#!@PYTHON@

# Copyright (C) 2010, 2011  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 os
import signal
import select
from time import time, strftime, gmtime
from optparse import OptionParser, OptionValueError
from collections import defaultdict
from isc.config.ccsession import ModuleCCSession, create_answer
from isc.cc import Session, SessionError

# for setproctitle
import isc.util.process
isc.util.process.rename()

# If B10_FROM_SOURCE is set in the environment, we use data files
# from a directory relative to that, otherwise we use the ones
# installed on the system
if "B10_FROM_SOURCE" in os.environ:
    BASE_LOCATION = os.environ["B10_FROM_SOURCE"] + os.sep + \
        "src" + os.sep + "bin" + os.sep + "stats"
else:
    PREFIX = "@prefix@"
    DATAROOTDIR = "@datarootdir@"
    BASE_LOCATION = "@datadir@" + os.sep + "@PACKAGE@"
    BASE_LOCATION = BASE_LOCATION.replace("${datarootdir}", DATAROOTDIR).replace("${prefix}", PREFIX)
SPECFILE_LOCATION = BASE_LOCATION + os.sep + "stats.spec"
SCHEMA_SPECFILE_LOCATION = BASE_LOCATION + os.sep + "stats-schema.spec"

class Singleton(type):
    """
    A abstract class of singleton pattern
    """
    # Because of singleton pattern: 
    #   At the beginning of coding, one UNIX domain socket is needed
    #  for config manager, another socket is needed for stats module,
    #  then stats module might need two sockets. So I adopted the
    #  singleton pattern because I avoid creating multiple sockets in
    #  one stats module. But in the initial version stats module
    #  reports only via bindctl, so just one socket is needed. To use
    #  the singleton pattern is not important now. :(

    def __init__(self, *args, **kwargs):
        type.__init__(self, *args, **kwargs)
        self._instances = {}

    def __call__(self, *args, **kwargs):
        if args not in self._instances:
            self._instances[args]={}
        kw = tuple(kwargs.items())
        if  kw not in self._instances[args]:
            self._instances[args][kw] = type.__call__(self, *args, **kwargs)
        return self._instances[args][kw]

class Callback():
    """
    A Callback handler class
    """
    def __init__(self, name=None, callback=None, args=(), kwargs={}):
        self.name = name
        self.callback = callback
        self.args = args
        self.kwargs = kwargs

    def __call__(self, *args, **kwargs):
        if not args:
            args = self.args
        if not kwargs:
            kwargs = self.kwargs
        if self.callback:
            return self.callback(*args, **kwargs)

class Subject():
    """
    A abstract subject class of observer pattern
    """
    # Because of observer pattern:
    #   In the initial release, I'm also sure that observer pattern
    #  isn't definitely needed because the interface between gathering
    #  and reporting statistics data is single.  However in the future
    #  release, the interfaces may be multiple, that is, multiple
    #  listeners may be needed. For example, one interface, which
    #  stats module has, is for between ''config manager'' and stats
    #  module, another interface is for between ''HTTP server'' and
    #  stats module, and one more interface is for between ''SNMP
    #  server'' and stats module. So by considering that stats module
    #  needs multiple interfaces in the future release, I adopted the
    #  observer pattern in stats module. But I don't have concrete
    #  ideas in case of multiple listener currently.

    def __init__(self):
        self._listeners = []

    def attach(self, listener):
        if not listener in self._listeners:
            self._listeners.append(listener)

    def detach(self, listener):
        try:
            self._listeners.remove(listener)
        except ValueError:
            pass

    def notify(self, event, modifier=None):
        for listener in self._listeners:
            if modifier != listener:
                listener.update(event)

class Listener():
    """
    A abstract listener class of observer pattern
    """
    def __init__(self, subject):
        self.subject = subject
        self.subject.attach(self)
        self.events = {}

    def update(self, name):
        if name in self.events:
            callback = self.events[name]
            return callback()

