"""Backend adapters used by :mod:`python_app.hardware_full.librevna_service`."""

from __future__ import annotations

from dataclasses import dataclass, field
from contextlib import suppress
from typing import Any

import numpy as np

from python_app.hardware_full.librevna_driver.models import SweepResult
from python_app.models.run_config_model import RadarSweepModel


@dataclass(slots=True)
class NativeLibreVnaBackend:
    """Native backend using direct USB LibreVNA Python driver."""

    serial: str | None
    strict_protocol_version: int
    _device: Any | None = field(init=False, default=None, repr=False)
    _settings: RadarSweepModel | None = field(init=False, default=None, repr=False)
    _libre_vna_device: type[Any] = field(init=False, repr=False)
    _vna_sweep_settings: type[Any] = field(init=False, repr=False)

    def __post_init__(self) -> None:
        """Import native driver classes lazily and initialize backend state."""
        from python_app.hardware_full.librevna_driver import LibreVNADevice, VNASweepSettings

        self._libre_vna_device = LibreVNADevice
        self._vna_sweep_settings = VNASweepSettings

    def open(self) -> None:
        """Open device connection if it is not already open."""
        if self._device is not None:
            return

        device = self._device = self._libre_vna_device()
        try:
            device.connect(serial=self.serial, strict_protocol_version=self.strict_protocol_version, timeout_s=2.0)
        except Exception:
            with suppress(Exception):
                self.close()
            raise

    @property
    def is_open(self) -> bool:
        """Return `True` when native device connection is open."""
        return self._device is not None

    def close(self) -> None:
        """Close device connection when open."""
        if self._device is None:
            return
        device, self._device = self._device, None
        device.disconnect()

    def configure(self, sweep: RadarSweepModel) -> None:
        """Store and apply sweep settings to connected hardware."""
        self._settings = sweep
        if self._device is None:
            return

        settings = self._vna_sweep_settings(
            f_start_hz=sweep.start_hz,
            f_stop_hz=sweep.stop_hz,
            points=sweep.points,
            if_bandwidth_hz=sweep.if_bandwidth_hz,
            power_start_dbm=sweep.power_dbm,
            power_stop_dbm=sweep.power_dbm,
            excited_ports=(1, 2),
        )
        self._device.vna.configure(settings)

    def read_device_limits(self) -> dict[str, float | int]:
        """Read frequency/IFBW/power/points limits from connected device."""
        if self._device is None:
            raise RuntimeError("Failed to connect to LibreVNA device")

        device_info = self._device.get_device_info()
        limits = device_info.limits
        return {
            "min_frequency_hz": float(limits.min_frequency_hz),
            "max_frequency_hz": float(limits.max_frequency_hz),
            "min_ifbw_hz": float(limits.min_ifbw_hz),
            "max_ifbw_hz": float(limits.max_ifbw_hz),
            "max_points": int(limits.max_points),
            "min_power_dbm": float(limits.min_power_dbm),
            "max_power_dbm": float(limits.max_power_dbm),
        }

    def acquire(self) -> SweepResult:
        """Acquire one sweep from hardware."""
        if self._settings is None:
            raise RuntimeError("Radar service is not configured")
        if self._device is None:
            raise RuntimeError("Device not found")

        result = self._device.vna.acquire(expected_points=self._settings.points, timeout_s=20.0)
        return SweepResult(
            x=np.asarray(result.x, dtype=np.float32),
            traces={
                "s11": np.asarray(result.trace("s11"), dtype=np.complex64),
                "s21": np.asarray(result.trace("s21"), dtype=np.complex64),
            },
        )