/*
     This file is part of GNUnet.
     (C)

     GNUnet 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, or (at your
     option) any later version.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file sensor/sensor_util_lib.c
 * @brief sensor utilities
 * @author Omar Tarabai
 */
#include <inttypes.h>
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_sensor_util_lib.h"
#include "gnunet_statistics_service.h"

#define LOG(kind,...) GNUNET_log_from (kind, "sensor-util",__VA_ARGS__)

/**
 * Supported sources of sensor information
 */
static const char *sources[] = { "gnunet-statistics", "process", NULL };

/**
 * Supported datatypes of sensor information
 */
static const char *datatypes[] = { "numeric", "string", NULL };

/**
 * Parses a version number string into major and minor
 *
 * @param version full version string
 * @param major pointer to parsed major value
 * @param minor pointer to parsed minor value
 * @return #GNUNET_OK if parsing went ok, #GNUNET_SYSERR in case of error
 */
static int
version_parse (char *version, uint16_t * major, uint16_t * minor)
{
  int majorval = 0;
  int minorval = 0;

  for (; isdigit (*version); version++)
  {
    majorval *= 10;
    majorval += *version - '0';
  }
  if (*version != '.')
    return GNUNET_SYSERR;
  version++;
  for (; isdigit (*version); version++)
  {
    minorval *= 10;
    minorval += *version - '0';
  }
  if (*version != 0)
    return GNUNET_SYSERR;
  *major = majorval;
  *minor = minorval;

  return GNUNET_OK;
}


/**
 * Load sensor definition from configuration
 *
 * @param cfg configuration handle
 * @param sectionname configuration section containing definition
 */
static struct GNUNET_SENSOR_SensorInfo *
load_sensor_from_cfg (struct GNUNET_CONFIGURATION_Handle *cfg,
                      const char *sectionname)
{
  struct GNUNET_SENSOR_SensorInfo *sensor;
  char *version_str;
  char *starttime_str;
  char *endtime_str;
  unsigned long long time_sec;
  char *dummy;
  struct GNUNET_CRYPTO_EddsaPublicKey public_key;

  sensor = GNUNET_new (struct GNUNET_SENSOR_SensorInfo);

