/*
  This file is part of TALER
  Copyright (C) 2014-2017, 2020 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU Lesser General Public License as published by the Free Software
  Foundation; either version 2.1, 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 Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License along with
  TALER; see the file COPYING.LGPL.  If not, see
  <http://www.gnu.org/licenses/>
*/
/**
 * @file lib/merchant_api_get_transfers.c
 * @brief Implementation of the GET /transfers request of the merchant's HTTP API
 * @author Marcello Stanisci
 * @author Christian Grothoff
 */
#include "platform.h"
#include <curl/curl.h>
#include <jansson.h>
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_curl_lib.h>
#include "taler_merchant_service.h"
#include <taler/taler_json_lib.h>
#include <taler/taler_signatures.h>


/**
 * @brief A Handle for tracking wire transfers.
 */
struct TALER_MERCHANT_GetTransfersHandle
{

  /**
   * The url for this request.
   */
  char *url;

  /**
   * Handle for the request.
   */
  struct GNUNET_CURL_Job *job;

  /**
   * Function to call with the result.
   */
  TALER_MERCHANT_GetTransfersCallback cb;

  /**
   * Closure for @a cb.
   */
  void *cb_cls;

  /**
   * Reference to the execution context.
   */
  struct GNUNET_CURL_Context *ctx;
};


/**
 * Function called when we're done processing the
 * HTTP GET /transfers request.
 *
 * @param cls the `struct TALER_MERCHANT_GetTransfersHandle`
 * @param response_code HTTP response code, 0 on error
 * @param json response body, NULL if not in JSON
 */
static void
handle_transfers_get_finished (void *cls,
                               long response_code,
                               const void *response)
{
  struct TALER_MERCHANT_GetTransfersHandle *gth = cls;
  const json_t *json = response;
  struct TALER_MERCHANT_HttpResponse hr = {
    .http_status = (unsigned int) response_code,
    .reply = json
  };

  gth->job = NULL;
  switch (response_code)
  {
  case 0:
    hr.ec = TALER_EC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    {
      json_t *transfers;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_json ("transfers",
                               &transfers),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json,
                             spec,
                             NULL, NULL))
      {
        GNUNET_break_op (0);
        hr.http_status = 0;
        hr.ec = TALER_EC_INVALID_RESPONSE;
        break;
      }
      else
      {
        size_t tds_length;
        struct TALER_MERCHANT_TransferData *tds;
        json_t *transfer;
        unsigned int i;
        bool ok;

        if (! json_is_array (transfers))
        {
          GNUNET_break_op (0);
          GNUNET_JSON_parse_free (spec);
          hr.http_status = 0;
          hr.ec = TALER_EC_INVALID_RESPONSE;
          break;
        }
        tds_length = json_array_size (transfers);
        tds = GNUNET_new_array (tds_length,
                                struct TALER_MERCHANT_TransferData);
        ok = true;
        json_array_foreach (transfers, i, transfer) {
          /* FIXME: handle 'execution_time', 'verified', and/or 'confirmed'
                    not present in the response. */
          struct TALER_MERCHANT_TransferData *td = &tds[i];
          struct GNUNET_JSON_Specification ispec[] = {
            TALER_JSON_spec_amount ("credit_amount",
                                    &td->credit_amount),
            GNUNET_JSON_spec_fixed_auto ("wtid",
                                         &td->wtid),
            GNUNET_JSON_spec_string ("payto_uri",
                                     &td->payto_uri),
            GNUNET_JSON_spec_string ("exchange_url",
                                     &td->exchange_url),
            GNUNET_JSON_spec_uint64 ("transfer_serial_id",
                                     &td->credit_serial),
            TALER_JSON_spec_absolute_time ("execution_time",
                                           &td->execution_time),
            GNUNET_JSON_spec_bool ("verified",
                                   &td->verified),
            GNUNET_JSON_spec_bool ("confirmed",
                                   &td->confirmed),
            GNUNET_JSON_spec_end ()
          };

          if (GNUNET_OK !=
              GNUNET_JSON_parse (transfer,
                                 ispec,
                                 NULL, NULL))
          {
            GNUNET_break_op (0);
            ok = false;
            break;
          }
        }

        if (! ok)
        {
          GNUNET_break_op (0);
          GNUNET_free (tds);
          GNUNET_JSON_parse_free (spec);
          hr.http_status = 0;
          hr.ec = TALER_EC_INVALID_RESPONSE;
          break;
        }
        gth->cb (gth->cb_cls,
                 &hr,
                 tds_length,
                 tds);
        GNUNET_free (tds);
        GNUNET_JSON_parse_free (spec);
        TALER_MERCHANT_transfers_get_cancel (gth);
        return;
      }
    }
  case MHD_HTTP_NOT_FOUND:
    /* Nothing really to verify, this should never
       happen, we should pass the JSON reply to the application */
    hr.ec = TALER_JSON_get_error_code (json);
    hr.hint = TALER_JSON_get_error_hint (json);
    break;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    /* Server had an internal issue; we should retry, but this API
       leaves this to the application */
    hr.ec = TALER_JSON_get_error_code (json);
    hr.hint = TALER_JSON_get_error_hint (json);
    break;
  default:
    /* unexpected response code */
    GNUNET_break_op (0);
    TALER_MERCHANT_parse_error_details_ (json,
                                         response_code,
                                         &hr);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d\n",
                (unsigned int) response_code,
                (int) hr.ec);
    response_code = 0;
    break;
  }
  gth->cb (gth->cb_cls,
           &hr,
           0,
           NULL);
  TALER_MERCHANT_transfers_get_cancel (gth);
}


