/**
 * collectd-nagios - src/collectd-nagios.c
 * Copyright (C) 2008-2010  Florian octo Forster
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *   Florian octo Forster <octo at collectd.org>
 **/

#if HAVE_CONFIG_H
#include "config.h"
#endif

#if !defined(__GNUC__) || !__GNUC__
#define __attribute__(x) /**/
#endif

#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>

#if NAN_STATIC_DEFAULT
#include <math.h>
/* #endif NAN_STATIC_DEFAULT*/
#elif NAN_STATIC_ISOC
#ifndef __USE_ISOC99
#define DISABLE_ISOC99 1
#define __USE_ISOC99 1
#endif /* !defined(__USE_ISOC99) */
#include <math.h>
#if DISABLE_ISOC99
#undef DISABLE_ISOC99
#undef __USE_ISOC99
#endif /* DISABLE_ISOC99 */
/* #endif NAN_STATIC_ISOC */
#elif NAN_ZERO_ZERO
#include <math.h>
#ifdef NAN
#undef NAN
#endif
#define NAN (0.0 / 0.0)
#ifndef isnan
#define isnan(f) ((f) != (f))
#endif /* !defined(isnan) */
#ifndef isfinite
#define isfinite(f) (((f) - (f)) == 0.0)
#endif
#ifndef isinf
#define isinf(f) (!isfinite(f) && !isnan(f))
#endif
#endif /* NAN_ZERO_ZERO */

#include "collectd/client.h"

#define RET_OKAY 0
#define RET_WARNING 1
#define RET_CRITICAL 2
#define RET_UNKNOWN 3

#define CON_NONE 0
#define CON_AVERAGE 1
#define CON_SUM 2
#define CON_PERCENTAGE 3

struct range_s {
  double min;
  double max;
  int invert;
};
typedef struct range_s range_t;

extern char *optarg;
extern int optind, opterr, optopt;

static char *socket_file_g;
static char *value_string_g;
static char *hostname_g;

static range_t range_critical_g;
static range_t range_warning_g;
static int consolitation_g = CON_NONE;
static bool nan_is_error_g;

static char **match_ds_g;
static size_t match_ds_num_g;

/* `strdup' is an XSI extension. I don't want to pull in all of XSI just for
 * that, so here's an own implementation.. It's easy enough. The GCC attributes
 * are supposed to get good performance..  -octo */
__attribute__((malloc, nonnull(1))) static char *
cn_strdup(const char *str) /* {{{ */
{
  size_t strsize;
  char *ret;

  strsize = strlen(str) + 1;
  ret = malloc(strsize);
  if (ret != NULL)
    memcpy(ret, str, strsize);
  return ret;
} /* }}} char *cn_strdup */

static int filter_ds(size_t *values_num, double **values,
                     char ***values_names) {
  gauge_t *new_values;
  char **new_names;

  if (match_ds_g == NULL)
    return RET_OKAY;

  new_values = calloc(match_ds_num_g, sizeof(*new_values));
  if (new_values == NULL) {
    fprintf(stderr, "calloc failed: %s\n", strerror(errno));
    return RET_UNKNOWN;
  }

  new_names = calloc(match_ds_num_g, sizeof(*new_names));
  if (new_names == NULL) {
    fprintf(stderr, "calloc failed: %s\n", strerror(errno));
    free(new_values);
    return RET_UNKNOWN;
  }

  for (size_t i = 0; i < match_ds_num_g; i++) {
    size_t j;

    /* match_ds_g keeps pointers into argv but the names will be freed */
    new_names[i] = cn_strdup(match_ds_g[i]);
    if (new_names[i] == NULL) {
      fprintf(stderr, "cn_strdup failed: %s\n", strerror(errno));
      free(new_values);
      for (j = 0; j < i; j++)
        free(new_names[j]);
      free(new_names);
      return RET_UNKNOWN;
    }

    for (j = 0; j < *values_num; j++)
      if (strcasecmp(new_names[i], (*values_names)[j]) == 0)
        break;

    if (j == *values_num) {
      printf("ERROR: DS `%s' is not available.\n", new_names[i]);
      free(new_values);
      for (j = 0; j <= i; j++)
        free(new_names[j]);
      free(new_names);
      return RET_CRITICAL;
    }

    new_values[i] = (*values)[j];
  }

  free(*values);
  for (size_t i = 0; i < *values_num; i++)
    free((*values_names)[i]);
  free(*values_names);

  *values = new_values;
  *values_names = new_names;
  *values_num = match_ds_num_g;
  return RET_OKAY;
} /* int filter_ds */

static void parse_range(char *string, range_t *range) {
  char *min_ptr;
  char *max_ptr;

  if (*string == '@') {
    range->invert = 1;
    string++;
  }

  max_ptr = strchr(string, ':');
  if (max_ptr == NULL) {
    min_ptr = NULL;
    max_ptr = string;
  } else {
    min_ptr = string;
    *max_ptr = '\0';
    max_ptr++;
  }

  assert(max_ptr != NULL);

