/*
  This file is part of TALER
  (C) 2014, 2015, 2016, 2018, 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 General Public License for more details.

  You should have received a copy of the GNU General Public
  License along with TALER; see the file COPYING.  If not,
  see <http://www.gnu.org/licenses/>
*/

/**
 * @file taler-merchant-httpd_post-orders-ID-claim.c
 * @brief headers for POST /orders/$ID/claim handler
 * @author Marcello Stanisci
 * @author Christian Grothoff
 */
#include "platform.h"
#include <jansson.h>
#include <taler/taler_signatures.h>
#include <taler/taler_json_lib.h>
#include "taler-merchant-httpd_private-get-orders.h"
#include "taler-merchant-httpd_post-orders-ID-claim.h"


/**
 * How often do we retry the database transaction?
 */
#define MAX_RETRIES 3


/**
 * Run transaction to claim @a order_id for @a nonce.
 *
 * @param instance_id instance to claim order at
 * @param order_id order to claim
 * @param nonce nonce to use for the claim
 * @param claim_token the token that should be used to verify the claim
 * @param[out] contract_terms set to the resulting contract terms
 *             (for any non-negative result;
 * @return transaction status code
 *         #GNUNET_DB_STATUS_SUCCESS_NO_RESULTS if the order was claimed by a different
 *         nonce (@a contract_terms set to non-NULL)
 *                OR if the order is is unknown (@a contract_terms is NULL)
 *         #GNUNET_DB_STATUS_SUCCESS_ONE_RESULT if the order was successfully claimed
 */
static enum GNUNET_DB_QueryStatus
claim_order (const char *instance_id,
             const char *order_id,
             const char *nonce,
             const struct TALER_ClaimTokenP *claim_token,
             json_t **contract_terms)
{
  struct TALER_ClaimTokenP order_ct;
  enum GNUNET_DB_QueryStatus qs;
  uint64_t order_serial;

  if (GNUNET_OK !=
      TMH_db->start (TMH_db->cls,
                     "claim order"))
  {
    GNUNET_break (0);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }
  qs = TMH_db->lookup_contract_terms (TMH_db->cls,
                                      instance_id,
                                      order_id,
                                      contract_terms,
                                      &order_serial,
                                      NULL);
  if (0 > qs)
  {
    TMH_db->rollback (TMH_db->cls);
    return qs;
  }

  if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
  {
    /* We already have claimed contract terms for this order_id */
    const char *stored_nonce;
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_string ("nonce",
                               &stored_nonce),
      GNUNET_JSON_spec_end ()
    };

    TMH_db->rollback (TMH_db->cls);
    GNUNET_assert (NULL != *contract_terms);

    if (GNUNET_OK !=
        GNUNET_JSON_parse (*contract_terms,
                           spec,
                           NULL,
                           NULL))
    {
      /* this should not be possible: contract_terms should always
         have a nonce! */
      GNUNET_break (0);
      return GNUNET_DB_STATUS_HARD_ERROR;
    }

    if (0 != strcmp (stored_nonce,
                     nonce))
    {
      GNUNET_JSON_parse_free (spec);
      return GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
    }
    GNUNET_JSON_parse_free (spec);
    return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
  }

  GNUNET_assert (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs);

  /* Now we need to claim the order. */
  {
    struct TALER_MerchantPostDataHashP unused;
    struct GNUNET_TIME_Timestamp timestamp;
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_timestamp ("timestamp",
                                  &timestamp),
      GNUNET_JSON_spec_end ()
    };

    /* see if we have this order in our table of unclaimed orders */
    qs = TMH_db->lookup_order (TMH_db->cls,
                               instance_id,
                               order_id,
                               &order_ct,
                               &unused,
                               contract_terms);
    if (0 >= qs)
    {
      TMH_db->rollback (TMH_db->cls);
      return qs;
    }
    GNUNET_assert (NULL != *contract_terms);
    if (GNUNET_OK !=
        GNUNET_JSON_parse (*contract_terms,
                           spec,
                           NULL,
                           NULL))
    {
      /* this should not be possible: contract_terms should always
         have a timestamp! */
      GNUNET_break (0);
      TMH_db->rollback (TMH_db->cls);
      return GNUNET_DB_STATUS_HARD_ERROR;
    }

