"""Fan platform for the Duco integration."""

import logging
from typing import override

from duco_connectivity.exceptions import DucoError, DucoRateLimitError
from duco_connectivity.models import Node, NodeType, VentilationState

from homeassistant.components.fan import FanEntity, FanEntityFeature
from homeassistant.core import HomeAssistant
from homeassistant.exceptions import HomeAssistantError
from homeassistant.helpers.entity_platform import AddConfigEntryEntitiesCallback
from homeassistant.util.percentage import percentage_to_ordered_list_item

from .const import DOMAIN
from .coordinator import DucoConfigEntry, DucoCoordinator
from .entity import DucoEntity

_LOGGER = logging.getLogger(__name__)

PARALLEL_UPDATES = 1

# Permanent speed states ordered low → high.
ORDERED_NAMED_FAN_SPEEDS: list[VentilationState] = [
    VentilationState.CNT1,
    VentilationState.CNT2,
    VentilationState.CNT3,
]

PRESET_AUTO = "auto"

# Upper-bound percentages for 3 speed levels: 33 / 66 / 100.
# Using upper bounds guarantees that reading a percentage back and writing it
# again always round-trips to the same Duco state.
_SPEED_LEVEL_PERCENTAGES: list[int] = [
    (i + 1) * 100 // len(ORDERED_NAMED_FAN_SPEEDS)
    for i, _ in enumerate(ORDERED_NAMED_FAN_SPEEDS)
]

# Maps every active Duco state (including timed MAN variants) to its
# display percentage so externally-set timed modes show the correct level.
_STATE_TO_PERCENTAGE: dict[VentilationState, int] = {
    VentilationState.CNT1: _SPEED_LEVEL_PERCENTAGES[0],
    VentilationState.MAN1: _SPEED_LEVEL_PERCENTAGES[0],
    VentilationState.MAN1x2: _SPEED_LEVEL_PERCENTAGES[0],
    VentilationState.MAN1x3: _SPEED_LEVEL_PERCENTAGES[0],
    VentilationState.CNT2: _SPEED_LEVEL_PERCENTAGES[1],
    VentilationState.MAN2: _SPEED_LEVEL_PERCENTAGES[1],
    VentilationState.MAN2x2: _SPEED_LEVEL_PERCENTAGES[1],
    VentilationState.MAN2x3: _SPEED_LEVEL_PERCENTAGES[1],
    VentilationState.CNT3: _SPEED_LEVEL_PERCENTAGES[2],
    VentilationState.MAN3: _SPEED_LEVEL_PERCENTAGES[2],
    VentilationState.MAN3x2: _SPEED_LEVEL_PERCENTAGES[2],
    VentilationState.MAN3x3: _SPEED_LEVEL_PERCENTAGES[2],
}


async def async_setup_entry(
    hass: HomeAssistant,
    entry: DucoConfigEntry,
    async_add_entities: AddConfigEntryEntitiesCallback,
) -> None:
    """Set up Duco fan entities."""
    coordinator = entry.runtime_data

    # BOX is always node 1 and is never dynamically added
    # or removed, so no listener needed.
    async_add_entities(
        DucoVentilationFanEntity(coordinator, node)
        for node in coordinator.data.nodes.values()
        if node.general.node_type == NodeType.BOX
    )


class DucoVentilationFanEntity(DucoEntity, FanEntity):
    """Fan entity for the ventilation control of a Duco node."""

    _attr_translation_key = "ventilation"
    _attr_name = None
    _attr_supported_features = FanEntityFeature.SET_SPEED | FanEntityFeature.PRESET_MODE
    _attr_preset_modes = [PRESET_AUTO]
    _attr_speed_count = len(ORDERED_NAMED_FAN_SPEEDS)

    def __init__(self, coordinator: DucoCoordinator, node: Node) -> None:
        """Initialize the fan entity."""
        super().__init__(coordinator, node)
        self._attr_unique_id = f"{coordinator.config_entry.unique_id}_{node.node_id}"

    @property
    @override
    def percentage(self) -> int | None:
        """Return the current speed as a percentage, or None when in AUTO mode."""
        node = self._node
        if node.ventilation is None:
            return None
        return _STATE_TO_PERCENTAGE.get(node.ventilation.state)

    @property
    @override
    def preset_mode(self) -> str | None:
        """Return the current preset mode (auto when Duco controls, else None)."""
        node = self._node
        if node.ventilation is None:
            return None
        if node.ventilation.state not in _STATE_TO_PERCENTAGE:
            return PRESET_AUTO
        return None

    @override
    async def async_set_preset_mode(self, preset_mode: str) -> None:
        """Set preset mode: 'auto' hands control back to Duco."""
        self._valid_preset_mode_or_raise(preset_mode)
        await self._async_set_state(VentilationState.AUTO)

    @override
    async def async_set_percentage(self, percentage: int) -> None:
        """Set the fan speed as a percentage (maps to low/medium/high)."""
        if percentage == 0:
            await self._async_set_state(VentilationState.AUTO)
            return
        state = percentage_to_ordered_list_item(ORDERED_NAMED_FAN_SPEEDS, percentage)
        await self._async_set_state(state)

    async def _async_set_state(self, state: VentilationState) -> None:
        """Send the ventilation state to the device and refresh coordinator."""
        try:
            await self.coordinator.client.async_set_ventilation_state(
                self._node_id, state
            )
        except DucoRateLimitError as err:
            _LOGGER.warning("Duco write rate limit exceeded for node %s", self._node_id)
            raise HomeAssistantError(
                translation_domain=DOMAIN,
                translation_key="rate_limit_exceeded",
            ) from err
        except DucoError as err:
            raise HomeAssistantError(
                translation_domain=DOMAIN,
                translation_key="failed_to_set_state",
            ) from err
        await self.coordinator.async_refresh()