"""
Commonly used messaging components.

Contains the base class for all components.

"""

import os
import uuid
import time
import socket
import humanhash

import zipline.util as qutil
from zipline.protocol import CONTROL_PROTOCOL, COMPONENT_STATE

class Component(object):
    """
    Base class for components. Defines the the base messaging
    interface for components.

    :param addresses: a dict of name_string -> zmq port address strings.
                      Must have the following entries

    :param sync_address: socket address used for synchronizing the start of
                         all workers, heartbeating, and exit notification
                         will be used in REP/REQ sockets. Bind is always on
                         the REP side.

    :param data_address: socket address used for data sources to stream
                         their records. Will be used in PUSH/PULL sockets
                         between data sources and a ParallelBuffer (aka
                         the Feed). Bind will always be on the PULL side
                         (we always have N producers and 1 consumer)

    :param feed_address: socket address used to publish consolidated feed
                         from serialization of data sources
                         will be used in PUB/SUB sockets between Feed and
                         Transforms. Bind is always on the PUB side.

    :param merge_address: socket address used to publish transformed
                          values.  will be used in PUSH/PULL from many
                          transforms to one MergedParallelBuffer (aka the
                          Merge). Bind will always be on the PULL side (we
                          always have N producers and 1 consumer)

    :param result_address: socket address used to publish merged data
                           source feed and transforms to clients will be
                           used in PUB/SUB from one Merge to one or many
                           clients. Bind is always on the PUB side.

    bind/connect methods will return the correct socket type for each
    address.

    """

    def __init__(self):
        self.zmq               = None
        self.context           = None
        self.addresses         = None
        self.out_socket        = None
        self.gevent_needed     = False
        self.killed            = False
        self.controller        = None
        self.heartbeat_timeout = 2000
        self.state_flag        = COMPONENT_STATE.OK # OK | DONE | EXCEPTION
        self._exception        = None

        self.start_tic         = None
        self.stop_tic          = None

        # Humanhashes make this way easier to debug because they
        # stick in your mind unlike a 32 byte string of random hex.
        self.guid = uuid.uuid4()
        self.huid = humanhash.humanize(self.guid.hex)

        self.init()

    def init(self):
        """
        Subclasses should override this to extend the setup for
        the class. Shouldn't have side effects.
        """
        pass

    # ------------
    # Core Methods
    # ------------

    def open(self):
        """
        Open the connections needed to start doing work.
        """
        raise NotImplementedError

    def ready(self):
        """
        Return ``True`` if and only if the component has finished execution.
        """
        return self.state_flag in [COMPONENT_STATE.DONE, \
            COMPONENT_STATE.EXCEPTION]

    def successful(self):
        """
        Return ``True`` if and only if the component has finished execution
        successfully, that is, without raising an error.
        """
        return self.state_flag == COMPONENT_STATE.DONE and not \
            self.exception

    @property
    def exception(self):
        """
        Holds the exception that the component failed on, or
        ``None`` if the component has not failed.
        """
        return self._exception

    def do_work(self):
        raise NotImplementedError

    def _run(self):
        self.start_tick = time.clock()

        self.done       = False # TODO: use state flag
        self.sockets    = []

        if self.gevent_needed:
            qutil.LOGGER.info("Loading gevent specific zmq for {id}".format(id=self.get_id))
            import gevent_zeromq
            self.zmq = gevent_zeromq.zmq
        else:
            import zmq
            self.zmq = zmq

        # TODO: this can cause max fd errors on BSD machines with
        # low ulimits, its perfectly fine to use one Context in
        # multithreaded enviroments, its only in multiprocess
        # systems where this becomes needed. Add this option.
        # 
        # http://zeromq.github.com/pyzmq/morethanbindings.html#thread-safety
        self.context = self.zmq.Context()

        self.setup_poller()

        self.open()
        self.setup_sync()
        self.setup_control()
        self.loop()


        self.end_tick = time.clock()

        # shouldn't block if we've done our job correctly
        # self.context.term()

    def run(self, catch_exceptions=True):
        """
        Run the component.

