import asyncio
from contextlib import asynccontextmanager
from contextvars import ContextVar
import time
from typing import Any

from pydantic import BaseModel, ConfigDict, Field

from zhenxun.services.ai.core.models import CancellationToken
from zhenxun.services.ai.utils.scope import BaseScopeBuilder, ScopeSelector


class PendingMessageQueue:
    """简单的运行时挂起消息队列"""

    def __init__(self):
        self._queue: list[Any] = []

    def enqueue(self, msg: Any):
        self._queue.append(msg)

    def drain(self) -> list[Any]:
        msgs = list(self._queue)
        self._queue.clear()
        return msgs

    def has_items(self) -> bool:
        return len(self._queue) > 0


class TaskStopper(BaseScopeBuilder["TaskStopper"]):
    """
    声明式任务中止器 (Fluent Task Stopper)。
    为第三方开发者提供友好的链式 API，精准中止正在运行或排队的大模型任务。
    """

    def __init__(self, manager: "AgentSessionManager"):
        super().__init__()
        self.manager = manager

    async def cancel(self) -> int:
        """执行中止动作，返回被成功中止的任务数量。"""
        return await self.manager.cancel_by_query(self._selector)


class SessionInfo(BaseModel):
    """会话信息的元数据视图。"""

    model_config = ConfigDict(arbitrary_types_allowed=True)

    session_id: str
    """会话的唯一标识符"""
    state: dict[str, Any] = Field(default_factory=dict)
    """业务流转的强类型载荷"""
    created_at: float = Field(default_factory=time.time)
    """会话创建的时间戳"""
    updated_at: float = Field(default_factory=time.time)
    """会话最后更新的时间戳"""
    active_task: Any | None = Field(default=None)
    """当前正在执行的 asyncio.Task"""
    cancel_token: CancellationToken | None = Field(default=None)
    """当前任务的取消令牌"""
    steer_queue: PendingMessageQueue = Field(default_factory=PendingMessageQueue)
    """动态转向指令干预队列"""
    follow_up_queue: PendingMessageQueue = Field(default_factory=PendingMessageQueue)
    """后续追加指令干预队列"""


class LockContext(BaseModel):
    """并发锁的执行追踪器（解决 INTERRUPT 需要跨 Session 取消任务的问题）"""

    model_config = ConfigDict(arbitrary_types_allowed=True)
    active_task: Any | None = None
    """当前持锁运行的异步任务"""
    cancel_token: CancellationToken | None = None
    """当前任务关联的取消令牌，以便由抢占者随时下发取消指令"""


class AgentSessionManager:
    """
    Agent 会话状态管理器。
    彻底拥抱无状态：只维护业务强类型载荷 (state payload) 以及并发锁，不干涉 LLM 历史。
    """

    def __init__(self):
        self._sessions: dict[str, SessionInfo] = {}
        self._locks: dict[str, asyncio.Lock] = {}
        self._exec_locks: dict[str, asyncio.Lock] = {}
        self.lock_contexts: dict[str, LockContext] = {}
        self.live_tasks: dict[str, list[tuple[CancellationToken, Any]]] = {}

    def stopper(self) -> TaskStopper:
        """获取声明式任务中止器，供第三方开发者极速中止运行中/排队中的任务"""
        return TaskStopper(self)

    async def cancel_by_query(self, query: ScopeSelector) -> int:
        """根据查询条件取消符合条件的会话任务。返回取消的数量"""
        count = 0
        scope_prefix = query.scope_prefix

        for sid, tasks in list(self.live_tasks.items()):
            if sid.startswith(scope_prefix) or (
                query.session_id and sid == query.session_id
            ):
                for token, task in tasks:
                    if not token.is_cancelled():
                        token.cancel()
                        count += 1
                    if task and not task.done():
                        task.cancel()
                from zhenxun.services.ai.utils.logger import log_agent as logger

                if count > 0:
                    logger.info(
                        f"🛑 [TaskStopper] 已强制终止排队或执行中的会话任务: {sid}"
                    )
        return count

    def _get_lock(self, session_id: str) -> asyncio.Lock:
        """获取或创建指定会话的内部同步锁"""
        if session_id not in self._locks:
            self._locks[session_id] = asyncio.Lock()
        return self._locks[session_id]

    def get_exec_lock(self, session_id: str) -> asyncio.Lock:
        """获取或创建指定会话的任务排队执行锁"""
        if session_id not in self._exec_locks:
            self._exec_locks[session_id] = asyncio.Lock()
        return self._exec_locks[session_id]

    async def get_or_create(self, session_id: str) -> SessionInfo:
        """获取或创建指定会话的信息，不存在则自动初始化"""
        async with self._get_lock(session_id):
            if session_id not in self._sessions:
                self._sessions[session_id] = SessionInfo(session_id=session_id)
            return self._sessions[session_id]

    async def get(self, session_id: str) -> SessionInfo | None:
        """获取指定会话的信息，不存在则返回 None"""
        async with self._get_lock(session_id):
            return self._sessions.get(session_id)

    async def update_state(self, session_id: str, new_state: dict[str, Any]):
        """用新字典更新指定会话的状态载荷"""
        async with self._get_lock(session_id):
            if session_id in self._sessions:
                self._sessions[session_id].state.update(new_state)
                self._sessions[session_id].updated_at = time.time()

    async def delete(self, session_id: str):
        """删除指定会话及其对应的长期内存上下文"""
        async with self._get_lock(session_id):
            self._sessions.pop(session_id, None)
            from zhenxun.services.ai.context.memory.manager import memory_manager
            from zhenxun.services.ai.context.memory.models import MemoryConfig
            from zhenxun.services.ai.context.memory.types import SessionMetadata

            default_ctx = memory_manager.get_chat_context(MemoryConfig())
            if default_ctx:
                await default_ctx.clear(SessionMetadata(session_id=session_id))


session_manager = AgentSessionManager()
active_session_id: ContextVar[str | None] = ContextVar(
    "active_session_id", default=None
)


@asynccontextmanager
async def agent_session_scope(session_id: str):
    """声明式上下文包装器。进入此作用域后的 Agent 都会自动吸附到指定的 SessionID 上。"""
    await session_manager.get_or_create(session_id)
    token = active_session_id.set(session_id)
    try:
        yield session_id
    finally:
        active_session_id.reset(token)