print( '/ipv6 address add interface="%s" address="%s" disabled=%s comment="%s" eui-64=yes advertise=yes' % ( vlan[ 'name' ], addr.network, disabled, comment ) )

                    else:
                        addr = ipaddress.ip_interface( addr )
                        prefix = _extract_bgp_announcement( addr, addr )
                        _adjust_filter( config, api, prefix, args.hostname,
                                        home = ( name in args.home ),
                                        standby = ( name not in args.home ) and ( name in args.standby ),
                                        selector = args.selector, rval = rval )
                        if isinstance( addr, ipaddress.IPv4Interface ):
                            v4addr = { 'interface': vlan[ 'name' ],
                                       'disabled': disabled,
                                       'comment': comment,
                                       }
                            if addr.network.prefixlen == 32:
                                v4addr[ 'address' ] = config[ 'default_ipv4_loopback' ]
                                v4addr[ 'network' ] = str( addr.network.network_address )
                            else:
                                v4addr[ 'address' ] = str( addr )
                            ip_address.add( **v4addr )

                        elif isinstance( addr, ipaddress.IPv6Interface ):
                            v6addr = { 'interface': vlan[ 'name' ],
                                       'disabled': disabled,
                                       'comment': comment,
                                       }
                            if args.static:
                                v6addr[ 'address' ] = str( addr )
                            else:
                                v6addr[ 'address' ] = str( addr.network )
                                v6addr[ 'eui-64' ] = 'yes'
                                v6addr[ 'advertise' ] = 'yes'
                            ipv6_address.add( **v6addr )

        if args.dry_run:
            print()

def monty_teardown( config, args, routers ):
    reverse = {}
    statics = {}
    if args.dry_run:
        print()
    for ( name, api ) in routers.items():
        if args.dry_run:
            print( '#' * ( len( name ) + 2 ) )
            print( '#', name )
            print()
        vlans = api.path( 'interface', 'vlan' )
        ip_address = api.path( 'ip', 'address' )
        ipv6_address = api.path( 'ipv6', 'address' )

        for addr in ip_address:
            ( sel, rval, hst ) = parse_comment( addr.get( 'comment', '' ) )
            if sel == args.hostname or hst == args.hostname:
                if args.delete:
                    if rval.get( 'teardown', False ):
                        if args.dry_run:
                            print( '/ip address remove [find where interface="%s" and network="%s" and comment~"teardown" and comment~"%s" ]' % ( addr[ 'interface' ], addr[ 'network' ], hst ) )
                        else:
                            print( "deleting %s %s from %s on %s" % ( addr[ 'address' ], addr[ 'network' ], addr[ 'interface' ], name ) )
                            ip_address.remove( addr[ '.id' ] )
                    else:
                        if args.dry_run:
                            print( "# ignoring %s %s on %s on %s" % ( addr[ 'address' ], addr[ 'network' ], addr[ 'interface' ], name ) )
                        else:
                            print( "ignoring %s %s on %s on %s" % ( addr[ 'address' ], addr[ 'network' ], addr[ 'interface' ], name ) )
                else:
                    rval[ 'teardown' ] = True
                    comment = make_comment( sel, rval, hst )
                    if args.dry_run:
                        print( '/ip address set [find where interface="%s" and network="%s" and comment~"%s" ] disabled=yes comment="%s"' % ( addr[ 'interface' ], addr[ 'network' ], hst, comment ) )
                    else:
                        print( "disabling %s %s on %s on %s" % ( addr[ 'address' ], addr[ 'network' ], addr[ 'interface' ], name ) )
                        ip_address.update( **{ '.id': addr[ '.id' ], 'disabled': 'yes', 'comment': comment } )

        for addr in ipv6_address:
            ( sel, rval, hst ) = parse_comment( addr.get( 'comment', '' ) )
            if sel == args.hostname or hst == args.hostname:
                if args.delete:
                    if rval.get( 'teardown', False ):
                        if args.dry_run:
                            print( '/ipv6 address remove [find where interface="%s" and address="%s" and comment="%s" ]' % ( addr[ 'interface' ], addr[ 'address' ], addr.get( 'comment', '' ) ) )
                        else:
                            print( "deleting %s from %s on %s" % ( addr[ 'address' ], addr[ 'interface' ], name ) )
                            ipv6_address.remove( addr[ '.id' ] )
                    else:
                        if args.dry_run:
                            print( "# ignoring %s on %s on %s" % ( addr[ 'address' ], addr[ 'interface' ], name ) )
                        else:
                            print( "ignoring %s on %s on %s" % ( addr[ 'address' ], addr[ 'interface' ], name ) )
                else:
                    rval[ 'teardown' ] = True
                    comment = make_comment( sel, rval, hst )
                    if args.dry_run:
                        print( '/ipv6 address set [find where interface="%s" and address="%s" and comment="%s" ] disabled=yes comment="%s"' % ( addr[ 'interface' ], addr[ 'address' ], addr.get( 'comment', '' ), comment ) )
                    else:
                        print( "disabling %s on %s on %s" % ( addr[ 'address' ], addr[ 'interface' ], name ) )
                        ipv6_address.update( **{ '.id': addr[ '.id' ], 'disabled': 'yes', 'comment': comment } )

