"""资源购买的有效价格与写事务准备；调用方负责提交/回滚。"""
import datetime
from tip_transaction import lock_wallet_accounts


def effective_resource_price(item):
    price = item.get("price", 0)
    pending = item.get("pending_price")
    effective = item.get("pending_price_effective_at")
    if pending is not None and effective:
        when = datetime.datetime.fromisoformat(effective)
        now = datetime.datetime.now(when.tzinfo) if when.tzinfo else datetime.datetime.now()
        if now >= when:
            price = pending
    if type(price) is float and price.is_integer() and 0 <= price <= 2147483647:
        price = int(price)
    if isinstance(price, bool) or not isinstance(price, int) or price < 0:
        raise ValueError("invalid resource price")
    return price


def lock_resource_purchase_wallets(session, buyer, seller, free):
    # 免费/作者本人仍需买方钱包行作为跨进程所有权查重的锁锚点。
    accounts = (buyer,) if free else (buyer, seller)
    create = (buyer,) if free else (seller,)
    wallets = lock_wallet_accounts(session, accounts, create)
    return wallets[buyer], wallets.get(seller)