"""
Wrappers to the LibXC C structs
"""

import ctypes
import numpy as np


class func_reference_type(ctypes.Structure):
    """
    Holds reference data for the LibXC functional
    """
    _fields_ = [("ref", ctypes.c_char_p), ("doi", ctypes.c_char_p),
                ("bibtex", ctypes.c_char_p)]


class func_params_type(ctypes.Structure):
    """
    Holds user defined parameters and their description.
    """
    _fields_ = [("value", ctypes.c_double), ("description", ctypes.c_char_p)]


class xc_func_info_type(ctypes.Structure):
    """
    Holds LibXC information about a single functional primitive.
    """
    _fields_ = [
        ("number", ctypes.c_int),
        ("name", ctypes.c_char_p),
        ("kind", ctypes.c_int),
        ("family", ctypes.c_int),
        ("refs", ctypes.POINTER(func_reference_type)),
        ("flags", ctypes.c_int),
        ("dens_threshold", ctypes.c_double),
        ("n_ext_params", ctypes.c_int),
        ("ext_params", ctypes.POINTER(func_params_type)),
        ("set_ext_params", ctypes.c_void_p),
        ("init", ctypes.c_void_p),
        ("end", ctypes.c_void_p),
        ("lda", ctypes.c_void_p),
        ("gga", ctypes.c_void_p),
        ("mgga", ctypes.c_void_p),
    ]


class xc_func_type(ctypes.Structure):
    """
    The primary xc_func_type used to hold all data pertaining to a given
    LibXC functional
    """
    _fields_ = [
        ("info", ctypes.POINTER(xc_func_info_type)),  # const xc_func_info_type *info;
        ("nspin", ctypes.c_int),
        ("n_func_aux", ctypes.c_int),
        ("xc_func_type", ctypes.c_void_p),
        ("mix_coef", ctypes.POINTER(ctypes.c_double)),

        # CAM
        ("cam_omega", ctypes.c_double),
        ("cam_alpha", ctypes.c_double),
        ("cam_beta", ctypes.c_double),

        # VV10
        ("nlc_b", ctypes.c_double),
        ("nlc_C", ctypes.c_double),

        # n terms
        ("n_rho", ctypes.c_int),
        ("n_sigma", ctypes.c_int),
        ("n_tau", ctypes.c_int),
        ("n_lapl", ctypes.c_int),
        ("n_zk", ctypes.c_int),

        # v terms
        ("n_vrho", ctypes.c_int),
        ("n_vsigma", ctypes.c_int),
        ("n_vtau", ctypes.c_int),
        ("n_vlapl", ctypes.c_int),

        # v2 terms
        ("n_v2rho2", ctypes.c_int),
        ("n_v2sigma2", ctypes.c_int),
        ("n_v2tau2", ctypes.c_int),
        ("n_v2lapl2", ctypes.c_int),
        ("n_v2rhosigma", ctypes.c_int),
        ("n_v2rhotau", ctypes.c_int),
        ("n_v2rholapl", ctypes.c_int),
        ("n_v2sigmatau", ctypes.c_int),
        ("n_v2sigmalapl", ctypes.c_int),
        ("n_v2lapltau", ctypes.c_int),

        # v3 terms
        ("n_v3rho3", ctypes.c_int),
        ("n_v3rho2sigma", ctypes.c_int),
        ("n_v3rhosigma2", ctypes.c_int),
        ("n_v3sigma3", ctypes.c_int),

        # parameters
        ("params", ctypes.c_void_p),  # void *params;
        ("dens_threshold", ctypes.c_double),
    ]