/* Chrysalide - Outil d'analyse de fichiers binaires
 * entropy.c - équivalent Python du fichier "common/entropy.c"
 *
 * Copyright (C) 2024 Cyrille Bagard
 *
 *  This file is part of Chrysalide.
 *
 *  Chrysalide is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  Chrysalide is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


#include "entropy.h"


#include <common/entropy.h>


#include "../access.h"
#include "../helpers.h"



/* Détermine l'entropie d'un contenu binaire. */
static PyObject *py_entropy_compute_entropy(PyObject *, PyObject *);



/******************************************************************************
*                                                                             *
*  Paramètres  : self = NULL car méthode statique.                            *
*                args = arguments fournis lors de l'appel à la fonction.      *
*                                                                             *
*  Description : Détermine l'entropie d'un contenu binaire.                   *
*                                                                             *
*  Retour      : Valeur d'entropie du contenu fourni.                         *
*                                                                             *
*  Remarques   : -                                                            *
*                                                                             *
******************************************************************************/

static PyObject *py_entropy_compute_entropy(PyObject *self, PyObject *args)
{
    PyObject *result;                       /* Instance à retourner        */
    const bin_t *data;                      /* Données à traiter           */
    int bits;                               /* Choix de référentiel        */
    size_t len;                             /* Quantité de ces données     */
    int ret;                                /* Bilan de lecture des args.  */
    double entropy;                         /* Valeur d'entropie déterminée*/

#define COMPUTE_ENTROPY_METHOD PYTHON_METHOD_DEF        \
(                                                       \
    compute_entropy, "data, /, bits=False",             \
    METH_VARARGS, py_entropy,                           \
    "Compute the entropy of provided data.\n"           \
    "\n"                                                \
    "The *data* to process can be a string or bytes."   \
    " The optional *bits* argument defines if the"      \
    " computed value is expressed in bits (log base 2)" \
    " or in bytes (log base 256).\n"                    \
    "\n"                                                \
    "The result is a float value."                      \
)

    bits = 0;

    ret = PyArg_ParseTuple(args, "s#|p", &data, &len, &bits);
    if (!ret) return NULL;

    entropy = compute_entropy((const bin_t *)data, len, bits);

    result = PyFloat_FromDouble(entropy);

    return result;

}


/******************************************************************************
*                                                                             *
*  Paramètres  : -                                                            *
*                                                                             *
*  Description : Définit une extension du module 'common' à compléter.        *
*                                                                             *
*  Retour      : Bilan de l'opération.                                        *
*                                                                             *
*  Remarques   : -                                                            *
*                                                                             *
******************************************************************************/

bool populate_common_module_with_entropy(void)
{
    bool result;                            /* Bilan à retourner           */
    PyObject *module;                       /* Module à recompléter        */

    static PyMethodDef py_entropy_methods[] = {
        COMPUTE_ENTROPY_METHOD,
        { NULL }
    };

    module = get_access_to_python_module("pychrysalide.common");

    result = register_python_module_methods(module, py_entropy_methods);

    return result;

}