/*
 * apds990x proximity sensor testing module
 *
 * Copyright (C) 2013  Andi Shyti <andi@etezian.org>
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define MAX_N	100
#define ENABLE	"1"
#define DISABLE	"0"

struct device {
	unsigned int n;

	int prox;

	char *power;
	char *prox_en;
	char *prox_raw;
};

struct device apds990x_dev = {
	.n = 10,
	.power = "/sys/class/i2c-adapter/i2c-12/12-0039/power_state",
	.prox_en = "/sys/class/i2c-adapter/i2c-12/12-0039/prox0_raw_en",
	.prox_raw = "/sys/class/i2c-adapter/i2c-12/12-0039/prox0_raw",
};

int write_file(char *fname, const char *val)
{
	int fd;
	ssize_t ret;
	int retval = 0;

	fd = open(fname, O_WRONLY);
	if (fd < 0) {
		retval = errno;
		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
		return retval;
	}

	ret = write(fd, val, 1);
	if (ret != 1) {
		retval = errno;
		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
		close(fd);
		return retval;
	}

	fd = close(fd);
	if (fd < 0) {
		retval = errno;
		fprintf(stderr, "%s: %s\n", fname, strerror(errno));
	}

	return retval;
}

int read_proxy(void)
{
	unsigned int i;
	int fd, retval = 0;
	ssize_t ret;
	char val[6];

	for (i = 0; i < apds990x_dev.n; i++) {
		sleep(1);

		fd = open(apds990x_dev.prox_raw, O_RDONLY);
		if (fd < 0) {
			retval = errno;
			fprintf(stderr, "%s: %s\n", apds990x_dev.prox_raw,
							strerror(errno));
			return retval;
		}

		ret = read(fd, val, sizeof(val));
		if (ret < 0) {
			retval = errno;
			fprintf(stderr, "%s: %s\n",
				apds990x_dev.prox_raw, strerror(errno));
			break;
		}

		/* replace EOF with \n */
		val[ret-1] = '\n';
		apds990x_dev.prox = (int) strtol(val, NULL, 10);
		printf("%d\n", apds990x_dev.prox);

		fd = close(fd);
		if (fd < 0) {
			retval = errno;
			fprintf(stderr, "%s: %s\n", apds990x_dev.prox_raw,
							strerror(errno));
			break;
		}
	}

	return retval;
}

void print_usage(char *name)
{
	printf("Usage: %s [-n <number>]\n", name);
	printf("\n");
	printf("	-n <number>	- number of readings on the device\n");
	printf("	-h, --help	- print help menu\n");
}

int parse_cmdline(int argc, char *argv[])
{
	int i;
	unsigned long int n;

	for (i = 1; i < argc; i++) {
		if (!strcmp(argv[i], "-n")) {
			n = strtoul(argv[++i], NULL, 10);
			/* check for overflow */
			if (errno)
				return errno;

			apds990x_dev.n = ((n > MAX_N) || (n <= 0)) ?
						MAX_N : (unsigned int) n;
		} else if (!strcmp(argv[i], "-h") ||
						!strcmp(argv[i], "--help")) {
			print_usage(argv[0]);
			exit(EXIT_SUCCESS);
		} else {
			fprintf(stderr, "%s: %s\n\n",
						argv[i], strerror(EINVAL));
			print_usage(argv[0]);
			return EINVAL;
		}
	}

	return 0;
}

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

	if (argc > 1) {
		err = parse_cmdline(argc, argv);
		if (err)
			return err;
	}

	err = write_file(apds990x_dev.power, ENABLE);
	if (err)
		return err;

	err = write_file(apds990x_dev.prox_en, ENABLE);
	if (!err) {
		read_proxy();
		write_file(apds990x_dev.prox_en, DISABLE);
	}

	err = write_file(apds990x_dev.power, DISABLE);

	return err;
}