"""资金账户相关 DTO。

金额统一序列化为两位小数字符串（如 "48000.00"），避免 JSON number 的浮点精度隐患。
"""
from datetime import datetime
from decimal import Decimal
from typing import Literal

from pydantic import BaseModel, Field, field_serializer


class BalanceResp(BaseModel):
    """用户余额响应体。available_balance = balance - frozen_amount，由 service 派生。"""

    customer_id: int
    balance: Decimal
    available_balance: Decimal
    frozen_amount: Decimal
    currency: str
    status: str
    update_time: datetime | None = None

    @field_serializer("balance", "available_balance", "frozen_amount")
    def _fmt_money(self, value: Decimal) -> str:
        return f"{value:.2f}"


class AdjustReq(BaseModel):
    """加减余额入参。amount 为正数（元），direction 决定加/减。"""

    direction: Literal["add", "sub"] = Field(
        ..., description="add=入账(充值)，sub=出账(提现)"
    )
    amount: Decimal = Field(gt=0)