        Optionally takes an argument to catch and log all exceptions raised
        during execution ues this with care since it makes it very hard to
        debug since it mucks up your stacktraces.
        """

        fail = None

        if catch_exceptions:
            try:
                self._run()
            except Exception as exc:
                # TODO, we want to do this grab the stack
                # frame so we can preserve stacktraces when we
                # reraise the exception.
                self.signal_exception(exc)
                fail = exc
            finally:

                self.shutdown()
                self.teardown_sockets()

                if self.context:
                    self.context.destroy()
                if fail:
                    raise fail
        else:
            try:
                self._run()
            finally:
                self.shutdown()
                self.teardown_sockets()


    def loop(self):
        """
        Loop to do work while we still have work to do.
        """
        while not self.done: # TODO: use state flag
            self.confirm()
            self.do_work()

    def confirm(self):
        """
        Send a synchronization request to the host.
        """

        # TODO: proper framing
        self.sync_socket.send(self.get_id + ":RUN")

        self.receive_sync_ack() # blocking

    def runtime(self):
        if self.ready():
            return self.stop_tic - self.start_tic

    # ----------------------------
    #  Cleanup & Modes of Failure
    # ----------------------------

    def teardown_sockets(self):
        """
        Close all zmq sockets safely. This is universal, no matter
        where this is running it will need the sockets closed.
        """
        #close all the sockets
        for sock in self.sockets:
            sock.close()

    def shutdown(self):
        """
        Clean shutdown.

        Tear down after normal operation.
        """
        pass

    def kill(self):
        """
        Unclean shutdown.

        Tear down ( fast ) as a mode of failure in the
        simulation or on service halt.

        Context specific.
        """
        raise NotImplementedError

    # ----------------------
    #  Internal Maintenance
    # ----------------------

    def signal_exception(self, exc=None):
        self.state_flag = COMPONENT_STATE.EXCEPTION
        self._exception = exc

        qutil.LOGGER.exception("Unexpected error in run for {id}.".format(id=self.get_id))

    def signal_done(self):
        """
        Notify down stream components that we're done.
        """

        self.state_flag = COMPONENT_STATE.DONE

        if self.out_socket:
            self.out_socket.send(str(CONTROL_PROTOCOL.DONE))

        #notify host we're done
        # TODO: proper framing
        self.sync_socket.send(self.get_id + ":" + str(CONTROL_PROTOCOL.DONE))

        self.receive_sync_ack()
        #notify internal work look that we're done
        self.done = True # TODO: use state flag

    # -----------
    #  Messaging
    # -----------

    def setup_poller(self):
        """
        Setup the poller used for multiplexing the incoming data
        handling sockets.
        """

        self.poll = self.zmq.Poller()

    def receive_sync_ack(self):
        """
        Wait for synchronization reply from the host.
        """

        socks = dict(self.sync_poller.poll(self.heartbeat_timeout))
        if self.sync_socket in socks and socks[self.sync_socket] == self.zmq.POLLIN:
            message = self.sync_socket.recv()
        else:
            raise Exception("Sync ack timed out on response for {id}".format(id=self.get_id))

    def bind_data(self):
        return self.bind_pull_socket(self.addresses['data_address'])

    def connect_data(self):
        return self.connect_push_socket(self.addresses['data_address'])

    def bind_feed(self):
        return self.bind_pub_socket(self.addresses['feed_address'])

    def connect_feed(self):
        return self.connect_sub_socket(self.addresses['feed_address'])

    def bind_merge(self):
        return self.bind_pull_socket(self.addresses['merge_address'])

    def connect_merge(self):
        return self.connect_push_socket(self.addresses['merge_address'])

    def bind_result(self):
        return self.bind_pub_socket(self.addresses['result_address'])

    def connect_result(self):
        return self.connect_sub_socket(self.addresses['result_address'])

