class OpenVPNAlreadyRunning(Exception):
    message = ("Another openvpn instance is already running, and could "
               "not be stopped.")


class AlienOpenVPNAlreadyRunning(Exception):
    message = ("Another openvpn instance is already running, and could "
               "not be stopped because it was not launched by LEAP.")


class VPNManagement(object):
    """
    This is a mixin that we use in the VPNProcess class.
    Here we get together all methods related with the openvpn management
    interface.

    For more info about management methods::

      zcat `dpkg -L openvpn | grep management`
    """

    # Timers, in secs
    # NOTE: We need to set a bigger poll time in OSX because it seems
    # openvpn malfunctions when you ask it a lot of things in a short
    # amount of time.
    POLL_TIME = 2.5 if IS_MAC else 1.0
    CONNECTION_RETRY_TIME = 1

    def __init__(self, signaler=None):
        """
        Initializes the VPNManager.

        :param signaler: Signaler object used to send notifications to the
                         backend
        :type signaler: backend.Signaler
        """
        self._tn = None
        self._signaler = signaler
        self._aborted = False

    @property
    def aborted(self):
        return self._aborted

    @aborted.setter
    def aborted(self, value):
        self._aborted = value

    def _seek_to_eof(self):
        """
        Read as much as available. Position seek pointer to end of stream
        """
        try:
            self._tn.read_eager()
        except EOFError:
            logger.debug("Could not read from socket. Assuming it died.")
            return

    def _send_command(self, command, until=b"END"):
        """
        Sends a command to the telnet connection and reads until END
        is reached.

        :param command: command to send
        :type command: str

        :param until: byte delimiter string for reading command output
        :type until: byte str

        :return: response read
        :rtype: list
        """
        # leap_assert(self._tn, "We need a tn connection!")

        try:
            self._tn.write("%s\n" % (command,))
            buf = self._tn.read_until(until, 2)
            self._seek_to_eof()
            blist = buf.split('\r\n')
            if blist[-1].startswith(until):
                del blist[-1]
                return blist
            else:
                return []

        except socket.error:
            # XXX should get a counter and repeat only
            # after mod X times.
            logger.warning('socket error (command was: "%s")' % (command,))
            self._close_management_socket(announce=False)
            logger.debug('trying to connect to management again')
            self.try_to_connect_to_management(max_retries=5)
            return []

        # XXX should move this to a errBack!
        except Exception as e:
            logger.warning("Error sending command %s: %r" %
                           (command, e))
        return []

    def _close_management_socket(self, announce=True):
        """
        Close connection to openvpn management interface.
        """
        logger.debug('closing socket')
        if announce:
            self._tn.write("quit\n")
            self._tn.read_all()
        self._tn.get_socket().close()
        self._tn = None

    def _connect_management(self, socket_host, socket_port):
        """
        Connects to the management interface on the specified
        socket_host socket_port.

        :param socket_host: either socket path (unix) or socket IP
        :type socket_host: str

        :param socket_port: either string "unix" if it's a unix
                            socket, or port otherwise
        :type socket_port: str
        """
        if self.is_connected():
            self._close_management_socket()

        try:
            self._tn = UDSTelnet(socket_host, socket_port)

            # XXX make password optional
            # specially for win. we should generate
            # the pass on the fly when invoking manager
            # from conductor

            # self.tn.read_until('ENTER PASSWORD:', 2)
            # self.tn.write(self.password + '\n')
            # self.tn.read_until('SUCCESS:', 2)
            if self._tn:
                self._tn.read_eager()

        # XXX move this to the Errback
        except Exception as e:
            logger.warning("Could not connect to OpenVPN yet: %r" % (e,))
            self._tn = None

    def _connectCb(self, *args):
        """
        Callback for connection.

        :param args: not used
        """
        if self._tn:
            logger.info('Connected to management')
        else:
            logger.debug('Cannot connect to management...')

    def _connectErr(self, failure):
        """
        Errorback for connection.

        :param failure: Failure
        """
        logger.warning(failure)

    def connect_to_management(self, host, port):
        """
        Connect to a management interface.

        :param host: the host of the management interface
        :type host: str

        :param port: the port of the management interface
        :type port: str

        :returns: a deferred
        """
        self.connectd = defer.maybeDeferred(
            self._connect_management, host, port)
        self.connectd.addCallbacks(self._connectCb, self._connectErr)
        return self.connectd

    def is_connected(self):
        """
        Returns the status of the management interface.

        :returns: True if connected, False otherwise
        :rtype: bool
        """
        return True if self._tn else False

    def try_to_connect_to_management(self, retry=0, max_retries=None):
        """
        Attempts to connect to a management interface, and retries
        after CONNECTION_RETRY_TIME if not successful.

        :param retry: number of the retry
        :type retry: int
        """
        if max_retries and retry > max_retries:
            logger.warning("Max retries reached while attempting to connect "
                           "to management. Aborting.")
            self.aborted = True
            return

        # _alive flag is set in the VPNProcess class.
        if not self._alive:
            logger.debug('Tried to connect to management but process is '
                         'not alive.')
            return
        logger.debug('trying to connect to management')
        if not self.aborted and not self.is_connected():
            self.connect_to_management(self._socket_host, self._socket_port)
            reactor.callLater(
                self.CONNECTION_RETRY_TIME,
                self.try_to_connect_to_management, retry + 1)

    def _parse_state_and_notify(self, output):
        """
        Parses the output of the state command and emits state_changed
        signal when the state changes.

