from decimal import Decimal, ROUND_DOWN
from unittest.mock import patch

import pytest
from django.test import TestCase, override_settings

from oscar.apps.offer.models import Benefit
from oscar.test import factories


@pytest.fixture
def range():
    return factories.RangeFactory()


@pytest.mark.django_db
class TestBenefitProxyModels(object):
    """

    https://docs.djangoproject.com/en/1.11/topics/db/models/#proxy-models

    """

    def test_name_and_description(self, range):
        """
        Tests that the benefit proxy classes all return a name and
        description. Unfortunately, the current implementations means
        a valid range is required.w
        """
        for benefit_type, __ in Benefit.TYPE_CHOICES:
            benefit = Benefit(type=benefit_type, range=range)
            assert all([
                benefit.name,
                benefit.description,
                str(benefit)])

    def test_proxy(self, range):
        for benefit_type, __ in Benefit.TYPE_CHOICES:
            benefit = Benefit(
                type=benefit_type, value=10, range=range, max_affected_items=1)
            proxy = benefit.proxy()
            assert benefit.type == proxy.type
            assert benefit.value == proxy.value
            assert benefit.range == proxy.range
            assert benefit.max_affected_items == proxy.max_affected_items


class TestBenefit(TestCase):

    def test_default_rounding(self):
        benefit = Benefit()

        decimal = Decimal(10.0570)

        self.assertEqual(
            benefit.round(decimal),
            decimal.quantize(Decimal('0.01'), ROUND_DOWN)
        )

    @override_settings(OSCAR_OFFER_ROUNDING_FUNCTION='tests._site.apps.offer.round.round_func')
    @patch('tests._site.apps.offer.round.round_func')
    def test_round_uses_function_defined_in_OSCAR_OFFER_ROUNDING_FUNCTION(self, round_func_mock):
        benefit = Benefit()

        decimal = Decimal(10.05)

        self.assertEqual(
            benefit.round(decimal),
            round_func_mock(decimal)
        )