/*
  This file is part of TALER
  Copyright (C) 2014-2021 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_csr.c
 * @brief Handle /csr requests
 * @author Lucien Heuzeveldt
 * @author Gian Demarmles
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include <jansson.h>
#include "taler_json_lib.h"
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_csr.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keys.h"


MHD_RESULT
TEH_handler_csr (struct TEH_RequestContext *rc,
                 const json_t *root,
                 const char *const args[])
{
  unsigned int csr_requests_num;
  json_t *csr_requests;
  json_t *csr_response;

  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_json ("nks",
                           &csr_requests),
    GNUNET_JSON_spec_end ()
  };
  enum TALER_ErrorCode ec;
  struct TEH_DenominationKey *dk;

  (void) args;

  // parse input
  {
    enum GNUNET_GenericReturnValue res;

    res = TALER_MHD_parse_json_data (rc->connection,
                                     root,
                                     spec);
    GNUNET_JSON_parse_free (spec);
    if (GNUNET_OK != res)
      return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
  }
  csr_requests_num = json_array_size (csr_requests);
  if (TALER_MAX_FRESH_COINS <= csr_requests_num)
  {
    return TALER_MHD_reply_with_error (
      rc->connection,
      MHD_HTTP_BAD_REQUEST,
      // FIXME: generalize error message
      TALER_EC_EXCHANGE_REFRESHES_REVEAL_NEW_DENOMS_ARRAY_SIZE_EXCESSIVE,
      NULL);
  }
  struct TALER_CsNonce nonces[GNUNET_NZL (csr_requests_num)];
  struct TALER_DenominationHash denom_pub_hashes[GNUNET_NZL (csr_requests_num)];
  for (unsigned int i = 0; i < csr_requests_num; i++)
  {
    struct TALER_CsNonce *nonce = &nonces[i];
    struct TALER_DenominationHash *denom_pub_hash = &denom_pub_hashes[i];
    struct GNUNET_JSON_Specification csr_spec[] = {
      GNUNET_JSON_spec_fixed ("nonce",
                              nonce,
                              sizeof (struct TALER_CsNonce)),
      GNUNET_JSON_spec_fixed ("denom_pub_hash",
                              denom_pub_hash,
                              sizeof (struct TALER_DenominationHash)),
      GNUNET_JSON_spec_end ()
    };
    enum GNUNET_GenericReturnValue res;

    res = TALER_MHD_parse_json_array (rc->connection,
                                      root,
                                      csr_spec,
                                      i,
                                      -1);
    if (GNUNET_OK != res)
      return (GNUNET_NO == res) ? MHD_YES : MHD_NO;
  }

  struct TALER_DenominationCsPublicR r_pubs[GNUNET_NZL (csr_requests_num)];
  for (unsigned int i = 0; i < csr_requests_num; i++)
  {
    const struct TALER_CsNonce *nonce = &nonces[i];
    const struct TALER_DenominationHash *denom_pub_hash = &denom_pub_hashes[i];
    struct TALER_DenominationCsPublicR *r_pub = &r_pubs[i];

    // check denomination referenced by denom_pub_hash
    {
      struct TEH_KeyStateHandle *ksh;

      ksh = TEH_keys_get_state ();
      if (NULL == ksh)
      {
        return TALER_MHD_reply_with_error (rc->connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING,
                                           NULL);
      }
      dk = TEH_keys_denomination_by_hash2 (ksh,
                                           denom_pub_hash,
                                           NULL,
                                           NULL);
      if (NULL == dk)
      {
        return TEH_RESPONSE_reply_unknown_denom_pub_hash (
          rc->connection,
          &denom_pub_hash[i]);
      }
      if (GNUNET_TIME_absolute_is_past (dk->meta.expire_withdraw.abs_time))
      {
        /* This denomination is past the expiration time for withdraws/refreshes*/
        return TEH_RESPONSE_reply_expired_denom_pub_hash (
          rc->connection,
          denom_pub_hash,
          TALER_EC_EXCHANGE_GENERIC_DENOMINATION_EXPIRED,
          "CSR");
      }
      if (GNUNET_TIME_absolute_is_future (dk->meta.start.abs_time))
      {
        /* This denomination is not yet valid, no need to check
           for idempotency! */
        return TEH_RESPONSE_reply_expired_denom_pub_hash (
          rc->connection,
          denom_pub_hash,
          TALER_EC_EXCHANGE_GENERIC_DENOMINATION_VALIDITY_IN_FUTURE,
          "CSR");
      }
      if (dk->recoup_possible)
      {
        /* This denomination has been revoked */
        return TEH_RESPONSE_reply_expired_denom_pub_hash (
          rc->connection,
          denom_pub_hash,
          TALER_EC_EXCHANGE_GENERIC_DENOMINATION_REVOKED,
          "CSR");
      }
      if (TALER_DENOMINATION_CS != dk->denom_pub.cipher)
      {
        // denomination is valid but not CS
        return TEH_RESPONSE_reply_invalid_denom_cipher_for_operation (
          rc->connection,
          denom_pub_hash);
      }
    }

    // derive r_pub
    // FIXME: bundle all requests into one derivation request (TEH_keys_..., crypto helper, security module)
    ec = TEH_keys_denomination_cs_r_pub (denom_pub_hash,
                                         nonce,
                                         r_pub);
    if (TALER_EC_NONE != ec)
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_ec (rc->connection,
                                      ec,
                                      NULL);
    }
  }

  // send response
  csr_response = json_array ();
  for (unsigned int i = 0; i < csr_requests_num; i++)
  {
    const struct TALER_DenominationCsPublicR *r_pub = &r_pubs[i];
    json_t *csr_obj;

    csr_obj = GNUNET_JSON_PACK (
      GNUNET_JSON_pack_data_varsize ("r_pub_0",
                                     &r_pub->r_pub[0],
                                     sizeof(struct GNUNET_CRYPTO_CsRPublic)),
      GNUNET_JSON_pack_data_varsize ("r_pub_1",
                                     &r_pub->r_pub[1],
                                     sizeof(struct GNUNET_CRYPTO_CsRPublic)));
    GNUNET_assert (NULL != csr_obj);
    GNUNET_assert (0 ==
                   json_array_append_new (csr_response,
                                          csr_obj));
  }
  return TALER_MHD_reply_json (rc->connection,
                               csr_response,
                               MHD_HTTP_OK);
}


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