    def add_event(self, event):
        self.events[event.name]=event

class SessionSubject(Subject, metaclass=Singleton):
    """
    A concrete subject class which creates CC session object
    """
    def __init__(self, session=None, verbose=False):
        Subject.__init__(self)
        self.verbose = verbose
        self.session=session
        self.running = False

    def start(self):
        self.running = True
        self.notify('start')

    def stop(self):
        self.running = False
        self.notify('stop')

    def check(self):
        self.notify('check')

class CCSessionListener(Listener):
    """
    A concrete listener class which creates SessionSubject object and
    ModuleCCSession object
    """
    def __init__(self, subject, verbose=False):
        Listener.__init__(self, subject)
        self.verbose = verbose
        self.session = subject.session
        self.boot_time = get_datetime()

        # create ModuleCCSession object
        self.cc_session = ModuleCCSession(SPECFILE_LOCATION,
                                          self.config_handler,
                                          self.command_handler,
                                          self.session)

        self.session = self.subject.session = self.cc_session._session

        # initialize internal data
        self.stats_spec = isc.config.module_spec_from_file(SCHEMA_SPECFILE_LOCATION).get_config_spec()
        self.stats_data = self.initialize_data(self.stats_spec)

        # add event handler invoked via SessionSubject object
        self.add_event(Callback('start', self.start))
        self.add_event(Callback('stop', self.stop))
        self.add_event(Callback('check', self.check))
        # don't add 'command_' suffix to the special commands in
        # order to prevent executing internal command via bindctl

        # get commands spec
        self.commands_spec = self.cc_session.get_module_spec().get_commands_spec()

        # add event handler related command_handler of ModuleCCSession
        # invoked via bindctl
        for cmd in self.commands_spec:
            try:
                # add prefix "command_"
                name = "command_" + cmd["command_name"]
                callback = getattr(self, name)
                kwargs = self.initialize_data(cmd["command_args"])
                self.add_event(Callback(name=name, callback=callback, args=(), kwargs=kwargs))
            except AttributeError as ae:
                sys.stderr.write("[b10-stats] Caught undefined command while parsing spec file: "
                                 +str(cmd["command_name"])+"\n")

    def start(self):
        """
        start the cc chanel
        """
        # set initial value
        self.stats_data['stats.boot_time'] = self.boot_time
        self.stats_data['stats.start_time'] = get_datetime()
        self.stats_data['stats.last_update_time'] = get_datetime()
        self.stats_data['stats.lname'] = self.session.lname
        self.cc_session.start()
        # request Bob to send statistics data
        if self.verbose:
            sys.stdout.write("[b10-stats] request Bob to send statistics data\n")
        cmd = isc.config.ccsession.create_command("sendstats", None)
        seq = self.session.group_sendmsg(cmd, 'Boss')
        self.session.group_recvmsg(True, seq)

    def stop(self):
        """
        stop the cc chanel
        """
        return self.cc_session.close()

    def check(self):
        """
        check the cc chanel
        """
        return self.cc_session.check_command(False)

    def config_handler(self, new_config):
        """
        handle a configure from the cc channel
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] newconfig received: "+str(new_config)+"\n")

        # do nothing currently
        return create_answer(0)

    def command_handler(self, command, *args, **kwargs):
        """
        handle commands from the cc channel
        """
        # add 'command_' suffix in order to executing command via bindctl
        name = 'command_' + command
        
        if name in self.events:
            event = self.events[name]
            return event(*args, **kwargs)
        else:
            return self.command_unknown(command, args)

    def command_shutdown(self, args):
        """
        handle shutdown command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] 'shutdown' command received\n")
        self.subject.running = False
        return create_answer(0)

    def command_set(self, args, stats_data={}):
        """
        handle set command
        """
        # 'args' must be dictionary type
        self.stats_data.update(args['stats_data'])

