"""ChannelManager — consumes inbound messages and dispatches them to the DeerFlow agent via LangGraph Server."""

from __future__ import annotations

import asyncio
import logging

from src.channels.message_bus import InboundMessage, InboundMessageType, MessageBus, OutboundMessage
from src.channels.store import ChannelStore

logger = logging.getLogger(__name__)

DEFAULT_LANGGRAPH_URL = "http://localhost:2024"
DEFAULT_GATEWAY_URL = "http://localhost:8001"
DEFAULT_ASSISTANT_ID = "lead_agent"


def _extract_response_text(result: dict | list) -> str:
    """Extract the last AI message text from a LangGraph runs.wait result.

    ``runs.wait`` returns the final state dict which contains a ``messages``
    list.  Each message is a dict with at least ``type`` and ``content``.

    Handles special cases:
    - Regular AI text responses
    - Clarification interrupts (``ask_clarification`` tool messages)
    - AI messages with tool_calls but no text content
    """
    if isinstance(result, list):
        messages = result
    elif isinstance(result, dict):
        messages = result.get("messages", [])
    else:
        return ""

    # Walk backwards to find usable response text
    for msg in reversed(messages):
        if not isinstance(msg, dict):
            continue

        msg_type = msg.get("type")

        # Check for tool messages from ask_clarification (interrupt case)
        if msg_type == "tool" and msg.get("name") == "ask_clarification":
            content = msg.get("content", "")
            if isinstance(content, str) and content:
                return content

        # Regular AI message with text content
        if msg_type == "ai":
            content = msg.get("content", "")
            if isinstance(content, str) and content:
                return content
            # content can be a list of content blocks
            if isinstance(content, list):
                parts = []
                for block in content:
                    if isinstance(block, dict) and block.get("type") == "text":
                        parts.append(block.get("text", ""))
                    elif isinstance(block, str):
                        parts.append(block)
                text = "".join(parts)
                if text:
                    return text
    return ""


def _extract_artifacts(result: dict | list) -> list[str]:
    """Extract artifact paths from the last AI response cycle only.

    Instead of reading the full accumulated ``artifacts`` state (which contains
    all artifacts ever produced in the thread), this inspects the messages after
    the last human message and collects file paths from ``present_files`` tool
    calls.  This ensures only newly-produced artifacts are returned.
    """
    if isinstance(result, list):
        messages = result
    elif isinstance(result, dict):
        messages = result.get("messages", [])
    else:
        return []

    artifacts: list[str] = []
    for msg in reversed(messages):
        if not isinstance(msg, dict):
            continue
        # Stop at the last human message — anything before it is a previous turn
        if msg.get("type") == "human":
            break
        # Look for AI messages with present_files tool calls
        if msg.get("type") == "ai":
            for tc in msg.get("tool_calls", []):
                if isinstance(tc, dict) and tc.get("name") == "present_files":
                    args = tc.get("args", {})
                    paths = args.get("filepaths", [])
                    if isinstance(paths, list):
                        artifacts.extend(p for p in paths if isinstance(p, str))
    return artifacts


def _format_artifact_text(artifacts: list[str]) -> str:
    """Format artifact paths into a human-readable text block listing filenames."""
    import posixpath

    filenames = [posixpath.basename(p) for p in artifacts]
    if len(filenames) == 1:
        return f"Created File: 📎 {filenames[0]}"
    return "Created Files: 📎 " + "、".join(filenames)


class ChannelManager:
    """Core dispatcher that bridges IM channels to the DeerFlow agent.

