"""资金账户服务：余额查询 + 余额加减（路由层只编排，不碰数据/逻辑）。"""
from __future__ import annotations

from decimal import Decimal

from sqlalchemy.ext.asyncio import AsyncSession

from model.fin_account import FinAccount
from model.sys_user import SysUser
from repositories.fin_account import FinAccountRepo
from schemas.account import BalanceResp
from utils.exceptions import ForbiddenError, NotFoundError, ParamError

_ZERO = Decimal("0.00")
_DEFAULT_CURRENCY = "CNY"


def _build_balance_resp(account: FinAccount) -> BalanceResp:
    return BalanceResp(
        customer_id=account.customer_id,
        balance=account.balance,
        available_balance=account.balance - account.frozen_amount,
        frozen_amount=account.frozen_amount,
        currency=account.currency,
        status=account.status,
        update_time=account.update_time,
    )


async def get_balance(db: AsyncSession, user: SysUser) -> BalanceResp:
    """查询当前用户现金余额。

    - 仅客户账号可查（员工共用 sys_user，但无资金账户）；
    - 未开资金户时按零余额返回，不报错。
    """
    if user.user_type != "CUSTOMER":
        raise ForbiddenError("仅客户账号可查询资金余额")

    account = await FinAccountRepo(db).get_by_customer_id(user.id)
    if account is None:
        return BalanceResp(
            customer_id=user.id,
            balance=_ZERO,
            available_balance=_ZERO,
            frozen_amount=_ZERO,
            currency=_DEFAULT_CURRENCY,
            status="正常",
        )

    return _build_balance_resp(account)


async def adjust_balance(
    db: AsyncSession, user: SysUser, direction: str, amount: Decimal
) -> BalanceResp:
    """加减余额：direction=add 入账 / sub 出账。

    - add：balance += amount，未开资金户时自动开户入账；
    - sub：balance -= amount，可用余额（balance - frozen_amount）不足时报错。
    """
    if user.user_type != "CUSTOMER":
        raise ForbiddenError("仅客户账号可调整余额")

    repo = FinAccountRepo(db)
    account = await repo.get_by_customer_id(user.id)

    if direction == "add":
        if account is None:
            account = await repo.create(user.id, amount)
        else:
            account = await repo.add_balance(user.id, amount)
    else:  # sub
        if account is None:
            raise NotFoundError("资金账户不存在")
        updated = await repo.subtract_balance(user.id, amount)
        if updated is None:
            raise ParamError("可用余额不足")
        account = updated

    return _build_balance_resp(account)