# utils.py
import numpy as np

from .constants import HBAR_C_MEV_FM, ME_MEV


def nuclear_radius(A: float, r0: float = 1.2) -> float:
    r0_fm = 1.2  # fm
    R_fm = r0_fm * A ** (1 / 3)

    return R_fm / (HBAR_C_MEV_FM / ME_MEV)


def momentum(W):
    return np.sqrt(W**2 - 1)


def neutrino_energy(W, W0):
    return W0 - W


def W_to_T(W: float | np.ndarray) -> np.ndarray:
    return (W - 1.0) * ME_MEV


def T_to_W(T_keV: float | np.ndarray) -> np.ndarray:
    return T_keV / ME_MEV + 1.0