fsm.py

"""
The DUL's finite state machine representation.
"""

import logging
import queue
from typing import TYPE_CHECKING, cast

from pynetdicom import evt
from pynetdicom.pdu import (
    A_ASSOCIATE_RQ,
    A_ASSOCIATE_RJ,
    A_ASSOCIATE_AC,
    P_DATA_TF,
    A_RELEASE_RQ,
    A_RELEASE_RP,
    A_ABORT_RQ,
)
from pynetdicom.pdu_primitives import A_P_ABORT, A_ABORT
from pynetdicom.transport import T_CONNECT

if TYPE_CHECKING:  # pragma: no cover
    from pynetdicom.dul import DULServiceProvider
    from pynetdicom.transport import AssociationSocket
    from pynetdicom.pdu_primitives import A_ASSOCIATE, P_DATA, A_RELEASE


LOGGER = logging.getLogger(__name__)


class InvalidEventError(Exception):
    """Exception for use when an invalid event occurs for a given state."""

    pass


# pylint: disable=invalid-name
class StateMachine:
    """Implementation of the DICOM Upper Layer State Machine.

    Attributes
    ----------
    current_state : str
        The current state of the state machine, ``'Sta1'`` to ``'Sta13'``.
    dul : dul.DULServiceProvider
        The DICOM Upper Layer service instance for the local AE

    References
    ----------

    * DICOM Standard, Part 8, :dcm:`Section 9.2<part08/sect_9.2.html>`
    """

    def __init__(self, dul: "DULServiceProvider"):
        """Create a new :class:`StateMachine`.

        Parameters
        ---------
        dul : dul.DULServiceProvider
            The DICOM Upper Layer Service instance for the association.
        """
        self.current_state = "Sta1"
        self.dul = dul

    def do_action(self, event: str) -> None:
        """Execute the action triggered by `event`.

        Parameters
        ----------
        event : str
            The event to be processed, ``'Evt1'`` to ``'Evt19'``
        """
        # Check (event + state) is valid
        if (event, self.current_state) not in TRANSITION_TABLE:
            msg = "Invalid event '{}' for the current state '{}'".format(
                event, self.current_state
            )
            LOGGER.error(msg)
            raise InvalidEventError(msg)

        action_name = TRANSITION_TABLE[(event, self.current_state)]

        # action is the (description, function, state) tuple
        #   associated with the action_name
        action = ACTIONS[action_name]

        # Attempt to execute the action and move the state machine to its
        #   next state
        try:
            # Execute the required action
            next_state = action[1](self.dul)

            # Event handler - FSM transition
            evt.trigger(
                self.dul.assoc,
                evt.EVT_FSM_TRANSITION,
                {
                    "action": action_name,
                    "current_state": self.current_state,
                    "fsm_event": event,
                    "next_state": next_state,
                },
            )
            # print(
            #     "{}: {} + {} -> {} -> {}".format(
            #         self.dul.assoc.mode[0].upper(),
            #         self.current_state,
            #         event,
            #         action_name,
            #         next_state,
            #     )
            # )

            # Move the state machine to the next state
            self.transition(next_state)

        except Exception as exc:
            LOGGER.error(
                "State Machine received an exception attempting "
                "to perform the action '%s' while in state '%s'",
                action_name,
                self.current_state,
            )
            LOGGER.exception(exc)
            self.dul.kill_dul()
            raise

    def transition(self, state: str) -> None:
        """Transition the state machine to the next state.

        Parameters
        ----------
        state : str
            The state to transition to, ``'Sta1'`` to ``'Sta13'``.

        Raises
        ------
        ValueError
            If `state` is not a valid state.
        """
        # Validate that state is acceptable
        if state in STATES.keys():
            self.current_state = state
        else:
            msg = f"Invalid state '{state}' for State Machine"
            LOGGER.error(msg)
            raise ValueError(msg)


def AE_1(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-1.

    *Event*

    Service user issued A-ASSOCIATE (request) to the service provider

    *Action*

    Issue TRANSPORT CONNECT request primitive to the transport service.

    *State/Event Triggers*

    - Sta1 + Evt1

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta4'``, the next state of the state machine.
    """
    # A-ASSOCIATE (request) primitive received from local user
    request = cast("A_ASSOCIATE", dul.to_provider_queue.get(False))

    # Issue TRANSPORT CONNECT request primitive to local transport service
    sock = cast("AssociationSocket", dul.socket)
    sock.connect(T_CONNECT(request))

    return "Sta4"


def AE_2(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-2.

