from __future__ import annotations

from gateway.core.channels.protocols import TraceBackend


class ChannelTraceRouter:
    """
    与具体 IM 无关：按渠道 user_id 解析 workspace_id，并委托 TraceBackend 与 Agent ``trace_id`` 对齐。

    飞书等渠道的入站消息路由见 ``gateway.core.channels.feishu.router.FeishuMessageRouter``。
    """

    def __init__(
        self,
        *,
        trace_backend: TraceBackend,
        workspace_prefix: str,
        default_agent_type: str = "personal_assistant",
    ) -> None:
        self._trace = trace_backend
        self._workspace_prefix = workspace_prefix
        self._agent_type = default_agent_type

    def _workspace_id_for_user(self, user_id: str) -> str:
        return f"{self._workspace_prefix}:{user_id}"

    async def get_trace_id(self, channel: str, user_id: str, *, create_if_missing: bool = True) -> str:
        """返回已绑定的 Agent trace_id；不存在时除非 ``create_if_missing=False`` 否则抛错（不再预分配 UUID）。"""
        tid = await self._trace.get_existing_trace_id(channel, user_id)
        if tid:
            return tid
        if not create_if_missing:
            raise NotImplementedError("无已绑定 trace_id 且 create_if_missing=False")
        raise RuntimeError(
            "尚无已绑定的 Agent trace_id：请先完成一次渠道入站（executor 成功返回后再 bind）。"
        )

    async def create_trace_for_user(self, channel: str, user_id: str) -> str:
        return await self.get_trace_id(channel, user_id, create_if_missing=True)