#!@PYTHON@

# Copyright (C) 2010  Internet Systems Consortium.
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SYSTEMS CONSORTIUM
# DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# INTERNET SYSTEMS CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
# FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
# WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


import sys; sys.path.append ('@@PYTHONPATH@@')
import isc
import bind10_config
from isc.dns import *
from isc.config.ccsession import *
from isc.cc import SessionError, SessionTimeout
import isc.util.process

from isc.log_messages.ddns_messages import *

from optparse import OptionParser, OptionValueError
import os
import signal
import threading

isc.log.init("b10-ddns")
logger = isc.log.Logger("ddns")

DATA_PATH = bind10_config.DATA_PATH
if "B10_FROM_BUILD" in os.environ:
    DATA_PATH = DATA_PATH + "/src/bin/ddns"
SPECFILE_LOCATION = DATA_PATH + "/ddns.spec"


isc.util.process.rename()

class DDNSConfigError(Exception):
    """An exception indicating an error in updating ddns configuration.

    This exception is raised when the ddns process encouters an error in
    handling configuration updates.  Not all syntax error can be caught
    at the module-CC layer, so ddns needs to (explicitly or implicitly)
    validate the given configuration data itself.  When it finds an error
    it raises this exception (either directly or by converting an exception
    from other modules) as a unified error in configuration.
    """
    pass

class DDNSSessionError(Exception):
    '''An exception raised for some unexpected events during an ddns session.
    '''
    pass

class DDNSSession:
    """Class to handle one DDNS update"""

    def __init__(self):
        self._handle()

    def _handle(self):
        '''
        Handle a DDNS update.
        This should be called from the initializer, and should contain the
        logic for doing the checks, handling the update, and responding with
        the result.
        '''
        pass

class DDNSServer:
    def __init__(self):
        self._cc = isc.config.ModuleCCSession(SPECFILE_LOCATION,
                                              self.config_handler,
                                              self.command_handler)
        self._config_data = self._cc.get_full_config()
        self._cc.start()
        self._shutdown_event = threading.Event()

    def config_handler(self, new_config):
        '''Update config data.'''
        answer = create_answer(0)
        return answer

    def command_handler(self, cmd, args):
        if cmd == "shutdown":
            logger.info(DDNS_RECEIVED_SHUTDOWN_COMMAND)
            self.shutdown()
            answer = create_answer(0)
        else:
            answer = create_answer(1, "Unknown command:" + str(cmd))
        return answer

    def shutdown(self):
        self._shutdown_event.set()
        main_thread = threading.currentThread()
        for th in threading.enumerate():
            if th is main_thread:
                continue
            th.join()

    def run(self):
        '''Get and process all commands sent from cfgmgr or other modules. '''
        logger.info(DDNS_RUNNING)
        while not self._shutdown_event.is_set():
            self._cc.check_command(False)

ddns_server = None

def signal_handler(signal, frame):
    if ddns_server is not None:
        ddns_server.shutdown()
        sys.exit(0)

def set_signal_handler():
    signal.signal(signal.SIGTERM, signal_handler)
    signal.signal(signal.SIGINT, signal_handler)

def set_cmd_options(parser):
    parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
            help="display more about what is going on")

if '__main__' == __name__:
    try:
        parser = OptionParser()
        set_cmd_options(parser)
        (options, args) = parser.parse_args()
        VERBOSE_MODE = options.verbose

        set_signal_handler()
        ddns_server = DDNSServer()
        ddns_server.run()
    except KeyboardInterrupt:
        logger.INFO(DDNS_STOPPED_BY_KEYBOARD)
    except SessionError as e:
        logger.error(DDNS_CC_SESSION_ERROR, str(e))
    except ModuleCCSessionError as e:
        logger.error(DDNS_MODULECC_SESSION_ERROR, str(e))
    except DDNSConfigError as e:
        logger.error(DDNS_CONFIG_ERROR, str(e))
    except SessionTimeout as e:
        logger.error(DDNS_CC_SESSION_TIMEOUT_ERROR)

    if ddns_server:
        ddns_server.shutdown()