/**
 * Request backend to return list of all wire transfers that
 * we received (or that the exchange claims we should have received).
 *
 * Note that when filtering by timestamp (using “before” and/or “after”), we
 * use the time reported by the exchange and thus will ONLY return results for
 * which we already have a response from the exchange. This should be
 * virtually all transfers, however it is conceivable that for some transfer
 * the exchange responded with a temporary error (i.e. HTTP status 500+) and
 * then we do not yet have an execution time to filter by. Thus, IF timestamp
 * filters are given, transfers for which we have no response from the
 * exchange yet are automatically excluded.
 *
 * @param ctx execution context
 * @param backend_url base URL of the backend
 * @param payto_uri filter by this credit account of the merchant
 * @param before limit to transactions before this timestamp, use
 *                 #GNUNET_TIME_UNIT_FOREVER_ABS to not filter by @a before
 * @param after limit to transactions after this timestamp, use
 *                 #GNUNET_TIME_UNIT_ZERO_ABS to not filter by @a after
 * @param limit return at most this number of results; negative to descend in execution time
 * @param offset start at this "credit serial" number (exclusive)
 * @param verified filter results by verification status
 * @param cb the callback to call when a reply for this request is available
 * @param cb_cls closure for @a cb
 * @return a handle for this request
 */
struct TALER_MERCHANT_GetTransfersHandle *
TALER_MERCHANT_transfers_get (
  struct GNUNET_CURL_Context *ctx,
  const char *backend_url,
  const char *payto_uri,
  const struct GNUNET_TIME_Absolute before,
  const struct GNUNET_TIME_Absolute after,
  int64_t limit,
  uint64_t offset,
  enum TALER_EXCHANGE_YesNoAll verified,
  TALER_MERCHANT_GetTransfersCallback cb,
  void *cb_cls)
{
  struct TALER_MERCHANT_GetTransfersHandle *gth;
  CURL *eh;
  const char *verified_s = NULL;
  char limit_s[30];
  char offset_s[30];
  char *before_s;
  char *after_s;

  gth = GNUNET_new (struct TALER_MERCHANT_GetTransfersHandle);
  gth->ctx = ctx;
  gth->cb = cb;
  gth->cb_cls = cb_cls;
  verified_s = TALER_yna_to_string (verified);
  GNUNET_snprintf (limit_s,
                   sizeof (limit_s),
                   "%lld",
                   (long long) limit);
  GNUNET_snprintf (offset_s,
                   sizeof (offset_s),
                   "%lld",
                   (unsigned long long) offset);
  before_s = GNUNET_strdup (GNUNET_STRINGS_absolute_time_to_string (before));
  after_s = GNUNET_strdup (GNUNET_STRINGS_absolute_time_to_string (after));
  gth->url = TALER_url_join (backend_url,
                             "private/transfers",
                             "payto_uri",
                             payto_uri,
                             "verified",
                             (TALER_EXCHANGE_YNA_ALL != verified)
                             ? verified_s
                             : NULL,
                             "limit",
                             0 != limit
                             ? limit_s
                             : NULL,
                             "offset",
                             ((0 != offset) && (UINT64_MAX != offset))
                             ? offset_s
                             : NULL,
                             "before",
                             before.abs_value_us !=
                             GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us
                             ? before_s
                             : NULL,
                             "after",
                             after.abs_value_us != 0
                             ? after_s
                             : NULL,
                             NULL);
  GNUNET_free (before_s);
  GNUNET_free (after_s);
  if (NULL == gth->url)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    GNUNET_free (gth);
    return NULL;
  }
  eh = curl_easy_init ();
  GNUNET_assert (CURLE_OK ==
                 curl_easy_setopt (eh,
                                   CURLOPT_URL,
                                   gth->url));
  gth->job = GNUNET_CURL_job_add (ctx,
                                  eh,
                                  &handle_transfers_get_finished,
                                  gth);
  return gth;
}


/**
 * Cancel a GET /transfers request.  This function cannot be used
 * on a request handle if a response is already served for it.
 *
 * @param gth handle to the tracking operation being cancelled
 */
void
TALER_MERCHANT_transfers_get_cancel (
  struct TALER_MERCHANT_GetTransfersHandle *gth)
{
  if (NULL != gth->job)
  {
    GNUNET_CURL_job_cancel (gth->job);
    gth->job = NULL;
  }
  GNUNET_free (gth->url);
  GNUNET_free (gth);
}


/* end of merchant_api_get_transfers.c */