/*
  This file is part of TALER
  Copyright (C) 2014-2023 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 merchant_api_reward_authorize.c
 * @brief Implementation of the /reward-authorize 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 "merchant_api_curl_defaults.h"
#include "merchant_api_common.h"
#include <taler/taler_json_lib.h>
#include <taler/taler_signatures.h>
#include <taler/taler_curl_lib.h>


/**
 * @brief A handle for reward authorizations.
 */
struct TALER_MERCHANT_RewardAuthorizeHandle
{

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

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

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

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

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

  /**
   * Minor context that holds body and headers.
   */
  struct TALER_CURL_PostContext post_ctx;
};


/**
 * We got a 200 response back from the exchange (or the merchant).
 * Now we need to parse the response and if it is well-formed,
 * call the callback (and set it to NULL afterwards).
 *
 * @param tao handle of the original authorization operation
 * @param json cryptographic proof returned by the exchange/merchant
 * @return #GNUNET_OK if response is valid
 */
static enum GNUNET_GenericReturnValue
check_ok (struct TALER_MERCHANT_RewardAuthorizeHandle *tao,
          const json_t *json)
{
  const char *reward_status_url;
  struct TALER_MERCHANT_RewardAuthorizeResponse tar = {
    .hr.http_status = MHD_HTTP_OK,
    .hr.reply = json
  };
  struct GNUNET_JSON_Specification spec[] = {
    TALER_JSON_spec_web_url ("reward_status_url",
                             &reward_status_url),
    GNUNET_JSON_spec_string ("taler_reward_uri",
                             &tar.details.ok.reward_uri),
    GNUNET_JSON_spec_timestamp ("reward_expiration",
                                &tar.details.ok.reward_expiration),
    GNUNET_JSON_spec_fixed_auto ("reward_id",
                                 &tar.details.ok.reward_id),
    GNUNET_JSON_spec_end ()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec,
                         NULL, NULL))
  {
    char *log;

    GNUNET_break_op (0);
    log = json_dumps (json,
                      0);
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "JSON %s\n",
                log);
    free (log);
    return GNUNET_SYSERR;
  }
  tao->cb (tao->cb_cls,
           &tar);
  tao->cb = NULL; /* do not call twice */
  GNUNET_JSON_parse_free (spec);
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /reservers/$REWARD_ID/reward-authorize request.
 *
 * @param cls the `struct TALER_MERCHANT_RewardAuthorizeHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response response body, NULL if not in JSON
 */
static void
handle_reward_authorize_finished (void *cls,
                                  long response_code,
                                  const void *response)
{
  struct TALER_MERCHANT_RewardAuthorizeHandle *tao = cls;
  const json_t *json = response;
  struct TALER_MERCHANT_RewardAuthorizeResponse tar = {
    .hr.http_status = (unsigned int) response_code,
    .hr.reply = json
  };

  tao->job = NULL;
  switch (response_code)
  {
  case MHD_HTTP_OK:
    if (GNUNET_OK ==
        check_ok (tao,
                  json))
    {
      TALER_MERCHANT_reward_authorize_cancel (tao);
      return;
    }
    GNUNET_break_op (0);
    tar.hr.http_status = 0;
    tar.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_UNAUTHORIZED:
    tar.hr.ec = TALER_JSON_get_error_code (json);
    tar.hr.hint = TALER_JSON_get_error_hint (json);
    /* Nothing really to verify, merchant says we need to authenticate. */
    break;
  case MHD_HTTP_NOT_FOUND:
    /* Well-defined status code, pass on to application! */
    tar.hr.ec = TALER_JSON_get_error_code (json);
    tar.hr.hint = TALER_JSON_get_error_hint (json);
    break;
  case MHD_HTTP_PRECONDITION_FAILED:
    /* Well-defined status code, pass on to application! */
    tar.hr.ec = TALER_JSON_get_error_code (json);
    tar.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 */
    tar.hr.ec = TALER_JSON_get_error_code (json);
    tar.hr.hint = TALER_JSON_get_error_hint (json);
    break;
  case MHD_HTTP_SERVICE_UNAVAILABLE:
    /* Server had an unclear (internal or external) issue; we should retry,
       but this API leaves this to the application */
    TALER_MERCHANT_parse_error_details_ (json,
                                         response_code,
                                         &tar.hr);
    break;
  default:
    /* unexpected response code */
    GNUNET_break_op (0);
    TALER_MERCHANT_parse_error_details_ (json,
                                         response_code,
                                         &tar.hr);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d\n",
                (unsigned int) response_code,
                (int) tar.hr.ec);
    break;
  }
  if (NULL != tao->cb)
    tao->cb (tao->cb_cls,
             &tar);
  TALER_MERCHANT_reward_authorize_cancel (tao);
}


struct TALER_MERCHANT_RewardAuthorizeHandle *
TALER_MERCHANT_reward_authorize2 (
  struct GNUNET_CURL_Context *ctx,
  const char *backend_url,
  const struct TALER_ReservePublicKeyP *reserve_pub,
  const char *next_url,
  const struct TALER_Amount *amount,
  const char *justification,
  TALER_MERCHANT_RewardAuthorizeCallback authorize_cb,
  void *authorize_cb_cls)
{
  struct TALER_MERCHANT_RewardAuthorizeHandle *tao;
  CURL *eh;
  json_t *te_obj;

  tao = GNUNET_new (struct TALER_MERCHANT_RewardAuthorizeHandle);
  tao->ctx = ctx;
  tao->cb = authorize_cb;
  tao->cb_cls = authorize_cb_cls;

