/*
 *
 * 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) 2005-2021 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 "diskio.h"
#include <sys/stat.h>
#include <cstdlib>
#include <vector>
#include "common.h"
#include "config.h"
#include "conky.h" /* text_buffer_size */
#include "core.h"
#include "logging.h"
#include "specials.h"
#include "text_object.h"

/* this is the root of all per disk stats,
 * also containing the totals. */
struct diskio_stat stats;

void clear_diskio_stats() {
  struct diskio_stat *cur;
  while (stats.next != nullptr) {
    cur = stats.next;
    stats.next = stats.next->next;
    free_and_zero(cur->dev);
    delete cur;
  }
}

struct diskio_stat *prepare_diskio_stat(const char *s) {
  struct stat sb {};
  std::vector<char> stat_name(text_buffer_size.get(*state)),
      device_name(text_buffer_size.get(*state)),
      device_s(text_buffer_size.get(*state));
  struct diskio_stat *cur = &stats;
  char *rpbuf;
  char rpbuf2[256];

  if (s == nullptr) { return &stats; }

  if (strncmp(s, "label:", 6) == 0) {
    snprintf(&(device_name[0]), text_buffer_size.get(*state),
             "/dev/disk/by-label/%s", s + 6);
    rpbuf = realpath(&(device_name[0]), nullptr);
  } else if (0 == (strncmp(s, "partuuid:", 9))) {
    snprintf(&(device_name[0]), text_buffer_size.get(*state),
             "/dev/disk/by-partuuid/%s", s + 9);
    rpbuf = realpath(&device_name[0], nullptr);
    snprintf(rpbuf2, 255, "%s", rpbuf);
  } else {
    rpbuf = realpath(s, nullptr);
  }

  if (rpbuf != nullptr) {
    strncpy(&device_s[0], rpbuf, text_buffer_size.get(*state));
    free(rpbuf);
  } else {
    strncpy(&device_s[0], s, text_buffer_size.get(*state));
  }

#if defined(__FreeBSD__) || defined(__DragonFly__) || defined(__linux__)
  if (strncmp(&device_s[0], "/dev/", 5) == 0) {
    device_s.erase(device_s.begin(), device_s.begin() + 5);
  }
#endif
  strncpy(&(device_name[0]), &device_s[0], text_buffer_size.get(*state));

#if !defined(__sun)
  /*
   * On Solaris we currently don't use the name of disk's special file so
   * this test is useless.
   */

  if (strncmp(s, "label:", 6) == 0) {
    snprintf(&(stat_name[0]), text_buffer_size.get(*state), "/dev/%s",
             &(device_name[0]));
    if ((stat(&(stat_name[0]), &sb) != 0) || !S_ISBLK(sb.st_mode)) {
      NORM_ERR("diskio device '%s' does not exist", &device_s[0]);
    }
  } else if ((0 == (strncmp(s, "partuuid:", 9))) &&
             ((stat(rpbuf2, &sb) != 0) || !S_ISBLK(sb.st_mode))) {
    NORM_ERR("diskio device '%s' does not exist", &device_s[0]);
  }

#endif

  /* lookup existing */
  while (cur->next != nullptr) {
    cur = cur->next;
    if (strcmp(cur->dev, &(device_name[0])) == 0) { return cur; }
  }

  /* no existing found, make a new one */
  cur->next = new diskio_stat;
  cur = cur->next;
  cur->dev = strndup(&(device_s[0]), text_buffer_size.get(*state));
  cur->last = UINT_MAX;
  cur->last_read = UINT_MAX;
  cur->last_write = UINT_MAX;

  return cur;
}

void parse_diskio_arg(struct text_object *obj, const char *arg) {
  obj->data.opaque = prepare_diskio_stat(arg);
}

/* dir indicates the direction:
 * -1: read
 *  0: read + write
 *  1: write
 */
static void print_diskio_dir(struct text_object *obj, int dir, char *p,
                             unsigned int p_max_size) {
  auto *diskio = static_cast<struct diskio_stat *>(obj->data.opaque);
  double val;

  if (diskio == nullptr) { return; }

  if (dir < 0) {
    val = diskio->current_read;
  } else if (dir == 0) {
    val = diskio->current;
  } else {
    val = diskio->current_write;
  }

  /* TODO: move this correction from kB to kB/s elsewhere
   * (or get rid of it??) */
  human_readable(val / active_update_interval(), p, p_max_size);
}

void print_diskio(struct text_object *obj, char *p, unsigned int p_max_size) {
  print_diskio_dir(obj, 0, p, p_max_size);
}

void print_diskio_read(struct text_object *obj, char *p,
                       unsigned int p_max_size) {
  print_diskio_dir(obj, -1, p, p_max_size);
}

void print_diskio_write(struct text_object *obj, char *p,
                        unsigned int p_max_size) {
  print_diskio_dir(obj, 1, p, p_max_size);
}

#ifdef BUILD_GUI
void parse_diskiograph_arg(struct text_object *obj, const char *arg) {
  auto [buf, skip] = scan_command(arg);
  scan_graph(obj, arg + skip, 0);

  obj->data.opaque = prepare_diskio_stat(dev_name(buf));
  free_and_zero(buf);
}

double diskiographval(struct text_object *obj) {
  auto *diskio = static_cast<struct diskio_stat *>(obj->data.opaque);

  return (diskio != nullptr ? diskio->current : 0);
}

double diskiographval_read(struct text_object *obj) {
  auto *diskio = static_cast<struct diskio_stat *>(obj->data.opaque);

  return (diskio != nullptr ? diskio->current_read : 0);
}

double diskiographval_write(struct text_object *obj) {
  auto *diskio = static_cast<struct diskio_stat *>(obj->data.opaque);

  return (diskio != nullptr ? diskio->current_write : 0);
}
#endif /* BUILD_GUI */

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 subtract
   * 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 */
  int samples = diskio_avg_samples.get(*state);
  for (i = 0; i < samples; i++) {
    sum += ds->sample[i] * 1024LL;
    sum_r += ds->sample_read[i] * 1024LL;
    sum_w += ds->sample_write[i] * 1024LL;
  }
  ds->current = sum / static_cast<double>(samples);
  ds->current_read = sum_r / static_cast<double>(samples);
  ds->current_write = sum_w / static_cast<double>(samples);

  /* shift sample history */
  for (i = 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;
}
