"""
Detector Configuration Module

Contains configuration parameters for Radiacode gamma spectrometers
and other detector settings.

Energy calibration matches the real Radiacode 103:
    E(keV) = 0.33 + 2.97 * channel_index
Uses 1023 channels (channel 1023 is overflow, excluded).
"""

from dataclasses import dataclass
from typing import Dict
import numpy as np


@dataclass
class DetectorConfig:
    """Configuration for a gamma spectrometer detector."""

    name: str
    # Energy calibration: E = calibration_offset + calibration_slope * channel
    # Must match the real detector calibration used in inference.
    calibration_offset_kev: float = 0.33
    calibration_slope_kev: float = 2.97

    # Number of usable channels (1023 for Radiacode, channel 1023 is overflow)
    num_channels: int = 1023

    # FWHM at 662 keV (Cs-137 reference) as fraction
    fwhm_at_662: float = 0.084  # 8.4%
    fwhm_uncertainty: float = 0.003  # ±0.3%

    # Detector crystal type
    crystal_type: str = "CsI(Tl)"

    # Sensitivity: counts per second at 1 μSv/h for Cs-137
    sensitivity_cps_per_usvh: float = 30.0

    # Detector volume in cm³
    detector_volume_cm3: float = 1.0

    def get_energy_bins(self) -> np.ndarray:
        """Get array of energy bin centers (keV) matching the real detector calibration."""
        channels = np.arange(self.num_channels, dtype=np.float64)
        return self.calibration_offset_kev + self.calibration_slope_kev * channels

    def get_fwhm_at_energy(self, energy_kev: float) -> float:
        """
        Calculate FWHM at a given energy.

        For scintillators, FWHM scales approximately as sqrt(E).
        FWHM(E) = FWHM_662 * sqrt(E/662)
        """
        return self.fwhm_at_662 * np.sqrt(energy_kev / 662.0) * 662.0

    def get_sigma_at_energy(self, energy_kev: float) -> float:
        """Get Gaussian sigma at a given energy."""
        fwhm = self.get_fwhm_at_energy(energy_kev)
        return fwhm / 2.355

    def energy_to_channel(self, energy_kev: float) -> int:
        """Convert energy in keV to channel index."""
        channel = int((energy_kev - self.calibration_offset_kev) / self.calibration_slope_kev)
        return max(0, min(self.num_channels - 1, channel))

    def channel_to_energy(self, channel: int) -> float:
        """Convert channel index to energy in keV."""
        return self.calibration_offset_kev + self.calibration_slope_kev * channel


# Pre-defined configurations for Radiacode devices
RADIACODE_CONFIGS: Dict[str, DetectorConfig] = {
    "radiacode_101": DetectorConfig(
        name="Radiacode 101",
        fwhm_at_662=0.095,  # 9.5%
        fwhm_uncertainty=0.004,
        crystal_type="CsI(Tl)",
        sensitivity_cps_per_usvh=30.0,
        detector_volume_cm3=1.0,
    ),
    "radiacode_102": DetectorConfig(
        name="Radiacode 102",
        fwhm_at_662=0.095,  # 9.5%
        fwhm_uncertainty=0.004,
        crystal_type="CsI(Tl)",
        sensitivity_cps_per_usvh=30.0,
        detector_volume_cm3=1.0,
    ),
    "radiacode_103": DetectorConfig(
        name="Radiacode 103",
        fwhm_at_662=0.084,  # 8.4%
        fwhm_uncertainty=0.003,
        crystal_type="CsI(Tl)",
        sensitivity_cps_per_usvh=30.0,
        detector_volume_cm3=1.0,
    ),
    "radiacode_103g": DetectorConfig(
        name="Radiacode 103G",
        fwhm_at_662=0.074,  # 7.4% (GAGG crystal)
        fwhm_uncertainty=0.003,
        crystal_type="GAGG(Ce)",
        sensitivity_cps_per_usvh=40.0,
        detector_volume_cm3=1.0,
    ),
    "radiacode_110": DetectorConfig(
        name="Radiacode 110",
        fwhm_at_662=0.084,  # 8.4%
        fwhm_uncertainty=0.003,
        crystal_type="CsI(Tl)",
        sensitivity_cps_per_usvh=77.0,
        detector_volume_cm3=2.5,
    ),
}


def get_default_config() -> DetectorConfig:
    """Get the default detector configuration (Radiacode 103)."""
    return RADIACODE_CONFIGS["radiacode_103"]