"""The tests for the derivative sensor platform."""
from datetime import timedelta
from math import sin
import random
from unittest.mock import patch

from homeassistant.const import UnitOfPower, UnitOfTime
from homeassistant.core import HomeAssistant
from homeassistant.setup import async_setup_component
import homeassistant.util.dt as dt_util


async def test_state(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    config = {
        "sensor": {
            "platform": "derivative",
            "name": "derivative",
            "source": "sensor.energy",
            "unit": "kW",
            "round": 2,
        }
    }

    assert await async_setup_component(hass, "sensor", config)

    entity_id = config["sensor"]["source"]
    base = dt_util.utcnow()
    with patch("homeassistant.util.dt.utcnow") as now:
        now.return_value = base
        hass.states.async_set(entity_id, 1, {})
        await hass.async_block_till_done()

        now.return_value += timedelta(seconds=3600)
        hass.states.async_set(entity_id, 1, {}, force_update=True)
        await hass.async_block_till_done()

    state = hass.states.get("sensor.derivative")
    assert state is not None

    # Testing a energy sensor at 1 kWh for 1hour = 0kW
    assert round(float(state.state), config["sensor"]["round"]) == 0.0

    assert state.attributes.get("unit_of_measurement") == "kW"


async def _setup_sensor(hass, config):
    default_config = {
        "platform": "derivative",
        "name": "power",
        "source": "sensor.energy",
        "round": 2,
    }

    config = {"sensor": dict(default_config, **config)}
    assert await async_setup_component(hass, "sensor", config)

    entity_id = config["sensor"]["source"]
    hass.states.async_set(entity_id, 0, {})
    await hass.async_block_till_done()

    return config, entity_id


async def setup_tests(hass, config, times, values, expected_state):
    """Test derivative sensor state."""
    config, entity_id = await _setup_sensor(hass, config)

    # Testing a energy sensor with non-monotonic intervals and values
    base = dt_util.utcnow()
    with patch("homeassistant.util.dt.utcnow") as now:
        for time, value in zip(times, values):
            now.return_value = base + timedelta(seconds=time)
            hass.states.async_set(entity_id, value, {}, force_update=True)
            await hass.async_block_till_done()

    state = hass.states.get("sensor.power")
    assert state is not None

    assert round(float(state.state), config["sensor"]["round"]) == expected_state

    return state


async def test_dataSet1(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    await setup_tests(
        hass,
        {"unit_time": UnitOfTime.SECONDS},
        times=[20, 30, 40, 50],
        values=[10, 30, 5, 0],
        expected_state=-0.5,
    )


async def test_dataSet2(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    await setup_tests(
        hass,
        {"unit_time": UnitOfTime.SECONDS},
        times=[20, 30],
        values=[5, 0],
        expected_state=-0.5,
    )


async def test_dataSet3(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    state = await setup_tests(
        hass,
        {"unit_time": UnitOfTime.SECONDS},
        times=[20, 30],
        values=[5, 10],
        expected_state=0.5,
    )

    assert state.attributes.get("unit_of_measurement") == f"/{UnitOfTime.SECONDS}"


async def test_dataSet4(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    await setup_tests(
        hass,
        {"unit_time": UnitOfTime.SECONDS},
        times=[20, 30],
        values=[5, 5],
        expected_state=0,
    )


async def test_dataSet5(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    await setup_tests(
        hass,
        {"unit_time": UnitOfTime.SECONDS},
        times=[20, 30],
        values=[10, -10],
        expected_state=-2,
    )


async def test_dataSet6(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    await setup_tests(hass, {}, times=[0, 60], values=[0, 1 / 60], expected_state=1)


async def test_data_moving_average_for_discrete_sensor(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    # We simulate the following situation:
    # The temperature rises 1 °C per minute for 30 minutes long.
    # There is a data point every 30 seconds, however, the sensor returns
    # the temperature rounded down to an integer value.
    # We use a time window of 10 minutes and therefore we can expect
    # (because the true derivative is 1 °C/min) an error of less than 10%.

    temperature_values = []
    for temperature in range(30):
        temperature_values += [temperature] * 2  # two values per minute
    time_window = 600
    times = list(range(0, 1800 + 30, 30))

    config, entity_id = await _setup_sensor(
        hass,
        {
            "time_window": {"seconds": time_window},
            "unit_time": UnitOfTime.MINUTES,
            "round": 1,
        },
    )  # two minute window

    base = dt_util.utcnow()
    for time, value in zip(times, temperature_values):
        now = base + timedelta(seconds=time)
        with patch("homeassistant.util.dt.utcnow", return_value=now):
            hass.states.async_set(entity_id, value, {}, force_update=True)
            await hass.async_block_till_done()

        if time_window < time < times[-1] - time_window:
            state = hass.states.get("sensor.power")
            derivative = round(float(state.state), config["sensor"]["round"])
            # Test that the error is never more than
            # (time_window_in_minutes / true_derivative * 100) = 10% + ε
            assert abs(1 - derivative) <= 0.1 + 1e-6