  //name
  sensor->name = GNUNET_strdup (sectionname);
  //version
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "VERSION",
                                             &version_str))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Error reading sensor version\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  if (GNUNET_OK !=
      version_parse (version_str, &(sensor->version_major),
                     &(sensor->version_minor)))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _("Invalid sensor version number, format should be major.minor\n"));
    GNUNET_free (sensor);
    GNUNET_free (version_str);
    return NULL;
  }
  GNUNET_free (version_str);
  //description
  GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "DESCRIPTION",
                                         &sensor->description);
  //category
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "CATEGORY",
                                             &sensor->category) ||
      NULL == sensor->category)
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Error reading sensor category\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  //enabled
  if (GNUNET_NO ==
      GNUNET_CONFIGURATION_get_value_yesno (cfg, sectionname, "ENABLED"))
    sensor->enabled = GNUNET_NO;
  else
    sensor->enabled = GNUNET_YES;
  //start time
  sensor->start_time = NULL;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "START_TIME",
                                             &starttime_str))
  {
    GNUNET_STRINGS_fancy_time_to_absolute (starttime_str, sensor->start_time);
    GNUNET_free (starttime_str);
  }
  //end time
  sensor->end_time = NULL;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "END_TIME",
                                             &endtime_str))
  {
    GNUNET_STRINGS_fancy_time_to_absolute (endtime_str, sensor->end_time);
    GNUNET_free (endtime_str);
  }
  //interval
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_number (cfg, sectionname, "INTERVAL",
                                             &time_sec))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Error reading sensor run interval\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  sensor->interval =
      GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, time_sec);
  //lifetime
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_number (cfg, sectionname, "LIFETIME",
                                             &time_sec))
  {
    sensor->lifetime =
        GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, time_sec);
    if (sensor->lifetime.rel_value_us < sensor->interval.rel_value_us)
      LOG (GNUNET_ERROR_TYPE_WARNING,
           "Lifetime of sensor data is preferred to be higher than interval for sensor `%s'.\n",
           sensor->name);
  }
  else
    sensor->lifetime = GNUNET_TIME_UNIT_FOREVER_REL;
  //capabilities TODO
  //source
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_choice (cfg, sectionname, "SOURCE",
                                             sources,
                                             (const char **) &sensor->source))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Error reading sensor source\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  if (sources[0] == sensor->source)     //gnunet-statistics
  {
    if (GNUNET_OK !=
        GNUNET_CONFIGURATION_get_value_string (cfg, sectionname,
                                               "GNUNET_STAT_SERVICE",
                                               &sensor->gnunet_stat_service) ||
        GNUNET_OK != GNUNET_CONFIGURATION_get_value_string (cfg, sectionname,
                                                            "GNUNET_STAT_NAME",
                                                            &sensor->gnunet_stat_name))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR,
           _("Error reading sensor gnunet-statistics source information\n"));
      GNUNET_free (sensor);
      return NULL;
    }
    sensor->gnunet_stat_get_handle = NULL;
  }
  else if (sources[1] == sensor->source)        //process
  {
    if (GNUNET_OK !=
        GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "EXT_PROCESS",
                                               &sensor->ext_process))
    {
      LOG (GNUNET_ERROR_TYPE_ERROR, _("Error reading sensor process name\n"));
      GNUNET_free (sensor);
      return NULL;
    }
    GNUNET_CONFIGURATION_get_value_string (cfg, sectionname, "EXT_ARGS",
                                           &sensor->ext_args);
  }
  //expected datatype
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_choice (cfg, sectionname,
                                             "EXPECTED_DATATYPE", datatypes,
                                             (const char **)
                                             &sensor->expected_datatype))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _("Error reading sensor expected datatype\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  if (sources[0] == sensor->source && datatypes[0] != sensor->expected_datatype)
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _
         ("Invalid expected datatype, gnunet-statistics returns uint64 values\n"));
    GNUNET_free (sensor);
    return NULL;
  }
  //reporting
  sensor->collection_point = NULL;
  sensor->report_values = GNUNET_NO;
  sensor->report_anomalies = GNUNET_NO;
  if (GNUNET_OK ==
      GNUNET_CONFIGURATION_get_value_string (cfg, sectionname,
                                             "COLLECTION_POINT", &dummy))
  {
    if (GNUNET_OK ==
        GNUNET_CRYPTO_eddsa_public_key_from_string (dummy, strlen (dummy),
                                                    &public_key))
    {
      sensor->collection_point = GNUNET_new (struct GNUNET_PeerIdentity);

      sensor->collection_point->public_key = public_key;
      if (GNUNET_OK ==
          GNUNET_CONFIGURATION_get_value_number (cfg, sectionname,
                                                 "VALUE_COLLECTION_INTERVAL",
                                                 &time_sec))
      {
        sensor->report_values = GNUNET_YES;
        sensor->value_reporting_interval =
            GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, time_sec);
      }
      if (GNUNET_YES ==
          GNUNET_CONFIGURATION_get_value_yesno (cfg, sectionname,
                                                "REPORT_ANOMALIES"))
        sensor->report_anomalies = GNUNET_YES;
    }
    GNUNET_free (dummy);
  }
  //execution task
  sensor->execution_task = GNUNET_SCHEDULER_NO_TASK;
  //running
  sensor->running = GNUNET_NO;
  return sensor;
}


/**
 * Load sensor definition from file
 *
 * @param filename full path to file containing sensor definition
 */
static struct GNUNET_SENSOR_SensorInfo *
load_sensor_from_file (const char *filename)
{
  struct GNUNET_CONFIGURATION_Handle *sensorcfg;
  const char *filebasename;
  struct GNUNET_SENSOR_SensorInfo *sensor;

