#pragma once

#include <stddef.h>
#include <stdlib.h>

#ifdef __cplusplus
extern "C" {
#endif

/*!
 * \file
 */

/*!
 * \brief The bignum_error enum
 */
enum bignum_error {
	NoError = 0,
	error = -1
};

/*!
 * \brief cMix internal bignum representation.
 */
struct Bignum {
	unsigned char* data; ///< Pointer to the start of the bignum.
	size_t len; ///< The length of the data array.
};

/*!
 * \brief allocate_bignum. Reserves space for a len size Bignum.
 * \param len The length of the bignum data array.
 * \return The Bignum array just allocated.
 */
inline struct Bignum allocate_bignum(size_t len) {
	return (struct Bignum){
		(unsigned char*) malloc(len),
		len
	};
}

/*!
 * \brief free_bignum. Counterpart to allocate_bignum.
 * \param b The bignum to free
 */
inline void free_bignum(struct Bignum* b) {
	free(b->data);
	b->data = 0;
	b->len = 0;
}

/*!
 * \brief get_curve25519_mod. Conveniance for now, but this returns the mod of curve25519 algorith (2^255-19)
 * \param result The bignum to store the modulus in, has to be preallocated.
 * \return Error status code based on backend errors.
 */
extern enum bignum_error get_curve25519_mod(struct Bignum* result);

/*!
 * \brief multiply_mod Multiplies 2 bignums module mod and stores the result in result.
 * \param result Preallocated Bignum where the result will be stored.
 * \param lh Lefthand of Multiplication.
 * \param rh Righthand of Multiplaction.
 * \param mod The modulus.
 * \return Error status code based on backend errors.
 */
extern enum bignum_error multiply_mod(struct Bignum* result, struct Bignum const lh, struct Bignum const rh, struct Bignum const mod);


#ifdef __cplusplus
}
#endif