"""A simple engine that talks to a controller over 0MQ.
it handles registration, etc. and launches a kernel
connected to the Controller's Schedulers.
"""

# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.

from __future__ import print_function

import sys
import time
from getpass import getpass

import zmq
from zmq.eventloop import ioloop, zmqstream

from IPython.utils.localinterfaces import localhost
from IPython.utils.traitlets import (
    Instance, Dict, Integer, Type, Float, Unicode, CBytes, Bool
)
from IPython.utils.py3compat import cast_bytes

from ipython_parallel.controller.heartmonitor import Heart
from ipython_parallel.factory import RegistrationFactory
from ipython_parallel.util import disambiguate_url

from IPython.kernel.zmq.ipkernel import IPythonKernel as Kernel
from IPython.kernel.zmq.kernelapp import IPKernelApp

class EngineFactory(RegistrationFactory):
    """IPython engine"""

    # configurables:
    out_stream_factory=Type('IPython.kernel.zmq.iostream.OutStream', config=True,
        help="""The OutStream for handling stdout/err.
        Typically 'IPython.kernel.zmq.iostream.OutStream'""")
    display_hook_factory=Type('IPython.kernel.zmq.displayhook.ZMQDisplayHook', config=True,
        help="""The class for handling displayhook.
        Typically 'IPython.kernel.zmq.displayhook.ZMQDisplayHook'""")
    location=Unicode(config=True,
        help="""The location (an IP address) of the controller.  This is
        used for disambiguating URLs, to determine whether
        loopback should be used to connect or the public address.""")
    timeout=Float(5.0, config=True,
        help="""The time (in seconds) to wait for the Controller to respond
        to registration requests before giving up.""")
    max_heartbeat_misses=Integer(50, config=True,
        help="""The maximum number of times a check for the heartbeat ping of a 
        controller can be missed before shutting down the engine.
        
        If set to 0, the check is disabled.""")
    sshserver=Unicode(config=True,
        help="""The SSH server to use for tunneling connections to the Controller.""")
    sshkey=Unicode(config=True,
        help="""The SSH private key file to use when tunneling connections to the Controller.""")
    paramiko=Bool(sys.platform == 'win32', config=True,
        help="""Whether to use paramiko instead of openssh for tunnels.""")
    
    @property
    def tunnel_mod(self):
        from zmq.ssh import tunnel
        return tunnel


    # not configurable:
    connection_info = Dict()
    user_ns = Dict()
    id = Integer(allow_none=True)
    registrar = Instance('zmq.eventloop.zmqstream.ZMQStream', allow_none=True)
    kernel = Instance(Kernel, allow_none=True)
    hb_check_period=Integer()
    
    # States for the heartbeat monitoring
    # Initial values for monitored and pinged must satisfy "monitored > pinged == False" so that 
    # during the first check no "missed" ping is reported. Must be floats for Python 3 compatibility.
    _hb_last_pinged = 0.0
    _hb_last_monitored = 0.0
    _hb_missed_beats = 0
    # The zmq Stream which receives the pings from the Heart
    _hb_listener = None

    bident = CBytes()
    ident = Unicode()
    def _ident_changed(self, name, old, new):
        self.bident = cast_bytes(new)
    using_ssh=Bool(False)


    def __init__(self, **kwargs):
        super(EngineFactory, self).__init__(**kwargs)
        self.ident = self.session.session

    def init_connector(self):
        """construct connection function, which handles tunnels."""
        self.using_ssh = bool(self.sshkey or self.sshserver)

        if self.sshkey and not self.sshserver:
            # We are using ssh directly to the controller, tunneling localhost to localhost
            self.sshserver = self.url.split('://')[1].split(':')[0]

        if self.using_ssh:
            if self.tunnel_mod.try_passwordless_ssh(self.sshserver, self.sshkey, self.paramiko):
                password=False
            else:
                password = getpass("SSH Password for %s: "%self.sshserver)
        else:
            password = False

