/*
  This file is part of TALER
  Copyright (C) 2016 GNUnet e.V.

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

  TALER 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
  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
*/

/**
 * @file taler-exchange-httpd_validation.c
 * @brief helpers for calling the wire plugins to validate addresses
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include "taler-exchange-httpd_validation.h"
#include "taler_wire_plugin.h"


/**
 * Information we keep for each plugin.
 */
struct Plugin
{

  /**
   * We keep plugins in a DLL.
   */
  struct Plugin *next;

  /**
   * We keep plugins in a DLL.
   */
  struct Plugin *prev;

  /**
   * Type of the wireformat.
   */
  char *type;

  /**
   * Pointer to the plugin.
   */
  struct TALER_WIRE_Plugin *plugin;

};

/**
 * Head of DLL of wire plugins.
 */
static struct Plugin *wire_head;

/**
 * Tail of DLL of wire plugins.
 */
static struct Plugin *wire_tail;


/**
 * Initialize validation subsystem.
 *
 * @param cfg configuration to use
 * @return #GNUNET_OK on success
 */
int
TMH_VALIDATION_init (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  struct Plugin *p;
  char *wireformats;
  char *lib_name;
  const char *token;

  /* Find out list of supported wire formats */
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_string (cfg,
                                             "exchange",
                                             "wireformat",
                                             &wireformats))
  {
    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
                               "exchange",
                               "wireformat");
    return GNUNET_SYSERR;
  }
  for (token = strtok (wireformats,
                       " ");
       NULL != token;
       token = strtok (NULL,
                       " "))
  {
    (void) GNUNET_asprintf (&lib_name,
                            "libtaler_plugin_wire_%s",
                            token);
    p = GNUNET_new (struct Plugin);
    p->type = GNUNET_strdup (token);
    p->plugin = GNUNET_PLUGIN_load (lib_name,
                                    (void *) cfg);
    if (NULL == p->plugin)
    {
      GNUNET_free (p);
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Failed to load plugin %s\n",
                  lib_name);
      GNUNET_free (lib_name);
      TMH_VALIDATION_done ();
      return GNUNET_SYSERR;
    }
    p->plugin->library_name = lib_name;
    GNUNET_CONTAINER_DLL_insert (wire_head,
                                 wire_tail,
                                 p);
  }
  GNUNET_free (wireformats);
  return GNUNET_OK;
}


/**
 * Shutdown validation subsystem.
 */
void
TMH_VALIDATION_done ()
{
  struct Plugin *p;
  char *lib_name;

  while (NULL != (p = wire_head))
  {
    GNUNET_CONTAINER_DLL_remove (wire_head,
                                 wire_tail,
                                 p);
    lib_name = p->plugin->library_name;
    GNUNET_assert (NULL == GNUNET_PLUGIN_unload (lib_name,
                                                 p->plugin));
    GNUNET_free (lib_name);
    GNUNET_free (p->type);
    GNUNET_free (p);
  }
}


/**
 * Check if the given wire format JSON object is correctly formatted as
 * a wire address.
 *
 * @param wire the JSON wire format object
 * @return #GNUNET_YES if correctly formatted; #GNUNET_NO if not
 */
int
TMH_json_validate_wireformat (const json_t *wire)
{
  const char *stype;
  json_error_t error;
  struct Plugin *p;

  if (0 != json_unpack_ex ((json_t *) wire,
                           &error, 0,
                           "{s:s}",
                           "type", &stype))
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  for (p=wire_head; NULL != p; p = p->next)
    if (0 == strcasecmp (p->type,
                         stype))
      return p->plugin->wire_validate (wire);
  return GNUNET_NO;
}


/**
 * Check if we support the given wire method.
 *
 * @param type type of wire method to check
 * @return #GNUNET_YES if the method is supported
 */
int
TMH_VALIDATION_test_method (const char *type)
{
  struct Plugin *p;

  for (p=wire_head;NULL != p;p = p->next)
    if (0 == strcasecmp (type,
                         p->type))
      return GNUNET_YES;
  return GNUNET_NO;
}


/**
 * Obtain supported validation methods as a JSON array,
 * and as a hash.
 *
 * @param[out] h set to the hash of the JSON methods
 * @return JSON array with the supported validation methods
 */
json_t *
TMH_VALIDATION_get_methods (struct GNUNET_HashCode *h)
{
  json_t *methods;
  struct GNUNET_HashContext *hc;
  const char *wf;
  struct Plugin *p;

  methods = json_array ();
  hc = GNUNET_CRYPTO_hash_context_start ();
  for (p=wire_head;NULL != p;p = p->next)
  {
    wf = p->type;
    json_array_append_new (methods,
                           json_string (wf));
    GNUNET_CRYPTO_hash_context_read (hc,
                                     wf,
                                     strlen (wf) + 1);
  }
  GNUNET_CRYPTO_hash_context_finish (hc,
                                     h);
  return methods;
}


/* end of taler-exchange-httpd_validation.c */