  {
    char res_str[sizeof (*reserve_pub) * 2];
    char arg_str[sizeof (res_str) + 48];
    char *end;

    end = GNUNET_STRINGS_data_to_string (reserve_pub,
                                         sizeof (*reserve_pub),
                                         res_str,
                                         sizeof (res_str));
    *end = '\0';
    GNUNET_snprintf (arg_str,
                     sizeof (arg_str),
                     "private/reserves/%s/authorize-reward",
                     res_str);
    tao->url = TALER_url_join (backend_url,
                               arg_str,
                               NULL);
  }
  if (NULL == tao->url)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    GNUNET_free (tao);
    return NULL;
  }
  te_obj = GNUNET_JSON_PACK (
    TALER_JSON_pack_amount ("amount",
                            amount),
    GNUNET_JSON_pack_string ("justification",
                             justification),
    GNUNET_JSON_pack_string ("next_url",
                             next_url));
  eh = curl_easy_init ();
  GNUNET_assert (NULL != eh);
  if (GNUNET_OK !=
      TALER_curl_easy_post (&tao->post_ctx,
                            eh,
                            te_obj))
  {
    GNUNET_break (0);
    curl_easy_cleanup (eh);
    json_decref (te_obj);
    GNUNET_free (tao->url);
    GNUNET_free (tao);
    return NULL;
  }

  json_decref (te_obj);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Requesting URL '%s'\n",
              tao->url);
  GNUNET_assert (CURLE_OK == curl_easy_setopt (eh,
                                               CURLOPT_URL,
                                               tao->url));

  tao->job = GNUNET_CURL_job_add2 (ctx,
                                   eh,
                                   tao->post_ctx.headers,
                                   &handle_reward_authorize_finished,
                                   tao);
  return tao;
}


struct TALER_MERCHANT_RewardAuthorizeHandle *
TALER_MERCHANT_reward_authorize (struct GNUNET_CURL_Context *ctx,
                                 const char *backend_url,
                                 const char *next_url,
                                 const struct TALER_Amount *amount,
                                 const char *justification,
                                 TALER_MERCHANT_RewardAuthorizeCallback
                                 authorize_cb,
                                 void *authorize_cb_cls)
{
  struct TALER_MERCHANT_RewardAuthorizeHandle *tao;
  CURL *eh;
  json_t *te_obj;

  tao = GNUNET_new (struct TALER_MERCHANT_RewardAuthorizeHandle);
  tao->ctx = ctx;
  tao->cb = authorize_cb;
  tao->cb_cls = authorize_cb_cls;

  tao->url = TALER_url_join (backend_url,
                             "private/rewards",
                             NULL);
  if (NULL == tao->url)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    GNUNET_free (tao);
    return NULL;
  }
  te_obj = GNUNET_JSON_PACK (
    TALER_JSON_pack_amount ("amount",
                            amount),
    GNUNET_JSON_pack_string ("justification",
                             justification),
    GNUNET_JSON_pack_string ("next_url",
                             next_url));
  eh = TALER_MERCHANT_curl_easy_get_ (tao->url);
  if (GNUNET_OK !=
      TALER_curl_easy_post (&tao->post_ctx,
                            eh,
                            te_obj))
  {
    GNUNET_break (0);
    curl_easy_cleanup (eh);
    json_decref (te_obj);
    GNUNET_free (tao->url);
    GNUNET_free (tao);
    return NULL;
  }
  json_decref (te_obj);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Requesting URL '%s'\n",
              tao->url);
  tao->job = GNUNET_CURL_job_add2 (ctx,
                                   eh,
                                   tao->post_ctx.headers,
                                   &handle_reward_authorize_finished,
                                   tao);
  return tao;
}


void
TALER_MERCHANT_reward_authorize_cancel (
  struct TALER_MERCHANT_RewardAuthorizeHandle *tao)
{
  if (NULL != tao->job)
  {
    GNUNET_CURL_job_cancel (tao->job);
    tao->job = NULL;
  }
  TALER_curl_easy_post_finished (&tao->post_ctx);
  GNUNET_free (tao->url);
  GNUNET_free (tao);
}


/* end of merchant_api_reward_authorize.c */