/**
 * collectd - src/target_scale.c
 * Copyright (C) 2008-2009  Florian 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 Forster <octo at collectd.org>
 **/

#include "collectd.h"

#include "filter_chain.h"
#include "utils/common/common.h"

#include "utils_cache.h"

struct ts_data_s {
  double factor;
  double offset;

  char **data_sources;
  size_t data_sources_num;
};
typedef struct ts_data_s ts_data_t;

static int ts_invoke_counter(const data_set_t *ds, value_list_t *vl, /* {{{ */
                             ts_data_t *data, int dsrc_index) {
  uint64_t curr_counter;
  int status;
  int failure;

  /* Required meta data */
  uint64_t prev_counter;
  char key_prev_counter[128];
  uint64_t int_counter;
  char key_int_counter[128];
  double int_fraction;
  char key_int_fraction[128];

  curr_counter = (uint64_t)vl->values[dsrc_index].counter;

  snprintf(key_prev_counter, sizeof(key_prev_counter),
           "target_scale[%p,%i]:prev_counter", (void *)data, dsrc_index);
  snprintf(key_int_counter, sizeof(key_int_counter),
           "target_scale[%p,%i]:int_counter", (void *)data, dsrc_index);
  snprintf(key_int_fraction, sizeof(key_int_fraction),
           "target_scale[%p,%i]:int_fraction", (void *)data, dsrc_index);

  prev_counter = curr_counter;
  int_counter = 0;
  int_fraction = 0.0;

  /* Query the meta data */
  failure = 0;

  status = uc_meta_data_get_unsigned_int(vl, key_prev_counter, &prev_counter);
  if (status != 0)
    failure++;

  status = uc_meta_data_get_unsigned_int(vl, key_int_counter, &int_counter);
  if (status != 0)
    failure++;

  status = uc_meta_data_get_double(vl, key_int_fraction, &int_fraction);
  if (status != 0)
    failure++;

  if (failure == 0) {
    uint64_t diff;
    double rate;

    diff = (uint64_t)counter_diff(prev_counter, curr_counter);
    rate = ((double)diff) / CDTIME_T_TO_DOUBLE(vl->interval);

    /* Modify the rate. */
    if (!isnan(data->factor))
      rate *= data->factor;
    if (!isnan(data->offset))
      rate += data->offset;

    /* Calculate the internal counter. */
    int_fraction += (rate * CDTIME_T_TO_DOUBLE(vl->interval));
    diff = (uint64_t)int_fraction;
    int_fraction -= ((double)diff);
    int_counter += diff;

    assert(int_fraction >= 0.0);
    assert(int_fraction < 1.0);

    DEBUG("Target `scale': ts_invoke_counter: %" PRIu64 " -> %g -> %" PRIu64
          "(+%g)",
          curr_counter, rate, int_counter, int_fraction);
  } else /* (failure != 0) */
  {
    int_counter = 0;
    int_fraction = 0.0;
  }

  vl->values[dsrc_index].counter = (counter_t)int_counter;

  /* Update to the new counter value */
  uc_meta_data_add_unsigned_int(vl, key_prev_counter, curr_counter);
  uc_meta_data_add_unsigned_int(vl, key_int_counter, int_counter);
  uc_meta_data_add_double(vl, key_int_fraction, int_fraction);

  return 0;
} /* }}} int ts_invoke_counter */

static int ts_invoke_gauge(const data_set_t *ds, value_list_t *vl, /* {{{ */
                           ts_data_t *data, int dsrc_index) {
  if (!isnan(data->factor))
    vl->values[dsrc_index].gauge *= data->factor;
  if (!isnan(data->offset))
    vl->values[dsrc_index].gauge += data->offset;

  return 0;
} /* }}} int ts_invoke_gauge */

static int ts_invoke_derive(const data_set_t *ds, value_list_t *vl, /* {{{ */
                            ts_data_t *data, int dsrc_index) {
  int64_t curr_derive;
  int status;
  int failure;

  /* Required meta data */
  int64_t prev_derive;
  char key_prev_derive[128];
  int64_t int_derive;
  char key_int_derive[128];
  double int_fraction;
  char key_int_fraction[128];

  curr_derive = (int64_t)vl->values[dsrc_index].derive;

  snprintf(key_prev_derive, sizeof(key_prev_derive),
           "target_scale[%p,%i]:prev_derive", (void *)data, dsrc_index);
  snprintf(key_int_derive, sizeof(key_int_derive),
           "target_scale[%p,%i]:int_derive", (void *)data, dsrc_index);
  snprintf(key_int_fraction, sizeof(key_int_fraction),
           "target_scale[%p,%i]:int_fraction", (void *)data, dsrc_index);

  prev_derive = curr_derive;
  int_derive = 0;
  int_fraction = 0.0;

