import asyncio
import inspect
import logging
import threading
from asyncio import Future
from collections import defaultdict
from collections.abc import Sequence
from dataclasses import dataclass
from typing import Any, Awaitable, Callable, DefaultDict, Dict, List, Mapping, ParamSpec, Set, TypeVar, cast

from ..core import (
    Agent,
    AgentId,
    AgentMetadata,
    AgentProxy,
    AgentRuntime,
    CancellationToken,
    agent_instantiation_context,
)
from ..core.exceptions import MessageDroppedException
from ..core.intervention import DropMessage, InterventionHandler

logger = logging.getLogger("agnext")
event_logger = logging.getLogger("agnext.events")


@dataclass(kw_only=True)
class PublishMessageEnvelope:
    """A message envelope for publishing messages to all agents that can handle
    the message of the type T."""

    message: Any
    cancellation_token: CancellationToken
    sender: AgentId | None
    namespace: str


@dataclass(kw_only=True)
class SendMessageEnvelope:
    """A message envelope for sending a message to a specific agent that can handle
    the message of the type T."""

    message: Any
    sender: AgentId | None
    recipient: AgentId
    future: Future[Any]
    cancellation_token: CancellationToken


@dataclass(kw_only=True)
class ResponseMessageEnvelope:
    """A message envelope for sending a response to a message."""

    message: Any
    future: Future[Any]
    sender: AgentId
    recipient: AgentId | None


P = ParamSpec("P")
T = TypeVar("T", bound=Agent)


class Counter:
    def __init__(self) -> None:
        self._count: int = 0
        self.threadLock = threading.Lock()

    def increment(self) -> None:
        self.threadLock.acquire()
        self._count += 1
        self.threadLock.release()

    def get(self) -> int:
        return self._count

    def decrement(self) -> None:
        self.threadLock.acquire()
        self._count -= 1
        self.threadLock.release()


class SingleThreadedAgentRuntime(AgentRuntime):
    def __init__(self, *, intervention_handler: InterventionHandler | None = None) -> None:
        self._message_queue: List[PublishMessageEnvelope | SendMessageEnvelope | ResponseMessageEnvelope] = []
        # (namespace, type) -> List[AgentId]
        self._per_type_subscribers: DefaultDict[tuple[str, type], Set[AgentId]] = defaultdict(set)
        self._agent_factories: Dict[str, Callable[[], Agent] | Callable[[AgentRuntime, AgentId], Agent]] = {}
        self._instantiated_agents: Dict[AgentId, Agent] = {}
        self._intervention_handler = intervention_handler
        self._known_namespaces: set[str] = set()
        self._outstanding_tasks = Counter()

    @property
    def unprocessed_messages(
        self,
    ) -> Sequence[PublishMessageEnvelope | SendMessageEnvelope | ResponseMessageEnvelope]:
        return self._message_queue

    @property
    def outstanding_tasks(self) -> int:
        return self._outstanding_tasks.get()

    @property
    def _known_agent_names(self) -> Set[str]:
        return set(self._agent_factories.keys())

    # Returns the response of the message
    def send_message(
        self,
        message: Any,
        recipient: AgentId,
        *,
        sender: AgentId | None = None,
        cancellation_token: CancellationToken | None = None,
    ) -> Future[Any | None]:
        if cancellation_token is None:
            cancellation_token = CancellationToken()

        # event_logger.info(
        #     MessageEvent(
        #         payload=message,
        #         sender=sender,
        #         receiver=recipient,
        #         kind=MessageKind.DIRECT,
        #         delivery_stage=DeliveryStage.SEND,
        #     )
        # )

        future = asyncio.get_event_loop().create_future()
        if recipient.name not in self._known_agent_names:
            future.set_exception(Exception("Recipient not found"))

        if sender is not None and sender.namespace != recipient.namespace:
            raise ValueError("Sender and recipient must be in the same namespace to communicate.")

        self._process_seen_namespace(recipient.namespace)

        logger.info(f"Sending message of type {type(message).__name__} to {recipient.name}: {message.__dict__}")

        self._message_queue.append(
            SendMessageEnvelope(
                message=message,
                recipient=recipient,
                future=future,
                cancellation_token=cancellation_token,
                sender=sender,
            )
        )

        return future

    def publish_message(
        self,
        message: Any,
        *,
        namespace: str | None = None,
        sender: AgentId | None = None,
        cancellation_token: CancellationToken | None = None,
    ) -> Future[None]:
        if cancellation_token is None:
            cancellation_token = CancellationToken()

        logger.info(f"Publishing message of type {type(message).__name__} to all subscribers: {message.__dict__}")

        # event_logger.info(
        #     MessageEvent(
        #         payload=message,
        #         sender=sender,
        #         receiver=None,
        #         kind=MessageKind.PUBLISH,
        #         delivery_stage=DeliveryStage.SEND,
        #     )
        # )

        if sender is None and namespace is None:
            raise ValueError("Namespace must be provided if sender is not provided.")