    On receiving connection confirmation, send A-ASSOCIATE-RQ to the peer AE
    This send a byte stream with the format given by Table 9-11

    State-event triggers: Sta4 + Evt2

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta5'``, the next state of the state machine.
    """
    # TRANSPORT CONNECTION primitive received from transport service
    primitive = cast("T_CONNECT", dul.to_provider_queue.get(False))

    # Send A-ASSOCIATE-RQ PDU to the peer
    dul._send(A_ASSOCIATE_RQ(primitive.request))

    return "Sta5"


def AE_3(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-3.

    On receiving A-ASSOCIATE-AC, issue acceptance confirmation

    State-event triggers: Sta5 + Evt3

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta6'``, the next state of the state machine
    """
    # Received A-ASSOCIATE-AC PDU from the peer
    pdu = dul._recv_pdu.get(False)

    # Issue A-ASSOCIATE confirmation (accept) primitive
    dul.to_user_queue.put(cast("A_ASSOCIATE", pdu.to_primitive()))

    return "Sta6"


def AE_4(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-4.

    On receiving A-ASSOCIATE-RJ, issue rejection confirmation and close
    connection

    State-event triggers: Sta5 + Evt4

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    # Received A-ASSOCIATE-RJ PDU from the peer
    pdu = dul._recv_pdu.get(False)

    # Issue A-ASSOCIATE confirmation (reject) primitive and close transport
    # connection
    dul.to_user_queue.put(cast("A_ASSOCIATE", pdu.to_primitive()))
    sock = cast("AssociationSocket", dul.socket)
    sock.close()

    assoc = dul.assoc
    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor

    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    dul.kill_dul()

    return "Sta1"


def AE_5(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-5.

    From Idle state, on receiving a remote connection attempt, respond and
    start ARTIM. This is the first step in associating a remote AE (requestor)
    to the local AE (acceptor).

    State-event triggers: Sta1 + Evt5

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta2'``, the next state of the state machine
    """
    # Start ARTIM timer
    dul.artim_timer.start()

    return "Sta2"


def AE_6(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-6.

    On receiving an A-ASSOCIATE-RQ PDU from the peer then stop the ARTIM timer
    and then either

    * issue an A-ASSOCIATE indication primitive if the -RQ is acceptable or
    * issue an A-ASSOCIATE-RJ PDU to the peer and start the ARTIM timer

    This is a lower-level DUL Service Provider initiated rejection - for
    example this could be where the protocol version is checked

    State-event triggers: Sta2 + Evt6

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        Either ``'Sta3'`` or ``'Sta13'``, the next state of the state machine
    """
    # Stop ARTIM timer
    dul.artim_timer.stop()

    recv_pdu = cast(A_ASSOCIATE_RQ, dul._recv_pdu.get(False))
    primitive = recv_pdu.to_primitive()

    # If A-ASSOCIATE-RQ not acceptable by service dul provider
    #   Then set reason and send -RJ PDU back to peer
    if recv_pdu.protocol_version != 0x0001:
        LOGGER.error(
            "A-ASSOCIATE-RQ: Unsupported protocol version "
            f"'0x{recv_pdu.protocol_version:04X}'"
        )

        # Send A-ASSOCIATE-RJ PDU and start ARTIM timer
        primitive.result = 0x01
        primitive.result_source = 0x02
        primitive.diagnostic = 0x02

        dul._send(A_ASSOCIATE_RJ(primitive))

        dul.artim_timer.start()

        return "Sta13"

    # If A-ASSOCIATE-RQ acceptable by service dul provider
    #   issue A-ASSOCIATE indication primitive and move to Sta3
    dul.to_user_queue.put(primitive)

    return "Sta3"


def AE_7(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-7.

    On receiving association request acceptance, issue A-ASSOCIATE-AC

    State-event triggers: Sta3 + Evt7

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta6'``, the next state of the state machine
    """
    # Received A-ASSOCIATE (AC) primitive from local user
    primitive = cast("A_ASSOCIATE", dul.to_provider_queue.get(False))

    # Send A-ASSOCIATE-AC PDU
    dul._send(A_ASSOCIATE_AC(primitive))

    return "Sta6"


def AE_8(dul: "DULServiceProvider") -> str:
    """Association establishment action AE-8.

