/*
  This file is part of TALER
  Copyright (C) 2014, 2015, 2016 GNUnet e.V. and INRIA

  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_contract.c
 * @brief Implementation of the /history request of the merchant's
 *        HTTP API
 * @author Marcello Stanisci
 */
#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>


/**
 * @brief A Contract Operation Handle
 */
struct TALER_MERCHANT_HistoryOperation
{

  /**
   * The url for this request, including parameters.
   */
  char *url;

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

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

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

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


/**
 * Cancel a pending /history request
 *
 * @param handle from the operation to cancel
 */
void
TALER_MERCHANT_history_cancel (struct TALER_MERCHANT_HistoryOperation *ho)
{
  if (NULL != ho->job)
  {
    GNUNET_CURL_job_cancel (ho->job);
    ho->job = NULL;
  }
  GNUNET_free (ho->url);
  GNUNET_free (ho);
}


/**
 * Function called when we're done processing the
 * HTTP /history request.
 *
 * @param cls the `struct TALER_MERCHANT_TrackTransactionHandle`
 * @param response_code HTTP response code, 0 on error
 * @param json response body, NULL if not in JSON
 */
static void
history_raw_cb (void *cls,
                long response_code,
                const void *response)
{
  struct TALER_MERCHANT_HistoryOperation *ho = cls;
  const json_t *json = response;

  ho->job = NULL;
  switch (response_code)
  {
  case 0:
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                "/history returned response code 0\n");
    /**
     * The response was malformed or didn't have the
     * application/json header.
     */
    ho->cb (ho->cb_cls,
            response_code,
            TALER_EC_INVALID_RESPONSE,
            json);
    TALER_MERCHANT_history_cancel (ho);
    return;
  case MHD_HTTP_OK:
    ho->cb (ho->cb_cls,
            MHD_HTTP_OK,
            TALER_EC_NONE,
            json);
    TALER_MERCHANT_history_cancel (ho);
    return;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "/history URL not found\n");
    break;
  case MHD_HTTP_BAD_REQUEST:
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Wrong/missing URL parameter\n");
    break;
  default:
    /* unexpected response code */
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u\n",
                (unsigned int) response_code);
    GNUNET_break (0);
    response_code = 0;
    break;
  }

  ho->cb (ho->cb_cls,
          response_code,
          TALER_JSON_get_error_code (json),
          json);
  TALER_MERCHANT_history_cancel (ho);
}


/**
 * Issue a /history request to the backend.
 *
 * @param ctx execution context
 * @param backend_url base URL of the merchant backend
 * @param start return `delta` records starting from position `start`.
 *        If given as zero, then no initial skip of `start` records is done.
 * @param use_default_start do NOT include the 'start' argument in URL.
 * @param delta return `delta` records starting from position `start`
 * @param date only transactions younger than/equals to date will be returned
 * @param history_cb callback which will work the response gotten from the backend
 * @param history_cb_cls closure to pass to @a history_cb
 * @return handle for this operation, NULL upon errors
 */
static struct TALER_MERCHANT_HistoryOperation *
TALER_MERCHANT_history2 (struct GNUNET_CURL_Context *ctx,
                         const char *backend_url,
                         unsigned long long start,
                         int use_default_start,
                         long long delta,
                         struct GNUNET_TIME_Absolute date,
                         TALER_MERCHANT_HistoryOperationCallback history_cb,
                         void *history_cb_cls)
{
  struct TALER_MERCHANT_HistoryOperation *ho;
  uint64_t seconds;
  CURL *eh;
  char *base;

  base = TALER_url_join (backend_url, "history", NULL);
  if (NULL == base)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    return NULL;
  }
  ho = GNUNET_new (struct TALER_MERCHANT_HistoryOperation);
  ho->ctx = ctx;
  ho->cb = history_cb;
  ho->cb_cls = history_cb_cls;
  seconds = date.abs_value_us / 1000LL / 1000LL;

  if (GNUNET_YES == use_default_start)
    GNUNET_asprintf (&ho->url,
                     "%s?date=%llu&delta=%lld",
                     base,
                     seconds,
                     delta);
  else
    GNUNET_asprintf (&ho->url,
                     "%s?date=%llu&delta=%lld&start=%llu",
                     base,
                     seconds,
                     delta,
                     start);
  GNUNET_free (base);
  eh = curl_easy_init ();
  if (CURLE_OK != curl_easy_setopt (eh,
                                    CURLOPT_URL,
                                    ho->url))
  {
    GNUNET_break (0);
    return NULL;
  }

  if (NULL == (ho->job = GNUNET_CURL_job_add (ctx,
                                              eh,
                                              GNUNET_YES,
                                              &history_raw_cb,
                                              ho)))
  {
    GNUNET_break (0);
    return NULL;
  }
  return ho;
}


/**
 * Issue a /history request to the backend.
 *
 * @param ctx execution context
 * @param backend_url base URL of the merchant backend
 * @param start return `delta` records starting from position
 *        `start`.  If given as zero, then no initial skip of
 *        `start` records is done.
 * @param delta return `delta` records starting from position
 *        `start`
 * @param date only transactions younger than/equals to date will
 *        be returned
 * @param history_cb callback which will work the response gotten
 *        from the backend
 * @param history_cb_cls closure to pass to @a history_cb
 * @return handle for this operation, NULL upon errors
 */
struct TALER_MERCHANT_HistoryOperation *
TALER_MERCHANT_history_default_start
  (struct GNUNET_CURL_Context *ctx,
  const char *backend_url,
  long long delta,
  struct GNUNET_TIME_Absolute date,
  TALER_MERCHANT_HistoryOperationCallback history_cb,
  void *history_cb_cls)
{
  return TALER_MERCHANT_history2 (ctx,
                                  backend_url,
                                  /* fake 'start' argument: will NOT be used */
                                  -1,
                                  /* Specifies "no start argument" in final URL */
                                  GNUNET_YES,
                                  delta,
                                  date,
                                  history_cb,
                                  history_cb_cls);
}


/**
 * Issue a /history request to the backend.
 *
 * @param ctx execution context
 * @param backend_url base URL of the merchant backend
 * @param start return `delta` records starting from position
 *        `start`.  If given as zero, then no initial skip of
 *        `start` records is done.
 * @param delta return `delta` records starting from position
 *        `start`
 * @param date only transactions younger than/equals to date will
 *        be returned
 * @param history_cb callback which will work the response gotten
 *        from the backend
 * @param history_cb_cls closure to pass to @a history_cb
 * @return handle for this operation, NULL upon errors
 */
struct TALER_MERCHANT_HistoryOperation *
TALER_MERCHANT_history
  (struct GNUNET_CURL_Context *ctx,
  const char *backend_url,
  unsigned long long start,
  long long delta,
  struct GNUNET_TIME_Absolute date,
  TALER_MERCHANT_HistoryOperationCallback history_cb,
  void *history_cb_cls)
{
  return TALER_MERCHANT_history2 (ctx,
                                  backend_url,
                                  start,
                                  GNUNET_NO,
                                  delta,
                                  date,
                                  history_cb,
                                  history_cb_cls);
}


/* end of merchant_api_contract.c */