  //test file
  if (GNUNET_YES != GNUNET_DISK_file_test (filename))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Failed to access sensor file: %s\n"),
         filename);
    return NULL;
  }
  //load file as configuration
  sensorcfg = GNUNET_CONFIGURATION_create ();
  if (GNUNET_SYSERR == GNUNET_CONFIGURATION_parse (sensorcfg, filename))
  {
    GNUNET_CONFIGURATION_destroy (sensorcfg);
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Failed to load sensor definition: %s\n"),
         filename);
    return NULL;
  }
  //configuration section should be the same as filename
  filebasename = GNUNET_STRINGS_get_short_name (filename);
  sensor = load_sensor_from_cfg (sensorcfg, filebasename);
  if (NULL == sensor)
  {
    GNUNET_CONFIGURATION_destroy (sensorcfg);
    return NULL;
  }
  sensor->def_file = GNUNET_strdup (filename);
  sensor->cfg = sensorcfg;
  return sensor;
}


/**
 * Given two version numbers as major and minor, compare them.
 *
 * @param v1_major First part of first version number
 * @param v1_minor Second part of first version number
 * @param v2_major First part of second version number
 * @param v2_minor Second part of second version number
 */
int
GNUNET_SENSOR_version_compare (uint16_t v1_major, uint16_t v1_minor,
                               uint16_t v2_major, uint16_t v2_minor)
{
  if (v1_major == v2_major)
    return (v1_minor < v2_minor) ? -1 : (v1_minor > v2_minor);
  else
    return (v1_major < v2_major) ? -1 : (v1_major > v2_major);
}


/**
 * Adds a new sensor to given hashmap.
 * If the same name exist, compares versions and update if old.
 *
 * @param sensor Sensor structure to add
 * @param map Hashmap to add to
 * @return #GNUNET_YES if added
 *         #GNUNET_NO if not added which is not necessarily an error
 */
static int
add_sensor_to_hashmap (struct GNUNET_SENSOR_SensorInfo *sensor,
                       struct GNUNET_CONTAINER_MultiHashMap *map)
{
  struct GNUNET_HashCode key;
  struct GNUNET_SENSOR_SensorInfo *existing;

  GNUNET_CRYPTO_hash (sensor->name, strlen (sensor->name) + 1, &key);
  existing = GNUNET_CONTAINER_multihashmap_get (map, &key);
  if (NULL != existing)         //sensor with same name already exists
  {
    if (GNUNET_SENSOR_version_compare
        (existing->version_major, existing->version_minor,
         sensor->version_major, sensor->version_minor) >= 0)
    {
      LOG (GNUNET_ERROR_TYPE_INFO,
           _("Sensor `%s' already exists with same or newer version\n"),
           sensor->name);
      return GNUNET_NO;
    }
    else
    {
      GNUNET_CONTAINER_multihashmap_remove (map, &key, existing);       //remove the old version
      GNUNET_free (existing);
      LOG (GNUNET_ERROR_TYPE_INFO, "Upgrading sensor `%s' to a newer version\n",
           sensor->name);
    }
  }
  if (GNUNET_SYSERR ==
      GNUNET_CONTAINER_multihashmap_put (map, &key, sensor,
                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
  {
    LOG (GNUNET_ERROR_TYPE_ERROR,
         _("Error adding new sensor `%s' to global hashmap.\n"), sensor->name);
    return GNUNET_NO;
  }
  return GNUNET_YES;
}


/**
 * Iterating over files in sensors directory
 *
 * @param cls closure
 * @param filename complete filename (absolute path)
 * @return #GNUNET_OK to continue to iterate
 */
static int
reload_sensors_dir_cb (void *cls, const char *filename)
{
  struct GNUNET_CONTAINER_MultiHashMap *sensors = cls;
  struct GNUNET_SENSOR_SensorInfo *sensor;

  if (GNUNET_YES != GNUNET_DISK_file_test (filename))
    return GNUNET_OK;
  sensor = load_sensor_from_file (filename);
  if (NULL == sensor)
  {
    LOG (GNUNET_ERROR_TYPE_ERROR, _("Error loading sensor from file: %s\n"),
         filename);
    return GNUNET_OK;
  }
  if (GNUNET_YES != add_sensor_to_hashmap (sensor, sensors))
    LOG (GNUNET_ERROR_TYPE_WARNING,
         "Could not add sensor `%s' to global hashmap\n", sensor->name);
  return GNUNET_OK;
}