  /* `10' == `0:10' */
  if (min_ptr == NULL)
    range->min = 0.0;
  /* :10 == ~:10 == -inf:10 */
  else if ((*min_ptr == '\0') || (*min_ptr == '~'))
    range->min = NAN;
  else
    range->min = atof(min_ptr);

  if ((*max_ptr == '\0') || (*max_ptr == '~'))
    range->max = NAN;
  else
    range->max = atof(max_ptr);
} /* void parse_range */

static int match_range(range_t *range, double value) {
  int ret = 0;

  if (!isnan(range->min) && (range->min > value))
    ret = 1;
  if (!isnan(range->max) && (range->max < value))
    ret = 1;

  return ((ret - range->invert) == 0) ? 0 : 1;
} /* int match_range */

__attribute__((noreturn)) static void usage(const char *name) {
  fprintf(stderr,
          "Usage: %s <-s socket> <-n value_spec> <-H hostname> [options]\n"
          "\n"
          "Valid options are:\n"
          "  -s <socket>    Path to collectd's UNIX-socket.\n"
          "  -n <v_spec>    Value specification to get from collectd.\n"
          "                 Format: `plugin-instance/type-instance'\n"
          "  -d <ds>        Select the DS to examine. May be repeated to "
          "examine multiple\n"
          "                 DSes. By default all DSes are used.\n"
          "  -g <consol>    Method to use to consolidate several DSes.\n"
          "                 See below for a list of valid arguments.\n"
          "  -H <host>      Hostname to query the values for.\n"
          "  -c <range>     Critical range\n"
          "  -w <range>     Warning range\n"
          "  -m             Treat \"Not a Number\" (NaN) as critical (default: "
          "warning)\n"
          "\n"
          "Consolidation functions:\n"
          "  none:          Apply the warning- and critical-ranges to each "
          "data-source\n"
          "                 individually.\n"
          "  average:       Calculate the average of all matching DSes and "
          "apply the\n"
          "                 warning- and critical-ranges to the calculated "
          "average.\n"
          "  sum:           Apply the ranges to the sum of all DSes.\n"
          "  percentage:    Apply the ranges to the ratio (in percent) of the "
          "first value\n"
          "                 and the sum of all values."
          "\n",
          name);
  exit(1);
} /* void usage */

static int do_listval(lcc_connection_t *connection) {
  lcc_identifier_t *ret_ident = NULL;
  size_t ret_ident_num = 0;

  char *hostname = NULL;

  int status;

  status = lcc_listval(connection, &ret_ident, &ret_ident_num);
  if (status != 0) {
    printf("UNKNOWN: %s\n", lcc_strerror(connection));
    if (ret_ident != NULL)
      free(ret_ident);
    return RET_UNKNOWN;
  }

  status = lcc_sort_identifiers(connection, ret_ident, ret_ident_num);
  if (status != 0) {
    printf("UNKNOWN: %s\n", lcc_strerror(connection));
    if (ret_ident != NULL)
      free(ret_ident);
    return RET_UNKNOWN;
  }

  for (size_t i = 0; i < ret_ident_num; ++i) {
    char id[1024];

    if ((hostname_g != NULL) && (strcasecmp(hostname_g, ret_ident[i].host)))
      continue;

    if ((hostname == NULL) || strcasecmp(hostname, ret_ident[i].host)) {
      free(hostname);
      hostname = strdup(ret_ident[i].host);
      printf("Host: %s\n", hostname);
    }

    /* empty hostname; not to be printed again */
    ret_ident[i].host[0] = '\0';

    status =
        lcc_identifier_to_string(connection, id, sizeof(id), ret_ident + i);
    if (status != 0) {
      printf("ERROR: listval: Failed to convert returned "
             "identifier to a string: %s\n",
             lcc_strerror(connection));
      free(hostname);
      hostname = NULL;
      continue;
    }

