"""
Thermostat Accessory Implementation for HomeKit

Implements thermostat control according to homekit_mapping.md:
- CurrentTemperature (read-only)
- TargetTemperature (read/write)
- CurrentHeatingCoolingState (fixed: 1 = heating)
- TargetHeatingCoolingState (fixed: 3 = auto)
"""

from pyhap.accessory import Accessory
from pyhap.const import CATEGORY_THERMOSTAT


class ThermostatAccessory(Accessory):
    """Thermostat with temperature control."""
    
    category = CATEGORY_THERMOSTAT
    
    def __init__(self, driver, device, api_client, display_name=None, *args, **kwargs):
        """
        Initialize the thermostat accessory.
        
        Args:
            driver: HAP driver instance
            device: Device object from DeviceRegistry
            api_client: ApiClient for sending commands
            display_name: Optional display name (defaults to device.friendly_name)
        """
        name = display_name or device.friendly_name or device.name
        super().__init__(driver, name, *args, **kwargs)
        self.device = device
        self.api_client = api_client
        
        # Add Thermostat service
        self.thermostat_service = self.add_preload_service('Thermostat')
        
        # Get characteristics
        self.current_temp_char = self.thermostat_service.get_characteristic('CurrentTemperature')
        self.target_temp_char = self.thermostat_service.get_characteristic('TargetTemperature')
        self.current_heating_cooling_char = self.thermostat_service.get_characteristic('CurrentHeatingCoolingState')
        self.target_heating_cooling_char = self.thermostat_service.get_characteristic('TargetHeatingCoolingState')
        
        # Set callback for target temperature
        self.target_temp_char.setter_callback = self.set_target_temperature
        
        # Set fixed heating/cooling states (mode is always "auto")
        # CurrentHeatingCoolingState: 0=Off, 1=Heat, 2=Cool
        self.current_heating_cooling_char.set_value(1)  # Always heating
        
        # TargetHeatingCoolingState: 0=Off, 1=Heat, 2=Cool, 3=Auto
        self.target_heating_cooling_char.set_value(3)  # Always auto
        
        # Set temperature range (5-30°C as per UI)
        self.target_temp_char.properties['minValue'] = 5
        self.target_temp_char.properties['maxValue'] = 30
        self.target_temp_char.properties['minStep'] = 0.5
    
    def set_target_temperature(self, value):
        """Called when HomeKit wants to change target temperature."""
        payload = {
            "type": "thermostat",
            "payload": {"target": float(value)}
        }
        self.api_client.post_device_set(self.device.device_id, payload["type"], payload["payload"])
    
    def update_state(self, state_payload):
        """Update state from API event."""
        if "current" in state_payload:
            self.current_temp_char.set_value(float(state_payload["current"]))
        if "target" in state_payload:
            self.target_temp_char.set_value(float(state_payload["target"]))