async def test_data_moving_average_for_irregular_times(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    # We simulate the following situation:
    # The temperature rises 1 °C per minute for 30 minutes long.
    # There is 60 random datapoints (and the start and end) and the signal is normally distributed
    # around the expected value with ±0.1°C
    # We use a time window of 1 minute and expect an error of less than the standard deviation. (0.01)

    time_window = 60
    random.seed(0)
    times = sorted(random.sample(range(1800), 60))

    def temp_function(time):
        random.seed(0)
        temp = time / (600)
        return random.gauss(temp, 0.1)

    temperature_values = list(map(temp_function, times))

    config, entity_id = await _setup_sensor(
        hass,
        {
            "time_window": {"seconds": time_window},
            "unit_time": UnitOfTime.MINUTES,
            "round": 3,
        },
    )

    base = dt_util.utcnow()
    for time, value in zip(times, temperature_values):
        now = base + timedelta(seconds=time)
        with patch("homeassistant.util.dt.utcnow", return_value=now):
            hass.states.async_set(entity_id, value, {}, force_update=True)
            await hass.async_block_till_done()

        if time_window < time and time > times[3]:
            state = hass.states.get("sensor.power")
            derivative = round(float(state.state), config["sensor"]["round"])
            # Test that the error is never more than
            # (time_window_in_minutes / true_derivative * 100) = 10% + ε
            assert abs(0.1 - derivative) <= 0.01 + 1e-6


async def test_double_signal_after_delay(hass: HomeAssistant) -> None:
    """Test derivative sensor state."""
    # The old algorithm would produce extreme values if, after a delay longer than the time window
    # there would be two signals, a large spike would be produced. Check explicitly for this situation
    time_window = 60
    times = [*range(time_window * 10)]
    times = times + [
        time_window * 20,
        time_window * 20 + 0.01,
    ]

    # just apply sine as some sort of temperature change and make sure the change after the delay is very small
    temperature_values = [sin(x) for x in times]
    temperature_values[-2] = temperature_values[-3] + 0.01
    temperature_values[-1] = temperature_values[-2] + 0.01

    config, entity_id = await _setup_sensor(
        hass,
        {
            "time_window": {"seconds": time_window},
            "unit_time": UnitOfTime.MINUTES,
            "round": 3,
        },
    )

    base = dt_util.utcnow()
    previous = 0
    for time, value in zip(times, temperature_values):
        now = base + timedelta(seconds=time)
        with patch("homeassistant.util.dt.utcnow", return_value=now):
            hass.states.async_set(entity_id, value, {}, force_update=True)
            await hass.async_block_till_done()
        state = hass.states.get("sensor.power")
        derivative = round(float(state.state), config["sensor"]["round"])
        if time == times[-1]:
            # Test that the error is never more than
            # (time_window_in_minutes / true_derivative * 100) = 10% + ε
            assert abs(previous - derivative) <= 0.01 + 1e-6
        previous = derivative


async def test_prefix(hass: HomeAssistant) -> None:
    """Test derivative sensor state using a power source."""
    config = {
        "sensor": {
            "platform": "derivative",
            "name": "derivative",
            "source": "sensor.power",
            "round": 2,
            "unit_prefix": "k",
        }
    }

    assert await async_setup_component(hass, "sensor", config)

    entity_id = config["sensor"]["source"]
    base = dt_util.utcnow()
    with patch("homeassistant.util.dt.utcnow") as now:
        now.return_value = base
        hass.states.async_set(
            entity_id,
            1000,
            {"unit_of_measurement": UnitOfPower.WATT},
            force_update=True,
        )
        await hass.async_block_till_done()

        now.return_value += timedelta(seconds=3600)
        hass.states.async_set(
            entity_id,
            1000,
            {"unit_of_measurement": UnitOfPower.WATT},
            force_update=True,
        )
        await hass.async_block_till_done()

    state = hass.states.get("sensor.derivative")
    assert state is not None

    # Testing a power sensor at 1000 Watts for 1hour = 0kW/h
    assert round(float(state.state), config["sensor"]["round"]) == 0.0
    assert state.attributes.get("unit_of_measurement") == f"kW/{UnitOfTime.HOURS}"


async def test_suffix(hass: HomeAssistant) -> None:
    """Test derivative sensor state using a network counter source."""
    config = {
        "sensor": {
            "platform": "derivative",
            "name": "derivative",
            "source": "sensor.bytes_per_second",
            "round": 2,
            "unit_prefix": "k",
            "unit_time": UnitOfTime.SECONDS,
        }
    }

    assert await async_setup_component(hass, "sensor", config)

    entity_id = config["sensor"]["source"]
    base = dt_util.utcnow()
    with patch("homeassistant.util.dt.utcnow") as now:
        now.return_value = base
        hass.states.async_set(entity_id, 1000, {})
        await hass.async_block_till_done()

        now.return_value += timedelta(seconds=10)
        hass.states.async_set(entity_id, 1000, {}, force_update=True)
        await hass.async_block_till_done()

    state = hass.states.get("sensor.derivative")
    assert state is not None

    # Testing a network speed sensor at 1000 bytes/s over 10s  = 10kbytes/s2
    assert round(float(state.state), config["sensor"]["round"]) == 0.0