    GNUNET_assert (0 ==
                   json_object_set_new (*contract_terms,
                                        "nonce",
                                        json_string (nonce)));
    if (0 != GNUNET_memcmp_priv (&order_ct,
                                 claim_token))
    {
      TMH_db->rollback (TMH_db->cls);
      json_decref (*contract_terms);
      *contract_terms = NULL;
      return GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
    }
    qs = TMH_db->insert_contract_terms (TMH_db->cls,
                                        instance_id,
                                        order_id,
                                        *contract_terms,
                                        &order_serial);
    if (0 >= qs)
    {
      TMH_db->rollback (TMH_db->cls);
      json_decref (*contract_terms);
      *contract_terms = NULL;
      return qs;
    }
    TMH_notify_order_change (TMH_lookup_instance (instance_id),
                             TMH_OSF_CLAIMED,
                             timestamp,
                             order_serial);
    qs = TMH_db->commit (TMH_db->cls);
    if (0 > qs)
      return qs;
    return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
  }
}


MHD_RESULT
TMH_post_orders_ID_claim (const struct TMH_RequestHandler *rh,
                          struct MHD_Connection *connection,
                          struct TMH_HandlerContext *hc)
{
  const char *order_id = hc->infix;
  const char *nonce;
  enum GNUNET_DB_QueryStatus qs;
  json_t *contract_terms;
  struct TALER_ClaimTokenP claim_token = { 0 };

  {
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_string ("nonce",
                               &nonce),
      GNUNET_JSON_spec_mark_optional (
        GNUNET_JSON_spec_fixed_auto ("token",
                                     &claim_token),
        NULL),
      GNUNET_JSON_spec_end ()
    };
    enum GNUNET_GenericReturnValue res;

    res = TALER_MHD_parse_json_data (connection,
                                     hc->request_body,
                                     spec);
    if (GNUNET_OK != res)
    {
      GNUNET_break_op (0);
      json_dumpf (hc->request_body,
                  stderr,
                  JSON_INDENT (2));
      return (GNUNET_NO == res)
             ? MHD_YES
             : MHD_NO;
    }
  }
  contract_terms = NULL;
  for (unsigned int i = 0; i<MAX_RETRIES; i++)
  {
    TMH_db->preflight (TMH_db->cls);
    qs = claim_order (hc->instance->settings.id,
                      order_id,
                      nonce,
                      &claim_token,
                      &contract_terms);
    if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
      break;
  }
  switch (qs)
  {
  case GNUNET_DB_STATUS_HARD_ERROR:
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                                       TALER_EC_GENERIC_DB_COMMIT_FAILED,
                                       NULL);
  case GNUNET_DB_STATUS_SOFT_ERROR:
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                                       TALER_EC_GENERIC_DB_SOFT_FAILURE,
                                       NULL);
  case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
    if (NULL == contract_terms)
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_NOT_FOUND,
                                         TALER_EC_MERCHANT_POST_ORDERS_ID_CLAIM_NOT_FOUND,
                                         order_id);
    /* already claimed! */
    json_decref (contract_terms);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_CONFLICT,
                                       TALER_EC_MERCHANT_POST_ORDERS_ID_CLAIM_ALREADY_CLAIMED,
                                       order_id);
  case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
    GNUNET_assert (NULL != contract_terms);
    break; /* Good! return signature (below) */
  }

  /* create contract signature */
  {
    struct TALER_PrivateContractHashP hash;
    struct TALER_MerchantSignatureP merchant_sig;

    /**
     * Hash of the JSON contract in UTF-8 including 0-termination,
     * using JSON_COMPACT | JSON_SORT_KEYS
     */

    if (GNUNET_OK !=
        TALER_JSON_contract_hash (contract_terms,
                                  &hash))
    {
      GNUNET_break (0);
      json_decref (contract_terms);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GENERIC_FAILED_COMPUTE_JSON_HASH,
                                         NULL);
    }

    TALER_merchant_contract_sign (&hash,
                                  &hc->instance->merchant_priv,
                                  &merchant_sig);
    return TALER_MHD_REPLY_JSON_PACK (
      connection,
      MHD_HTTP_OK,
      GNUNET_JSON_pack_object_steal ("contract_terms",
                                     contract_terms),
      GNUNET_JSON_pack_data_auto ("sig",
                                  &merchant_sig));
  }
}


/* end of taler-merchant-httpd_post-orders-ID-claim.c */