        sender_namespace = sender.namespace if sender is not None else None
        explicit_namespace = namespace
        if explicit_namespace is not None and sender_namespace is not None and explicit_namespace != sender_namespace:
            raise ValueError(
                f"Explicit namespace {explicit_namespace} does not match sender namespace {sender_namespace}"
            )

        assert explicit_namespace is not None or sender_namespace is not None
        namespace = cast(str, explicit_namespace or sender_namespace)
        self._process_seen_namespace(namespace)

        self._message_queue.append(
            PublishMessageEnvelope(
                message=message,
                cancellation_token=cancellation_token,
                sender=sender,
                namespace=namespace,
            )
        )

        future = asyncio.get_event_loop().create_future()
        future.set_result(None)
        return future

    def save_state(self) -> Mapping[str, Any]:
        state: Dict[str, Dict[str, Any]] = {}
        for agent_id in self._instantiated_agents:
            state[str(agent_id)] = dict(self._get_agent(agent_id).save_state())
        return state

    def load_state(self, state: Mapping[str, Any]) -> None:
        for agent_id_str in state:
            agent_id = AgentId.from_str(agent_id_str)
            if agent_id.name in self._known_agent_names:
                self._get_agent(agent_id).load_state(state[str(agent_id)])

    async def _process_send(self, message_envelope: SendMessageEnvelope) -> None:
        recipient = message_envelope.recipient
        # todo: check if recipient is in the known namespaces
        # assert recipient in self._agents

        try:
            sender_name = message_envelope.sender.name if message_envelope.sender is not None else "Unknown"
            logger.info(
                f"Calling message handler for {recipient} with message type {type(message_envelope.message).__name__} sent by {sender_name}"
            )
            # event_logger.info(
            #     MessageEvent(
            #         payload=message_envelope.message,
            #         sender=message_envelope.sender,
            #         receiver=recipient,
            #         kind=MessageKind.DIRECT,
            #         delivery_stage=DeliveryStage.DELIVER,
            #     )
            # )
            recipient_agent = self._get_agent(recipient)
            response = await recipient_agent.on_message(
                message_envelope.message,
                cancellation_token=message_envelope.cancellation_token,
            )
        except BaseException as e:
            message_envelope.future.set_exception(e)
            return

        self._message_queue.append(
            ResponseMessageEnvelope(
                message=response,
                future=message_envelope.future,
                sender=message_envelope.recipient,
                recipient=message_envelope.sender,
            )
        )
        self._outstanding_tasks.decrement()

    async def _process_publish(self, message_envelope: PublishMessageEnvelope) -> None:
        responses: List[Awaitable[Any]] = []
        target_namespace = message_envelope.namespace
        for agent_id in self._per_type_subscribers[(target_namespace, type(message_envelope.message))]:
            if message_envelope.sender is not None and agent_id.name == message_envelope.sender.name:
                continue

            sender_agent = self._get_agent(message_envelope.sender) if message_envelope.sender is not None else None
            sender_name = sender_agent.metadata["name"] if sender_agent is not None else "Unknown"
            logger.info(
                f"Calling message handler for {agent_id.name} with message type {type(message_envelope.message).__name__} published by {sender_name}"
            )
            # event_logger.info(
            #     MessageEvent(
            #         payload=message_envelope.message,
            #         sender=message_envelope.sender,
            #         receiver=agent,
            #         kind=MessageKind.PUBLISH,
            #         delivery_stage=DeliveryStage.DELIVER,
            #     )
            # )

            agent = self._get_agent(agent_id)
            future = agent.on_message(
                message_envelope.message,
                cancellation_token=message_envelope.cancellation_token,
            )
            responses.append(future)

        try:
            _all_responses = await asyncio.gather(*responses)
        except BaseException:
            logger.error("Error processing publish message", exc_info=True)
            return

        self._outstanding_tasks.decrement()
        # TODO if responses are given for a publish

    async def _process_response(self, message_envelope: ResponseMessageEnvelope) -> None:
        content = (
            message_envelope.message.__dict__
            if hasattr(message_envelope.message, "__dict__")
            else message_envelope.message
        )
        logger.info(
            f"Resolving response with message type {type(message_envelope.message).__name__} for recipient {message_envelope.recipient} from {message_envelope.sender.name}: {content}"
        )
        # event_logger.info(
        #     MessageEvent(
        #         payload=message_envelope.message,
        #         sender=message_envelope.sender,
        #         receiver=message_envelope.recipient,
        #         kind=MessageKind.RESPOND,
        #         delivery_stage=DeliveryStage.DELIVER,
        #     )
        # )
        self._outstanding_tasks.decrement()
        message_envelope.future.set_result(message_envelope.message)

    async def process_next(self) -> None:
        if len(self._message_queue) == 0:
            # Yield control to the event loop to allow other tasks to run
            await asyncio.sleep(0)
            return

        message_envelope = self._message_queue.pop(0)