        def connect(s, url):
            url = disambiguate_url(url, self.location)
            if self.using_ssh:
                self.log.debug("Tunneling connection to %s via %s", url, self.sshserver)
                return self.tunnel_mod.tunnel_connection(s, url, self.sshserver,
                            keyfile=self.sshkey, paramiko=self.paramiko,
                            password=password,
                )
            else:
                return s.connect(url)

        def maybe_tunnel(url):
            """like connect, but don't complete the connection (for use by heartbeat)"""
            url = disambiguate_url(url, self.location)
            if self.using_ssh:
                self.log.debug("Tunneling connection to %s via %s", url, self.sshserver)
                url, tunnelobj = self.tunnel_mod.open_tunnel(url, self.sshserver,
                            keyfile=self.sshkey, paramiko=self.paramiko,
                            password=password,
                )
            return str(url)
        return connect, maybe_tunnel

    def register(self):
        """send the registration_request"""

        self.log.info("Registering with controller at %s"%self.url)
        ctx = self.context
        connect,maybe_tunnel = self.init_connector()
        reg = ctx.socket(zmq.DEALER)
        reg.setsockopt(zmq.IDENTITY, self.bident)
        connect(reg, self.url)
        self.registrar = zmqstream.ZMQStream(reg, self.loop)


        content = dict(uuid=self.ident)
        self.registrar.on_recv(lambda msg: self.complete_registration(msg, connect, maybe_tunnel))
        # print (self.session.key)
        self.session.send(self.registrar, "registration_request", content=content)

    def _report_ping(self, msg):
        """Callback for when the heartmonitor.Heart receives a ping"""
        #self.log.debug("Received a ping: %s", msg)
        self._hb_last_pinged = time.time()

    def complete_registration(self, msg, connect, maybe_tunnel):
        # print msg
        self.loop.remove_timeout(self._abort_timeout)
        ctx = self.context
        loop = self.loop
        identity = self.bident
        idents,msg = self.session.feed_identities(msg)
        msg = self.session.deserialize(msg)
        content = msg['content']
        info = self.connection_info
        
        def url(key):
            """get zmq url for given channel"""
            return str(info["interface"] + ":%i" % info[key])
        
        if content['status'] == 'ok':
            self.id = int(content['id'])

            # launch heartbeat
            # possibly forward hb ports with tunnels
            hb_ping = maybe_tunnel(url('hb_ping'))
            hb_pong = maybe_tunnel(url('hb_pong'))
            
            hb_monitor = None
            if self.max_heartbeat_misses > 0:
                # Add a monitor socket which will record the last time a ping was seen
                mon = self.context.socket(zmq.SUB)
                mport = mon.bind_to_random_port('tcp://%s' % localhost())
                mon.setsockopt(zmq.SUBSCRIBE, b"")
                self._hb_listener = zmqstream.ZMQStream(mon, self.loop)
                self._hb_listener.on_recv(self._report_ping)
            
            
                hb_monitor = "tcp://%s:%i" % (localhost(), mport)

            heart = Heart(hb_ping, hb_pong, hb_monitor , heart_id=identity)
            heart.start()

            # create Shell Connections (MUX, Task, etc.):
            shell_addrs = url('mux'), url('task')

            # Use only one shell stream for mux and tasks
            stream = zmqstream.ZMQStream(ctx.socket(zmq.ROUTER), loop)
            stream.setsockopt(zmq.IDENTITY, identity)
            shell_streams = [stream]
            for addr in shell_addrs:
                connect(stream, addr)

            # control stream:
            control_addr = url('control')
            control_stream = zmqstream.ZMQStream(ctx.socket(zmq.ROUTER), loop)
            control_stream.setsockopt(zmq.IDENTITY, identity)
            connect(control_stream, control_addr)

            # create iopub stream:
            iopub_addr = url('iopub')
            iopub_socket = ctx.socket(zmq.PUB)
            iopub_socket.setsockopt(zmq.IDENTITY, identity)
            connect(iopub_socket, iopub_addr)

