/*
  This file is part of TALER
  Copyright (C) 2014-2017 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, see <http://www.gnu.org/licenses/>
*/
/**
 * @file taler-exchange-httpd_track_transaction.c
 * @brief Handle wire transfer tracking-related requests
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include <jansson.h>
#include <microhttpd.h>
#include <pthread.h>
#include "taler_signatures.h"
#include "taler-exchange-httpd_parsing.h"
#include "taler-exchange-httpd_keystate.h"
#include "taler-exchange-httpd_track_transaction.h"
#include "taler-exchange-httpd_responses.h"


/**
 * A merchant asked for details about a deposit, but
 * we did not execute the deposit yet. Generate a 202 reply.
 *
 * @param connection connection to the client
 * @param planned_exec_time planned execution time
 * @return MHD result code
 */
static int
reply_transfer_pending (struct MHD_Connection *connection,
			struct GNUNET_TIME_Absolute planned_exec_time)
{
  return TEH_RESPONSE_reply_json_pack (connection,
                                       MHD_HTTP_ACCEPTED,
                                       "{s:o}",
                                       "execution_time", GNUNET_JSON_from_time_abs (planned_exec_time));
}


/**
 * A merchant asked for details about a deposit.  Provide
 * them. Generates the 200 reply.
 *
 * @param connection connection to the client
 * @param h_contract_terms hash of the contract
 * @param h_wire hash of wire account details
 * @param coin_pub public key of the coin
 * @param coin_contribution how much did the coin we asked about
 *        contribute to the total transfer value? (deposit value minus fee)
 * @param wtid raw wire transfer identifier
 * @param exec_time execution time of the wire transfer
 * @return MHD result code
 */
static int
reply_track_transaction (struct MHD_Connection *connection,
			 const struct GNUNET_HashCode *h_contract_terms,
			 const struct GNUNET_HashCode *h_wire,
			 const struct TALER_CoinSpendPublicKeyP *coin_pub,
			 const struct TALER_Amount *coin_contribution,
			 const struct TALER_WireTransferIdentifierRawP *wtid,
			 struct GNUNET_TIME_Absolute exec_time)
{
  struct TALER_ConfirmWirePS cw;
  struct TALER_ExchangePublicKeyP pub;
  struct TALER_ExchangeSignatureP sig;

  cw.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_WIRE);
  cw.purpose.size = htonl (sizeof (struct TALER_ConfirmWirePS));
  cw.h_wire = *h_wire;
  cw.h_contract_terms = *h_contract_terms;
  cw.wtid = *wtid;
  cw.coin_pub = *coin_pub;
  cw.execution_time = GNUNET_TIME_absolute_hton (exec_time);
  TALER_amount_hton (&cw.coin_contribution,
                     coin_contribution);
  if (GNUNET_OK !=
      TEH_KS_sign (&cw.purpose,
		   &pub,
		   &sig))
  {
    return TEH_RESPONSE_reply_internal_error (connection,
                                              TALER_EC_EXCHANGE_BAD_CONFIGURATION,
                                              "no keys");
  }
  return TEH_RESPONSE_reply_json_pack (connection,
                                       MHD_HTTP_OK,
                                       "{s:o, s:o, s:o, s:o, s:o}",
                                       "wtid", GNUNET_JSON_from_data_auto (wtid),
                                       "execution_time", GNUNET_JSON_from_time_abs (exec_time),
                                       "coin_contribution", TALER_JSON_from_amount (coin_contribution),
                                       "exchange_sig", GNUNET_JSON_from_data_auto (&sig),
                                       "exchange_pub", GNUNET_JSON_from_data_auto (&pub));
}


/**
 * Closure for #handle_wtid_data.
 */
struct DepositWtidContext
{

  /**
   * Deposit details.
   */
  const struct TALER_DepositTrackPS *tps;

  /**
   * Public key of the merchant.
   */
  const struct TALER_MerchantPublicKeyP *merchant_pub;

  /**
   * Set by #handle_wtid data to the wire transfer ID.
   */
  struct TALER_WireTransferIdentifierRawP wtid;

