/*
     This file is part of GNUnet.
     Copyright (C) 2011 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */

/**
 * @file fs/gnunet-service-fs_put.c
 * @brief API to PUT zero-anonymity index data from our datastore into the DHT
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet-service-fs.h"
#include "gnunet-service-fs_put.h"


/**
 * How often do we at most PUT content into the DHT?
 */
#define MAX_DHT_PUT_FREQ GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_SECONDS, 5)

/**
 * How many replicas do we try to create per PUT?
 */
#define DEFAULT_PUT_REPLICATION 5


/**
 * Context for each zero-anonymity iterator.
 */
struct PutOperator
{
  /**
   * Request to datastore for DHT PUTs (or NULL).
   */
  struct GNUNET_DATASTORE_QueueEntry *dht_qe;

  /**
   * Type we request from the datastore.
   */
  enum GNUNET_BLOCK_Type dht_put_type;

  /**
   * Handle to PUT operation.
   */
  struct GNUNET_DHT_PutHandle *dht_put;

  /**
   * ID of task that collects blocks for DHT PUTs.
   */
  struct GNUNET_SCHEDULER_Task *dht_task;

  /**
   * How many entires with zero anonymity of our type do we currently
   * estimate to have in the database?
   */
  uint64_t zero_anonymity_count_estimate;

  /**
   * Count of results received from the database.
   */
  uint64_t result_count;

  /**
   * Next UID to request when iterating the database.
   */
  uint64_t next_uid;
};


/**
 * ANY-terminated list of our operators (one per type
 * of block that we're putting into the DHT).
 */
static struct PutOperator operators[] = {
  { NULL, GNUNET_BLOCK_TYPE_FS_UBLOCK, 0, 0, 0 },
  { NULL, GNUNET_BLOCK_TYPE_ANY, 0, 0, 0 }
};


/**
 * Task that is run periodically to obtain blocks for DHT PUTs.
 *
 * @param cls type of blocks to gather
 * @param tc scheduler context (unused)
 */
static void
gather_dht_put_blocks (void *cls);


/**
 * Calculate when to run the next PUT operation and schedule it.
 *
 * @param po put operator to schedule
 */
static void
schedule_next_put (struct PutOperator *po)
{
  struct GNUNET_TIME_Relative delay;

  if (po->zero_anonymity_count_estimate > 0)
  {
    delay =
      GNUNET_TIME_relative_divide (GNUNET_DHT_DEFAULT_REPUBLISH_FREQUENCY,
                                   po->zero_anonymity_count_estimate);
    delay = GNUNET_TIME_relative_min (delay, MAX_DHT_PUT_FREQ);
  }
  else
  {
    /* if we have NO zero-anonymity content yet, wait 5 minutes for some to
     * (hopefully) appear */
    delay = GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5);
  }
  po->dht_task =
    GNUNET_SCHEDULER_add_delayed (delay, &gather_dht_put_blocks, po);
}


/**
 * Continuation called after DHT PUT operation has finished.
 *
 * @param cls type of blocks to gather
 */
static void
delay_dht_put_blocks (void *cls)
{
  struct PutOperator *po = cls;

  po->dht_put = NULL;
  schedule_next_put (po);
}


/**
 * Task that is run periodically to obtain blocks for DHT PUTs.
 *
 * @param cls type of blocks to gather
 */
static void
delay_dht_put_task (void *cls)
{
  struct PutOperator *po = cls;

  po->dht_task = NULL;
  schedule_next_put (po);
}


/**
 * Store content in DHT.
 *
 * @param cls closure
 * @param key key for the content
 * @param size number of bytes in data
 * @param data content stored
 * @param type type of the content
 * @param priority priority of the content
 * @param anonymity anonymity-level for the content
 * @param replication replication-level for the content
 * @param expiration expiration time for the content
 * @param uid unique identifier for the datum;
 *        maybe 0 if no unique identifier is available
 */
static void
process_dht_put_content (void *cls,
                         const struct GNUNET_HashCode *key,
                         size_t size,
                         const void *data,
                         enum GNUNET_BLOCK_Type type,
                         uint32_t priority,
                         uint32_t anonymity,
                         uint32_t replication,
                         struct GNUNET_TIME_Absolute expiration,
                         uint64_t uid)
{
  struct PutOperator *po = cls;

  po->dht_qe = NULL;
  if (key == NULL)
  {
    po->zero_anonymity_count_estimate = po->result_count;
    po->result_count = 0;
    po->next_uid = 0;
    po->dht_task = GNUNET_SCHEDULER_add_now (&delay_dht_put_task, po);
    return;
  }
  po->result_count++;
  po->next_uid = uid + 1;
  po->zero_anonymity_count_estimate =
    GNUNET_MAX (po->result_count, po->zero_anonymity_count_estimate);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Retrieved block `%s' of type %u for DHT PUT\n", GNUNET_h2s (key),
              type);
  po->dht_put = GNUNET_DHT_put (GSF_dht,
                                key,
                                DEFAULT_PUT_REPLICATION,
                                GNUNET_DHT_RO_DEMULTIPLEX_EVERYWHERE,
                                type,
                                size,
                                data,
                                expiration,
                                &delay_dht_put_blocks,
                                po);
}


/**
 * Task that is run periodically to obtain blocks for DHT PUTs.
 *
 * @param cls type of blocks to gather
 */
static void
gather_dht_put_blocks (void *cls)
{
  struct PutOperator *po = cls;

  po->dht_task = NULL;
  po->dht_qe =
    GNUNET_DATASTORE_get_zero_anonymity (GSF_dsh,
                                         po->next_uid,
                                         0,
                                         UINT_MAX,
                                         po->dht_put_type,
                                         &process_dht_put_content,
                                         po);
  if (NULL == po->dht_qe)
    po->dht_task = GNUNET_SCHEDULER_add_now (&delay_dht_put_task, po);
}


/**
 * Setup the module.
 */
void
GSF_put_init_ ()
{
  unsigned int i;

  i = 0;
  while (operators[i].dht_put_type != GNUNET_BLOCK_TYPE_ANY)
  {
    operators[i].dht_task =
      GNUNET_SCHEDULER_add_now (&gather_dht_put_blocks, &operators[i]);
    i++;
  }
}


/**
 * Shutdown the module.
 */
void
GSF_put_done_ ()
{
  struct PutOperator *po;
  unsigned int i;

  i = 0;
  while ((po = &operators[i])->dht_put_type != GNUNET_BLOCK_TYPE_ANY)
  {
    if (NULL != po->dht_task)
    {
      GNUNET_SCHEDULER_cancel (po->dht_task);
      po->dht_task = NULL;
    }
    if (NULL != po->dht_put)
    {
      GNUNET_DHT_put_cancel (po->dht_put);
      po->dht_put = NULL;
    }
    if (NULL != po->dht_qe)
    {
      GNUNET_DATASTORE_cancel (po->dht_qe);
      po->dht_qe = NULL;
    }
    i++;
  }
}


/* end of gnunet-service-fs_put.c */