            # disable history:
            self.config.HistoryManager.hist_file = ':memory:'
            
            # Redirect input streams and set a display hook.
            if self.out_stream_factory:
                sys.stdout = self.out_stream_factory(self.session, iopub_socket, u'stdout')
                sys.stdout.topic = cast_bytes('engine.%i.stdout' % self.id)
                sys.stderr = self.out_stream_factory(self.session, iopub_socket, u'stderr')
                sys.stderr.topic = cast_bytes('engine.%i.stderr' % self.id)
            if self.display_hook_factory:
                sys.displayhook = self.display_hook_factory(self.session, iopub_socket)
                sys.displayhook.topic = cast_bytes('engine.%i.execute_result' % self.id)

            self.kernel = Kernel(parent=self, int_id=self.id, ident=self.ident, session=self.session,
                    control_stream=control_stream, shell_streams=shell_streams, iopub_socket=iopub_socket,
                    loop=loop, user_ns=self.user_ns, log=self.log)
            
            self.kernel.shell.display_pub.topic = cast_bytes('engine.%i.displaypub' % self.id)
            
                
            # periodically check the heartbeat pings of the controller
            # Should be started here and not in "start()" so that the right period can be taken 
            # from the hubs HeartBeatMonitor.period
            if self.max_heartbeat_misses > 0:
                # Use a slightly bigger check period than the hub signal period to not warn unnecessary 
                self.hb_check_period = int(content['hb_period'])+10
                self.log.info("Starting to monitor the heartbeat signal from the hub every %i ms." , self.hb_check_period)
                self._hb_reporter = ioloop.PeriodicCallback(self._hb_monitor, self.hb_check_period, self.loop)
                self._hb_reporter.start()
            else:
                self.log.info("Monitoring of the heartbeat signal from the hub is not enabled.")

            
            # FIXME: This is a hack until IPKernelApp and IPEngineApp can be fully merged
            app = IPKernelApp(parent=self, shell=self.kernel.shell, kernel=self.kernel, log=self.log)
            app.init_profile_dir()
            app.init_code()
            
            self.kernel.start()
        else:
            self.log.fatal("Registration Failed: %s"%msg)
            raise Exception("Registration Failed: %s"%msg)

        self.log.info("Completed registration with id %i"%self.id)


    def abort(self):
        self.log.fatal("Registration timed out after %.1f seconds"%self.timeout)
        if self.url.startswith('127.'):
            self.log.fatal("""
            If the controller and engines are not on the same machine,
            you will have to instruct the controller to listen on an external IP (in ipcontroller_config.py):
                c.HubFactory.ip='*' # for all interfaces, internal and external
                c.HubFactory.ip='192.168.1.101' # or any interface that the engines can see
            or tunnel connections via ssh.
            """)
        self.session.send(self.registrar, "unregistration_request", content=dict(id=self.id))
        time.sleep(1)
        sys.exit(255)

    def _hb_monitor(self):
        """Callback to monitor the heartbeat from the controller"""
        self._hb_listener.flush()
        if self._hb_last_monitored > self._hb_last_pinged:
            self._hb_missed_beats += 1
            self.log.warn("No heartbeat in the last %s ms (%s time(s) in a row).", self.hb_check_period, self._hb_missed_beats)
        else:
            #self.log.debug("Heartbeat received (after missing %s beats).", self._hb_missed_beats)
            self._hb_missed_beats = 0

        if self._hb_missed_beats >= self.max_heartbeat_misses:
            self.log.fatal("Maximum number of heartbeats misses reached (%s times %s ms), shutting down.",
                           self.max_heartbeat_misses, self.hb_check_period)
            self.session.send(self.registrar, "unregistration_request", content=dict(id=self.id))
            self.loop.stop()

        self._hb_last_monitored = time.time()
            
        
    def start(self):
        loop = self.loop
        def _start():
            self.register()
            self._abort_timeout = loop.add_timeout(loop.time() + self.timeout, self.abort)
        self.loop.add_callback(_start)