Add hvac_action attribute to iAqualink Thermostat climate entities (#107803)

* Update climate.py

* Reorder if/else statements per @dcmeglio's suggestion

* Don't infer state, actually read it from the underlying device

* HVACAction has a HEATING state, not ON

* Update homeassistant/components/iaqualink/climate.py

---------

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/iaqualink/climate.py

@@ -6,11 +6,13 @@ import logging
 from typing import Any
 
 from iaqualink.device import AqualinkThermostat
+from iaqualink.systems.iaqua.device import AqualinkState
 
 from homeassistant.components.climate import (
     DOMAIN as CLIMATE_DOMAIN,
     ClimateEntity,
     ClimateEntityFeature,
+    HVACAction,
     HVACMode,
 )
 from homeassistant.config_entries import ConfigEntry
@@ -82,6 +84,16 @@ class HassAqualinkThermostat(AqualinkEntity, ClimateEntity):
         else:
             _LOGGER.warning("Unknown operation mode: %s", hvac_mode)
 
+    @property
+    def hvac_action(self) -> HVACAction:
+        """Return the current HVAC action."""
+        state = AqualinkState(self.dev._heater.state)
+        if state == AqualinkState.ON:
+            return HVACAction.HEATING
+        if state == AqualinkState.ENABLED:
+            return HVACAction.IDLE
+        return HVACAction.OFF
+
     @property
     def target_temperature(self) -> float:
         """Return the current target temperature."""