    On receiving association request rejection, issue A-ASSOCIATE-RJ

    State-event triggers: Sta3 + Evt8

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    # Received A-ASSOCIATE (RJ) primitive from local user
    primitive = cast("A_ASSOCIATE", dul.to_provider_queue.get(False))

    # Send A-ASSOCIATE-RJ PDU and start ARTIM timer
    dul._send(A_ASSOCIATE_RJ(primitive))
    dul.artim_timer.start()

    return "Sta13"


def DT_1(dul: "DULServiceProvider") -> str:
    """Data transfer DT-1.

    On receiving a P-DATA request, send P-DATA-TF

    State-event triggers: Sta6 + Evt9

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta6'``, the next state of the state machine
    """
    # P-DATA request received from local user
    primitive = cast("P_DATA", dul.to_provider_queue.get(False))

    # Send P-DATA-TF PDU
    dul._send(P_DATA_TF(primitive))

    return "Sta6"


def DT_2(dul: "DULServiceProvider") -> str:
    """Data transfer DT-2.

    On receiving a P-DATA-TF request, send P-DATA indication

    State-event triggers: Sta6 + Evt10

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta6'``, the next state of the state machine
    """
    # P-DATA-TF PDU received from peer
    pdu = dul._recv_pdu.get(False)

    # Send P-DATA indication primitive directly to DIMSE for processing
    dul.assoc.dimse.receive_primitive(cast("P_DATA", pdu.to_primitive()))

    return "Sta6"


def AR_1(dul: "DULServiceProvider") -> str:
    """Association release AR-1.

    Send Association release request

    State-event triggers: Sta6 + Evt11

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta7'``, the next state of the state machine
    """
    # Received A-RELEASE request from local user
    primitive = cast("A_RELEASE", dul.to_provider_queue.get(False))

    # Send A-RELEASE-RQ PDU
    dul._send(A_RELEASE_RQ(primitive))

    return "Sta7"


def AR_2(dul: "DULServiceProvider") -> str:
    """Association release AR-2.

    On receiving an association release request, send release indication

    State-event triggers: Sta6 + Evt12

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta8'``, the next state of the state machine
    """
    # A-RELEASE-RQ PDU received from peer
    pdu = dul._recv_pdu.get(False)

    # Send A-RELEASE indication primitive
    dul.to_user_queue.put(pdu.to_primitive())

    return "Sta8"


def AR_3(dul: "DULServiceProvider") -> str:
    """Association release AR-3.

    On receiving an association release response, send release confirmation,
    close connection and go back to Idle state

    State-event triggers: Sta7 + Evt13, Sta11 + Evt13

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    # A-RELEASE-RP PDU received from peer
    pdu = dul._recv_pdu.get(False)

    # Issue A-RELEASE confirmation primitive and close transport connection
    dul.to_user_queue.put(pdu.to_primitive())
    sock = cast("AssociationSocket", dul.socket)
    sock.close()

    assoc = dul.assoc
    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor

    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    dul.kill_dul()

    return "Sta1"


def AR_4(dul: "DULServiceProvider") -> str:
    """Association release AR-4.

    On receiving an association release response, send release response

    State-event triggers: Sta8 + Evt14, Sta12 + Evt14

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    # A-RELEASE (response) primitive received from local user
    primitive = cast("A_RELEASE", dul.to_provider_queue.get(False))

    # Issue A-RELEASE-RP PDU and start ARTIM timer
    dul._send(A_RELEASE_RP(primitive))
    dul.artim_timer.start()

    return "Sta13"


def AR_5(dul: "DULServiceProvider") -> str:
    """Association release AR-5.

    On receiving transport connection closed, stop the ARTIM timer and go back
    to Idle state

    State-event triggers: Sta13 + Evt17

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    assoc = dul.assoc
    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor

    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    # Stop ARTIM timer
    dul.artim_timer.stop()
    dul.kill_dul()

    return "Sta1"


def AR_6(dul: "DULServiceProvider") -> str:
    """Association release AR-6.

    On receiving P-DATA-TF during attempted association release request
    send P-DATA indication

    State-event triggers: Sta7 + Evt10

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta7'``, the next state of the state machine
    """
    # P-DATA-TF PDU received from peer
    pdu = cast("P_DATA_TF", dul._recv_pdu.get(False))

    # Issue P-DATA indication
    dul.to_user_queue.put(pdu.to_primitive())

    return "Sta7"


def AR_7(dul: "DULServiceProvider") -> str:
    """Association release AR-7.

