"""A股单批entry_date可卖检查；给定2026国庆跨休市会话，不做全批次冻结。"""
from decimal import Decimal as D
import json

sessions=['2026-09-30','2026-10-08','2026-10-09']


class Account:
    def __init__(self):
        self.cash,self.quantity,self.entry,self.fees,self.realized=D(5000),0,None,0,D(0)

    def buy(self,day,quantity,price):
        if day not in sessions: raise ValueError('not_a_session')
        if self.quantity: raise ValueError('additional_batch_unsupported')
        price=D(str(price))
        if type(quantity) is not int or quantity<=0 or not price.is_finite() or price<=0:
            raise ValueError('invalid_order')
        cost=quantity*price+1
        if cost>self.cash: raise ValueError('cash')
        self.cash-=cost;self.quantity=quantity;self.entry=day;self.entry_price=price;self.fees+=1

    def sell(self,day,price):
        if day not in sessions: return {'status':'not_a_session'}
        if not self.quantity: return {'status':'no_position'}
        if sessions.index(day)<=sessions.index(self.entry): return {'status':'T_plus_1_blocked'}
        price=D(str(price))
        if not price.is_finite() or price<=0: raise ValueError('invalid_price')
        quantity=self.quantity
        self.cash+=quantity*price-1;self.realized+=quantity*(price-self.entry_price)
        self.quantity=0;self.fees+=1
        return {'status':'filled','day':day,'quantity':quantity,'price':str(price),'fee':1}


a=Account();a.buy('2026-09-30',100,10)
assert a.cash==3999 and a.quantity==100 and a.fees==1 and a.realized==0
buy_record={'day':a.entry,'side':'buy','quantity':a.quantity,'price':str(a.entry_price),
            'cash_after':str(a.cash),'fees':a.fees}
blocked=a.sell('2026-09-30',10.5)
assert blocked=={'status':'T_plus_1_blocked'}
assert a.cash==3999 and a.quantity==100 and a.fees==1 and a.realized==0
blocked_state={'cash':str(a.cash),'quantity':a.quantity,'fees':a.fees,'realized_price_pnl':str(a.realized)}
holiday=a.sell('2026-10-01',10.5)
assert holiday=={'status':'not_a_session'} and a.cash==3999 and a.quantity==100
try: a.buy('2026-10-08',100,9.5)
except ValueError as e: assert str(e)=='additional_batch_unsupported'
else: raise AssertionError('单entry_date模型不能冒充逐批次持仓系统')
filled=a.sell('2026-10-08',9.5)
assert filled=={'status':'filled','day':'2026-10-08','quantity':100,'price':'9.5','fee':1}
assert a.cash==4948 and a.quantity==0 and a.fees==2 and a.realized==-50
assert a.cash-D(5000)==a.realized-a.fees==D(-52)
assert (D('10.5')-D(10))*100-D(2)==48  # 被禁止同日卖出的虚假净利，不能入账
print(json.dumps({'provided_sessions':sessions,'buy':buy_record,'same_day_attempt':blocked,
                  'blocked_state':blocked_state,'holiday_attempt':holiday,
                  'next_session_fill':filled,'ending_cash':str(a.cash),'quantity':a.quantity,
                  'fees':a.fees,'realized_price_pnl':str(a.realized),'net_cash_pnl':str(a.cash-D(5000)),
                  'scope':'ordinary A-share synthetic single-entry cash model, no per-lot freeze system'}))