        # overwrite "stats.LastUpdateTime"
        self.stats_data['stats.last_update_time'] = get_datetime()

        return create_answer(0)

    def command_remove(self, args, stats_item_name=''):
        """
        handle remove command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] 'remove' command received, args: "+str(args)+"\n")

        # 'args' must be dictionary type
        if args and args['stats_item_name'] in self.stats_data:
            stats_item_name = args['stats_item_name']

        # just remove one item
        self.stats_data.pop(stats_item_name)

        return create_answer(0)

    def command_show(self, args, stats_item_name=''):
        """
        handle show command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] 'show' command received, args: "+str(args)+"\n")

        # always overwrite 'report_time' and 'stats.timestamp'
        # if "show" command invoked
        self.stats_data['report_time'] = get_datetime()
        self.stats_data['stats.timestamp'] = get_timestamp()

        # if with args
        if args and args['stats_item_name'] in self.stats_data:
            stats_item_name = args['stats_item_name']
            return create_answer(0, {stats_item_name: self.stats_data[stats_item_name]})

        return create_answer(0, self.stats_data)

    def command_reset(self, args):
        """
        handle reset command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] 'reset' command received\n")

        # re-initialize internal variables
        self.stats_data = self.initialize_data(self.stats_spec)

        # reset initial value
        self.stats_data['stats.boot_time'] = self.boot_time
        self.stats_data['stats.start_time'] = get_datetime()
        self.stats_data['stats.last_update_time'] = get_datetime()
        self.stats_data['stats.lname'] = self.session.lname

        return create_answer(0)

    def command_status(self, args):
        """
        handle status command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] 'status' command received\n")
        # just return "I'm alive."
        return create_answer(0, "I'm alive.")

    def command_unknown(self, command, args):
        """
        handle an unknown command
        """
        if self.verbose:
            sys.stdout.write("[b10-stats] Unknown command received: '"
                             + str(command) + "'\n")
        return create_answer(1, "Unknown command: '"+str(command)+"'")


    def initialize_data(self, spec):
        """
        initialize stats data
        """
        def __get_init_val(spec):
            if spec['item_type'] == 'null':
                return None
            elif spec['item_type'] == 'boolean':
                return bool(spec.get('item_default', False))
            elif spec['item_type'] == 'string':
                return str(spec.get('item_default', ''))
            elif spec['item_type'] in set(['number', 'integer']):
                return int(spec.get('item_default', 0))
            elif spec['item_type'] in set(['float', 'double', 'real']):
                return float(spec.get('item_default', 0.0))
            elif spec['item_type'] in set(['list', 'array']):
                return spec.get('item_default',
                                [ __get_init_val(s) for s in spec['list_item_spec'] ])
            elif spec['item_type'] in set(['map', 'object']):
                return spec.get('item_default',
                                dict([ (s['item_name'], __get_init_val(s)) for s in spec['map_item_spec'] ]) )
            else:
                return spec.get('item_default')
        return dict([ (s['item_name'], __get_init_val(s)) for s in spec ])

def get_timestamp():
    """
    get current timestamp
    """
    return time()

def get_datetime():
    """
    get current datetime
    """
    return strftime("%Y-%m-%dT%H:%M:%SZ", gmtime())

def main(session=None):
    try:
        parser = OptionParser()
        parser.add_option("-v", "--verbose", dest="verbose", action="store_true",
                      help="display more about what is going on")
        (options, args) = parser.parse_args()
        subject = SessionSubject(session=session, verbose=options.verbose)
        listener = CCSessionListener(subject, verbose=options.verbose)
        subject.start()
        while subject.running:
            subject.check()
        subject.stop()

    except OptionValueError:
        sys.stderr.write("[b10-stats] Error parsing options\n")
    except SessionError as se:
        sys.stderr.write("[b10-stats] Error creating Stats module, "
              + "is the command channel daemon running?\n")
    except KeyboardInterrupt as kie:
        sys.stderr.write("[b10-stats] Interrupted, exiting\n")

if __name__ == "__main__":
    main()