from __future__ import annotations

from fastapi import HTTPException
from sqlalchemy.ext.asyncio import AsyncSession

from app.enums.resource_capacity import RESOURCE_CAPACITY_EXCEEDED_MESSAGE, ResourceCapacityErrorCodeEnum
from app.models.user import User
from app.services.resource_capacity_service import get_user_resource_capacity_usage
from app.services.upload_resource.accounting_service import get_or_create_total_stat


def is_admin_user(user: User | object | None) -> bool:
    if user is None:
        return False
    try:
        if getattr(user, "user_type", None) == "admin":
            return True
        if bool(getattr(user, "is_admin", False)):
            return True
    except Exception:
        return False
    return False


async def assert_upload_capacity_available(
    db: AsyncSession,
    *,
    user: User,
    file_size_bytes: int,
) -> None:
    """上传容量拦截。

    admin 用户不拦截，但统计仍会入账。普通用户锁定 total_stat 行后判断：
    active_size_bytes + 本次上传大小 <= 容量上限。
    """
    if is_admin_user(user):
        return

    total_stat = await get_or_create_total_stat(db, user.id, for_update=True)
    usage = await get_user_resource_capacity_usage(db, user.id)
    if not usage.enabled or usage.total_bytes is None:
        return

    used = int(total_stat.active_size_bytes or 0)
    size = max(int(file_size_bytes or 0), 0)
    if used + size > int(usage.total_bytes or 0):
        raise HTTPException(
            status_code=400,
            detail=f"{RESOURCE_CAPACITY_EXCEEDED_MESSAGE}，本次上传 {size} 字节，当前已用 {used} 字节，总容量 {usage.total_bytes} 字节",
            headers={"X-Error-Code": ResourceCapacityErrorCodeEnum.RESOURCE_CAPACITY_EXCEEDED.value},
        )