/*
 * Usurpation – wearable device udp packet handling
 *
 * 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
 */

#include <time.h>
#include <stdlib.h>
#include <string.h>
#include "net.h"
#include "protocol.h"
#include "protocol_private.h"
#include "protocol_device_private.h"
#include "settings.h"

#define READ_AS(type, from)	(*((type*)(from)))

static struct connection_t connection;

cd_t protocol_init(void)
{
	connection.is_live = 1;
	connection.nd = net_init(setting_port());
	return 0;
}

int clear_data(cd_t cd)
{
	int ret = 0;
	if (cd >= MAX_CONNECTIONS) {
		ret = E_IVALID_DESCRIPTOR;
	} else {
		connection.inp_crs = 0;
	}
	return ret;
}

static int push_bytes(cd_t cd, const char *data, size_t size)
{
	int ret = 0;

	if (cd >= MAX_CONNECTIONS) {
		ret = E_IVALID_DESCRIPTOR;
	} else if (connection.outp_crs + size >= sizeof(connection.outp_buf)) {
		ret = E_PACKET_OVERFLOW;
	} else {
		memcpy(connection.outp_buf, data, size);
		connection.outp_crs += size;
	}
	return ret;
}

static int push_tlv_header(cd_t cd, enum tlv_type type, size_t size)
{
	int ret = 0;

	if (cd >= MAX_CONNECTIONS) {
		errno = E_IVALID_DESCRIPTOR;
		ret = NULL;
	} else if (connection.outp_crs >= MAX_PACKET_SIZE_IN) {
		errno = E_TLV_OVERFLOW;
		ret = NULL;
	} else {
		READ_AS(enum tlv_type, connection.outp_buf + connection.outp_crs)
			= type;
		connection.outp_crs += sizeof(enum tlv_type);
		READ_AS(size_t, connection.outp_buf + connection.outp_crs) = size;
		connection.outp_crs += sizeof(size_t);
	}
	return ret;
}

struct tlv * get_tlv(cd_t cd)
{
	struct tlv *ret = &connection.next_tlv;
	size_t offset = connection.inp_crs;
	char *data = connection.inp_buf;

	if (cd >= MAX_CONNECTIONS) {
		errno = E_IVALID_DESCRIPTOR;
		ret = NULL;
	} else if (offset >= MAX_PACKET_SIZE_IN) {
		errno = E_TLV_OVERFLOW;
		ret = NULL;
	} else {
		ret->type = READ_AS(enum tlv_type, data + offset);
		offset += sizeof(enum tlv_type);
		ret->length = READ_AS(size_t, data + offset);
		offset += sizeof(size_t);
		ret->data = data + offset;
		connection.inp_crs = offset;
	}
	return ret;
}

int flush_data(cd_t cd)
{
	return 0;
}

int get_last_data(cd_t cd)
{
	if (cd >= MAX_CONNECTIONS) {
		return E_IVALID_DESCRIPTOR;
	}
	net_getlastdata(connection.nd, connection.inp_buf);
}