"""无参类常量与显式适配器区分；不假设JSON自动注入。"""
import inspect
import json
from math import isfinite


class SignalEngine:
    WINDOW = 3
    THRESHOLD = 0.0

    def generate(self, closes):
        if type(self.WINDOW) is not int or self.WINDOW < 2:
            raise ValueError('window必须为至少2的整数')
        if not isfinite(self.THRESHOLD) or self.THRESHOLD < 0:
            raise ValueError('threshold必须是有限非负数')
        return [int(i >= self.WINDOW - 1 and
                    close > sum(closes[i-self.WINDOW+1:i+1]) / self.WINDOW * (1+self.THRESHOLD))
                for i, close in enumerate(closes)]


def reference_style_load(config):
    return SignalEngine()  # 此最小路径没有策略参数注入；config只作为反例输入


def explicit_adapter(spec):
    if set(spec) != {'window', 'threshold'}:
        raise ValueError('策略参数字段不符')
    cls = type('ConfiguredEngine', (SignalEngine,),
               {'WINDOW': spec['window'], 'THRESHOLD': spec['threshold']})
    return cls()


closes = [10, 20, 18]
base = reference_style_load({})
ignored = reference_style_load({'window': 2})
window_two = explicit_adapter({'window': 2, 'threshold': 0})
threshold_high = explicit_adapter({'window': 3, 'threshold': .2})
assert str(inspect.signature(SignalEngine)) == '()'
assert base.generate(closes) == ignored.generate(closes) == [0, 0, 1]
assert ignored.WINDOW == 3
assert window_two.generate(closes) == [0, 1, 0]
assert threshold_high.generate(closes) == [0, 0, 0]
try:
    explicit_adapter({'window': 2, 'threshold': 0, 'commission': 1})
except ValueError:
    pass
else:
    raise AssertionError('引擎费用不能静默成为策略参数')
for spec in [{'window': 0, 'threshold': 0}, {'window': True, 'threshold': 0},
             {'window': 3, 'threshold': float('nan')}]:
    try:
        explicit_adapter(spec).generate(closes)
    except ValueError:
        pass
    else:
        raise AssertionError('无效参数必须拒绝')
print(json.dumps({'closes': closes, 'default': base.generate(closes),
                  'ignored_json_window': {'requested': 2, 'effective': ignored.WINDOW,
                                          'signals': ignored.generate(closes)},
                  'explicit_window_2': window_two.generate(closes),
                  'explicit_threshold_point_2': threshold_high.generate(closes),
                  'scope': 'explicit adapter is authored here, not a verified product feature'}))