# © Crown-owned copyright 2024, Defence Science and Technology Laboratory UK
from abc import abstractmethod
from enum import Enum
from typing import Any, Dict, Optional, Set

from primaite.interface.request import RequestResponse
from primaite.simulator.core import RequestManager, RequestType
from primaite.simulator.system.software import IOSoftware, SoftwareHealthState


class ApplicationOperatingState(Enum):
    """Enumeration of Application Operating States."""

    RUNNING = 1
    "The application is running."
    CLOSED = 2
    "The application is closed or not running."
    INSTALLING = 3
    "The application is being installed or updated."


class Application(IOSoftware):
    """
    Represents an Application in the simulation environment.

    Applications are user-facing programs that may perform input/output operations.
    """

    operating_state: ApplicationOperatingState = ApplicationOperatingState.CLOSED
    "The current operating state of the Application."
    execution_control_status: str = "manual"
    "Control status of the application's execution. It could be 'manual' or 'automatic'."
    num_executions: int = 0
    "The number of times the application has been executed. Default is 0."
    groups: Set[str] = set()
    "The set of groups to which the application belongs."
    install_duration: int = 2
    "How long it takes to install the application."
    install_countdown: Optional[int] = None
    "The countdown to the end of the installation process. None if not currently installing"

    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def _init_request_manager(self) -> RequestManager:
        """
        Initialise the request manager.

        More information in user guide and docstring for SimComponent._init_request_manager.
        """
        rm = super()._init_request_manager()

        rm.add_request("close", RequestType(func=lambda request, context: RequestResponse.from_bool(self.close())))
        return rm

    @abstractmethod
    def describe_state(self) -> Dict:
        """
        Produce a dictionary describing the current state of this object.

        Please see :py:meth:`primaite.simulator.core.SimComponent.describe_state` for a more detailed explanation.

        :return: Current state of this object and child objects.
        :rtype: Dict
        """
        state = super().describe_state()
        state.update(
            {
                "operating_state": self.operating_state.value,
                "execution_control_status": self.execution_control_status,
                "num_executions": self.num_executions,
                "groups": list(self.groups),
            }
        )
        return state

    def apply_timestep(self, timestep: int) -> None:
        """
        Apply a timestep to the application.

        :param timestep: The current timestep of the simulation.
        """
        super().apply_timestep(timestep=timestep)
        if self.operating_state is ApplicationOperatingState.INSTALLING:
            self.install_countdown -= 1
            if self.install_countdown <= 0:
                self.operating_state = ApplicationOperatingState.RUNNING
                self.health_state_actual = SoftwareHealthState.GOOD
                self.install_countdown = None

    def pre_timestep(self, timestep: int) -> None:
        """Apply pre-timestep logic."""
        super().pre_timestep(timestep)
        self.num_executions = 0

    def _can_perform_action(self) -> bool:
        """
        Checks if the application can perform actions.

        This is done by checking if the application is operating properly or the node it is installed
        in is operational.

        Returns true if the software can perform actions.
        """
        if not super()._can_perform_action():
            return False

        if self.operating_state is not self.operating_state.RUNNING:
            # service is not running
            self.sys_log.error(f"Cannot perform action: {self.name} is {self.operating_state.name}")
            return False

        return True

    def run(self) -> None:
        """Open the Application."""
        if not super()._can_perform_action():
            return

        if self.operating_state == ApplicationOperatingState.CLOSED:
            self.sys_log.info(f"Running Application {self.name}")
            self.operating_state = ApplicationOperatingState.RUNNING
            # set software health state to GOOD if initially set to UNUSED
            if self.health_state_actual == SoftwareHealthState.UNUSED:
                self.set_health_state(SoftwareHealthState.GOOD)

    def _application_loop(self):
        """The main application loop."""
        pass

    def close(self) -> bool:
        """Close the Application."""
        if self.operating_state == ApplicationOperatingState.RUNNING:
            self.sys_log.info(f"Closed Application{self.name}")
            self.operating_state = ApplicationOperatingState.CLOSED
        return True

    def install(self) -> None:
        """Install Application."""
        super().install()
        if self.operating_state == ApplicationOperatingState.CLOSED:
            self.operating_state = ApplicationOperatingState.INSTALLING
            self.install_countdown = self.install_duration

    def receive(self, payload: Any, session_id: str, **kwargs) -> bool:
        """
        Receives a payload from the SessionManager.

        The specifics of how the payload is processed and whether a response payload
        is generated should be implemented in subclasses.

        :param payload: The payload to receive.
        :return: True if successful, False otherwise.
        """
        return super().receive(payload=payload, session_id=session_id, **kwargs)