    It reads from the MessageBus inbound queue, creates/reuses threads on
    the LangGraph Server, sends messages via ``runs.wait``, and publishes
    outbound responses back through the bus.
    """

    def __init__(
        self,
        bus: MessageBus,
        store: ChannelStore,
        *,
        max_concurrency: int = 5,
        langgraph_url: str = DEFAULT_LANGGRAPH_URL,
        gateway_url: str = DEFAULT_GATEWAY_URL,
        assistant_id: str = DEFAULT_ASSISTANT_ID,
    ) -> None:
        self.bus = bus
        self.store = store
        self._max_concurrency = max_concurrency
        self._langgraph_url = langgraph_url
        self._gateway_url = gateway_url
        self._assistant_id = assistant_id
        self._client = None  # lazy init — langgraph_sdk async client
        self._semaphore: asyncio.Semaphore | None = None
        self._running = False
        self._task: asyncio.Task | None = None

    # -- LangGraph SDK client (lazy) ----------------------------------------

    def _get_client(self):
        """Return the ``langgraph_sdk`` async client, creating it on first use."""
        if self._client is None:
            from langgraph_sdk import get_client

            self._client = get_client(url=self._langgraph_url)
        return self._client

    # -- lifecycle ---------------------------------------------------------

    async def start(self) -> None:
        """Start the dispatch loop."""
        if self._running:
            return
        self._running = True
        self._semaphore = asyncio.Semaphore(self._max_concurrency)
        self._task = asyncio.create_task(self._dispatch_loop())
        logger.info("ChannelManager started (max_concurrency=%d)", self._max_concurrency)

    async def stop(self) -> None:
        """Stop the dispatch loop."""
        self._running = False
        if self._task:
            self._task.cancel()
            try:
                await self._task
            except asyncio.CancelledError:
                pass
            self._task = None
        logger.info("ChannelManager stopped")

    # -- dispatch loop -----------------------------------------------------

    async def _dispatch_loop(self) -> None:
        logger.info("[Manager] dispatch loop started, waiting for inbound messages")
        while self._running:
            try:
                msg = await asyncio.wait_for(self.bus.get_inbound(), timeout=1.0)
            except TimeoutError:
                continue
            except asyncio.CancelledError:
                break

            logger.info(
                "[Manager] received inbound: channel=%s, chat_id=%s, type=%s, text=%r",
                msg.channel_name,
                msg.chat_id,
                msg.msg_type.value,
                msg.text[:100] if msg.text else "",
            )
            task = asyncio.create_task(self._handle_message(msg))
            task.add_done_callback(self._log_task_error)

    @staticmethod
    def _log_task_error(task: asyncio.Task) -> None:
        """Surface unhandled exceptions from background tasks."""
        if task.cancelled():
            return
        exc = task.exception()
        if exc:
            logger.error("[Manager] unhandled error in message task: %s", exc, exc_info=exc)

    async def _handle_message(self, msg: InboundMessage) -> None:
        async with self._semaphore:
            try:
                if msg.msg_type == InboundMessageType.COMMAND:
                    await self._handle_command(msg)
                else:
                    await self._handle_chat(msg)
            except Exception:
                logger.exception(
                    "Error handling message from %s (chat=%s)",
                    msg.channel_name,
                    msg.chat_id,
                )
                await self._send_error(msg, "An internal error occurred. Please try again.")

    # -- chat handling -----------------------------------------------------

    async def _create_thread(self, client, msg: InboundMessage) -> str:
        """Create a new thread on the LangGraph Server and store the mapping."""
        thread = await client.threads.create()
        thread_id = thread["thread_id"]
        self.store.set_thread_id(
            msg.channel_name,
            msg.chat_id,
            thread_id,
            topic_id=msg.topic_id,
            user_id=msg.user_id,
        )
        logger.info("[Manager] new thread created on LangGraph Server: thread_id=%s for chat_id=%s topic_id=%s", thread_id, msg.chat_id, msg.topic_id)
        return thread_id

    async def _handle_chat(self, msg: InboundMessage) -> None:
        client = self._get_client()

        # Look up existing DeerFlow thread by topic_id (if present)
        thread_id = None
        if msg.topic_id:
            thread_id = self.store.get_thread_id(msg.channel_name, msg.chat_id, topic_id=msg.topic_id)
            if thread_id:
                logger.info("[Manager] reusing thread: thread_id=%s for topic_id=%s", thread_id, msg.topic_id)

