"""MessageBus — async pub/sub hub that decouples channels from the agent dispatcher."""

from __future__ import annotations

import asyncio
import logging
import time
from collections.abc import Callable, Coroutine
from dataclasses import dataclass, field
from enum import StrEnum
from typing import Any

logger = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Message types
# ---------------------------------------------------------------------------


class InboundMessageType(StrEnum):
    """Types of messages arriving from IM channels."""

    CHAT = "chat"
    COMMAND = "command"


@dataclass
class InboundMessage:
    """A message arriving from an IM channel toward the agent dispatcher.

    Attributes:
        channel_name: Name of the source channel (e.g. "feishu", "slack").
        chat_id: Platform-specific chat/conversation identifier.
        user_id: Platform-specific user identifier.
        text: The message text.
        msg_type: Whether this is a regular chat message or a command.
        thread_ts: Optional platform thread identifier (for threaded replies).
        topic_id: Conversation topic identifier used to map to a DeerFlow thread.
            Messages sharing the same ``topic_id`` within a ``chat_id`` will
            reuse the same DeerFlow thread.  When ``None``, each message
            creates a new thread (one-shot Q&A).
        files: Optional list of file attachments (platform-specific dicts).
        metadata: Arbitrary extra data from the channel.
        created_at: Unix timestamp when the message was created.
    """

    channel_name: str
    chat_id: str
    user_id: str
    text: str
    msg_type: InboundMessageType = InboundMessageType.CHAT
    thread_ts: str | None = None
    topic_id: str | None = None
    files: list[dict[str, Any]] = field(default_factory=list)
    metadata: dict[str, Any] = field(default_factory=dict)
    created_at: float = field(default_factory=time.time)


@dataclass
class OutboundMessage:
    """A message from the agent dispatcher back to a channel.

    Attributes:
        channel_name: Target channel name (used for routing).
        chat_id: Target chat/conversation identifier.
        thread_id: DeerFlow thread ID that produced this response.
        text: The response text.
        artifacts: List of artifact paths produced by the agent.
        is_final: Whether this is the final message in the response stream.
        thread_ts: Optional platform thread identifier for threaded replies.
        metadata: Arbitrary extra data.
        created_at: Unix timestamp.
    """

    channel_name: str
    chat_id: str
    thread_id: str
    text: str
    artifacts: list[str] = field(default_factory=list)
    is_final: bool = True
    thread_ts: str | None = None
    metadata: dict[str, Any] = field(default_factory=dict)
    created_at: float = field(default_factory=time.time)


# ---------------------------------------------------------------------------
# MessageBus
# ---------------------------------------------------------------------------

OutboundCallback = Callable[[OutboundMessage], Coroutine[Any, Any, None]]


class MessageBus:
    """Async pub/sub hub connecting channels and the agent dispatcher.

    Channels publish inbound messages; the dispatcher consumes them.
    The dispatcher publishes outbound messages; channels receive them
    via registered callbacks.
    """

    def __init__(self) -> None:
        self._inbound_queue: asyncio.Queue[InboundMessage] = asyncio.Queue()
        self._outbound_listeners: list[OutboundCallback] = []

    # -- inbound -----------------------------------------------------------

    async def publish_inbound(self, msg: InboundMessage) -> None:
        """Enqueue an inbound message from a channel."""
        await self._inbound_queue.put(msg)
        logger.info(
            "[Bus] inbound enqueued: channel=%s, chat_id=%s, type=%s, queue_size=%d",
            msg.channel_name,
            msg.chat_id,
            msg.msg_type.value,
            self._inbound_queue.qsize(),
        )

    async def get_inbound(self) -> InboundMessage:
        """Block until the next inbound message is available."""
        return await self._inbound_queue.get()

    @property
    def inbound_queue(self) -> asyncio.Queue[InboundMessage]:
        return self._inbound_queue

    # -- outbound ----------------------------------------------------------

    def subscribe_outbound(self, callback: OutboundCallback) -> None:
        """Register an async callback for outbound messages."""
        self._outbound_listeners.append(callback)

    def unsubscribe_outbound(self, callback: OutboundCallback) -> None:
        """Remove a previously registered outbound callback."""
        self._outbound_listeners = [cb for cb in self._outbound_listeners if cb is not callback]

    async def publish_outbound(self, msg: OutboundMessage) -> None:
        """Dispatch an outbound message to all registered listeners."""
        logger.info(
            "[Bus] outbound dispatching: channel=%s, chat_id=%s, listeners=%d, text_len=%d",
            msg.channel_name,
            msg.chat_id,
            len(self._outbound_listeners),
            len(msg.text),
        )
        for callback in self._outbound_listeners:
            try:
                await callback(msg)
            except Exception:
                logger.exception("Error in outbound callback for channel=%s", msg.channel_name)