"""OEM 用户与 oem 表主键解析（全局缓存，多模块共用）。"""

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.oem import Oem
from app.models.user import User

# user_id -> oem 表主键（desktop_configs.oem_id 等同此值）
_oem_id_by_user_id: dict[int, int] = {}


def invalidate_oem_id_cache(user_id: int | None = None) -> None:
    """清除 resolve 缓存；user_id 为 None 时清空全部。"""
    if user_id is None:
        _oem_id_by_user_id.clear()
    else:
        _oem_id_by_user_id.pop(user_id, None)


async def resolve_oem_id_for_user_id(db: AsyncSession, user_id: int) -> int:
    """
    解析 OEM 用户在业务表中的 oem_id（oem 表主键）。
    若尚无 oem 记录，回退为 user_id（与 desktop_configs 历史逻辑一致）。
    """
    cached = _oem_id_by_user_id.get(user_id)
    if cached is not None:
        return cached

    oem_pk = await db.scalar(select(Oem.id).where(Oem.user_id == user_id))
    resolved = int(oem_pk) if oem_pk is not None else user_id
    _oem_id_by_user_id[user_id] = resolved
    return resolved


async def resolve_oem_id(db: AsyncSession, oem_user: User) -> int:
    """根据 User 模型解析 oem_id。"""
    return await resolve_oem_id_for_user_id(db, oem_user.id)


async def get_or_create_oem_for_user(db: AsyncSession, user_id: int) -> Oem:
    """按 user_id 获取 oem 行；不存在则创建并刷新缓存。"""
    existing = await db.scalar(select(Oem).where(Oem.user_id == user_id))
    if existing is not None:
        _oem_id_by_user_id[user_id] = existing.id
        return existing

    owner = await db.get(User, user_id)
    if owner is None:
        raise ValueError("关联用户不存在")

    oem = Oem(user_id=user_id, software_name="")
    db.add(oem)
    await db.flush()
    await db.refresh(oem)
    _oem_id_by_user_id[user_id] = oem.id
    return oem