    On receiving P-DATA request during attempted association release request
    send P-DATA-TF

    State-event triggers: Sta8 + Evt9

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta8'``, the next state of the state machine
    """
    # P-DATA primitive received from local user
    primitive = cast("P_DATA", dul.to_provider_queue.get(False))

    # Issue P-DATA-TF PDU
    dul._send(P_DATA_TF(primitive))

    return "Sta8"


def AR_8(dul: "DULServiceProvider") -> str:
    """Association release AR-8.

    On receiving association release request while local is requesting release
    then issue release collision indication

    State-event triggers: Sta7 + Evt12

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        Either ``'Sta9'`` or ``'Sta10'``, the next state of the state machine
    """
    # A-RELEASE-RQ PDU received from peer
    pdu = cast("A_RELEASE_RQ", dul._recv_pdu.get(False))

    # Issue A-RELEASE indication (release collision)
    dul.to_user_queue.put(pdu.to_primitive())
    if dul.assoc.is_requestor:
        return "Sta9"

    return "Sta10"


def AR_9(dul: "DULServiceProvider") -> str:
    """Association release AR-9.

    On receiving A-RELEASE primitive, send release response

    State-event triggers: Sta9 + Evt14

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta11'``, the next state of the state machine
    """
    # A-RELEASE (response) primitive received from local user
    primitive = cast("A_RELEASE", dul.to_provider_queue.get(False))

    # Send A-RELEASE-RP PDU
    dul._send(A_RELEASE_RP(primitive))

    return "Sta11"


def AR_10(dul: "DULServiceProvider") -> str:
    """Association release AR-10.

    On receiving A-RELEASE-RP, issue release confirmation

    State-event triggers: Sta10 + Evt13

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta12'``, the next state of the state machine
    """
    # A-RELEASE-RP PDU received from peer
    pdu = cast("A_RELEASE_RP", dul._recv_pdu.get(False))

    # Issue A-RELEASE confirmation primitive
    dul.to_user_queue.put(pdu.to_primitive())

    return "Sta12"


def AA_1(dul: "DULServiceProvider") -> str:
    """Association abort AA-1.

    If on sending A-ASSOCIATE-RQ we receive an invalid reply, or an abort
    request then abort

    State-event triggers: Sta2 + Evt3/Evt4/Evt10/Evt12/Evt13/Evt19,
    Sta3/Sta5/Sta6/Sta7/Sta8/Sta9/Sta10/Sta11/Sta12 + Evt15

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    # Received invalid PDU from peer or an A-ABORT primitive from local user
    try:
        primitive = dul.to_provider_queue.queue[0]
        if isinstance(primitive, (A_ABORT, A_P_ABORT)):
            primitive = dul.to_provider_queue.get(False)
    except (queue.Empty, IndexError):
        primitive = None

    # Send A-ABORT PDU (service-user source) and start (or restart
    # if already started) ARTIM timer.
    pdu = A_ABORT_RQ()
    if primitive is not None:
        pdu.from_primitive(primitive)
    else:
        # Reason not specified
        pdu.source = 0x00
        pdu.reason_diagnostic = 0x00

    dul._send(pdu)
    dul.artim_timer.restart()

    return "Sta13"


def AA_2(dul: "DULServiceProvider") -> str:
    """Association abort AA-2.

    On receiving an A-ABORT or if the ARTIM timer expires, close connection and
    return to Idle

    State-event triggers: Sta2 + Evt16/Evt18, Sta4 + Evt15, Sta13 + Evt16/Evt18

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    # Stop ARTIM timer if running. Close transport connection.
    dul.artim_timer.stop()
    sock = cast("AssociationSocket", dul.socket)
    sock.close()

    assoc = dul.assoc
    assoc.dimse.msg_queue.put((None, None))

    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor
    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    dul.kill_dul()

    return "Sta1"


def AA_3(dul: "DULServiceProvider") -> str:
    """Association abort AA-3.

