"""Helper to test significant Water Heater state changes."""
from __future__ import annotations

from typing import Any

from homeassistant.const import UnitOfTemperature
from homeassistant.core import HomeAssistant, callback
from homeassistant.helpers.significant_change import (
    check_absolute_change,
    check_valid_float,
)

from . import (
    ATTR_AWAY_MODE,
    ATTR_CURRENT_TEMPERATURE,
    ATTR_OPERATION_MODE,
    ATTR_TARGET_TEMP_HIGH,
    ATTR_TARGET_TEMP_LOW,
    ATTR_TEMPERATURE,
)

SIGNIFICANT_ATTRIBUTES: set[str] = {
    ATTR_CURRENT_TEMPERATURE,
    ATTR_TEMPERATURE,
    ATTR_TARGET_TEMP_HIGH,
    ATTR_TARGET_TEMP_LOW,
    ATTR_OPERATION_MODE,
    ATTR_AWAY_MODE,
}


@callback
def async_check_significant_change(
    hass: HomeAssistant,
    old_state: str,
    old_attrs: dict,
    new_state: str,
    new_attrs: dict,
    **kwargs: Any,
) -> bool | None:
    """Test if state significantly changed."""
    if old_state != new_state:
        return True

    old_attrs_s = set(
        {k: v for k, v in old_attrs.items() if k in SIGNIFICANT_ATTRIBUTES}.items()
    )
    new_attrs_s = set(
        {k: v for k, v in new_attrs.items() if k in SIGNIFICANT_ATTRIBUTES}.items()
    )
    changed_attrs: set[str] = {item[0] for item in old_attrs_s ^ new_attrs_s}
    ha_unit = hass.config.units.temperature_unit

    for attr_name in changed_attrs:
        if attr_name in [ATTR_OPERATION_MODE, ATTR_AWAY_MODE]:
            return True

        old_attr_value = old_attrs.get(attr_name)
        new_attr_value = new_attrs.get(attr_name)
        if new_attr_value is None or not check_valid_float(new_attr_value):
            # New attribute value is invalid, ignore it
            continue

        if old_attr_value is None or not check_valid_float(old_attr_value):
            # Old attribute value was invalid, we should report again
            return True

        if ha_unit == UnitOfTemperature.FAHRENHEIT:
            absolute_change = 1.0
        else:
            absolute_change = 0.5

        if check_absolute_change(old_attr_value, new_attr_value, absolute_change):
            return True

    # no significant attribute change detected
    return False