        if args.dry_run:
            print()

def _extract_bgp_announcement( address, network = None ):
    addr = ipaddress.ip_interface( address )
    if isinstance( addr, ipaddress.IPv4Interface ):
        if addr.network.prefixlen == 32:
            return ipaddress.ip_interface( network )
        return addr.network
    elif isinstance( addr, ipaddress.IPv6Interface ):
        return addr.network

def monty_promote( config, args, routers ):
    for new_home in args.new_home:
        if new_home not in routers:
            raise ValueError( 'cannot find new home "%s" in routers' % new_home )
    for standby in args.standby:
        if standby not in routers:
            raise ValueError( 'cannot find new standby "%s" in routers' % standby )

    done_work = False

    for ( name, api ) in routers.items():
        vlans = api.path( 'interface', 'vlan' )
        ip_address = api.path( 'ip', 'address' )
        ipv6_address = api.path( 'ipv6', 'address' )

        spare_vlans = {}
        for vlan in vlans:
            if vlan[ 'vlan-id' ] == args.vlan:
                spare_vlans[ vlan[ 'name' ] ] = True

        for af in ( ip_address, ipv6_address ):
            for addr in af:
                ( sel, rval, hst ) = parse_comment( addr.get( 'comment', '' ) )
                if sel == args.hostname or hst == args.hostname:
                    if addr.get( 'disabled', False ):
                        if ( name in args.standby ) or ( name in args.new_home ):
                            address = _extract_bgp_announcement( addr[ 'address' ], addr.get( 'network', None ) )
                            rval = _adjust_filter( config, api, address, hst, selector = sel,
                                                   home = ( name in args.new_home ),
                                                   standby = ( name not in args.new_home ) and ( name in args.standby ),
                                                   static = args.static,
                                                   rval = rval,
                                                   )
                            new_comment = make_comment( sel, rval, hst )
                            af.update( **{ '.id': addr[ '.id' ],
                                           'disabled': False,
                                           'comment': new_comment,
                                           } )
                            done_work = True
                    else:
                        if ( name in args.new_home ):
                            address = _extract_bgp_announcement( addr[ 'address' ], addr.get( 'network', None ) )
                            rval = _adjust_filter( config, api, address, hst, selector = sel,
                                                   home = ( name in args.new_home ),
                                                   standby = False,
                                                   static = args.static,
                                                   rval = rval,
                                                   )
                            new_comment = make_comment( sel, rval, hst )
                            af.update( **{ '.id': addr[ '.id' ],
                                           'disabled': False,
                                           'comment': new_comment,
                                           } )
                            done_work = True

                    spare_vlans.pop( addr[ 'interface' ], None )

        for vlan in spare_vlans:
            spare.append( ( name, ip_address, ipv6_address, vlan ) )

    if args.create:
        for ( name, ip_address, ipv6_address, vlan ) in spare:
            rval = {}
            disabled = 'yes'
            if name in args.new_home:
                rval[ 'home' ] = True
                disabled = 'no'
            elif name in args.standby:
                disabled = 'no'
            new_comment = make_comment( args.selector, rval, args.hostname )
            for addr in args.create:
                rval = _adjust_filter( config, api, addr.network, args.hostname, selector = args.selector,
                                       home = ( name in args.new_home ),
                                       standby = ( name not in args.new_home ) and ( name in args.standby ),
                                       static = args.static,
                                       rval = rval,
                                       )
                if isinstance( addr, ipnetwork.IPv4Interface ):
                    print( "creating address on interface" )
                    v4addr = { 'interface': vlan,
                               'disabled': disabled,
                               'comment': new_comment,
                               }
                    if addr.network.prefixlen == 32:
                        v4addr[ 'address' ] = config[ 'default_ipv4_loopback' ]
                        v4addr[ 'network' ] = str( addr.network.network_address )
                    else:
                        v4addr[ 'address' ] = str( addr )
                    ip_address.create( **v4addr )
                    done_work = True
                elif isinstance( addr, ipnetwork.IPv6Interface ):
                    print( "creating address on interface" )
                    v6addr = { 'interface': vlan,
                               'disabled': disabled,
                               'comment': comment,
                               }
                    if args.static:
                        v6addr[ 'address' ] = str( addr )
                    else:
                        v6addr[ 'address' ] = str( addr.network )
                        v6addr[ 'eui-64' ] = 'yes'
                        v6addr[ 'advertise' ] = 'yes'
                    ipv6_address.create( **v6addr )
                    done_work = True
    return done_work

def monty_demote( config, args, routers ):
    for disable in args.disable:
        if disable not in routers:
            raise ValueError( 'cannot find disable "%s" in routers' % disable )
    for standby in args.standby:
        if standby not in routers:
            raise ValueError( 'cannot find standby "%s" in routers' % standby )

