"""R631：相同固定排名的有状态缓冲成员政策，空位留现金。"""
from math import isfinite

RANKINGS=[['A','B','C','D'],['A','C','B','D'],['A','B','C','D'],['A','C','B','D'],['C','D','A','B'],['C','D','B','A']]


def select(ranking,old,buffered,blocked=()):
    if len(set(ranking))!=len(ranking):raise ValueError('duplicate security')
    ranks={s:i+1 for i,s in enumerate(ranking)}
    retained=[s for s in old if ranks.get(s,999)<=3] if buffered else []
    desired=list(retained)
    for s in ranking[:2]:
        if s not in desired and len(desired)<2:desired.append(s)
    if any(s in blocked for s in set(old)-set(desired)):
        return {'status':'blocked_exit','actual':list(old),'desired':desired,'retained':retained}
    return {'status':'applied','actual':desired,'desired':desired,'retained':retained}


def run(buffered):
    held=[];cash=1000.;qty={s:0. for s in 'ABCD'};notional=0.;rows=[];exits=0
    for t,ranking in enumerate(RANKINGS):
        result=select(ranking,held,buffered);new=result['actual']
        added=sorted(set(new)-set(held));removed=sorted(set(held)-set(new));exits+=len(removed)
        target={s:5. if s in new else 0. for s in qty}
        for side in ['sell','buy']:
            for s in qty:
                delta=target[s]-qty[s]
                if (side=='sell' and delta>=0) or (side=='buy' and delta<=0):continue
                cash-=delta*100;notional+=abs(delta)*100;qty[s]=target[s]
                assert cash>=0
        qty=target;held=new
        assert cash>=0 and cash+sum(q*100 for q in qty.values())==1000
        rows.append({'session':t,'members':sorted(new),'added':added,'removed':removed,'cash':cash})
    return exits,notional/1000,rows


a=run(False);b=run(True)
assert a[0]==4 and b[0]==2 and a[1]==5 and b[1]==3
assert b[2][1]['members']==['A','B'] and b[2][4]['members']==['A','C']
assert select(['A'],[],True)['actual']==['A']
assert 1-len(select(['A'],[],True)['actual'])*.5==.5
blocked=select(['A','C','D','B'],['A','B'],True,blocked=['B'])
assert blocked['status']=='blocked_exit' and blocked['actual']==['A','B']
scores={'B':1.,'A':1.,'C':0.}
assert all(isfinite(v) for v in scores.values())
assert sorted(scores,key=lambda s:(-scores[s],s))==['A','B','C']
print('top2_exits=4 buffer_exits=2 gross_turnover_including_formation=5.0,3.0 ending=1000,1000')
print('buffer_members='+str([row['members'] for row in b[2]]))
print('vacancy_cash_weight=0.5 suspended_exit=blocked_not_approved_retention ties=score_then_security')