/*
 * An unnamed project – client module
 *
 * Copyright (C) 2017 Gediminas Jakutis
 *
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#include <poll.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <ncurses.h>
#include <stddef.h>
#include <stdlib.h>
#include <time.h>

static void init(const unsigned int port, int *sock);
static int getpacket(char *data, size_t buffsize, int *sock, struct sockaddr_in *sender);
static void draw_idle(void);
static void draw_busy(const char * const data);
static float digest_mpu_temp(const short int rawdata);
static float digest_thermistor_voltage(const short int rawdata);

int main(void)
{
	static const char servermagic[] = "I love coffee!";
	static const char clientmagic[] = "I love tea!";
	struct sockaddr_in srvaddr = {0};
	char buff[9001] = {0};
	int sock;
	int pstatus;
	struct timespec lastreply;
	struct timespec now;

	init(2191, &sock);

	clock_gettime(CLOCK_MONOTONIC_RAW, &now);
	lastreply = now;
	lastreply.tv_sec -= 5;

	do {
		clock_gettime(CLOCK_MONOTONIC_RAW, &now);
		pstatus = getpacket(buff, sizeof(buff), &sock, &srvaddr);

		switch (pstatus) {
		case 0:
			if ((now.tv_sec - lastreply.tv_sec) >= 5) {
				draw_idle();
			}
			break;
		case 1:
			lastreply = now;
			if (buff[0] == 'I') {
				if (!(strcmp(buff, servermagic))) {
					sendto(sock, clientmagic, sizeof(clientmagic),
							MSG_DONTWAIT, (struct sockaddr *) &srvaddr, sizeof(srvaddr));
				}
				draw_idle();
				continue;
			}
			draw_busy(buff);
			break;
		default:
			; /* noop */
		}
	} while (getch() != 'q' && pstatus >= 0);

	close(sock);
	endwin();

	return 0;
}

static void init(const unsigned int port, int *sock)
{
	struct sockaddr_in bindaddress = {0};

	bindaddress.sin_family = AF_INET;
	bindaddress.sin_port = htons(port);
	*sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	bind(*sock, (struct sockaddr*) &bindaddress, sizeof(bindaddress));

	initscr();
	nodelay(stdscr, 1);
	noecho();
}

static int getpacket(char *data, size_t buffsize, int *sock, struct sockaddr_in *sender)
{
	static struct pollfd pfd = {0};
	int ret;
	socklen_t sender_len = sizeof(*sender);

	if (!pfd.fd) {
		pfd.fd = *sock;
		pfd.events = POLLIN;
		pfd.revents = 0;
	}

	ret = poll(&pfd, 1, 25);
	if (ret <= 0) {
		return ret;
	}
	if (pfd.revents & POLLIN) {
		recvfrom(*sock, data, buffsize, MSG_DONTWAIT, (struct sockaddr *) sender, &sender_len);
		ret = 1;
	} else {
		ret = 0;
	}

	return ret;
}

static void draw_idle(void)
{
	move(0, 0);
	clrtoeol();
	printw("sequence: [waiting for ESP8266...]");
	move(1, 0);
	clrtoeol();
	mvprintw(1, 0, "mpu temp: [waiting for ESP8266...]");
	move(2, 0);
	clrtoeol();
	mvprintw(2, 0, "thermistor voltage: [waiting for ESP8266...]");
	move(3, 0);
	clrtoeol();
	mvprintw(3, 0, "press 'q' to exit");
	refresh();
}

static void draw_busy(const char * const data)
{
	unsigned int sequence;
	short int mpu_data;
	short int thermistor_data;
	float mpu_temp;
	float thermistor_voltage;

	memcpy(&sequence, data + 2, sizeof(sequence));
	memcpy(&mpu_data, data + 6, sizeof(mpu_data));
	memcpy(&thermistor_data, data + 8, sizeof(thermistor_data));
	mpu_temp = digest_mpu_temp(mpu_data);
	thermistor_voltage = digest_thermistor_voltage(thermistor_data);

	move(0, 0);
	clrtoeol();
	printw("sequence: %u", sequence);
	move(1, 0);
	clrtoeol();
	mvprintw(1, 0, "mpu temp: %.3fC", mpu_temp);
	move(2, 0);
	clrtoeol();
	mvprintw(2, 0, "thermistor voltage: %.3fV", thermistor_voltage);
	move(3, 0);
	clrtoeol();
	mvprintw(3, 0, "press 'q' to exit");
	refresh();
}

static float digest_mpu_temp(const short int rawdata)
{
	float ret;

	ret = rawdata / 340.0f + 36.53f;

	return ret;
}

static float digest_thermistor_voltage(const short int rawdata)
{
	float ret;

	ret = rawdata * 0.003222656f;

	return ret;
}