  /**
   * Set by #handle_wtid data to the coin's contribution to the wire transfer.
   */
  struct TALER_Amount coin_contribution;

  /**
   * Set by #handle_wtid data to the fee charged to the coin.
   */
  struct TALER_Amount coin_fee;

  /**
   * Set by #handle_wtid data to the wire transfer execution time.
   */
  struct GNUNET_TIME_Absolute execution_time;

  /**
   * Set by #handle_wtid to the coin contribution to the transaction
   * (that is, @e coin_contribution minus @e coin_fee).
   */
  struct TALER_Amount coin_delta;

  /**
   * Set to #GNUNET_YES by #handle_wtid if the wire transfer is still pending
   * (and the above were not set).
   * Set to #GNUNET_SYSERR if there was a serious error.
   */
  int pending;
};


/**
 * Function called with the results of the lookup of the
 * wire transfer identifier information.
 *
 * @param cls our context for transmission
 * @param wtid raw wire transfer identifier, NULL
 *         if the transaction was not yet done
 * @param coin_contribution how much did the coin we asked about
 *        contribute to the total transfer value? (deposit value including fee)
 * @param coin_fee how much did the exchange charge for the deposit fee
 * @param execution_time when was the transaction done, or
 *         when we expect it to be done (if @a wtid was NULL);
 *         #GNUNET_TIME_UNIT_FOREVER_ABS if the /deposit is unknown
 *         to the exchange
 */
static void
handle_wtid_data (void *cls,
		  const struct TALER_WireTransferIdentifierRawP *wtid,
                  const struct TALER_Amount *coin_contribution,
                  const struct TALER_Amount *coin_fee,
		  struct GNUNET_TIME_Absolute execution_time)
{
  struct DepositWtidContext *ctx = cls;

  if (NULL == wtid)
  {
    ctx->pending = GNUNET_YES;
    ctx->execution_time = execution_time;
    return;
  }
  if (GNUNET_SYSERR ==
      TALER_amount_subtract (&ctx->coin_delta,
			     coin_contribution,
			     coin_fee))
  {
    GNUNET_break (0);
    ctx->pending = GNUNET_SYSERR;
    return;
  }
  ctx->wtid = *wtid;
  ctx->execution_time = execution_time;
  ctx->coin_contribution = *coin_contribution;
  ctx->coin_fee = *coin_fee;
}


/**
 * Execute a "/track/transaction".  Returns the transfer information
 * associated with the given deposit.
 *
 * 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 of type `struct DepositWtidContext *`
 * @param connection MHD request which triggered the transaction
 * @param session database session to use
 * @param[out] mhd_ret set to MHD response status for @a connection,
 *             if transaction failed (!)
 * @return transaction status
 */
static enum GNUNET_DB_QueryStatus
track_transaction_transaction (void *cls,
			       struct MHD_Connection *connection,
			       struct TALER_EXCHANGEDB_Session *session,
			       int *mhd_ret)
{
  struct DepositWtidContext *ctx = cls;
  enum GNUNET_DB_QueryStatus qs;

  qs = TEH_plugin->wire_lookup_deposit_wtid (TEH_plugin->cls,
					     session,
					     &ctx->tps->h_contract_terms,
					     &ctx->tps->h_wire,
					     &ctx->tps->coin_pub,
					     ctx->merchant_pub,
					     &handle_wtid_data,
					     ctx);
  if (0 > qs)
  {
    if (GNUNET_DB_STATUS_HARD_ERROR == qs)
    {
      GNUNET_break (0);
      *mhd_ret = TEH_RESPONSE_reply_internal_db_error (connection,
						       TALER_EC_TRACK_TRANSACTION_DB_FETCH_FAILED);
    }
    return qs;
  }
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    *mhd_ret = TEH_RESPONSE_reply_transaction_unknown (connection,
						       TALER_EC_TRACK_TRANSACTION_NOT_FOUND);
    return GNUNET_DB_STATUS_HARD_ERROR;
  }
  return qs;
}