    def bind_pull_socket(self, addr):
        pull_socket = self.context.socket(self.zmq.PULL)
        pull_socket.bind(addr)
        self.poll.register(pull_socket, self.zmq.POLLIN)

        self.sockets.append(pull_socket)

        return pull_socket

    def connect_push_socket(self, addr):
        push_socket = self.context.socket(self.zmq.PUSH)
        push_socket.connect(addr)
        #push_socket.setsockopt(self.zmq.LINGER,0)
        self.sockets.append(push_socket)
        self.out_socket = push_socket

        return push_socket

    def bind_pub_socket(self, addr):
        pub_socket = self.context.socket(self.zmq.PUB)
        pub_socket.bind(addr)
        #pub_socket.setsockopt(self.zmq.LINGER,0)
        self.out_socket = pub_socket

        return pub_socket

    def connect_sub_socket(self, addr):
        sub_socket = self.context.socket(self.zmq.SUB)
        sub_socket.connect(addr)
        sub_socket.setsockopt(self.zmq.SUBSCRIBE,'')
        self.sockets.append(sub_socket)

        self.poll.register(sub_socket, self.zmq.POLLIN)

        return sub_socket

    def setup_control(self):
        """
        Set up the control socket. Used to monitor the
        overall status of the simulation and to forcefully tear
        down the simulation in case of a failure.
        """
        assert self.controller

        self.control_out = self.controller.message_sender(context=self.context)
        self.control_in = self.controller.message_listener(context=self.context)

        self.poll.register(self.control_in, self.zmq.POLLIN)
        self.sockets.extend([self.control_in, self.control_out])

    def setup_sync(self):
        """
        Setup the sync socket and poller. ( Connect )
        """

        qutil.LOGGER.debug("Connecting sync client for {id}".format(id=self.get_id))

        self.sync_socket = self.context.socket(self.zmq.REQ)
        self.sync_socket.connect(self.addresses['sync_address'])
        #self.sync_socket.setsockopt(self.zmq.LINGER,0)

        # Explictly a different poller for obvious reasons.
        # I'm not fond of having this poller init'd as a side
        # effect of a method call. Still thinking about where to
        # put it at the moment though...
        self.sync_poller = self.zmq.Poller()
        self.sync_poller.register(self.sync_socket, self.zmq.POLLIN)

        self.sockets.append(self.sync_socket)

    # ---------------------
    # Description and Debug
    # ---------------------

    def extern_logger(self):
        """
        Pipe logs out to a provided logging interface.
        """
        pass

    def setup_extern_logger(self):
        """
        Pipe logs out to a provided logging interface.
        """
        pass

    @property
    def get_id(self):
        """
        The descriptive name of the component.
        """
        return 'UNKNOWN COMPONENT'

    @property
    def get_type(self):
        """
        The data flow type of the component.

        - ``SOURCE``
        - ``CONDUIT``
        - ``SINK``

        """
        raise NotImplementedError

    @property
    def get_pure(self):
        """
        Describes whehter this component purely functional,
        i.e.  for a given set of inputs is it guaranteed to
        always give the same output . Components that are
        side-effectful are, generally, not pure.
        """
        return False

    def debug(self):
        """
        Debug information about the component.
        """
        return {
            'id'         : self.get_id          ,
            'huid'       : self.huid            ,
            'host'       : socket.gethostname() ,
            'pid'        : os.getpid()          ,
            'memaddress' : hex(id(self))        ,
            'ready'      : self.successful()    ,
            'succesfull' : self.ready()         ,
        }

    def __len__(self):
        """
        Some components overload this for debug purposes
        """
        raise NotImplementedError

    def __repr__(self):
        """
        Return a usefull string representation of the component
        to indicate its type, unique identifier, and computational
        context identifier name.
        """

        return "<{name} {uuid} at {host} {pid} {pointer}>".format(
            name    = self.get_id          ,
            uuid    = self.huid            ,
            host    = socket.gethostname() ,
            pid     = os.getpid()          ,
            pointer = hex(id(self))        ,
        )