import logging
from datetime import UTC, datetime
from typing import NotRequired, override

from langchain.agents import AgentState
from langchain.agents.middleware import AgentMiddleware
from langchain_core.messages import HumanMessage
from langgraph.config import get_config
from langgraph.runtime import Runtime

from deerflow.agents.thread_state import ThreadDataState
from deerflow.config.paths import Paths, get_paths
from deerflow.runtime.user_context import get_effective_user_id
from deerflow.runtime.workspace_context import get_effective_workspace_id

logger = logging.getLogger(__name__)


class ThreadDataMiddlewareState(AgentState):
    """Compatible with the `ThreadState` schema."""

    thread_data: NotRequired[ThreadDataState | None]


class ThreadDataMiddleware(AgentMiddleware[ThreadDataMiddlewareState]):
    """Create thread data directories for each thread execution.

    PR6 routes thread storage through the workspace dimension. When a
    workspace contextvar is set (production via AuthMiddleware; tests via
    the autouse fixture), directories live at
    ``{base_dir}/workspaces/{wid}/threads/{thread_id}/user-data/{workspace,uploads,outputs}``.
    In no-auth dev mode ``get_effective_workspace_id()`` returns
    ``"default"`` so the layout stays valid; the ``user_id`` falls through
    to the same default constant. Either way thread state lives below a
    workspace bucket, never directly under ``{base_dir}/threads`` (legacy)
    or ``{base_dir}/users`` (PR4 layout).

    Lifecycle Management:
    - With lazy_init=True (default): Only compute paths, directories created on-demand
    - With lazy_init=False: Eagerly create directories in before_agent()
    """

    state_schema = ThreadDataMiddlewareState

    def __init__(self, base_dir: str | None = None, lazy_init: bool = True):
        """Initialize the middleware.

        Args:
            base_dir: Base directory for thread data. Defaults to Paths resolution.
            lazy_init: If True, defer directory creation until needed.
                      If False, create directories eagerly in before_agent().
                      Default is True for optimal performance.
        """
        super().__init__()
        self._paths = Paths(base_dir) if base_dir else get_paths()
        self._lazy_init = lazy_init

    def _get_thread_paths(self, thread_id: str, *, workspace_id: str, user_id: str) -> dict[str, str]:
        return {
            "workspace_path": str(self._paths.sandbox_work_dir(thread_id, workspace_id=workspace_id)),
            "uploads_path": str(self._paths.sandbox_uploads_dir(thread_id, workspace_id=workspace_id)),
            "outputs_path": str(self._paths.sandbox_outputs_dir(thread_id, workspace_id=workspace_id)),
            "user_id": user_id,
            "workspace_id": workspace_id,
        }

    def _create_thread_directories(self, thread_id: str, *, workspace_id: str, user_id: str) -> dict[str, str]:
        self._paths.ensure_thread_dirs(thread_id, workspace_id=workspace_id)
        return self._get_thread_paths(thread_id, workspace_id=workspace_id, user_id=user_id)

    @override
    def before_agent(self, state: ThreadDataMiddlewareState, runtime: Runtime) -> dict | None:
        context = runtime.context or {}
        thread_id = context.get("thread_id")
        if thread_id is None:
            config = get_config()
            thread_id = config.get("configurable", {}).get("thread_id")

        if thread_id is None:
            raise ValueError("Thread ID is required in runtime context or config.configurable")

        user_id = get_effective_user_id()
        workspace_id = get_effective_workspace_id()

        if self._lazy_init:
            # Lazy initialization: only compute paths, don't create directories
            paths = self._get_thread_paths(thread_id, workspace_id=workspace_id, user_id=user_id)
        else:
            # Eager initialization: create directories immediately
            paths = self._create_thread_directories(thread_id, workspace_id=workspace_id, user_id=user_id)
            logger.debug("Created thread data directories for thread %s under workspace %s", thread_id, workspace_id)

        messages = list(state.get("messages", []))
        last_message = messages[-1] if messages else None

        if last_message and isinstance(last_message, HumanMessage):
            messages[-1] = HumanMessage(
                content=last_message.content,
                id=last_message.id,
                name=last_message.name or "user-input",
                additional_kwargs={**last_message.additional_kwargs, "run_id": runtime.context.get("run_id"), "timestamp": datetime.now(UTC).isoformat()},
            )

        return {
            "thread_data": {
                **paths,
            },
            "messages": messages,
        }