/*
     This file is part of GNUnet
     Copyright (C) 2017 GNUnet e.V.

     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., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/

/**
 * @file consensus/plugin_block_consensus.c
 * @brief consensus block, either nested block or marker
 * @author Christian Grothoff
 */

#include "platform.h"
#include "consensus_protocol.h"
#include "gnunet_block_plugin.h"
#include "gnunet_block_group_lib.h"


/**
 * Function called to validate a reply or a request.  For
 * request evaluation, simply pass "NULL" for the reply_block.
 *
 * @param cls closure
 * @param ctx context
 * @param type block type
 * @param group block group to use
 * @param eo control flags
 * @param query original query (hash)
 * @param xquery extrended query data (can be NULL, depending on type)
 * @param xquery_size number of bytes in xquery
 * @param reply_block response to validate
 * @param reply_block_size number of bytes in reply block
 * @return characterization of result
 */
static enum GNUNET_BLOCK_EvaluationResult
block_plugin_consensus_evaluate (void *cls,
                                 struct GNUNET_BLOCK_Context *ctx,
                                 enum GNUNET_BLOCK_Type type,
                                 struct GNUNET_BLOCK_Group *group,
                                 enum GNUNET_BLOCK_EvaluationOptions eo,
                                 const struct GNUNET_HashCode *query,
                                 const void *xquery,
                                 size_t xquery_size,
                                 const void *reply_block,
                                 size_t reply_block_size)
{
  if (reply_block_size < sizeof (struct ConsensusElement))
    return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;

  const struct ConsensusElement *ce = reply_block;

  if ( (0 != ce->marker) ||
       (0 == ce->payload_type ) )
    return GNUNET_BLOCK_EVALUATION_OK_MORE;

  return GNUNET_BLOCK_evaluate (ctx,
                                type,
                                group,
                                eo,
                                query,
                                xquery,
                                xquery_size,
                                &ce[1],
                                reply_block_size - sizeof (struct ConsensusElement));
}


/**
 * Function called to obtain the key for a block.
 *
 * @param cls closure
 * @param type block type
 * @param block block to get the key for
 * @param block_size number of bytes in block
 * @param key set to the key (query) for the given block
 * @return #GNUNET_OK on success, #GNUNET_SYSERR if type not supported
 *         (or if extracting a key from a block of this type does not work)
 */
static int
block_plugin_consensus_get_key (void *cls,
                               enum GNUNET_BLOCK_Type type,
                               const void *block,
                               size_t block_size,
			       struct GNUNET_HashCode *key)
{
  return GNUNET_SYSERR;
}


/**
 * Entry point for the plugin.
 */
void *
libgnunet_plugin_block_consensus_init (void *cls)
{
  static enum GNUNET_BLOCK_Type types[] =
  {
    GNUNET_BLOCK_TYPE_CONSENSUS_ELEMENT,
    GNUNET_BLOCK_TYPE_ANY       /* end of list */
  };
  struct GNUNET_BLOCK_PluginFunctions *api;

  api = GNUNET_new (struct GNUNET_BLOCK_PluginFunctions);
  api->evaluate = &block_plugin_consensus_evaluate;
  api->get_key = &block_plugin_consensus_get_key;
  api->types = types;
  return api;
}


/**
 * Exit point from the plugin.
 */
void *
libgnunet_plugin_block_consensus_done (void *cls)
{
  struct GNUNET_BLOCK_PluginFunctions *api = cls;

  GNUNET_free (api);
  return NULL;
}

/* end of plugin_block_consensus.c */