/*
   Copyright (c) 2022 Fraunhofer AISEC. See the COPYRIGHT
   file at the top-level directory of this distribution.

   Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   option. This file may not be copied, modified, or distributed
   except according to those terms.
*/

/*
 * In the most general case the user of this library should use only the  
 * functions exposed in edhoc.h. Some more advance users may want to manage the 
 * edhoc state by themself. The functions in this file are meant to be used by 
 * such users. An example how the functions in this file can be used can be 
 * found in responder.c and initiator.c
 */

#ifndef EDHOC_INTERNAL_H
#define EDHOC_INTERNAL_H

#include <stdint.h>

#include "edhoc/runtime_context.h"

#include "common/oscore_edhoc_error.h"

/**
 * @brief Initializes the EDHOC runtime context
 * 
 * @param c Pointer to the runtime context
 */
void runtime_context_init(struct runtime_context *c);

/**
 * @brief Generates message 1. This function should by used by on the 
 *        initiator side.
 * 
 * @param c initiator context
 * @param rc runtime context
 */
enum err msg1_gen(const struct edhoc_initiator_context *c,
		  struct runtime_context *rc);

/**
 * @brief Generates message 3. This function should by used by on the 
 *        initiator side.
 * 
 * @param c initiator context
 * @param rc runtime context
 * @param cred_r_array array of CRED_Rs
 * @param num_cred_r Number of elements in CRED_R
 * @param ead_2 EAD_2 contained in message 2
 * @param ead_2_len length of EAD_2
 * @param prk_4x3m the derived secret (output)
 * @param prk_4x3m_len length of prk_4x3m
 * @param th4 the transcript hash 4 (output)
 * @param th4_len length of th4
 * @return enum err 
 */
enum err msg3_gen(const struct edhoc_initiator_context *c,
		  struct runtime_context *rc,
		  struct other_party_cred *cred_r_array, uint16_t num_cred_r,
		  uint8_t *ead_2, uint32_t *ead_2_len, uint8_t *prk_4x3m,
		  uint32_t prk_4x3m_len, uint8_t *th4);

/**
 * @brief Processes message 4. This function should by used by on the initiator 
 *        side. 
 * 
 * @param c initiator context
 * @param rc runtime context
 * @param ead_4 EAD_4 (output)
 * @param ead_4_len lenhgt of EAD_4
 * @param prk_4x3m the derived secret 
 * @param prk_4x3m_len length of prk_4x3m
 * @param th4 the transcript hash 4 
 * @param th4_len length of th4
 * @return enum err 
 */
enum err msg4_process(struct runtime_context *rc, uint8_t *ead_4,
		      uint32_t *ead_4_len, uint8_t *prk_4x3m,
		      uint32_t prk_4x3m_len, uint8_t *th4, uint32_t th4_len);

/**
 * @brief Generates message 2. This function should by used by on the responder 
 *        side.
 * 
 * @param c responder context
 * @param rc runtime context
 * @param ead_1 EAD_1 from message 1 (output)
 * @param ead_1_len length of EAD_1 
 * @return enum err 
 */
enum err msg2_gen(struct edhoc_responder_context *c, struct runtime_context *rc,
		  uint8_t *ead_1, uint32_t *ead_1_len);

/**
 * @brief Processes message 3. This function should by used by on the responder 
 *        side. prk_4x3m and th4 are the outpus used in the exporter interface.
 * 
 * @param c responder context
 * @param rc runtime context
 * @param cred_i_array Array of CRED_Is
 * @param num_cred_i Number of elements in cred_i_array
 * @param ead_3 EAD_3 from message 3 (output)
 * @param ead_3_len length of EAD_3
 * @param prk_4x3m the derived secret (output)
 * @param prk_4x3m_len length of prk_4x3m
 * @param th4 the transcript hash 4 (output)
 * @param th4_len length of th4
 * @return enum err 
 */
enum err msg3_process(struct edhoc_responder_context *c,
		      struct runtime_context *rc,
		      struct other_party_cred *cred_i_array,
		      uint16_t num_cred_i, uint8_t *ead_3, uint32_t *ead_3_len,
		      uint8_t *prk_4x3m, uint32_t prk_4x3m_len, uint8_t *th4);

/**
 * @brief Generates message 4. This function should by used by on the responder 
 *        side.
 * 
 * @param c responder context
 * @param rc runtime context
 * @param prk_4x3m the derived secret
 * @param prk_4x3m_len length of prk_4x3m
 * @param th4 the transcript hash 4 
 * @param th4_len length of th4
 * @return enum err 
 */
enum err msg4_gen(struct edhoc_responder_context *c, struct runtime_context *rc,
		  uint8_t *prk_4x3m, uint32_t prk_4x3m_len, uint8_t *th4,
		  uint32_t th4_len);
#endif