    /* skip over the (empty) hostname and following '/' */
    printf("\t%s\n", id + 1);
  }

  free(ret_ident);
  free(hostname);
  return RET_OKAY;
} /* int do_listval */

static int do_check_con_none(size_t values_num, double *values,
                             char **values_names) {
  int num_critical = 0;
  int num_warning = 0;
  int num_okay = 0;
  const char *status_str = "UNKNOWN";
  int status_code = RET_UNKNOWN;

  for (size_t i = 0; i < values_num; i++) {
    if (isnan(values[i])) {
      if (nan_is_error_g)
        num_critical++;
      else
        num_warning++;
    } else if (match_range(&range_critical_g, values[i]) != 0)
      num_critical++;
    else if (match_range(&range_warning_g, values[i]) != 0)
      num_warning++;
    else
      num_okay++;
  }

  if ((num_critical == 0) && (num_warning == 0) && (num_okay == 0)) {
    printf("WARNING: No defined values found\n");
    return RET_WARNING;
  } else if ((num_critical == 0) && (num_warning == 0)) {
    status_str = "OKAY";
    status_code = RET_OKAY;
  } else if (num_critical == 0) {
    status_str = "WARNING";
    status_code = RET_WARNING;
  } else {
    status_str = "CRITICAL";
    status_code = RET_CRITICAL;
  }

  printf("%s: %i critical, %i warning, %i okay", status_str, num_critical,
         num_warning, num_okay);
  if (values_num > 0) {
    printf(" |");
    for (size_t i = 0; i < values_num; i++)
      printf(" %s=%f;;;;", values_names[i], values[i]);
  }
  printf("\n");

  return status_code;
} /* int do_check_con_none */

static int do_check_con_average(size_t values_num, double *values,
                                char **values_names) {
  double total;
  int total_num;
  double average;
  const char *status_str = "UNKNOWN";
  int status_code = RET_UNKNOWN;

  total = 0.0;
  total_num = 0;
  for (size_t i = 0; i < values_num; i++) {
    if (isnan(values[i])) {
      if (!nan_is_error_g)
        continue;

      printf("CRITICAL: Data source \"%s\" is NaN\n", values_names[i]);
      return RET_CRITICAL;
    }

    total += values[i];
    total_num++;
  }

  if (total_num == 0) {
    printf("WARNING: No defined values found\n");
    return RET_WARNING;
  }

  average = total / total_num;

  if (match_range(&range_critical_g, average) != 0) {
    status_str = "CRITICAL";
    status_code = RET_CRITICAL;
  } else if (match_range(&range_warning_g, average) != 0) {
    status_str = "WARNING";
    status_code = RET_WARNING;
  } else {
    status_str = "OKAY";
    status_code = RET_OKAY;
  }

  printf("%s: %g average |", status_str, average);
  for (size_t i = 0; i < values_num; i++)
    printf(" %s=%f;;;;", values_names[i], values[i]);
  printf("\n");

  return status_code;
} /* int do_check_con_average */

static int do_check_con_sum(size_t values_num, double *values,
                            char **values_names) {
  double total;
  int total_num;
  const char *status_str = "UNKNOWN";
  int status_code = RET_UNKNOWN;

  total = 0.0;
  total_num = 0;
  for (size_t i = 0; i < values_num; i++) {
    if (isnan(values[i])) {
      if (!nan_is_error_g)
        continue;

      printf("CRITICAL: Data source \"%s\" is NaN\n", values_names[i]);
      return RET_CRITICAL;
    }

    total += values[i];
    total_num++;
  }

  if (total_num == 0) {
    printf("WARNING: No defined values found\n");
    return RET_WARNING;
  }

  if (match_range(&range_critical_g, total) != 0) {
    status_str = "CRITICAL";
    status_code = RET_CRITICAL;
  } else if (match_range(&range_warning_g, total) != 0) {
    status_str = "WARNING";
    status_code = RET_WARNING;
  } else {
    status_str = "OKAY";
    status_code = RET_OKAY;
  }

  printf("%s: %g sum |", status_str, total);
  for (size_t i = 0; i < values_num; i++)
    printf(" %s=%f;;;;", values_names[i], values[i]);
  printf("\n");

  return status_code;
} /* int do_check_con_sum */

static int do_check_con_percentage(size_t values_num, double *values,
                                   char **values_names) {
  double sum = 0.0;
  double percentage;

  const char *status_str = "UNKNOWN";
  int status_code = RET_UNKNOWN;

  if ((values_num < 1) || (isnan(values[0]))) {
    printf("WARNING: The first value is not defined\n");
    return RET_WARNING;
  }

  for (size_t i = 0; i < values_num; i++) {
    if (isnan(values[i])) {
      if (!nan_is_error_g)
        continue;

      printf("CRITICAL: Data source \"%s\" is NaN\n", values_names[i]);
      return RET_CRITICAL;
    }

    sum += values[i];
  }

  if (sum == 0.0) {
    printf("WARNING: Values sum up to zero\n");
    return RET_WARNING;
  }

  percentage = 100.0 * values[0] / sum;

  if (match_range(&range_critical_g, percentage) != 0) {
    status_str = "CRITICAL";
    status_code = RET_CRITICAL;
  } else if (match_range(&range_warning_g, percentage) != 0) {
    status_str = "WARNING";
    status_code = RET_WARNING;
  } else {
    status_str = "OKAY";
    status_code = RET_OKAY;
  }