/**
 * Check the merchant signature, and if it is valid,
 * return the wire transfer identifier.
 *
 * @param connection the MHD connection to handle
 * @param tps signed request to execute
 * @param merchant_pub public key from the merchant
 * @param merchant_sig signature from the merchant (to be checked)
 * @return MHD result code
 */
static int
check_and_handle_track_transaction_request (struct MHD_Connection *connection,
                                            const struct TALER_DepositTrackPS *tps,
                                            const struct TALER_MerchantPublicKeyP *merchant_pub,
                                            const struct TALER_MerchantSignatureP *merchant_sig)
{
  struct DepositWtidContext ctx;
  int mhd_ret;

  if (GNUNET_OK !=
      GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION,
				  &tps->purpose,
				  &merchant_sig->eddsa_sig,
				  &merchant_pub->eddsa_pub))
  {
    GNUNET_break_op (0);
    return TEH_RESPONSE_reply_signature_invalid (connection,
						 TALER_EC_TRACK_TRANSACTION_MERCHANT_SIGNATURE_INVALID,
						 "merchant_sig");
  }
  ctx.pending = GNUNET_NO;
  ctx.tps = tps;
  ctx.merchant_pub = merchant_pub;

  if (GNUNET_OK !=
      TEH_DB_run_transaction (connection,
                              "handle track transaction",
			      &mhd_ret,
			      &track_transaction_transaction,
			      &ctx))
    return mhd_ret;
  if (GNUNET_YES == ctx.pending)
    return reply_transfer_pending (connection,
				   ctx.execution_time);
  if (GNUNET_SYSERR == ctx.pending)
    return TEH_RESPONSE_reply_internal_db_error (connection,
						 TALER_EC_TRACK_TRANSACTION_DB_FEE_INCONSISTENT);
  return reply_track_transaction (connection,
				  &tps->h_contract_terms,
				  &tps->h_wire,
				  &tps->coin_pub,
				  &ctx.coin_delta,
				  &ctx.wtid,
				  ctx.execution_time);
}


/**
 * Handle a "/track/transaction" request.
 *
 * @param rh context of the handler
 * @param connection the MHD connection to handle
 * @param[in,out] connection_cls the connection's closure (can be updated)
 * @param upload_data upload data
 * @param[in,out] upload_data_size number of bytes (left) in @a upload_data
 * @return MHD result code
 */
int
TEH_TRACKING_handler_track_transaction (struct TEH_RequestHandler *rh,
                                        struct MHD_Connection *connection,
                                        void **connection_cls,
                                        const char *upload_data,
                                        size_t *upload_data_size)
{
  int res;
  json_t *json;
  struct TALER_DepositTrackPS tps;
  struct TALER_MerchantSignatureP merchant_sig;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_fixed_auto ("H_wire", &tps.h_wire),
    GNUNET_JSON_spec_fixed_auto ("h_contract_terms", &tps.h_contract_terms),
    GNUNET_JSON_spec_fixed_auto ("coin_pub", &tps.coin_pub),
    GNUNET_JSON_spec_fixed_auto ("merchant_pub", &tps.merchant),
    GNUNET_JSON_spec_fixed_auto ("merchant_sig", &merchant_sig),
    GNUNET_JSON_spec_end ()
  };

  res = TEH_PARSE_post_json (connection,
                             connection_cls,
                             upload_data,
                             upload_data_size,
                             &json);
  if (GNUNET_SYSERR == res)
    return MHD_NO;
  if ( (GNUNET_NO == res) || (NULL == json) )
    return MHD_YES;
  res = TEH_PARSE_json_data (connection,
                             json,
                             spec);
  if (GNUNET_OK != res)
  {
    json_decref (json);
    return (GNUNET_NO == res) ? MHD_YES : MHD_NO;
  }
  tps.purpose.size = htonl (sizeof (struct TALER_DepositTrackPS));
  tps.purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_TRACK_TRANSACTION);
  res = check_and_handle_track_transaction_request (connection,
                                                    &tps,
                                                    &tps.merchant,
                                                    &merchant_sig);
  GNUNET_JSON_parse_free (spec);
  json_decref (json);
  return res;
}


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