  /* Query the meta data */
  failure = 0;

  status = uc_meta_data_get_signed_int(vl, key_prev_derive, &prev_derive);
  if (status != 0)
    failure++;

  status = uc_meta_data_get_signed_int(vl, key_int_derive, &int_derive);
  if (status != 0)
    failure++;

  status = uc_meta_data_get_double(vl, key_int_fraction, &int_fraction);
  if (status != 0)
    failure++;

  if (failure == 0) {
    int64_t difference;
    double rate;

    /* Calcualte the rate */
    difference = curr_derive - prev_derive;
    rate = ((double)difference) / CDTIME_T_TO_DOUBLE(vl->interval);

    /* Modify the rate. */
    if (!isnan(data->factor))
      rate *= data->factor;
    if (!isnan(data->offset))
      rate += data->offset;

    /* Calculate the internal derive. */
    int_fraction += (rate * CDTIME_T_TO_DOUBLE(vl->interval));
    if (int_fraction < 0.0) /* handle negative integer rounding correctly */
      difference = ((int64_t)int_fraction) - 1;
    else
      difference = (int64_t)int_fraction;
    int_fraction -= ((double)difference);
    int_derive += difference;

    assert(int_fraction >= 0.0);
    assert(int_fraction < 1.0);

    DEBUG("Target `scale': ts_invoke_derive: %" PRIu64 " -> %g -> %" PRIu64
          "(+%g)",
          curr_derive, rate, int_derive, int_fraction);
  } else /* (failure != 0) */
  {
    int_derive = 0;
    int_fraction = 0.0;
  }

  vl->values[dsrc_index].derive = (derive_t)int_derive;

  /* Update to the new derive value */
  uc_meta_data_add_signed_int(vl, key_prev_derive, curr_derive);
  uc_meta_data_add_signed_int(vl, key_int_derive, int_derive);
  uc_meta_data_add_double(vl, key_int_fraction, int_fraction);

  return 0;
} /* }}} int ts_invoke_derive */

static int ts_invoke_absolute(const data_set_t *ds, value_list_t *vl, /* {{{ */
                              ts_data_t *data, int dsrc_index) {
  uint64_t curr_absolute;
  double rate;
  int status;

  /* Required meta data */
  double int_fraction;
  char key_int_fraction[128];

  curr_absolute = (uint64_t)vl->values[dsrc_index].absolute;

  snprintf(key_int_fraction, sizeof(key_int_fraction),
           "target_scale[%p,%i]:int_fraction", (void *)data, dsrc_index);

  int_fraction = 0.0;

  /* Query the meta data */
  status = uc_meta_data_get_double(vl, key_int_fraction, &int_fraction);
  if (status != 0)
    int_fraction = 0.0;

  rate = ((double)curr_absolute) / CDTIME_T_TO_DOUBLE(vl->interval);

  /* Modify the rate. */
  if (!isnan(data->factor))
    rate *= data->factor;
  if (!isnan(data->offset))
    rate += data->offset;

  /* Calculate the new absolute. */
  int_fraction += (rate * CDTIME_T_TO_DOUBLE(vl->interval));
  curr_absolute = (uint64_t)int_fraction;
  int_fraction -= ((double)curr_absolute);

  vl->values[dsrc_index].absolute = (absolute_t)curr_absolute;

  /* Update to the new absolute value */
  uc_meta_data_add_double(vl, key_int_fraction, int_fraction);

  return 0;
} /* }}} int ts_invoke_absolute */

static int ts_config_set_double(double *ret, oconfig_item_t *ci) /* {{{ */
{
  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_NUMBER)) {
    WARNING("scale target: The `%s' config option needs "
            "exactly one numeric argument.",
            ci->key);
    return -1;
  }

  *ret = ci->values[0].value.number;
  DEBUG("ts_config_set_double: *ret = %g", *ret);

  return 0;
} /* }}} int ts_config_set_double */

static int ts_config_add_data_source(ts_data_t *data, /* {{{ */
                                     oconfig_item_t *ci) {
  size_t new_data_sources_num;
  char **temp;

  /* Check number of arbuments. */
  if (ci->values_num < 1) {
    ERROR("`value' match: `%s' needs at least one argument.", ci->key);
    return -1;
  }

  /* Check type of arguments */
  for (int i = 0; i < ci->values_num; i++) {
    if (ci->values[i].type == OCONFIG_TYPE_STRING)
      continue;

    ERROR("`value' match: `%s' accepts only string arguments "
          "(argument %i is a %s).",
          ci->key, i + 1,
          (ci->values[i].type == OCONFIG_TYPE_BOOLEAN) ? "truth value"
                                                       : "number");
    return -1;
  }

