/*
 * Usurpataion --- server-client protocol private interface.
 *
 * Copyright (C) 2019 Ramūnas Mažeikis
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; version 2.1
 * of the License.
 *
 * This program 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#ifndef PROTOCOL_H_PRIVATE
#define PROTOCOL_H_PRIVATE

#include "utils.h"

/**
 * Returns the amount of tlv's int a packet.
 *
 * If a tlv reports length that goes beyond the end of a packet, errno is set
 * to TLV_OVERFLOW. To check this, set errno to 0 first.
 *
 * @param packet data parsed from a packet. Function cannot use raw packets.
 *
 * @return Amount of tlv's in a packet.
 * */
size_t tlv_count(const struct packet_data * const packet_data);

/**
 * Parses tlv's from packet data and writes them to a buffer of given size.
 *
 * Returns how many tlv's were actually parsed.
 *
 * To check for errors, set errno to 0 and check after calling.
 *
 * Not yet implemented.
 *
 * @param data Data from network packet
 * @param buf Buffer to store parsed tlv's
 * @param buf_size Size of buffer used to store tlv's
 *
 * @return Number of tlv's actually parsed. Greter than or equal to buffer
 * size, if an error occurs.
 * */
size_t get_tlvs(	const struct packet_data * const data,
			const struct tlv *buf,
			size_t buf_size);

/** Takes a null-terminated string and appends it to the next outgoing packet.
 *
 * @return Returns 0 on success. Otherwise: E_PACKET_OVERFLOW.
 *
 * */
int push_string(cd_t connection, char *str);

/** Reinterprets char * as fpi1_t * and appends it to the outgoing packet as a
 * tlv.
 */
int push_fpi1(cd_t connection, char *num);

/** Reinterprets char * as time_t * and appends it to the outgoing packet as a
 * tlv.
 */
int push_timestamp(cd_t connection, char *data);

/**
 * Pushes a request for daemon to repeat a message identified by a msg_index_t.
 *
 * @param data Pointer to a msg_index_t.
 *
 * @return 0 on success or E_PACKET_OVERFLOW, if not enough space is available
 * to push all the data.
 */
int push_request(cd_t connection, char *data);

/**
 * Pushes a message to the outgoing packet buffer as a reply. A reply is just
 * a null terminated string.
 *
 * @param data msg_idx_t representing sequence number since beggining of
 * connection and a null-terminated string.
 *
 * @return On success --- 0 or E_PACKET_OVERFLOW, if not enough buffer is
 * available.
 */
int push_reply(cd_t connection, char *data);

/** Reinterprets char * as uuid_t * and appends it to the outgoing packet as a
 * tlv.
 */
int push_uuid(cd_t connection, char *data);

/* Appends tlv_type and size of data to a packet effectively creating a tlv
 * header.
 */
int push_tlv_header(cd_t connection, enum tlv_type type, size_t size);

#endif /* PROTOCOL_H_PRIVATE */