    On receiving A-ABORT, issue abort indication, close connection and
    return to Idle

    State-event triggers: Sta3/Sta5/Sta6/Sta7/Sta8/Sta9/Sta10/Sta11/Sta12 +
    Evt16

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    # A-ABORT PDU received from peer
    pdu = cast("A_ABORT_RQ", dul._recv_pdu.get(False))

    # If (service-user initiated abort):
    #   - Issue A-ABORT indication and close transport connection.
    # Otherwise (service-dul initiated abort):
    #   - Issue A-P-ABORT indication and close transport connection.
    # This action is triggered by the reception of an A-ABORT PDU
    dul.to_user_queue.put(pdu.to_primitive())
    sock = cast("AssociationSocket", dul.socket)
    sock.close()

    assoc = dul.assoc
    assoc.dimse.msg_queue.put((None, None))

    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor
    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    dul.kill_dul()

    return "Sta1"


def AA_4(dul: "DULServiceProvider") -> str:
    """Association abort AA-4.

    If connection closed, issue A-P-ABORT and return to Idle

    State-event triggers: Sta3/Sta4/Sta5/Sta6/Sta7/Sta8/Sta9/Sta10/Sta11/Sta12
    + Evt17

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    assoc = dul.assoc
    assoc.dimse.msg_queue.put((None, None))

    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor
    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    # Issue A-P-ABORT indication primitive.
    primitive = A_P_ABORT()
    primitive.provider_reason = 0x00
    dul.to_user_queue.put(primitive)
    dul.kill_dul()

    return "Sta1"


def AA_5(dul: "DULServiceProvider") -> str:
    """Association abort AA-5.

    If connection closed during association request, stop ARTIM timer and
    return to Idle

    State-event triggers: Sta2 + Evt17

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta1'``, the next state of the state machine
    """
    assoc = dul.assoc
    remote = assoc.acceptor if assoc.is_requestor else assoc.requestor

    address = (remote.address, remote.port)
    evt.trigger(dul.assoc, evt.EVT_CONN_CLOSE, {"address": address})

    # Stop ARTIM timer.
    dul.artim_timer.stop()
    dul.kill_dul()

    return "Sta1"


def AA_6(dul: "DULServiceProvider") -> str:
    """Association abort AA-6.

    If receive a PDU while waiting for connection to close, ignore it

    State-event triggers: Sta13 + Evt3/Evt4/Evt10/Evt12/Evt13

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    # Ignore PDU
    try:
        dul._recv_pdu.get(False)
    except queue.Empty:
        pass

    return "Sta13"


def AA_7(dul: "DULServiceProvider") -> str:
    """Association abort AA-7.

    If receive a association request or invalid PDU while waiting for
    connection to close, send A-ABORT PDU

    State-event triggers: Sta13 + Evt6/Evt19

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    primitive = A_P_ABORT()
    primitive.provider_reason = 0x02

    # Send A-ABORT PDU
    dul._send(A_ABORT_RQ(primitive))

    return "Sta13"


def AA_8(dul: "DULServiceProvider") -> str:
    """Association abort AA-8.

    If receive invalid event, send A-ABORT PDU, issue A-P-ABORT indication and
    start ARTIM timer

    State-event triggers: Evt3 + Sta3/6/7/8/9/10/11/12,
    Evt4 + Sta3/5/6/7/8/9/10/11/12, Evt6 + Sta3/5/6/7/8/9/10/11/12,
    Evt10 + Sta3/5/8/9/10/11/12, Evt12 + Sta3/5/8/9/10/11/12,
    Evt13 + Sta3/5/6/8/9/12, Evt19 + Sta3/5/6/7/8/9/10/11/12

    Parameters
    ----------
    dul : dul.DULServiceProvider
        The DICOM Upper Layer Service instance for the local AE

    Returns
    -------
    str
        ``'Sta13'``, the next state of the state machine
    """
    # Send A-ABORT PDU (service-dul source), issue A-P-ABORT
    # indication, and start ARTIM timer.
    pdu = A_ABORT_RQ()
    pdu.source = 0x02  # A-P-ABORT
    pdu.reason_diagnostic = 0x00

    # Send A-ABORT PDU
    dul._send(pdu)

    # Issue A-P-ABORT to user
    primitive = A_P_ABORT()
    primitive.provider_reason = 0x05
    dul.to_user_queue.put(primitive)
    dul.artim_timer.start()

    return "Sta13"