  /* Allocate space for the char pointers */
  new_data_sources_num = data->data_sources_num + ((size_t)ci->values_num);
  temp = realloc(data->data_sources, new_data_sources_num * sizeof(char *));
  if (temp == NULL) {
    ERROR("`value' match: realloc failed.");
    return -1;
  }
  data->data_sources = temp;

  /* Copy the strings, allocating memory as needed.  */
  for (int i = 0; i < ci->values_num; i++) {
    size_t j;

    /* If we get here, there better be memory for us to write to.  */
    assert(data->data_sources_num < new_data_sources_num);

    j = data->data_sources_num;
    data->data_sources[j] = sstrdup(ci->values[i].value.string);
    if (data->data_sources[j] == NULL) {
      ERROR("`value' match: sstrdup failed.");
      continue;
    }
    data->data_sources_num++;
  }

  return 0;
} /* }}} int ts_config_add_data_source */

static int ts_destroy(void **user_data) /* {{{ */
{
  ts_data_t *data;

  if (user_data == NULL)
    return -EINVAL;

  data = (ts_data_t *)*user_data;

  if ((data != NULL) && (data->data_sources != NULL)) {
    for (size_t i = 0; i < data->data_sources_num; i++)
      sfree(data->data_sources[i]);
    sfree(data->data_sources);
  }

  sfree(data);
  *user_data = NULL;

  return 0;
} /* }}} int ts_destroy */

static int ts_create(const oconfig_item_t *ci, void **user_data) /* {{{ */
{
  ts_data_t *data;
  int status;

  data = calloc(1, sizeof(*data));
  if (data == NULL) {
    ERROR("ts_create: calloc failed.");
    return -ENOMEM;
  }

  data->factor = NAN;
  data->offset = NAN;

  status = 0;
  for (int i = 0; i < ci->children_num; i++) {
    oconfig_item_t *child = ci->children + i;

    if (strcasecmp("Factor", child->key) == 0)
      status = ts_config_set_double(&data->factor, child);
    else if (strcasecmp("Offset", child->key) == 0)
      status = ts_config_set_double(&data->offset, child);
    else if (strcasecmp("DataSource", child->key) == 0)
      status = ts_config_add_data_source(data, child);
    else {
      ERROR("Target `scale': The `%s' configuration option is not understood "
            "and will be ignored.",
            child->key);
      status = 0;
    }

    if (status != 0)
      break;
  }

  /* Additional sanity-checking */
  while (status == 0) {
    if (isnan(data->factor) && isnan(data->offset)) {
      ERROR("Target `scale': You need to at least set either the `Factor' "
            "or `Offset' option!");
      status = -1;
    }

    break;
  }

  if (status != 0) {
    ts_destroy((void *)&data);
    return status;
  }

  *user_data = data;
  return 0;
} /* }}} int ts_create */

static int ts_invoke(const data_set_t *ds, value_list_t *vl, /* {{{ */
                     notification_meta_t __attribute__((unused)) * *meta,
                     void **user_data) {
  ts_data_t *data;

  if ((ds == NULL) || (vl == NULL) || (user_data == NULL))
    return -EINVAL;

  data = *user_data;
  if (data == NULL) {
    ERROR("Target `scale': Invoke: `data' is NULL.");
    return -EINVAL;
  }

  for (size_t i = 0; i < ds->ds_num; i++) {
    /* If we've got a list of data sources, is it in the list? */
    if (data->data_sources) {
      size_t j;
      for (j = 0; j < data->data_sources_num; j++)
        if (strcasecmp(ds->ds[i].name, data->data_sources[j]) == 0)
          break;

      /* No match, ignore */
      if (j >= data->data_sources_num)
        continue;
    }

    if (ds->ds[i].type == DS_TYPE_COUNTER)
      ts_invoke_counter(ds, vl, data, i);
    else if (ds->ds[i].type == DS_TYPE_GAUGE)
      ts_invoke_gauge(ds, vl, data, i);
    else if (ds->ds[i].type == DS_TYPE_DERIVE)
      ts_invoke_derive(ds, vl, data, i);
    else if (ds->ds[i].type == DS_TYPE_ABSOLUTE)
      ts_invoke_absolute(ds, vl, data, i);
    else
      ERROR("Target `scale': Ignoring unknown data source type %i",
            ds->ds[i].type);
  }

  return FC_TARGET_CONTINUE;
} /* }}} int ts_invoke */

void module_register(void) {
  target_proc_t tproc = {0};

  tproc.create = ts_create;
  tproc.destroy = ts_destroy;
  tproc.invoke = ts_invoke;
  fc_register_target("scale", tproc);
} /* module_register */