        # No existing thread found — create a new one
        if thread_id is None:
            thread_id = await self._create_thread(client, msg)

        logger.info("[Manager] invoking runs.wait(thread_id=%s, text=%r)", thread_id, msg.text[:100])
        result = await client.runs.wait(
            thread_id,
            self._assistant_id,
            input={"messages": [{"role": "human", "content": msg.text}]},
            config={"recursion_limit": 100},
            context={
                "thread_id": thread_id,
                "thinking_enabled": True,
                "is_plan_mode": False,
                "subagent_enabled": False,
            },
        )

        response_text = _extract_response_text(result)
        artifacts = _extract_artifacts(result)

        logger.info(
            "[Manager] agent response received: thread_id=%s, response_len=%d, artifacts=%d",
            thread_id,
            len(response_text) if response_text else 0,
            len(artifacts),
        )

        # Append artifact filenames when present
        if artifacts:
            artifact_text = _format_artifact_text(artifacts)
            if response_text:
                response_text = response_text + "\n\n" + artifact_text
            else:
                response_text = artifact_text

        if not response_text:
            response_text = "(No response from agent)"

        outbound = OutboundMessage(
            channel_name=msg.channel_name,
            chat_id=msg.chat_id,
            thread_id=thread_id,
            text=response_text,
            artifacts=artifacts,
            thread_ts=msg.thread_ts,
        )
        logger.info("[Manager] publishing outbound message to bus: channel=%s, chat_id=%s", msg.channel_name, msg.chat_id)
        await self.bus.publish_outbound(outbound)

    # -- command handling --------------------------------------------------

    async def _handle_command(self, msg: InboundMessage) -> None:
        text = msg.text.strip()
        parts = text.split(maxsplit=1)
        command = parts[0].lower().lstrip("/")

        if command == "new":
            # Create a new thread on the LangGraph Server
            client = self._get_client()
            thread = await client.threads.create()
            new_thread_id = thread["thread_id"]
            self.store.set_thread_id(
                msg.channel_name,
                msg.chat_id,
                new_thread_id,
                topic_id=msg.topic_id,
                user_id=msg.user_id,
            )
            reply = "New conversation started."
        elif command == "status":
            thread_id = self.store.get_thread_id(msg.channel_name, msg.chat_id, topic_id=msg.topic_id)
            reply = f"Active thread: {thread_id}" if thread_id else "No active conversation."
        elif command == "models":
            reply = await self._fetch_gateway("/api/models", "models")
        elif command == "memory":
            reply = await self._fetch_gateway("/api/memory", "memory")
        elif command == "help":
            reply = "Available commands:\n/new — Start a new conversation\n/status — Show current thread info\n/models — List available models\n/memory — Show memory status\n/help — Show this help"
        else:
            reply = f"Unknown command: /{command}. Type /help for available commands."

        outbound = OutboundMessage(
            channel_name=msg.channel_name,
            chat_id=msg.chat_id,
            thread_id=self.store.get_thread_id(msg.channel_name, msg.chat_id) or "",
            text=reply,
            thread_ts=msg.thread_ts,
        )
        await self.bus.publish_outbound(outbound)

    async def _fetch_gateway(self, path: str, kind: str) -> str:
        """Fetch data from the Gateway API for command responses."""
        import httpx

        try:
            async with httpx.AsyncClient() as http:
                resp = await http.get(f"{self._gateway_url}{path}", timeout=10)
                resp.raise_for_status()
                data = resp.json()
        except Exception:
            logger.exception("Failed to fetch %s from gateway", kind)
            return f"Failed to fetch {kind} information."

        if kind == "models":
            names = [m["name"] for m in data.get("models", [])]
            return ("Available models:\n" + "\n".join(f"• {n}" for n in names)) if names else "No models configured."
        elif kind == "memory":
            facts = data.get("facts", [])
            return f"Memory contains {len(facts)} fact(s)."
        return str(data)

    # -- error helper ------------------------------------------------------

    async def _send_error(self, msg: InboundMessage, error_text: str) -> None:
        outbound = OutboundMessage(
            channel_name=msg.channel_name,
            chat_id=msg.chat_id,
            thread_id=self.store.get_thread_id(msg.channel_name, msg.chat_id) or "",
            text=error_text,
            thread_ts=msg.thread_ts,
        )
        await self.bus.publish_outbound(outbound)