# Finite State Machine
# Machine State Definitions, PS3.8 Tables 9-1, 9-2, 9-3, 9-4, 9-5
# pylint: disable=line-too-long
STATES = {
    # No association
    "Sta1": "Idle",
    # Association establishment
    "Sta2": "Transport connection open (Awaiting A-ASSOCIATE-RQ PDU)",
    "Sta3": "Awaiting local A-ASSOCIATE response primitive (from local user)",
    "Sta4": "Awaiting transport connection opening to complete (from local transport service)",
    "Sta5": "Awaiting A-ASSOCIATE-AC or A-ASSOCIATE-RJ PDU",
    # Data transfer
    "Sta6": "Association established and ready for data transfer",
    # Association release
    "Sta7": "Awaiting A-RELEASE-RP PDU",
    "Sta8": "Awaiting local A-RELEASE response primitive (from local user)",
    "Sta9": "Release collision requestor side; awaiting A-RELEASE response (from local user)",
    "Sta10": "Release collision acceptor side; awaiting A-RELEASE-RP PDU",
    "Sta11": "Release collision requestor side; awaiting A-RELEASE-RP PDU",
    "Sta12": "Release collision acceptor side; awaiting A-RELEASE response primitive (from local user)",
    # Waiting for transport connection close
    "Sta13": "Awaiting Transport Connection Close Indication (Association no longer exists)",
}

# State Machine Action Definitions, PS3.8 Tables 9-6, 9-7, 9-8, 9-9
ACTIONS = {
    # Association establishment related actions
    "AE-1": (
        "Issue TRANSPORT CONNECT request primitive to local transport service",
        AE_1,
        "Sta4",
    ),
    "AE-2": ("Send A-ASSOCIATE-RQ-PDU", AE_2, "Sta5"),
    "AE-3": ("Issue A-ASSOCIATE confirmation (accept) primitive", AE_3, "Sta6"),
    "AE-4": (
        "Issue A-ASSOCIATE confirmation (reject) primitive and close "
        "transport connection",
        AE_4,
        "Sta1",
    ),
    "AE-5": (
        "Issue Transport connection response primitive; start ARTIM timer",
        AE_5,
        "Sta2",
    ),
    "AE-6": (
        "Stop ARTIM timer and if A-ASSOCIATE-RQ acceptable by "
        "service-dul: issue A-ASSOCIATE indication primitive "
        "otherwise issue A-ASSOCIATE-RJ-PDU and start ARTIM timer",
        AE_6,
        ("Sta3", "Sta13"),
    ),
    "AE-7": ("Send A-ASSOCIATE-AC PDU", AE_7, "Sta6"),
    "AE-8": ("Send A-ASSOCIATE-RJ PDU and start ARTIM timer", AE_8, "Sta13"),
    # Data transfer related actions
    "DT-1": ("Send P-DATA-TF PDU", DT_1, "Sta6"),
    "DT-2": ("Send P-DATA indication primitive", DT_2, "Sta6"),
    # Association Release related actions
    "AR-1": ("Send A-RELEASE-RQ PDU", AR_1, "Sta7"),
    "AR-2": ("Issue A-RELEASE indication primitive", AR_2, "Sta8"),
    "AR-3": (
        "Issue A-RELEASE confirmation primitive and close transport connection",
        AR_3,
        "Sta1",
    ),
    "AR-4": ("Issue A-RELEASE-RP PDU and start ARTIM timer", AR_4, "Sta13"),
    "AR-5": ("Stop ARTIM timer", AR_5, "Sta1"),
    "AR-6": ("Issue P-DATA indication", AR_6, "Sta7"),
    "AR-7": ("Issue P-DATA-TF PDU", AR_7, "Sta8"),
    "AR-8": (
        "Issue A-RELEASE indication (release collision): if "
        "association-requestor, next state is Sta9, if not next "
        "state is Sta10",
        AR_8,
        ("Sta9", "Sta10"),
    ),
    "AR-9": ("Send A-RELEASE-RP PDU", AR_9, "Sta11"),
    "AR-10": ("Issue A-RELEASE confirmation primitive", AR_10, "Sta12"),
    # Association abort related actions
    "AA-1": (
        "Send A-ABORT PDU (service-user source) and start (or "
        "restart if already started) ARTIM timer",
        AA_1,
        "Sta13",
    ),
    "AA-2": ("Stop ARTIM timer if running. Close transport connection", AA_2, "Sta1"),
    "AA-3": (
        "If (service-user initiated abort): issue A-ABORT "
        "indication and close transport connection, otherwise "
        "(service-dul initiated abort): issue A-P-ABORT indication "
        "and close transport connection",
        AA_3,
        "Sta1",
    ),
    "AA-4": ("Issue A-P-ABORT indication primitive", AA_4, "Sta1"),
    "AA-5": ("Stop ARTIM timer", AA_5, "Sta1"),
    "AA-6": ("Ignore PDU", AA_6, "Sta13"),
    "AA-7": ("Send A-ABORT PDU", AA_7, "Sta13"),
    "AA-8": (
        "Send A-ABORT PDU (service-dul source), issue an A-P-ABORT "
        "indication and start ARTIM timer",
        AA_8,
        "Sta13",
    ),
}