    done_work = False

    for ( name, api ) in routers.items():
        vlans = api.path( 'interface', 'vlan' )
        ip_address = api.path( 'ip', 'address' )
        ipv6_address = api.path( 'ipv6', 'address' )

        for af in ( ip_address, ipv6_address ):
            for addr in af:
                ( sel, rval, hst ) = parse_comment( addr.get( 'comment', '' ) )
                if sel == args.hostname or hst == args.hostname:
                    if ( name in args.standby ) or ( name in args.disable ):
                        address = _extract_bgp_announcement( addr[ 'address' ], addr.get( 'network', None ) )
                        rval = _adjust_filter( config, api, address, hst, selector = sel,
                                               home = False,
                                               standby = ( name in args.standby ),
                                               rval = rval,
                                               )
                        new_comment = make_comment( sel, rval, hst )
                        af.update( **{ '.id': addr[ '.id' ],
                                       'disabled': ( name in args.disable ),
                                       'comment': new_comment,
                                       } )
                        done_work = True

def monty_migrate( config, args, routers ):
    if monty_promote( config, args, routers ):
        monty_demote( config, args, routers )

def load_configuration():
    try:
        config = open( os.path.expanduser( '~/.automonty.yaml' ), 'r' )
    except IOError:
        return {}
    return yaml.load( config.read(), yaml.SafeLoader )

def main():
    config = load_configuration()

    parser = argparse.ArgumentParser( prog = "automonty",
                                      description = 'AutoMonty (re-)configures routers',
                                      )
    subparsers = parser.add_subparsers()

    parser.add_argument( '--only-router', action = 'append', default = [] )
    parser.add_argument( '--only-group', action = 'append', default = [] )
    parser.add_argument( '-n', '--dry-run', action = 'store_true', default = False )

    parser_check = subparsers.add_parser( 'check' )
    parser_check.add_argument( 'addr', nargs = "*" )
    parser_check.set_defaults( func = monty_check )

    parser_fixup = subparsers.add_parser( 'fixup' )
    parser_fixup.set_defaults( func = monty_fixup )

    parser_provision = subparsers.add_parser( 'provision' )
    parser_provision.add_argument( '--home', action = 'append', default = [] )
    parser_provision.add_argument( '--standby', action = 'append', default = [] )
    parser_provision.add_argument( '-s', '--static', action = 'store_true', default = False )
    parser_provision.add_argument( '--selector', type = str, default = None )
    parser_provision.add_argument( 'hostname' )
    parser_provision.add_argument( 'vlan', type = int )
    parser_provision.add_argument( 'address', type = ipaddress.ip_interface, nargs = "+" )
    parser_provision.set_defaults( func = monty_provision )

    parser_promote = subparsers.add_parser( 'promote' )
    parser_promote.add_argument( '-e', '--enable', action = 'store_true', default = False )
    parser_promote.add_argument( '-c', '--create', type = ipaddress.ip_interface, default = [], action = 'append' )
    parser_promote.add_argument( '-s', '--static', action = 'store_true', default = False )
    parser_promote.add_argument( '--standby', action = 'append', default = [] )
    parser_promote.add_argument( '--selector', type = str, default = None )
    parser_promote.add_argument( 'hostname' )
    parser_promote.add_argument( 'vlan', type = int )
    parser_promote.add_argument( 'new_home', nargs = "*" )
    parser_promote.set_defaults( func = monty_promote )

    parser_demote = subparsers.add_parser( 'demote' )
    parser_demote.add_argument( '--standby', action = 'append', default = [] )
    parser_demote.add_argument( 'hostname' )
    parser_demote.add_argument( 'vlan', type = int )
    parser_demote.add_argument( 'disable', nargs = "*" )
    parser_demote.set_defaults( func = monty_demote )

    parser_migrate = subparsers.add_parser( 'migrate' )
    parser_migrate.add_argument( '-e', '--enable', action = 'store_true', default = False )
    parser_migrate.add_argument( '-c', '--create', type = ipaddress.ip_interface, default = [], action = 'append' )
    parser_migrate.add_argument( '-s', '--static', action = 'store_true', default = False )
    parser_migrate.add_argument( '--selector', type = str, default = None )
    parser_migrate.add_argument( '--standby', action = 'append', default = [] )
    parser_migrate.add_argument( '--disable', action = 'append', default = [] )
    parser_migrate.add_argument( 'hostname' )
    parser_migrate.add_argument( 'vlan', type = int )
    parser_migrate.add_argument( 'new_home', nargs = "*" )
    parser_migrate.set_defaults( func = monty_migrate )

    parser_teardown = subparsers.add_parser( 'teardown' )
    parser_teardown.add_argument( '--delete', action = 'store_true', default = False )
    parser_teardown.add_argument( 'hostname' )
    parser_teardown.add_argument( 'vlan', type = int, default = None, nargs = "?" )
    parser_teardown.set_defaults( func = monty_teardown )

    args = parser.parse_args()
    routers = connect_routers( config, args )
    args.func( config, args, routers )

if __name__ == '__main__':
    main()