/*
  This file is part of TALER
  Copyright (C) 2014-2022 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU 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 lib/exchange_api_reserves_get.c
 * @brief Implementation of the GET /reserves/$RESERVE_PUB requests
 * @author Christian Grothoff
 */
#include "platform.h"
#include <jansson.h>
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_json_lib.h>
#include <gnunet/gnunet_curl_lib.h>
#include "taler_exchange_service.h"
#include "taler_json_lib.h"
#include "exchange_api_handle.h"
#include "taler_signatures.h"
#include "exchange_api_curl_defaults.h"


/**
 * @brief A /reserves/ GET Handle
 */
struct TALER_EXCHANGE_ReservesGetHandle
{

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

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

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

  /**
   * Public key of the reserve we are querying.
   */
  struct TALER_ReservePublicKeyP reserve_pub;

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

};


/**
 * We received an #MHD_HTTP_OK status code. Handle the JSON
 * response.
 *
 * @param rgh handle of the request
 * @param j JSON response
 * @return #GNUNET_OK on success
 */
static enum GNUNET_GenericReturnValue
handle_reserves_get_ok (struct TALER_EXCHANGE_ReservesGetHandle *rgh,
                        const json_t *j)
{
  struct TALER_EXCHANGE_ReserveSummary rs = {
    .hr.reply = j,
    .hr.http_status = MHD_HTTP_OK
  };
  struct GNUNET_JSON_Specification spec[] = {
    TALER_JSON_spec_amount_any ("balance",
                                &rs.details.ok.balance),
    GNUNET_JSON_spec_end ()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (j,
                         spec,
                         NULL,
                         NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  rgh->cb (rgh->cb_cls,
           &rs);
  rgh->cb = NULL;
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /reserves/ GET request.
 *
 * @param cls the `struct TALER_EXCHANGE_ReservesGetHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response parsed JSON result, NULL on error
 */
static void
handle_reserves_get_finished (void *cls,
                              long response_code,
                              const void *response)
{
  struct TALER_EXCHANGE_ReservesGetHandle *rgh = cls;
  const json_t *j = response;
  struct TALER_EXCHANGE_ReserveSummary rs = {
    .hr.reply = j,
    .hr.http_status = (unsigned int) response_code
  };

  rgh->job = NULL;
  switch (response_code)
  {
  case 0:
    rs.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        handle_reserves_get_ok (rgh,
                                j))
    {
      rs.hr.http_status = 0;
      rs.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
    }
    break;
  case MHD_HTTP_BAD_REQUEST:
    /* This should never happen, either us or the exchange is buggy
       (or API version conflict); just pass JSON reply to the application */
    rs.hr.ec = TALER_JSON_get_error_code (j);
    rs.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_NOT_FOUND:
    /* Nothing really to verify, this should never
       happen, we should pass the JSON reply to the application */
    rs.hr.ec = TALER_JSON_get_error_code (j);
    rs.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    /* Server had an internal issue; we should retry, but this API
       leaves this to the application */
    rs.hr.ec = TALER_JSON_get_error_code (j);
    rs.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  default:
    /* unexpected response code */
    GNUNET_break_op (0);
    rs.hr.ec = TALER_JSON_get_error_code (j);
    rs.hr.hint = TALER_JSON_get_error_hint (j);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d for GET %s\n",
                (unsigned int) response_code,
                (int) rs.hr.ec,
                rgh->url);
    break;
  }
  if (NULL != rgh->cb)
  {
    rgh->cb (rgh->cb_cls,
             &rs);
    rgh->cb = NULL;
  }
  TALER_EXCHANGE_reserves_get_cancel (rgh);
}


struct TALER_EXCHANGE_ReservesGetHandle *
TALER_EXCHANGE_reserves_get (
  struct GNUNET_CURL_Context *ctx,
  const char *url,
  const struct TALER_ReservePublicKeyP *reserve_pub,
  struct GNUNET_TIME_Relative timeout,
  TALER_EXCHANGE_ReservesGetCallback cb,
  void *cb_cls)
{
  struct TALER_EXCHANGE_ReservesGetHandle *rgh;
  CURL *eh;
  char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 16 + 32];
  unsigned int tms
    = (unsigned int) timeout.rel_value_us
      / GNUNET_TIME_UNIT_MILLISECONDS.rel_value_us;

  {
    char pub_str[sizeof (struct TALER_ReservePublicKeyP) * 2];
    char *end;
    char timeout_str[32];

    end = GNUNET_STRINGS_data_to_string (
      reserve_pub,
      sizeof (*reserve_pub),
      pub_str,
      sizeof (pub_str));
    *end = '\0';
    GNUNET_snprintf (timeout_str,
                     sizeof (timeout_str),
                     "%u",
                     tms);
    if (0 == tms)
      GNUNET_snprintf (arg_str,
                       sizeof (arg_str),
                       "reserves/%s",
                       pub_str);
    else
      GNUNET_snprintf (arg_str,
                       sizeof (arg_str),
                       "reserves/%s?timeout_ms=%s",
                       pub_str,
                       timeout_str);
  }
  rgh = GNUNET_new (struct TALER_EXCHANGE_ReservesGetHandle);
  rgh->cb = cb;
  rgh->cb_cls = cb_cls;
  rgh->reserve_pub = *reserve_pub;
  rgh->url = TALER_url_join (url,
                             arg_str,
                             NULL);
  if (NULL == rgh->url)
  {
    GNUNET_free (rgh);
    return NULL;
  }
  eh = TALER_EXCHANGE_curl_easy_get_ (rgh->url);
  if (NULL == eh)
  {
    GNUNET_break (0);
    GNUNET_free (rgh->url);
    GNUNET_free (rgh);
    return NULL;
  }
  if (0 != tms)
  {
    GNUNET_break (CURLE_OK ==
                  curl_easy_setopt (eh,
                                    CURLOPT_TIMEOUT_MS,
                                    (long) (tms + 100L)));
  }
  rgh->job = GNUNET_CURL_job_add (ctx,
                                  eh,
                                  &handle_reserves_get_finished,
                                  rgh);
  return rgh;
}


void
TALER_EXCHANGE_reserves_get_cancel (
  struct TALER_EXCHANGE_ReservesGetHandle *rgh)
{
  if (NULL != rgh->job)
  {
    GNUNET_CURL_job_cancel (rgh->job);
    rgh->job = NULL;
  }
  GNUNET_free (rgh->url);
  GNUNET_free (rgh);
}


/* end of exchange_api_reserves_get.c */