# State Machine Event Definitions, PS3.8 Table 9-10
EVENTS = {
    "Evt1": "A-ASSOCIATE request (local user)",
    "Evt2": "Transport connect confirmation (local transport service)",
    "Evt3": "A-ASSOCIATE-AC PDU (received on transport connection)",
    "Evt4": "A-ASSOCIATE-RJ PDU (received on transport connection)",
    "Evt5": "Transport connection indication (local transport service)",
    "Evt6": "A-ASSOCIATE-RQ PDU (on transport connection)",
    "Evt7": "A-ASSOCIATE response primitive (accept)",
    "Evt8": "A-ASSOCIATE response primitive (reject)",
    "Evt9": "P-DATA request primitive",
    "Evt10": "P-DATA-TF PDU (on transport connection)",
    "Evt11": "A-RELEASE request primitive",
    "Evt12": "A-RELEASE-RQ PDU (on transport)",
    "Evt13": "A-RELEASE-RP PDU (on transport)",
    "Evt14": "A-RELEASE response primitive",
    "Evt15": "A-ABORT request primitive",
    "Evt16": "A-ABORT PDU (on transport)",
    "Evt17": "Transport connection closed indication (local transport service)",
    "Evt18": "ARTIM timer expired (Association reject/release timer)",
    "Evt19": "Unrecognized or invalid PDU received",
}

