import pytest
from unittest.mock import MagicMock
from recommendations import recommendation_utils


class TestRecommendationUtils:
    @pytest.fixture
    def property_mock(self):
        PropertyMock = MagicMock()
        PropertyMock.data = {
            'total_floor_area_group_decile': 'Decile 1',
            'number-habitable-rooms': 3,
            'number-heated-rooms': 2
        }
        return PropertyMock

    def test_r_value_per_mm_to_u_value(self):
        assert recommendation_utils.r_value_per_mm_to_u_value(1, 2) == 0.5
        with pytest.raises(ZeroDivisionError):
            recommendation_utils.r_value_per_mm_to_u_value(0, 2)

    def test_calculate_u_value_uplift(self):
        assert recommendation_utils.calculate_u_value_uplift(1, 2) == (0.33333333333333337, 0.6666666666666666)
        with pytest.raises(ZeroDivisionError):
            recommendation_utils.calculate_u_value_uplift(0, 2)
        with pytest.raises(ZeroDivisionError):
            recommendation_utils.calculate_u_value_uplift(1, 0)

    def test_is_diminishing_returns(self):
        assert not recommendation_utils.is_diminishing_returns([1, 2, 3], 1, 1, 1)
        assert recommendation_utils.is_diminishing_returns([1, 2, 3], 0.5, 1, 1)
        assert not recommendation_utils.is_diminishing_returns([], 1, None, 1)

    def test_update_lowest_selected_u_value(self):
        assert recommendation_utils.update_lowest_selected_u_value(1, 2) == 1
        assert recommendation_utils.update_lowest_selected_u_value(None, 2) == 2
        assert recommendation_utils.update_lowest_selected_u_value(1, 0.5) == 0.5

    def test_get_recommended_part(self):
        part = {'depths': [1, 2, 3]}
        assert recommendation_utils.get_recommended_part(part, 1) == {'depths': [1]}

    def test_get_uvalue_estimate(self, property_mock):
        uvalue_estimates = [
            {
                'total-floor-area_group': 'Decile 1',
                'number-habitable-rooms': 3,
                'number-heated-rooms': 2,
                'median_thermal_transmittance': 1
            },
            {
                'total-floor-area_group': 'Decile 1',
                'number-habitable-rooms': 3,
                'number-heated-rooms': 2,
                'median_thermal_transmittance': 2
            }
        ]

        assert recommendation_utils.get_uvalue_estimate(uvalue_estimates, property_mock, "Decile 1") == 1.5

        with pytest.raises(ValueError):
            recommendation_utils.get_uvalue_estimate([], property_mock, "Decile 1")

        # Test with missing 'median_thermal_transmittance' key
        uvalue_estimates_missing_key = [
            {
                'total-floor-area_group': 'Decile 1',
                'number-habitable-rooms': 3,
                'number-heated-rooms': 2
            }
        ]

        with pytest.raises(KeyError):
            recommendation_utils.get_uvalue_estimate(uvalue_estimates_missing_key, property_mock, "Decile 1")