/*
 * (c) Copyright, Real-Time Innovations, 2025.
 * All rights reserved.
 *
 * No duplications, whole or partial, manual or electronic, may be made
 * without express written permission.  Any such copies, or
 * revisions thereof, must display this notice unaltered.
 * This code contains trade secrets of Real-Time Innovations, Inc.
 */

#ifndef osapi_sha256_h
#define osapi_sha256_h

#include "osapi/osapi_dll.h"
#include "osapi/osapi_type.h"

#define RTI_OSAPI_SHA256_DIGEST_SIZE 32

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @internal
 * @brief SHA256 state structure for incremental hashing.
 */
struct RTIOsapiSHA256State {
    RTI_UINT64 length;
    RTI_UINT32 state[8];
    RTI_UINT32 curlen;
    RTI_UINT8 buf[64];
};

/**
 * @internal
 * @brief Initializes or resets a SHA256 state.
 *
 * @attention This SHA256 implementation is not intended for use in any
 * security-related features and MUST NOT BE USED for such purposes.
 *
 * @param[out] self Pointer to the SHA256 state to initialize.
 */
extern RTIOsapiDllExport void RTIOsapiSHA256State_start(
        struct RTIOsapiSHA256State *self);

/**
 * @internal
 * @brief Adds data to the SHA256 state.
 *
 * This processes the data and updates the internal state.
 * Call repeatedly until all data is added, then call
 * RTIOsapiSHA256State_finish.
 *
 * @attention This SHA256 implementation is not intended for use in any
 * security-related features and MUST NOT BE USED for such purposes.
 *
 * @param[in,out] self Pointer to the SHA256 state.
 * @param[in] input Pointer to the data buffer to add.
 * @param[in] inputSize Size of the data buffer in bytes.
 */
extern RTIOsapiDllExport void RTIOsapiSHA256State_update(
        struct RTIOsapiSHA256State *self,
        const RTI_UINT8 *input,
        RTI_UINT32 inputSize);

/**
 * @internal
 * @brief Finalizes the SHA256 hash and writes the digest.
 *
 * After calling this, RTIOsapiSHA256State_start must be used to reuse the
 * state.
 *
 * @attention This SHA256 implementation is not intended for use in any
 * security-related features and MUST NOT BE USED for such purposes.
 *
 * @param[in,out] self Pointer to the SHA256 state.
 * @param[out] digest Pointer to a buffer to receive the hash.
 */
extern RTIOsapiDllExport void RTIOsapiSHA256State_finish(
        struct RTIOsapiSHA256State *self,
        RTI_UINT8 *digest);

/**
 * @internal
 * @brief Calculates the SHA256 hash of a buffer in one call.
 *
 * Combines start, update, and finish into a single operation.
 *
 * @attention This SHA256 implementation is not intended for use in any
 * security-related features and MUST NOT BE USED for such purposes.
 *
 * @param[out] digest Pointer to a buffer to receive the hash.
 * @param[in] input Pointer to the data buffer to hash.
 * @param[in] inputSize Size of the data buffer in bytes.
 */
extern RTIOsapiDllExport void RTIOsapiSHA256_computeSHA256(
        RTI_UINT8 *digest,
        const char *input,
        size_t inputSize);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif