/*
  This file is part of TALER
  Copyright (C) 2023, 2024 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_get_kyc_statistics.c
 * @brief Implementation of the /aml/$OFFICER_PUB/kyc-statistics/$NAME request
 * @author Christian Grothoff
 */
#include "platform.h"
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_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 GET /aml/$OFFICER_PUB/kyc-statistics/$NAME Handle
 */
struct TALER_EXCHANGE_KycGetStatisticsHandle
{

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

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

  /**
   * Function to call with the result.
   */
  TALER_EXCHANGE_KycStatisticsCallback stats_cb;

  /**
   * Closure for @e cb.
   */
  void *stats_cb_cls;

  /**
   * HTTP headers for the job.
   */
  struct curl_slist *job_headers;

};


/**
 * Parse the provided decision data from the "200 OK" response.
 *
 * @param[in,out] lh handle (callback may be zero'ed out)
 * @param json json reply with the data for one coin
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
static enum GNUNET_GenericReturnValue
parse_stats_ok (
  struct TALER_EXCHANGE_KycGetStatisticsHandle *lh,
  const json_t *json)
{
  struct TALER_EXCHANGE_KycGetStatisticsResponse lr = {
    .hr.reply = json,
    .hr.http_status = MHD_HTTP_OK
  };
  uint64_t cnt;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_uint64 ("counter",
                             &cnt),
    GNUNET_JSON_spec_end ()
  };

  if (GNUNET_OK !=
      GNUNET_JSON_parse (json,
                         spec,
                         NULL,
                         NULL))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  lr.details.ok.counter = (unsigned long long) cnt;
  lh->stats_cb (lh->stats_cb_cls,
                &lr);
  lh->stats_cb = NULL;
  return GNUNET_OK;
}


/**
 * Function called when we're done processing the
 * HTTP /aml/$OFFICER_PUB/kyc-statistics/$NAME request.
 *
 * @param cls the `struct TALER_EXCHANGE_KycGetStatisticsHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response parsed JSON result, NULL on error
 */
static void
handle_lookup_finished (void *cls,
                        long response_code,
                        const void *response)
{
  struct TALER_EXCHANGE_KycGetStatisticsHandle *lh = cls;
  const json_t *j = response;
  struct TALER_EXCHANGE_KycGetStatisticsResponse lr = {
    .hr.reply = j,
    .hr.http_status = (unsigned int) response_code
  };

  lh->job = NULL;
  switch (response_code)
  {
  case 0:
    lr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    if (GNUNET_OK !=
        parse_stats_ok (lh,
                        j))
    {
      GNUNET_break_op (0);
      lr.hr.http_status = 0;
      lr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
      break;
    }
    GNUNET_assert (NULL == lh->stats_cb);
    TALER_EXCHANGE_kyc_get_statistics_cancel (lh);
    return;
  case MHD_HTTP_NO_CONTENT:
    break;
  case MHD_HTTP_BAD_REQUEST:
    lr.hr.ec = TALER_JSON_get_error_code (j);
    lr.hr.hint = TALER_JSON_get_error_hint (j);
    /* This should never happen, either us or the exchange is buggy
       (or API version conflict); just pass JSON reply to the application */
    break;
  case MHD_HTTP_FORBIDDEN:
    lr.hr.ec = TALER_JSON_get_error_code (j);
    lr.hr.hint = TALER_JSON_get_error_hint (j);
    /* Nothing really to verify, exchange says this coin was not melted; we
       should pass the JSON reply to the application */
    break;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    lr.hr.ec = TALER_JSON_get_error_code (j);
    lr.hr.hint = TALER_JSON_get_error_hint (j);
    /* Server had an internal issue; we should retry, but this API
       leaves this to the application */
    break;
  default:
    /* unexpected response code */
    GNUNET_break_op (0);
    lr.hr.ec = TALER_JSON_get_error_code (j);
    lr.hr.hint = TALER_JSON_get_error_hint (j);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d for GET KYC statistics\n",
                (unsigned int) response_code,
                (int) lr.hr.ec);
    break;
  }
  if (NULL != lh->stats_cb)
    lh->stats_cb (lh->stats_cb_cls,
                  &lr);
  TALER_EXCHANGE_kyc_get_statistics_cancel (lh);
}


struct TALER_EXCHANGE_KycGetStatisticsHandle *
TALER_EXCHANGE_get_kyc_statistics (
  struct GNUNET_CURL_Context *ctx,
  const char *exchange_url,
  const char *name,
  struct GNUNET_TIME_Timestamp start_date,
  struct GNUNET_TIME_Timestamp end_date,
  const struct TALER_AmlOfficerPrivateKeyP *officer_priv,
  TALER_EXCHANGE_KycStatisticsCallback cb,
  void *cb_cls)
{
  struct TALER_EXCHANGE_KycGetStatisticsHandle *lh;
  CURL *eh;
  struct TALER_AmlOfficerPublicKeyP officer_pub;
  struct TALER_AmlOfficerSignatureP officer_sig;
  char arg_str[sizeof (struct TALER_AmlOfficerPublicKeyP) * 2
               + 32];
  char sd_str[32];
  char ed_str[32];
  const char *sd = NULL;
  const char *ed = NULL;

  if (! GNUNET_TIME_absolute_is_zero (start_date.abs_time))
  {
    unsigned long long sec;

    sec = (unsigned long long) GNUNET_TIME_timestamp_to_s (start_date);
    GNUNET_snprintf (sd_str,
                     sizeof (sd_str),
                     "%llu",
                     sec);
    sd = sd_str;
  }
  if (! GNUNET_TIME_absolute_is_never (end_date.abs_time))
  {
    unsigned long long sec;

    sec = (unsigned long long) GNUNET_TIME_timestamp_to_s (end_date);
    GNUNET_snprintf (ed_str,
                     sizeof (ed_str),
                     "%llu",
                     sec);
    ed = ed_str;
  }
  GNUNET_CRYPTO_eddsa_key_get_public (&officer_priv->eddsa_priv,
                                      &officer_pub.eddsa_pub);
  TALER_officer_aml_query_sign (officer_priv,
                                &officer_sig);
  {
    char pub_str[sizeof (officer_pub) * 2];
    char *end;

    end = GNUNET_STRINGS_data_to_string (
      &officer_pub,
      sizeof (officer_pub),
      pub_str,
      sizeof (pub_str));
    *end = '\0';
    GNUNET_snprintf (arg_str,
                     sizeof (arg_str),
                     "aml/%s/kyc-statistics/%s",
                     pub_str,
                     name);
  }
  lh = GNUNET_new (struct TALER_EXCHANGE_KycGetStatisticsHandle);
  lh->stats_cb = cb;
  lh->stats_cb_cls = cb_cls;
  lh->url = TALER_url_join (exchange_url,
                            arg_str,
                            "start_date",
                            sd,
                            "end_date",
                            ed,
                            NULL);
  if (NULL == lh->url)
  {
    GNUNET_free (lh);
    return NULL;
  }
  eh = TALER_EXCHANGE_curl_easy_get_ (lh->url);
  if (NULL == eh)
  {
    GNUNET_break (0);
    GNUNET_free (lh->url);
    GNUNET_free (lh);
    return NULL;
  }
  {
    char *hdr;
    char sig_str[sizeof (officer_sig) * 2];
    char *end;

    end = GNUNET_STRINGS_data_to_string (
      &officer_sig,
      sizeof (officer_sig),
      sig_str,
      sizeof (sig_str));
    *end = '\0';

    GNUNET_asprintf (&hdr,
                     "%s: %s",
                     TALER_AML_OFFICER_SIGNATURE_HEADER,
                     sig_str);
    lh->job_headers = curl_slist_append (NULL,
                                         hdr);
    GNUNET_free (hdr);
    lh->job_headers = curl_slist_append (lh->job_headers,
                                         "Content-type: application/json");
    lh->job = GNUNET_CURL_job_add2 (ctx,
                                    eh,
                                    lh->job_headers,
                                    &handle_lookup_finished,
                                    lh);
  }
  return lh;
}


void
TALER_EXCHANGE_kyc_get_statistics_cancel (
  struct TALER_EXCHANGE_KycGetStatisticsHandle *lh)
{
  if (NULL != lh->job)
  {
    GNUNET_CURL_job_cancel (lh->job);
    lh->job = NULL;
  }
  curl_slist_free_all (lh->job_headers);
  GNUNET_free (lh->url);
  GNUNET_free (lh);
}


/* end of exchange_api_get_kyc_statistics.c */