"""DataUpdateCoordinator for the Xiaoxiang Smart BMS."""
from __future__ import annotations

import logging
from datetime import timedelta

from homeassistant.core import HomeAssistant
from homeassistant.helpers.update_coordinator import DataUpdateCoordinator, UpdateFailed

from .bluetooth_handler import BmsBluetoothHandler
from .const import CMD_CELL, CMD_GENERAL, DOMAIN

_LOGGER = logging.getLogger(__name__)


class BmsCoordinator(DataUpdateCoordinator[dict]):
    """Polls the BMS over BLE and distributes data to all sensor entities."""

    def __init__(
        self,
        hass: HomeAssistant,
        address: str,
        poll_interval: int,
    ) -> None:
        super().__init__(
            hass,
            _LOGGER,
            name=DOMAIN,
            update_interval=timedelta(seconds=poll_interval),
        )
        self.address = address
        self._handler = BmsBluetoothHandler(address)

    # ------------------------------------------------------------------
    # Lifecycle
    # ------------------------------------------------------------------

    async def async_setup(self) -> None:
        """Connect to the BMS. Called once during config entry setup."""
        await self._handler.connect()

    async def async_teardown(self) -> None:
        """Disconnect cleanly. Called on entry unload."""
        await self._handler.disconnect()

    # ------------------------------------------------------------------
    # Poll
    # ------------------------------------------------------------------

    async def _async_update_data(self) -> dict:
        """Fetch data from the BMS. Reconnects automatically if disconnected."""
        if not self._handler.is_connected:
            _LOGGER.debug("BMS not connected, attempting reconnect…")
            try:
                await self._handler.connect()
            except Exception as exc:
                raise UpdateFailed(f"BMS reconnect failed: {exc}") from exc

        try:
            general_frame = await self._handler.request(CMD_GENERAL)
            if general_frame is None:
                raise UpdateFailed("No response to general info request (0x03)")

            cell_frame = await self._handler.request(CMD_CELL)
            if cell_frame is None:
                raise UpdateFailed("No response to cell info request (0x04)")
        except UpdateFailed:
            raise
        except Exception as exc:
            raise UpdateFailed(f"BLE communication error: {exc}") from exc

        data = BmsBluetoothHandler.parse_general_info(general_frame)
        data.update(BmsBluetoothHandler.parse_cell_info(cell_frame))

        # Derived fields
        data["power"] = round(data["voltage"] * data["current"], 2)

        if data["cell_voltages"]:
            v_max = max(data["cell_voltages"])
            v_min = min(data["cell_voltages"])
            data["cell_delta"] = round((v_max - v_min) * 1000, 1)
        else:
            data["cell_delta"] = None

        _LOGGER.debug(
            "BMS data: %.2fV  %.2fA  %d%%  %.2fAh  %d cells",
            data["voltage"],
            data["current"],
            data["state_of_charge"],
            data["residual_capacity"],
            len(data["cell_voltages"]),
        )
        return data