        :param output: list of lines that the state command printed as
                       its output
        :type output: list
        """
        for line in output:
            stripped = line.strip()
            if stripped == "END":
                continue
            parts = stripped.split(",")
            if len(parts) < 5:
                continue
            ts, status_step, ok, ip, remote = parts

            state = status_step
            if state != self._last_state:
                if self._signaler is not None:
                    self._signaler.signal(self._signaler.eip_state_changed, state)
                self._last_state = state

    def _parse_status_and_notify(self, output):
        """
        Parses the output of the status command and emits
        status_changed signal when the status changes.

        :param output: list of lines that the status command printed
                       as its output
        :type output: list
        """
        tun_tap_read = ""
        tun_tap_write = ""

        for line in output:
            stripped = line.strip()
            if stripped.endswith("STATISTICS") or stripped == "END":
                continue
            parts = stripped.split(",")
            if len(parts) < 2:
                continue

            text, value = parts
            # text can be:
            #   "TUN/TAP read bytes"
            #   "TUN/TAP write bytes"
            #   "TCP/UDP read bytes"
            #   "TCP/UDP write bytes"
            #   "Auth read bytes"

            if text == "TUN/TAP read bytes":
                tun_tap_read = value  # download
            elif text == "TUN/TAP write bytes":
                tun_tap_write = value  # upload

        status = (tun_tap_read, tun_tap_write)
        if status != self._last_status:
            if self._signaler is not None:
                self._signaler.signal(self._signaler.eip_status_changed, status)
            self._last_status = status

    def get_state(self):
        """
        Notifies the gui of the output of the state command over
        the openvpn management interface.
        """
        if self.is_connected():
            return self._parse_state_and_notify(self._send_command("state"))

    def get_status(self):
        """
        Notifies the gui of the output of the status command over
        the openvpn management interface.
        """
        if self.is_connected():
            return self._parse_status_and_notify(self._send_command("status"))

    @property
    def vpn_env(self):
        """
        Return a dict containing the vpn environment to be used.
        """
        return self._launcher.get_vpn_env()

    def terminate_openvpn(self, shutdown=False):
        """
        Attempts to terminate openvpn by sending a SIGTERM.
        """
        if self.is_connected():
            self._send_command("signal SIGTERM")
        if shutdown:
            self._cleanup_tempfiles()

    def _cleanup_tempfiles(self):
        """
        Remove all temporal files we might have left behind.

        Iif self.port is 'unix', we have created a temporal socket path that,
        under normal circumstances, we should be able to delete.
        """
        if self._socket_port == "unix":
            logger.debug('cleaning socket file temp folder')
            tempfolder = first(os.path.split(self._socket_host))
            if tempfolder and os.path.isdir(tempfolder):
                try:
                    shutil.rmtree(tempfolder)
                except OSError:
                    logger.error('could not delete tmpfolder %s' % tempfolder)

    def get_openvpn_process(self):
        """
        Looks for openvpn instances running.

        :rtype: process
        """
        openvpn_process = None
        for p in psutil.process_iter():
            try:
                # XXX Not exact!
                # Will give false positives.
                # we should check that cmdline BEGINS
                # with openvpn or with our wrapper
                # (pkexec / osascript / whatever)

                # This needs more work, see #3268, but for the moment
                # we need to be able to filter out arguments in the form
                # --openvpn-foo, since otherwise we are shooting ourselves
                # in the feet.

                if PSUTIL_2:
                    cmdline = p.cmdline()
                else:
                    cmdline = p.cmdline
                if any(map(lambda s: s.find(
                        "LEAPOPENVPN") != -1, cmdline)):
                    openvpn_process = p
                    break
            except psutil_AccessDenied:
                pass
        return openvpn_process

    def stop_if_already_running(self):
        """
        Checks if VPN is already running and tries to stop it.

        Might raise OpenVPNAlreadyRunning.

        :return: True if stopped, False otherwise

        """
        process = self.get_openvpn_process()
        if not process:
            logger.debug('Could not find openvpn process while '
                         'trying to stop it.')
            return

        logger.debug("OpenVPN is already running, trying to stop it...")
        cmdline = process.cmdline

        manag_flag = "--management"
        if isinstance(cmdline, list) and manag_flag in cmdline:
            # we know that our invocation has this distinctive fragment, so
            # we use this fingerprint to tell other invocations apart.
            # this might break if we change the configuration path in the
            # launchers
            smellslikeleap = lambda s: "leap" in s and "providers" in s

            if not any(map(smellslikeleap, cmdline)):
                logger.debug("We cannot stop this instance since we do not "
                             "recognise it as a leap invocation.")
                raise AlienOpenVPNAlreadyRunning

            try:
                index = cmdline.index(manag_flag)
                host = cmdline[index + 1]
                port = cmdline[index + 2]
                logger.debug("Trying to connect to %s:%s"
                             % (host, port))
                self.connect_to_management(host, port)

                # XXX this has a problem with connections to different
                # remotes. So the reconnection will only work when we are
                # terminating instances left running for the same provider.
                # If we are killing an openvpn instance configured for another
                # provider, we will get:
                # TLS Error: local/remote TLS keys are out of sync
                # However, that should be a rare case right now.
                self._send_command("signal SIGTERM")
                self._close_management_socket(announce=True)
            except (Exception, AssertionError) as e:
                logger.warning("Problem trying to terminate OpenVPN: %r"
                               % (e,))
        else:
            logger.debug("Could not find the expected openvpn command line.")

        process = self.get_openvpn_process()
        if process is None:
            logger.debug("Successfully finished already running "
                         "openvpn process.")
            return True
        else:
            logger.warning("Unable to terminate OpenVPN")
            raise OpenVPNAlreadyRunning