/* 
 * modbuslog
 *
 * Copyright (C) 2011 Jonathan McCrohan
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.

 * 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 General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

// gcc modbuslog.c -o modbuslog `pkg-config --libs --cflags libmodbus libconfig`
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <sys/select.h>
#include <signal.h>

#include <libconfig.h>
#include <modbus.h>

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <string.h>

#define SLAVE_ID 1
#define START_ADDRESS 0
#define NUMBER_REGISTERS 14
#define DEBUG 1

void minute_check(int signum) {
	alarm(60);
}

void find_mac(unsigned char* mac_address) {
	int s;
	struct ifreq ifr;

	s = socket(PF_INET, SOCK_DGRAM, 0);
	memset(&ifr, 0x00, sizeof(ifr));
	strcpy(ifr.ifr_name, "eth0");
	ioctl(s, SIOCGIFHWADDR, &ifr);
	close(s);

	unsigned char mac_address_internal[6];
	sprintf(mac_address_internal, "%.2X%.2X%.2X%.2X%.2X%.2X",
			(unsigned char) ifr.ifr_hwaddr.sa_data[0],
			(unsigned char) ifr.ifr_hwaddr.sa_data[1],
			(unsigned char) ifr.ifr_hwaddr.sa_data[2],
			(unsigned char) ifr.ifr_hwaddr.sa_data[3],
			(unsigned char) ifr.ifr_hwaddr.sa_data[4],
			(unsigned char) ifr.ifr_hwaddr.sa_data[5]);

	strcpy(mac_address, mac_address_internal);
}

int main(int argc, char *argv[]) {

	const char *CONFIG_FILE = "modbuslog.cfg";

	config_t cfg;
	//config_setting_t *setting;

	unsigned char mac_address[6];

	const char *modbus_device_address;
	int modbus_baud_rate;
	int modbus_data_bits;
	const char *modbus_parity;
	int modbus_stop_bits;

	config_init(&cfg);

	find_mac(mac_address);

	if (!config_read_file(&cfg, CONFIG_FILE)) {
		fprintf(stderr, "%s:%d - %s\n", config_error_file(&cfg),
				config_error_line(&cfg), config_error_text(&cfg));
		config_destroy(&cfg);
		fprintf(stderr, "Unable to find CONFIG_FILE.\n");
		return -1;
	}

	if (!(config_lookup_string(&cfg, "modbus.device", &modbus_device_address)
			&& config_lookup_int(&cfg, "modbus.baud", &modbus_baud_rate)
			&& config_lookup_int(&cfg, "modbus.data_bits", &modbus_data_bits)
			&& config_lookup_string(&cfg, "modbus.parity", &modbus_parity)
			&& config_lookup_int(&cfg, "modbus.stop_bits", &modbus_stop_bits))) {
		fprintf(stderr,
				"Incomplete modbus configuration. Check configuration file.\n");
		return -1;
	}

	if (DEBUG) {
		printf("%s %s %d %c %d %d\n", mac_address, modbus_device_address,
				modbus_baud_rate, modbus_parity[0], modbus_data_bits,
				modbus_stop_bits);
	}

	modbus_t *ctx;
	uint16_t tab_reg[64];
	int rc;
	int i;

	signal(SIGALRM, minute_check);
	alarm(60);

	for (;;) {
		select(0, NULL, NULL, NULL, NULL);

		time_t t = time(NULL);
		int unixtime_min = (((int) t) / 60 * 60);
		//int unixtime = (int) t;
		//printf("%d\n", unixtime);

		config_setting_t *registers;

		registers = config_lookup(&cfg, "register");

		unsigned int num_registers = config_setting_length(registers);

		int i;
		for (i = 0; i < num_registers; ++i) {
			config_setting_t *register_element = config_setting_get_elem(
					registers, i);
			int slaveid;
			config_setting_lookup_int(register_element, "slaveid", &slaveid);
			int intervalvalue;
			config_setting_lookup_int(register_element, "intervalvalue",
					&intervalvalue);
			//printf("%d", intervalvalue);

			int startaddress;
			config_setting_lookup_int(register_element, "startaddress",
					&startaddress);

			int numregisters;
			config_setting_lookup_int(register_element, "numregisters",
					&numregisters);

			const char *intervalunit;
			config_setting_lookup_string(register_element, "intervalunit",
					&intervalunit);

			//printf("%c", intervalunit[0]);

			int intervalduration;

			if (intervalunit[0] == 'H')
				intervalduration = intervalvalue * 3600;
			else
				intervalduration = intervalvalue * 60;

			if (unixtime_min % intervalduration == 0) {
				//printf("specified minute.  %d %d\n", unixtime_min,
				//		intervalduration);

				ctx = modbus_new_rtu(modbus_device_address, modbus_baud_rate,
						modbus_parity[0], modbus_data_bits, modbus_stop_bits);

				modbus_set_slave(ctx, slaveid);
				modbus_set_debug(ctx, DEBUG);

				if (ctx == NULL) {
					fprintf(stderr, "Unable to create libmodbus object.\n");
					//return -1;
				}

				if (modbus_connect(ctx) == -1) {
					fprintf(stderr, "Connection failed: %s\n",
							modbus_strerror(errno));
					modbus_free(ctx);
					//return -1;
				}

				rc = modbus_read_input_registers(ctx, startaddress,
						numregisters, tab_reg);

				if (rc == -1) {
					fprintf(stderr, "ERROR: %s\n", modbus_strerror(errno));
					//return -1;
				}

				for (i = 0; i < rc; i = i + 2) {
					printf("reg[%d]=%d\n", i, tab_reg[i] + tab_reg[i + 1]);
				}

				modbus_close(ctx);
				modbus_free(ctx);

				//return 0;

			}

			//printf("%d ", slaveid);
		}
		//printf("%d\n", unixtime_min);
	}
}