        match message_envelope:
            case SendMessageEnvelope(message=message, sender=sender, recipient=recipient, future=future):
                if self._intervention_handler is not None:
                    try:
                        temp_message = await self._intervention_handler.on_send(
                            message, sender=sender, recipient=recipient
                        )
                    except BaseException as e:
                        future.set_exception(e)
                        return
                    if temp_message is DropMessage or isinstance(temp_message, DropMessage):
                        future.set_exception(MessageDroppedException())
                        return

                    message_envelope.message = temp_message
                self._outstanding_tasks.increment()
                asyncio.create_task(self._process_send(message_envelope))
            case PublishMessageEnvelope(
                message=message,
                sender=sender,
            ):
                if self._intervention_handler is not None:
                    try:
                        temp_message = await self._intervention_handler.on_publish(message, sender=sender)
                    except BaseException as e:
                        # TODO: we should raise the intervention exception to the publisher.
                        logger.error(f"Exception raised in in intervention handler: {e}", exc_info=True)
                        return
                    if temp_message is DropMessage or isinstance(temp_message, DropMessage):
                        # TODO log message dropped
                        return

                    message_envelope.message = temp_message
                self._outstanding_tasks.increment()
                asyncio.create_task(self._process_publish(message_envelope))
            case ResponseMessageEnvelope(message=message, sender=sender, recipient=recipient, future=future):
                if self._intervention_handler is not None:
                    try:
                        temp_message = await self._intervention_handler.on_response(
                            message, sender=sender, recipient=recipient
                        )
                    except BaseException as e:
                        # TODO: should we raise the exception to sender of the response instead?
                        future.set_exception(e)
                        return
                    if temp_message is DropMessage or isinstance(temp_message, DropMessage):
                        future.set_exception(MessageDroppedException())
                        return

                    message_envelope.message = temp_message
                self._outstanding_tasks.increment()
                asyncio.create_task(self._process_response(message_envelope))

        # Yield control to the message loop to allow other tasks to run
        await asyncio.sleep(0)

    def agent_metadata(self, agent: AgentId) -> AgentMetadata:
        return self._get_agent(agent).metadata

    def agent_save_state(self, agent: AgentId) -> Mapping[str, Any]:
        return self._get_agent(agent).save_state()

    def agent_load_state(self, agent: AgentId, state: Mapping[str, Any]) -> None:
        self._get_agent(agent).load_state(state)

    def register(
        self,
        name: str,
        agent_factory: Callable[[], T] | Callable[[AgentRuntime, AgentId], T],
    ) -> None:
        if name in self._agent_factories:
            raise ValueError(f"Agent with name {name} already exists.")
        self._agent_factories[name] = agent_factory

        # For all already prepared namespaces we need to prepare this agent
        for namespace in self._known_namespaces:
            self._get_agent(AgentId(name=name, namespace=namespace))

    def _invoke_agent_factory(
        self, agent_factory: Callable[[], T] | Callable[[AgentRuntime, AgentId], T], agent_id: AgentId
    ) -> T:
        token = agent_instantiation_context.set((self, agent_id))

        if len(inspect.signature(agent_factory).parameters) == 0:
            factory_one = cast(Callable[[], T], agent_factory)
            agent = factory_one()
        elif len(inspect.signature(agent_factory).parameters) == 2:
            factory_two = cast(Callable[[AgentRuntime, AgentId], T], agent_factory)
            agent = factory_two(self, agent_id)
        else:
            raise ValueError("Agent factory must take 0 or 2 arguments.")

        agent_instantiation_context.reset(token)

        return agent

    def _get_agent(self, agent_id: AgentId) -> Agent:
        self._process_seen_namespace(agent_id.namespace)
        if agent_id in self._instantiated_agents:
            return self._instantiated_agents[agent_id]

        if agent_id.name not in self._agent_factories:
            raise ValueError(f"Agent with name {agent_id.name} not found.")

        agent_factory = self._agent_factories[agent_id.name]

        agent = self._invoke_agent_factory(agent_factory, agent_id)
        for message_type in agent.metadata["subscriptions"]:
            self._per_type_subscribers[(agent_id.namespace, message_type)].add(agent_id)
        self._instantiated_agents[agent_id] = agent
        return agent

    def get(self, name: str, *, namespace: str = "default") -> AgentId:
        return self._get_agent(AgentId(name=name, namespace=namespace)).id

    def get_proxy(self, name: str, *, namespace: str = "default") -> AgentProxy:
        id = self.get(name, namespace=namespace)
        return AgentProxy(id, self)

    # Hydrate the agent instances in a namespace. The primary reason for this is
    # to ensure message type subscriptions are set up.
    def _process_seen_namespace(self, namespace: str) -> None:
        if namespace in self._known_namespaces:
            return

        self._known_namespaces.add(namespace)
        for name in self._known_agent_names:
            self._get_agent(AgentId(name=name, namespace=namespace))