/*
  This file is part of TALER
  Copyright (C) 2020 Taler Systems SA

  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, see <http://www.gnu.org/licenses/>
*/
/**
 * @file taler-exchange-httpd_auditors.c
 * @brief Handle request to add auditor signature on a denomination.
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_json_lib.h>
#include <jansson.h>
#include <microhttpd.h>
#include <pthread.h>
#include "taler_json_lib.h"
#include "taler_mhd_lib.h"
#include "taler_signatures.h"
#include "taler-exchange-httpd_auditors.h"
#include "taler-exchange-httpd_responses.h"


/**
 * Closure for the #add_auditor_denom_sig transaction.
 */
struct AddAuditorDenomContext
{
  /**
   * Auditor's signature affirming the AUDITORS XXX operation
   * (includes timestamp).
   */
  struct TALER_AuditorSignatureP auditor_sig;

  /**
   * Denomination this is about.
   */
  const struct TALER_DenominationHashP *h_denom_pub;

  /**
   * Auditor this is about.
   */
  const struct TALER_AuditorPublicKeyP *auditor_pub;

};


/**
 * Function implementing database transaction to add an auditors.  Runs the
 * transaction logic; IF it returns a non-error code, the transaction logic
 * MUST NOT queue a MHD response.  IF it returns an hard error, the
 * transaction logic MUST queue a MHD response and set @a mhd_ret.  IF it
 * returns the soft error code, the function MAY be called again to retry and
 * MUST not queue a MHD response.
 *
 * @param cls closure with a `struct AddAuditorDenomContext`
 * @param connection MHD request which triggered the transaction
 * @param[out] mhd_ret set to MHD response status for @a connection,
 *             if transaction failed (!)
 * @return transaction status
 */
static enum GNUNET_DB_QueryStatus
add_auditor_denom_sig (void *cls,
                       struct MHD_Connection *connection,
                       MHD_RESULT *mhd_ret)
{
  struct AddAuditorDenomContext *awc = cls;
  struct TALER_EXCHANGEDB_DenominationKeyMetaData meta;
  enum GNUNET_DB_QueryStatus qs;
  char *auditor_url;
  bool enabled;

  qs = TEH_plugin->lookup_denomination_key (
    TEH_plugin->cls,
    awc->h_denom_pub,
    &meta);
  if (qs < 0)
  {
    if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
      return qs;
    GNUNET_break (0);
    *mhd_ret = TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GENERIC_DB_FETCH_FAILED,
                                           "lookup denomination key");
    return qs;
  }
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    *mhd_ret = TALER_MHD_reply_with_error (
      connection,
      MHD_HTTP_NOT_FOUND,
      TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN,
      GNUNET_h2s (&awc->h_denom_pub->hash));
    return GNUNET_DB_STATUS_HARD_ERROR;
  }

  qs = TEH_plugin->lookup_auditor_status (
    TEH_plugin->cls,
    awc->auditor_pub,
    &auditor_url,
    &enabled);
  if (qs < 0)
  {
    if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
      return qs;
    GNUNET_break (0);
    *mhd_ret = TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GENERIC_DB_FETCH_FAILED,
                                           "lookup auditor");
    return qs;
  }
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    *mhd_ret = TALER_MHD_reply_with_error (
      connection,
      MHD_HTTP_PRECONDITION_FAILED,
      TALER_EC_EXCHANGE_AUDITORS_AUDITOR_UNKNOWN,
      TALER_B2S (awc->auditor_pub));
    return GNUNET_DB_STATUS_HARD_ERROR;
  }
  if (! enabled)
  {
    GNUNET_free (auditor_url);
    *mhd_ret = TALER_MHD_reply_with_error (
      connection,
      MHD_HTTP_GONE,
      TALER_EC_EXCHANGE_AUDITORS_AUDITOR_INACTIVE,
      TALER_B2S (awc->auditor_pub));
    return GNUNET_DB_STATUS_HARD_ERROR;
  }
  if (GNUNET_OK !=
      TALER_auditor_denom_validity_verify (
        auditor_url,
        awc->h_denom_pub,
        &TEH_master_public_key,
        meta.start,
        meta.expire_withdraw,
        meta.expire_deposit,
        meta.expire_legal,
        &meta.value,
        &meta.fees,
        awc->auditor_pub,
        &awc->auditor_sig))
  {
    GNUNET_free (auditor_url);
    /* signature invalid */
    GNUNET_break_op (0);
    *mhd_ret = TALER_MHD_reply_with_error (
      connection,
      MHD_HTTP_FORBIDDEN,
      TALER_EC_EXCHANGE_AUDITORS_AUDITOR_SIGNATURE_INVALID,
      NULL);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }
  GNUNET_free (auditor_url);

  qs = TEH_plugin->insert_auditor_denom_sig (TEH_plugin->cls,
                                             awc->h_denom_pub,
                                             awc->auditor_pub,
                                             &awc->auditor_sig);
  if (qs < 0)
  {
    GNUNET_break (0);
    if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
      return qs;
    *mhd_ret = TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GENERIC_DB_STORE_FAILED,
                                           "add auditor signature");
    return qs;
  }
  return qs;
}


MHD_RESULT
TEH_handler_auditors (
  struct MHD_Connection *connection,
  const struct TALER_AuditorPublicKeyP *auditor_pub,
  const struct TALER_DenominationHashP *h_denom_pub,
  const json_t *root)
{
  struct AddAuditorDenomContext awc = {
    .auditor_pub = auditor_pub,
    .h_denom_pub = h_denom_pub
  };
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_fixed_auto ("auditor_sig",
                                 &awc.auditor_sig),
    GNUNET_JSON_spec_end ()
  };
  MHD_RESULT res;
  enum GNUNET_GenericReturnValue ret;

  ret = TALER_MHD_parse_json_data (connection,
                                   root,
                                   spec);
  if (GNUNET_SYSERR == ret)
    return MHD_NO;   /* hard failure */
  if (GNUNET_NO == ret)
    return MHD_YES;   /* failure */
  ret = TEH_DB_run_transaction (connection,
                                "add auditor denom sig",
                                TEH_MT_OTHER,
                                &res,
                                &add_auditor_denom_sig,
                                &awc);
  if (GNUNET_SYSERR == ret)
    return res;
  return TALER_MHD_reply_static (
    connection,
    MHD_HTTP_NO_CONTENT,
    NULL,
    NULL,
    0);
}


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