"""链路追踪模块"""
import uuid
from contextvars import ContextVar
from typing import Optional

# 上下文变量存储trace_id
_trace_id_var: ContextVar[Optional[str]] = ContextVar("trace_id", default=None)
_tenant_id_var: ContextVar[Optional[int]] = ContextVar("tenant_id", default=None)
_user_id_var: ContextVar[Optional[int]] = ContextVar("user_id", default=None)


def generate_trace_id() -> str:
    """生成新的trace_id"""
    return str(uuid.uuid4())


def get_trace_id() -> Optional[str]:
    """获取当前trace_id"""
    return _trace_id_var.get()


def set_trace_id(trace_id: str) -> None:
    """设置当前trace_id"""
    _trace_id_var.set(trace_id)


def get_tenant_id() -> Optional[int]:
    """获取当前租户ID"""
    return _tenant_id_var.get()


def set_tenant_id(tenant_id: int) -> None:
    """设置当前租户ID"""
    _tenant_id_var.set(tenant_id)


def get_user_id() -> Optional[int]:
    """获取当前用户ID"""
    return _user_id_var.get()


def set_user_id(user_id: int) -> None:
    """设置当前用户ID"""
    _user_id_var.set(user_id)


class TraceContext:
    """链路追踪上下文管理器
    
    使用示例:
        with TraceContext(tenant_id=1, user_id=100) as ctx:
            print(ctx.trace_id)
            # 在此上下文中的所有操作都会使用相同的trace_id
    """
    
    def __init__(
        self,
        trace_id: Optional[str] = None,
        tenant_id: Optional[int] = None,
        user_id: Optional[int] = None
    ):
        self.trace_id = trace_id or generate_trace_id()
        self.tenant_id = tenant_id
        self.user_id = user_id
        self._tokens = []
    
    def __enter__(self):
        self._tokens.append(_trace_id_var.set(self.trace_id))
        if self.tenant_id is not None:
            self._tokens.append(_tenant_id_var.set(self.tenant_id))
        if self.user_id is not None:
            self._tokens.append(_user_id_var.set(self.user_id))
        return self
    
    def __exit__(self, exc_type, exc_val, exc_tb):
        for token in self._tokens:
            # 重置为之前的值
            pass
        return False