/*
 * Usurpation – wearable device udp packet handling
 *
 * Copyright (C) 2019 Gediminas Jakutis
 * 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 <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include "device_network.h"
#include "utils.h"
#include "tlv.h"

static struct netstate {
	WiFiUDP udp;
	char udppacketbuffer[MTU];
	char *udppacketcursor;
	IPAddress daemon_ip;
	bool acquired;
} state;


static void udp_init_packet_expaddr(IPAddress ip, const int port);

void udp_init(const int port)
{
	state.udp.begin(com_port);
}

void udp_init_packet(const int port)
{
	state.udp.beginPacket(state.daemon_ip, port);
	memset(state.udppacketbuffer, 0, sizeof(state.udppacketbuffer));
	state.udppacketcursor = state.udppacketbuffer;
}

void udp_push(const void * const data, const size_t size)
{
	memcpy(state.udppacketcursor, data, size);
	state.udppacketcursor += size;
}

int udp_flush(void)
{
	state.udp.write((const uint8_t *) state.udppacketbuffer, state.udppacketcursor - state.udppacketbuffer);
	return state.udp.endPacket();
}

size_t udp_get_data(char *buf, size_t size)
{
	size_t ret;

	state.udp.parsePacket();

	if ((ret = state.udp.available())) {
		state.udp.read(buf, size);
	}

	return ret;
}

IPAddress *discover_client(const int port)
{
	IPAddress bcastip(255, 255, 255, 255);
	char buffer[128] = {0};
	struct tlv field;
	struct tlv_packet pack;
	size_t expected_s;

	tlv_init(&field, HEARTBEAT);
	field.data = strdup(heartbeat_device);
	field.head.size = sizeof(heartbeat_device);
	tlv_packet_init(&pack);
	tlv_pack(&pack, &field);
	tlv_packet_finalize(&pack);
	tlv_destroy(&field);

	do {
		udp_init_packet_expaddr(bcastip, port);
		udp_push(pack.data, pack.cursor + 1);
		udp_flush();
		delay(5);

		expected_s = sizeof(field.head) + sizeof(heartbeat_server);
		if (udp_get_data(buffer, sizeof(buffer)) >= expected_s) {
			tlv_get(buffer, &field, NULL);
			if (field.head.type == HEARTBEAT && !(strcmp(heartbeat_server, field.data))) {
				state.daemon_ip = state.udp.remoteIP();
				++state.acquired;
			}
		}
		delay(95);
	} while (!state.acquired);

	tlv_packet_destroy(&pack);

	return &state.daemon_ip;
}

IPAddress *get_daemon_address(void)
{
	IPAddress *ret;
	if (!state.acquired) {
		ret = new IPAddress(0, 0, 0, 0);
	} else {
		ret = new IPAddress(state.daemon_ip);
	}

	return ret;
}

static void udp_init_packet_expaddr(IPAddress ip, const int port)
{
	state.udp.beginPacket(ip, port);
	memset(state.udppacketbuffer, 0, sizeof(state.udppacketbuffer));
	state.udppacketcursor = state.udppacketbuffer;
}