/**
 * Get path to the default directory containing the sensor definition files with
 * a trailing directory separator.
 *
 * @return Default sensor files directory full path
 */
char *
GNUNET_SENSOR_get_default_sensor_dir ()
{
  char *datadir;
  char *sensordir;

  datadir = GNUNET_OS_installation_get_path (GNUNET_OS_IPK_DATADIR);
  GNUNET_asprintf (&sensordir, "%ssensors%s", datadir, DIR_SEPARATOR_STR);
  GNUNET_free (datadir);
  return sensordir;
}


/**
 * Reads sensor definitions from given sensor directory.
 *
 * @param sensordir Path to sensor directory.
 * @return a multihashmap of loaded sensors
 */
struct GNUNET_CONTAINER_MultiHashMap *
GNUNET_SENSOR_load_all_sensors (char *sensor_dir)
{
  struct GNUNET_CONTAINER_MultiHashMap *sensors;

  GNUNET_assert (NULL != sensor_dir);
  sensors = GNUNET_CONTAINER_multihashmap_create (10, GNUNET_NO);
  LOG (GNUNET_ERROR_TYPE_INFO,
       "Loading sensor definitions from directory `%s'\n", sensor_dir);
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_DISK_directory_test (sensor_dir, GNUNET_YES));
  /* read all files in sensors directory */
  GNUNET_DISK_directory_scan (sensor_dir, &reload_sensors_dir_cb, sensors);
  LOG (GNUNET_ERROR_TYPE_INFO, "Loaded %d sensors from directory `%s'\n",
       GNUNET_CONTAINER_multihashmap_size (sensors), sensor_dir);
  return sensors;
}


/**
 * Remove sensor execution from scheduler
 *
 * @param cls unused
 * @param key hash of sensor name, key to hashmap
 * @param value a `struct GNUNET_SENSOR_SensorInfo *`
 * @return #GNUNET_YES if we should continue to
 *         iterate,
 *         #GNUNET_NO if not.
 */
static int
destroy_sensor (void *cls, const struct GNUNET_HashCode *key, void *value)
{
  struct GNUNET_SENSOR_SensorInfo *sensor = value;

  if (GNUNET_SCHEDULER_NO_TASK != sensor->execution_task)
  {
    GNUNET_SCHEDULER_cancel (sensor->execution_task);
    sensor->execution_task = GNUNET_SCHEDULER_NO_TASK;
  }
  if (NULL != sensor->gnunet_stat_get_handle)
  {
    GNUNET_STATISTICS_get_cancel (sensor->gnunet_stat_get_handle);
    sensor->gnunet_stat_get_handle = NULL;
  }
  if (NULL != sensor->ext_cmd)
  {
    GNUNET_OS_command_stop (sensor->ext_cmd);
    sensor->ext_cmd = NULL;
  }
  if (NULL != sensor->cfg)
    GNUNET_CONFIGURATION_destroy (sensor->cfg);
  if (NULL != sensor->name)
    GNUNET_free (sensor->name);
  if (NULL != sensor->def_file)
    GNUNET_free (sensor->def_file);
  if (NULL != sensor->description)
    GNUNET_free (sensor->description);
  if (NULL != sensor->category)
    GNUNET_free (sensor->category);
  if (NULL != sensor->capabilities)
    GNUNET_free (sensor->capabilities);
  if (NULL != sensor->gnunet_stat_service)
    GNUNET_free (sensor->gnunet_stat_service);
  if (NULL != sensor->gnunet_stat_name)
    GNUNET_free (sensor->gnunet_stat_name);
  if (NULL != sensor->ext_process)
    GNUNET_free (sensor->ext_process);
  if (NULL != sensor->ext_args)
    GNUNET_free (sensor->ext_args);
  if (NULL != sensor->collection_point)
    GNUNET_free (sensor->collection_point);
  GNUNET_free (sensor);
  return GNUNET_YES;
}


/**
 * Destroys a group of sensors in a hashmap and the hashmap itself
 *
 * @param sensors hashmap containing the sensors
 */
void
GNUNET_SENSOR_destroy_sensors (struct GNUNET_CONTAINER_MultiHashMap *sensors)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG, "Destroying sensor list.\n");
  GNUNET_CONTAINER_multihashmap_iterate (sensors, &destroy_sensor, NULL);
  GNUNET_CONTAINER_multihashmap_destroy (sensors);
}