"""NL2SQL Supervisor 的意图和会话并发控制。"""
from __future__ import annotations

from uuid import uuid4


class UnsupportedIntent(ValueError):
    """当前版本不支持的查询意图。"""


class SessionBusyError(RuntimeError):
    """同一会话已有查询运行。"""


def detect_intent(question: str) -> str:
    """根据有限关键词识别当前版本的任务类型。"""
    text = question.lower()
    if "etl" in text or "数据任务" in text:
        return "etl_build"
    if "口径" in text or "caliber" in text:
        return "caliber_maintain"
    if "血缘" in text or "lineage" in text:
        return "lineage_query"
    return "query"


def ensure_query_intent(question: str) -> None:
    """M1 只允许 query 意图进入 SQL 主链路。"""
    intent = detect_intent(question)
    if intent != "query":
        raise UnsupportedIntent(f"当前不支持 {intent} 意图")


class SessionLock:
    """基于 Redis NX 的同会话互斥锁。"""

    def __init__(self, redis, session_id: str, *, ttl: int = 120):
        self.redis = redis
        self.key = f"nl2sql:session:{session_id}:lock"
        self.token = uuid4().hex
        self.ttl = ttl
        self.acquired = False

    async def acquire(self) -> None:
        if not await self.redis.set(self.key, self.token, nx=True, ex=self.ttl):
            raise SessionBusyError("同一会话已有查询运行")
        self.acquired = True

    async def release(self) -> None:
        if not self.acquired:
            return
        release_script = """
        if redis.call('get', KEYS[1]) == ARGV[1] then
            return redis.call('del', KEYS[1])
        end
        return 0
        """
        if hasattr(self.redis, "eval"):
            await self.redis.eval(release_script, 1, self.key, self.token)
        else:
            current = await self.redis.get(self.key)
            if current in {self.token, self.token.encode()}:
                await self.redis.delete(self.key)
        self.acquired = False