// SPDX-License-Identifier: BSD-3-Clause OR Apache-2.0
#ifndef AAP2_UTIL_H_INCLUDED
#define AAP2_UTIL_H_INCLUDED

// Common functions for the AAP 2.0 Agent and Client.

#include "aap2/aap2.pb.h"

#include <pb.h>

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif // __cplusplus

// SENDING

/**
 * @brief Send a message to the AAP socket.
 *
 * @param socket_fd Socket on which to send the message
 * @param fields Nanopb Protobuf message specification
 * @param src_struct Pointer to the Nanopb Protobuf message struct to send
 * @return 0 if successful, errno otherwise
 */
int aap2_send_message(const int socket_fd,
		      const pb_msgdesc_t *const fields,
		      const void *const src_struct);

// RECEIVING

/**
 * @brief A Nanopb-compatible callback function to receive data from a stream socket.
 *
 * @param stream Pointer to the Nanopb input stream (contains the socket fd)
 * @param buf A buffer provided by Nanopb to read the raw data into
 * @param count Length of the provided buffer
 * @return true if successful, false if not (evaluated by Nanopb)
 */
bool aap2_pb_recv_callback(pb_istream_t *stream, uint8_t *buf, size_t count);

/**
 * @brief Receive a message from the AAP socket.
 *
 * @param stream Pointer to the Nanopb input stream (contains the socket fd)
 * @param fields Nanopb Protobuf message specification
 * @param dest_struct Pointer to the Nanopb Protobuf message struct to be populated
 * @return 0 if successful, -1 otherwise
 */
int aap2_recv_message(pb_istream_t *stream, const pb_msgdesc_t *const fields, void *dest_struct);

// ADU FLAGS HANDLING

/**
 * @brief Representation of the AAP 2.0 BundleADUFlags repeated enum field.
 */
struct aap2_bundle_adu_flags {
	/**
	 * The payload of this ADU is a BIBE protocol data unit.
	 */
	bool is_bpdu;
	/**
	 * The payload of this ADU is a bundle status report.
	 */
	bool is_status_report;
	/**
	 * This ADU was or shall be authorized with administrative (bundle dispatch module)
	 * permissions. Clients sending bundles with this flag set must authenticate with the
	 * administrative (BDM) AAP 2.0 secret. Receivers of bundles with this flag set can assume
	 * that it comes from a trusted source. Bundles with this flag may transmit, e.g., local
	 * configuration and monitoring information. The flag does not leave the local node.
	 */
	bool with_bdm_auth;
};
// Number of flags that may be set
#define AAP2_BUNDLE_ADU_FLAGS_COUNT (_aap2_BundleADUFlags_MAX)
#ifdef __cplusplus
#define _Static_assert static_assert
#endif // __cplusplus
_Static_assert(AAP2_BUNDLE_ADU_FLAGS_COUNT == 3, "do not forget to update aap2.options");

/**
 * @brief Populate the given ADU flags field from the provided set of flags.
 *
 * @param flags_field The ADU flags array part of the BundleADU Nanopb message struct
 * @param flags The flags to be set
 * @return The number of flags set
 */
size_t aap2_set_adu_flags(aap2_BundleADUFlags *flags_field, struct aap2_bundle_adu_flags flags);

/**
 * @brief Read the ADU flags from the provided Nanopb array.
 *
 * @param flags_field The ADU flags array part of the BundleADU Nanopb message struct
 * @param flags_count The number of entries set in the given array
 * @return A struct bundle_adu_flags containing the values of the individual ADU flags
 */
struct aap2_bundle_adu_flags aap2_get_adu_flags(const aap2_BundleADUFlags *flags_field,
						size_t flags_count);

#ifdef __cplusplus
}
#endif // __cplusplus

#endif // AAP2_UTIL_H_INCLUDED