"""同一时点跨股票排名；上市历史、池生效和输入重排分别验收。"""
import itertools
import json
from math import isfinite

prices = {'A': [10, 11, 12], 'B': [10, 12, 11], 'C': [None, 20, 22]}
active_from = {'A': 0, 'B': 0, 'C': 1}


def select(data, membership):
    length = len(next(iter(data.values())))
    if any(len(values) != length for values in data.values()):
        raise ValueError('必须先显式对齐共同交易期')
    result = []
    for i in range(length):
        scores = {}
        for symbol, values in data.items():
            if i == 0 or i < membership[symbol]:
                continue
            past, current = values[i - 1:i + 1]
            if (past is not None and current is not None and isfinite(past)
                    and isfinite(current) and past > 0 and current > 0):
                scores[symbol] = current / past - 1
        chosen = sorted(scores, key=lambda s: (-scores[s], s))[:1]
        result.append({'i': i, 'scores': scores, 'chosen': chosen,
                       'signals': {s: int(s in chosen) for s in data}})
    return result


expected = select(prices, active_from)
assert [r['chosen'] for r in expected] == [[], ['B'], ['C']]
assert 'C' not in expected[1]['scores']
for order in itertools.permutations(prices):
    assert select({s: prices[s] for s in order}, active_from) == expected
late = select(prices, dict(active_from, C=3))
assert late[2]['chosen'] == ['A']
naive = [s for s in prices if prices[s][0] and prices[s][1] > prices[s][0]]
assert naive == ['A', 'B'] and naive != expected[1]['chosen']
assert select({s: xs + [1000] for s, xs in prices.items()}, active_from)[:3] == expected
try:
    select({'A': [10, 11], 'B': [10]}, {'A': 0, 'B': 0})
except ValueError as error:
    assert '对齐' in str(error)
else:
    raise AssertionError('未对齐长度必须明确拒绝')
print(json.dumps({'cross_sections': expected, 'late_membership_last': late[2],
                  'permutations_checked': 6, 'per_stock_positive_counterexample': naive}))