  printf("%s: %lf percent |", status_str, percentage);
  for (size_t i = 0; i < values_num; i++)
    printf(" %s=%lf;;;;", values_names[i], values[i]);
  return status_code;
} /* int do_check_con_percentage */

static int do_check(lcc_connection_t *connection) {
  gauge_t *values;
  char **values_names;
  size_t values_num;
  char ident_str[1024];
  lcc_identifier_t ident;
  int status;

  snprintf(ident_str, sizeof(ident_str), "%s/%s", hostname_g, value_string_g);
  ident_str[sizeof(ident_str) - 1] = '\0';

  status = lcc_string_to_identifier(connection, &ident, ident_str);
  if (status != 0) {
    printf("ERROR: Creating an identifier failed: %s.\n",
           lcc_strerror(connection));
    LCC_DESTROY(connection);
    return RET_CRITICAL;
  }

  status = lcc_getval(connection, &ident, &values_num, &values, &values_names);
  if (status != 0) {
    printf("ERROR: Retrieving values from the daemon failed: %s.\n",
           lcc_strerror(connection));
    LCC_DESTROY(connection);
    return RET_CRITICAL;
  }

  LCC_DESTROY(connection);

  status = filter_ds(&values_num, &values, &values_names);
  if (status != RET_OKAY)
    return status;

  status = RET_UNKNOWN;
  if (consolitation_g == CON_NONE)
    status = do_check_con_none(values_num, values, values_names);
  else if (consolitation_g == CON_AVERAGE)
    status = do_check_con_average(values_num, values, values_names);
  else if (consolitation_g == CON_SUM)
    status = do_check_con_sum(values_num, values, values_names);
  else if (consolitation_g == CON_PERCENTAGE)
    status = do_check_con_percentage(values_num, values, values_names);

  free(values);
  if (values_names != NULL)
    for (size_t i = 0; i < values_num; i++)
      free(values_names[i]);
  free(values_names);

  return status;
} /* int do_check */

int main(int argc, char **argv) {
  char address[1024];
  lcc_connection_t *connection;

  int status;

  range_critical_g.min = NAN;
  range_critical_g.max = NAN;
  range_critical_g.invert = 0;

  range_warning_g.min = NAN;
  range_warning_g.max = NAN;
  range_warning_g.invert = 0;

  while (42) {
    int c;

    c = getopt(argc, argv, "w:c:s:n:H:g:d:hm");
    if (c < 0)
      break;

    switch (c) {
    case 'c':
      parse_range(optarg, &range_critical_g);
      break;
    case 'w':
      parse_range(optarg, &range_warning_g);
      break;
    case 's':
      socket_file_g = optarg;
      break;
    case 'n':
      value_string_g = optarg;
      break;
    case 'H':
      hostname_g = optarg;
      break;
    case 'g':
      if (strcasecmp(optarg, "none") == 0)
        consolitation_g = CON_NONE;
      else if (strcasecmp(optarg, "average") == 0)
        consolitation_g = CON_AVERAGE;
      else if (strcasecmp(optarg, "sum") == 0)
        consolitation_g = CON_SUM;
      else if (strcasecmp(optarg, "percentage") == 0)
        consolitation_g = CON_PERCENTAGE;
      else {
        fprintf(stderr, "Unknown consolidation function `%s'.\n", optarg);
        usage(argv[0]);
      }
      break;
    case 'd': {
      char **tmp;
      tmp = realloc(match_ds_g, (match_ds_num_g + 1) * sizeof(char *));
      if (tmp == NULL) {
        fprintf(stderr, "realloc failed: %s\n", strerror(errno));
        return RET_UNKNOWN;
      }
      match_ds_g = tmp;
      match_ds_g[match_ds_num_g] = cn_strdup(optarg);
      if (match_ds_g[match_ds_num_g] == NULL) {
        fprintf(stderr, "cn_strdup failed: %s\n", strerror(errno));
        return RET_UNKNOWN;
      }
      match_ds_num_g++;
      break;
    }
    case 'm':
      nan_is_error_g = true;
      break;
    default:
      usage(argv[0]);
    } /* switch (c) */
  }

  if ((socket_file_g == NULL) || (value_string_g == NULL) ||
      ((hostname_g == NULL) && (strcasecmp(value_string_g, "LIST")))) {
    fprintf(stderr, "Missing required arguments.\n");
    usage(argv[0]);
  }

  snprintf(address, sizeof(address), "unix:%s", socket_file_g);
  address[sizeof(address) - 1] = '\0';

  connection = NULL;
  status = lcc_connect(address, &connection);
  if (status != 0) {
    printf("ERROR: Connecting to daemon at %s failed.\n", socket_file_g);
    return RET_CRITICAL;
  }

  if (0 == strcasecmp(value_string_g, "LIST"))
    return do_listval(connection);

  return do_check(connection);
} /* int main */