/*
 * Conky, a system monitor, based on torsmo
 *
 * Any original torsmo code is licensed under the BSD license
 *
 * All code written since the fork of torsmo is licensed under the GPL
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2004, Hannu Saransaari and Lauri Hakkarainen
 * Copyright (c) 2005-2009 Brenden Matthews, Philip Kovacs, et. al.
 * (see AUTHORS)
 * All rights reserved.
 *
 * 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/>.
 *
 */

#include "config.h"
#include "conky.h"	/* text_buffer_size */
#include "logging.h"
#include "diskio.h"
#include "common.h"
#include <stdlib.h>
#include <limits.h>
#include <sys/stat.h>

/* this is the root of all per disk stats,
 * also containing the totals. */
struct diskio_stat stats = {
	.next = NULL,
	.sample = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
	.sample_read = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
	.sample_write = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
	.current = 0,
	.current_read = 0,
	.current_write = 0,
	.last = UINT_MAX,
	.last_read = UINT_MAX,
	.last_write = UINT_MAX,
};

void clear_diskio_stats(void)
{
	struct diskio_stat *cur;
	while (stats.next) {
		cur = stats.next;
		stats.next = stats.next->next;
		free(cur);
	}
}

struct diskio_stat *prepare_diskio_stat(const char *s)
{
	struct stat sb;
	char stat_name[text_buffer_size], device_name[text_buffer_size];
	struct diskio_stat *cur = &stats;

	if (!s)
		return &stats;

#if defined(__FreeBSD__)
	if (strncmp(s, "/dev/", 5) == 0) {
		// supplied a /dev/device arg, so cut off the /dev part
		strncpy(device_name, s + 5, text_buffer_size);
	} else
#endif
	strncpy(device_name, s, text_buffer_size);

	snprintf(stat_name, text_buffer_size, "/dev/%s", device_name);

	if (stat(stat_name, &sb)) {
		ERR("diskio device '%s' does not exist", s);
		return 0;
	}

	/* lookup existing */
	while (cur->next) {
		cur = cur->next;
		if (!strcmp(cur->dev, device_name)) {
			return cur;
		}
	}

	/* no existing found, make a new one */
	cur->next = calloc(1, sizeof(struct diskio_stat));
	cur = cur->next;
	cur->dev = strndup(device_name, text_buffer_size);
	cur->last = UINT_MAX;
	cur->last_read = UINT_MAX;
	cur->last_write = UINT_MAX;

	return cur;
}

void update_diskio_values(struct diskio_stat *ds,
		unsigned int reads, unsigned int writes)
{
	int i;
	double sum=0, sum_r=0, sum_w=0;

	if (reads < ds->last_read || writes < ds->last_write) {
		/* counter overflow or reset - rebase to sane values */
		ds->last = reads+writes;
		ds->last_read = reads;
		ds->last_write = writes;
	}
	/* since the values in /proc/diskstats are absolute, we have to substract
	 * our last reading. The numbers stand for "sectors read", and we therefore
	 * have to divide by two to get KB */
	ds->sample_read[0] = (reads - ds->last_read) / 2;
	ds->sample_write[0] = (writes - ds->last_write) / 2;
	ds->sample[0] = ds->sample_read[0] + ds->sample_write[0];

	/* compute averages */
	for (i = 0; i < (signed) info.diskio_avg_samples; i++) {
		sum += ds->sample[i];
		sum_r += ds->sample_read[i];
		sum_w += ds->sample_write[i];
	}
	ds->current = sum / (double) info.diskio_avg_samples;
	ds->current_read = sum_r / (double) info.diskio_avg_samples;
	ds->current_write = sum_w / (double) info.diskio_avg_samples;

	/* shift sample history */
	for (i = info.diskio_avg_samples-1; i > 0; i--) {
		ds->sample[i] = ds->sample[i-1];
		ds->sample_read[i] = ds->sample_read[i-1];
		ds->sample_write[i] = ds->sample_write[i-1];
	}

	/* save last */
	ds->last_read = reads;
	ds->last_write = writes;
	ds->last = ds->last_read + ds->last_write;
}