"""Test the unit system helper."""
import pytest

from homeassistant.util.unit_system import (
    UnitSystem,
    METRIC_SYSTEM,
    IMPERIAL_SYSTEM,
)
from homeassistant.const import (
    LENGTH_METERS,
    LENGTH_KILOMETERS,
    MASS_GRAMS,
    PRESSURE_PA,
    VOLUME_LITERS,
    TEMP_CELSIUS,
    LENGTH,
    MASS,
    PRESSURE,
    TEMPERATURE,
    VOLUME
)
SYSTEM_NAME = 'TEST'
INVALID_UNIT = 'INVALID'


def test_invalid_units():
    """Test errors are raised when invalid units are passed in."""
    with pytest.raises(ValueError):
        UnitSystem(SYSTEM_NAME, INVALID_UNIT, LENGTH_METERS, VOLUME_LITERS,
                   MASS_GRAMS, PRESSURE_PA)

    with pytest.raises(ValueError):
        UnitSystem(SYSTEM_NAME, TEMP_CELSIUS, INVALID_UNIT, VOLUME_LITERS,
                   MASS_GRAMS, PRESSURE_PA)

    with pytest.raises(ValueError):
        UnitSystem(SYSTEM_NAME, TEMP_CELSIUS, LENGTH_METERS, INVALID_UNIT,
                   MASS_GRAMS, PRESSURE_PA)

    with pytest.raises(ValueError):
        UnitSystem(SYSTEM_NAME, TEMP_CELSIUS, LENGTH_METERS, VOLUME_LITERS,
                   INVALID_UNIT, PRESSURE_PA)

    with pytest.raises(ValueError):
        UnitSystem(SYSTEM_NAME, TEMP_CELSIUS, LENGTH_METERS, VOLUME_LITERS,
                   MASS_GRAMS, INVALID_UNIT)


def test_invalid_value():
    """Test no conversion happens if value is non-numeric."""
    with pytest.raises(TypeError):
        METRIC_SYSTEM.length('25a', LENGTH_KILOMETERS)
    with pytest.raises(TypeError):
        METRIC_SYSTEM.temperature('50K', TEMP_CELSIUS)
    with pytest.raises(TypeError):
        METRIC_SYSTEM.volume('50L', VOLUME_LITERS)
    with pytest.raises(TypeError):
        METRIC_SYSTEM.pressure('50Pa', PRESSURE_PA)


def test_as_dict():
    """Test that the as_dict() method returns the expected dictionary."""
    expected = {
        LENGTH: LENGTH_KILOMETERS,
        TEMPERATURE: TEMP_CELSIUS,
        VOLUME: VOLUME_LITERS,
        MASS: MASS_GRAMS,
        PRESSURE: PRESSURE_PA
    }

    assert expected == METRIC_SYSTEM.as_dict()


def test_temperature_same_unit():
    """Test no conversion happens if to unit is same as from unit."""
    assert METRIC_SYSTEM.temperature(5, METRIC_SYSTEM.temperature_unit) == 5


def test_temperature_unknown_unit():
    """Test no conversion happens if unknown unit."""
    with pytest.raises(ValueError):
        METRIC_SYSTEM.temperature(5, 'K')


def test_temperature_to_metric():
    """Test temperature conversion to metric system."""
    assert METRIC_SYSTEM.temperature(25, METRIC_SYSTEM.temperature_unit) == 25
    assert round(METRIC_SYSTEM.temperature(
        80, IMPERIAL_SYSTEM.temperature_unit), 1) == 26.7


def test_temperature_to_imperial():
    """Test temperature conversion to imperial system."""
    assert IMPERIAL_SYSTEM.temperature(
        77, IMPERIAL_SYSTEM.temperature_unit) == 77
    assert IMPERIAL_SYSTEM.temperature(
        25, METRIC_SYSTEM.temperature_unit) == 77


def test_length_unknown_unit():
    """Test length conversion with unknown from unit."""
    with pytest.raises(ValueError):
        METRIC_SYSTEM.length(5, 'fr')


def test_length_to_metric():
    """Test length conversion to metric system."""
    assert METRIC_SYSTEM.length(100, METRIC_SYSTEM.length_unit) == 100
    assert METRIC_SYSTEM.length(5, IMPERIAL_SYSTEM.length_unit) == 8.04672


def test_length_to_imperial():
    """Test length conversion to imperial system."""
    assert IMPERIAL_SYSTEM.length(100, IMPERIAL_SYSTEM.length_unit) == 100
    assert IMPERIAL_SYSTEM.length(5, METRIC_SYSTEM.length_unit) == 3.106855


def test_pressure_same_unit():
    """Test no conversion happens if to unit is same as from unit."""
    assert METRIC_SYSTEM.pressure(5, METRIC_SYSTEM.pressure_unit) == 5


def test_pressure_unknown_unit():
    """Test no conversion happens if unknown unit."""
    with pytest.raises(ValueError):
        METRIC_SYSTEM.pressure(5, 'K')


def test_pressure_to_metric():
    """Test pressure conversion to metric system."""
    assert METRIC_SYSTEM.pressure(25, METRIC_SYSTEM.pressure_unit) == 25
    assert METRIC_SYSTEM.pressure(14.7, IMPERIAL_SYSTEM.pressure_unit) == \
        pytest.approx(101352.932, abs=1e-1)


def test_pressure_to_imperial():
    """Test pressure conversion to imperial system."""
    assert IMPERIAL_SYSTEM.pressure(77, IMPERIAL_SYSTEM.pressure_unit) == 77
    assert IMPERIAL_SYSTEM.pressure(
        101352.932, METRIC_SYSTEM.pressure_unit) == \
        pytest.approx(14.7, abs=1e-4)


def test_properties():
    """Test the unit properties are returned as expected."""
    assert LENGTH_KILOMETERS == METRIC_SYSTEM.length_unit
    assert TEMP_CELSIUS == METRIC_SYSTEM.temperature_unit
    assert MASS_GRAMS == METRIC_SYSTEM.mass_unit
    assert VOLUME_LITERS == METRIC_SYSTEM.volume_unit
    assert PRESSURE_PA == METRIC_SYSTEM.pressure_unit


def test_is_metric():
    """Test the is metric flag."""
    assert METRIC_SYSTEM.is_metric
    assert not IMPERIAL_SYSTEM.is_metric