# State Machine Transitions, PS3.8 Table 9-10
TRANSITION_TABLE = {
    ("Evt1", "Sta1"): "AE-1",
    ("Evt2", "Sta4"): "AE-2",
    ("Evt3", "Sta2"): "AA-1",
    ("Evt3", "Sta3"): "AA-8",
    ("Evt3", "Sta5"): "AE-3",
    ("Evt3", "Sta6"): "AA-8",
    ("Evt3", "Sta7"): "AA-8",
    ("Evt3", "Sta8"): "AA-8",
    ("Evt3", "Sta9"): "AA-8",
    ("Evt3", "Sta10"): "AA-8",
    ("Evt3", "Sta11"): "AA-8",
    ("Evt3", "Sta12"): "AA-8",
    ("Evt3", "Sta13"): "AA-6",
    ("Evt4", "Sta2"): "AA-1",
    ("Evt4", "Sta3"): "AA-8",
    ("Evt4", "Sta5"): "AE-4",
    ("Evt4", "Sta6"): "AA-8",
    ("Evt4", "Sta7"): "AA-8",
    ("Evt4", "Sta8"): "AA-8",
    ("Evt4", "Sta9"): "AA-8",
    ("Evt4", "Sta10"): "AA-8",
    ("Evt4", "Sta11"): "AA-8",
    ("Evt4", "Sta12"): "AA-8",
    ("Evt4", "Sta13"): "AA-6",
    ("Evt5", "Sta1"): "AE-5",
    ("Evt6", "Sta2"): "AE-6",
    ("Evt6", "Sta3"): "AA-8",
    ("Evt6", "Sta5"): "AA-8",
    ("Evt6", "Sta6"): "AA-8",
    ("Evt6", "Sta7"): "AA-8",
    ("Evt6", "Sta8"): "AA-8",
    ("Evt6", "Sta9"): "AA-8",
    ("Evt6", "Sta10"): "AA-8",
    ("Evt6", "Sta11"): "AA-8",
    ("Evt6", "Sta12"): "AA-8",
    ("Evt6", "Sta13"): "AA-7",
    ("Evt7", "Sta3"): "AE-7",
    ("Evt8", "Sta3"): "AE-8",
    ("Evt9", "Sta6"): "DT-1",
    ("Evt9", "Sta8"): "AR-7",
    ("Evt10", "Sta2"): "AA-1",
    ("Evt10", "Sta3"): "AA-8",
    ("Evt10", "Sta5"): "AA-8",
    ("Evt10", "Sta6"): "DT-2",
    ("Evt10", "Sta7"): "AR-6",
    ("Evt10", "Sta8"): "AA-8",
    ("Evt10", "Sta9"): "AA-8",
    ("Evt10", "Sta10"): "AA-8",
    ("Evt10", "Sta11"): "AA-8",
    ("Evt10", "Sta12"): "AA-8",
    ("Evt10", "Sta13"): "AA-6",
    ("Evt11", "Sta6"): "AR-1",
    ("Evt12", "Sta2"): "AA-1",
    ("Evt12", "Sta3"): "AA-8",
    ("Evt12", "Sta5"): "AA-8",
    ("Evt12", "Sta6"): "AR-2",
    ("Evt12", "Sta7"): "AR-8",
    ("Evt12", "Sta8"): "AA-8",
    ("Evt12", "Sta9"): "AA-8",
    ("Evt12", "Sta10"): "AA-8",
    ("Evt12", "Sta11"): "AA-8",
    ("Evt12", "Sta12"): "AA-8",
    ("Evt12", "Sta13"): "AA-6",
    ("Evt13", "Sta2"): "AA-1",
    ("Evt13", "Sta3"): "AA-8",
    ("Evt13", "Sta5"): "AA-8",
    ("Evt13", "Sta6"): "AA-8",
    ("Evt13", "Sta7"): "AR-3",
    ("Evt13", "Sta8"): "AA-8",
    ("Evt13", "Sta9"): "AA-8",
    ("Evt13", "Sta10"): "AR-10",
    ("Evt13", "Sta11"): "AR-3",
    ("Evt13", "Sta12"): "AA-8",
    ("Evt13", "Sta13"): "AA-6",
    ("Evt14", "Sta8"): "AR-4",
    ("Evt14", "Sta9"): "AR-9",
    ("Evt14", "Sta12"): "AR-4",
    ("Evt15", "Sta3"): "AA-1",
    ("Evt15", "Sta4"): "AA-2",
    ("Evt15", "Sta5"): "AA-1",
    ("Evt15", "Sta6"): "AA-1",
    ("Evt15", "Sta7"): "AA-1",
    ("Evt15", "Sta8"): "AA-1",
    ("Evt15", "Sta9"): "AA-1",
    ("Evt15", "Sta10"): "AA-1",
    ("Evt15", "Sta11"): "AA-1",
    ("Evt15", "Sta12"): "AA-1",
    ("Evt16", "Sta2"): "AA-2",
    ("Evt16", "Sta3"): "AA-3",
    ("Evt16", "Sta5"): "AA-3",
    ("Evt16", "Sta6"): "AA-3",
    ("Evt16", "Sta7"): "AA-3",
    ("Evt16", "Sta8"): "AA-3",
    ("Evt16", "Sta9"): "AA-3",
    ("Evt16", "Sta10"): "AA-3",
    ("Evt16", "Sta11"): "AA-3",
    ("Evt16", "Sta12"): "AA-3",
    ("Evt16", "Sta13"): "AA-2",
    ("Evt17", "Sta2"): "AA-5",
    ("Evt17", "Sta3"): "AA-4",
    ("Evt17", "Sta4"): "AA-4",
    ("Evt17", "Sta5"): "AA-4",
    ("Evt17", "Sta6"): "AA-4",
    ("Evt17", "Sta7"): "AA-4",
    ("Evt17", "Sta8"): "AA-4",
    ("Evt17", "Sta9"): "AA-4",
    ("Evt17", "Sta10"): "AA-4",
    ("Evt17", "Sta11"): "AA-4",
    ("Evt17", "Sta12"): "AA-4",
    ("Evt17", "Sta13"): "AR-5",
    ("Evt18", "Sta2"): "AA-2",
    ("Evt18", "Sta13"): "AA-2",
    ("Evt19", "Sta2"): "AA-1",
    ("Evt19", "Sta3"): "AA-8",
    ("Evt19", "Sta5"): "AA-8",
    ("Evt19", "Sta6"): "AA-8",
    ("Evt19", "Sta7"): "AA-8",
    ("Evt19", "Sta8"): "AA-8",
    ("Evt19", "Sta9"): "AA-8",
    ("Evt19", "Sta10"): "AA-8",
    ("Evt19", "Sta11"): "AA-8",
    ("Evt19", "Sta12"): "AA-8",
    ("Evt19", "Sta13"): "AA-7",
}