/*
  This file is part of TALER
  Copyright (C) 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_get_kyc.c
 * @brief Implementation of the GET /kyc request of the merchant's HTTP API
 * @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 <taler/taler_json_lib.h>
#include <taler/taler_signatures.h>


/**
 * Maximum length of the KYC arrays supported.
 */
#define MAX_KYC 1024

/**
 * Handle for a GET /kyc operation.
 */
struct TALER_MERCHANT_KycGetHandle
{
  /**
   * The url for this request.
   */
  char *url;

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

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

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

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

};


/**
 * Parse @a kyc response and call the continuation on success.
 *
 * @param kyc operation handle
 * @param[in,out] kr response details
 * @param pends pending_kycs array from the reply
 * @param touts timeout_kycs array from the reply
 * @return #GNUNET_OK on success (callback was called)
 */
static enum GNUNET_GenericReturnValue
parse_kyc (struct TALER_MERCHANT_KycGetHandle *kyc,
           struct TALER_MERCHANT_KycResponse *kr,
           const json_t *pends,
           const json_t *touts)
{
  unsigned int num_pends = (unsigned int) json_array_size (pends);
  unsigned int num_touts = (unsigned int) json_array_size (touts);

  if ( (json_array_size (pends) != (size_t)  num_pends) ||
       (num_pends > MAX_KYC) )
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  if ( (json_array_size (touts) != (size_t)  num_touts) ||
       (num_touts > MAX_KYC) )
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }

  {
    struct TALER_MERCHANT_AccountKycRedirectDetail pending_kycs[
      GNUNET_NZL (num_pends)];
    struct TALER_MERCHANT_ExchangeKycFailureDetail timeout_kycs[
      GNUNET_NZL (num_touts)];

    memset (pending_kycs,
            0,
            sizeof (pending_kycs));
    for (unsigned int i = 0; i<num_pends; i++)
    {
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_mark_optional (
          TALER_JSON_spec_web_url ("kyc_url",
                                   &pending_kycs[i].kyc_url),
          NULL),
        TALER_JSON_spec_aml_decision ("aml_status",
                                      &pending_kycs[i].aml_status),
        TALER_JSON_spec_web_url ("exchange_url",
                                 &pending_kycs[i].exchange_url),
        TALER_JSON_spec_payto_uri ("payto_uri",
                                   &pending_kycs[i].payto_uri),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json_array_get (pends,
                                             i),
                             spec,
                             NULL, NULL))
      {
        GNUNET_break (0);
        return GNUNET_SYSERR;
      }
    }
    for (unsigned int i = 0; i<num_touts; i++)
    {
      uint32_t hs;
      struct GNUNET_JSON_Specification spec[] = {
        TALER_JSON_spec_web_url ("exchange_url",
                                 &timeout_kycs[i].exchange_url),
        TALER_JSON_spec_ec ("exchange_code",
                            &timeout_kycs[i].exchange_code),
        GNUNET_JSON_spec_uint32 ("exchange_http_status",
                                 &hs),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json_array_get (touts,
                                             i),
                             spec,
                             NULL, NULL))
      {
        GNUNET_break (0);
        return GNUNET_SYSERR;
      }
      timeout_kycs[i].exchange_http_status = (unsigned int) hs;
    }
    kr->details.kyc_status.pending_kycs = pending_kycs;
    kr->details.kyc_status.timeout_kycs = timeout_kycs;
    kr->details.kyc_status.pending_kycs_length = num_pends;
    kr->details.kyc_status.timeout_kycs_length = num_touts;
    kyc->cb (kyc->cb_cls,
             kr);
  }
  return GNUNET_OK;
}


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

  kyc->job = NULL;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Got /kyc response with status code %u\n",
              (unsigned int) response_code);
  switch (response_code)
  {
  case MHD_HTTP_NO_CONTENT:
    break;
  case MHD_HTTP_ACCEPTED:
  case MHD_HTTP_BAD_GATEWAY:
  case MHD_HTTP_GATEWAY_TIMEOUT:
    {
      const json_t *pends;
      const json_t *touts;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_array_const ("pending_kycs",
                                      &pends),
        GNUNET_JSON_spec_array_const ("timeout_kycs",
                                      &touts),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json,
                             spec,
                             NULL, NULL))
      {
        kr.hr.http_status = 0;
        kr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
        break;
      }
      if (GNUNET_OK !=
          parse_kyc (kyc,
                     &kr,
                     pends,
                     touts))
      {
        kr.hr.http_status = 0;
        kr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
        break;
      }
      /* parse_kyc called the continuation already */
      TALER_MERCHANT_kyc_get_cancel (kyc);
      return;
    }
  case MHD_HTTP_UNAUTHORIZED:
    kr.hr.ec = TALER_JSON_get_error_code (json);
    kr.hr.hint = TALER_JSON_get_error_hint (json);
    /* Nothing really to verify, merchant says we need to authenticate. */
    break;
  case MHD_HTTP_SERVICE_UNAVAILABLE:
    break;
  default:
    /* unexpected response code */
    kr.hr.ec = TALER_JSON_get_error_code (json);
    kr.hr.hint = TALER_JSON_get_error_hint (json);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d\n",
                (unsigned int) response_code,
                (int) kr.hr.ec);
    break;
  }
  kyc->cb (kyc->cb_cls,
           &kr);
  TALER_MERCHANT_kyc_get_cancel (kyc);
}


/**
 * Issue a GET KYC request to the backend.
 * Returns KYC status of bank accounts.
 *
 * @param ctx execution context
 * @param[in] url URL to use for the request, consumed!
 * @param h_wire which bank account to query, NULL for all
 * @param exchange_url which exchange to query, NULL for all
 * @param timeout how long to wait for a (positive) reply
 * @param cb function to call with the result
 * @param cb_cls closure for @a cb
 * @return handle for this operation, NULL upon errors
 */
static struct TALER_MERCHANT_KycGetHandle *
kyc_get (struct GNUNET_CURL_Context *ctx,
         char *url,
         const struct TALER_MerchantWireHashP *h_wire,
         const char *exchange_url,
         struct GNUNET_TIME_Relative timeout,
         TALER_MERCHANT_KycGetCallback cb,
         void *cb_cls)
{
  struct TALER_MERCHANT_KycGetHandle *kyc;
  CURL *eh;
  char timeout_ms[32];
  unsigned int tms;

  kyc = GNUNET_new (struct TALER_MERCHANT_KycGetHandle);
  kyc->ctx = ctx;
  kyc->cb = cb;
  kyc->cb_cls = cb_cls;
  tms = (unsigned int) (timeout.rel_value_us
                        / GNUNET_TIME_UNIT_MILLISECONDS.
                        rel_value_us);
  GNUNET_snprintf (timeout_ms,
                   sizeof (timeout_ms),
                   "%u",
                   tms);
  kyc->url = TALER_url_join (url,
                             "kyc",
                             "h_wire",
                             NULL == h_wire
                             ? NULL
                             : GNUNET_h2s_full (&h_wire->hash),
                             "exchange_url",
                             NULL == exchange_url
                             ? NULL
                             : exchange_url,
                             "timeout_ms",
                             GNUNET_TIME_relative_is_zero (timeout)
                             ? NULL
                             : timeout_ms,
                             NULL);
  GNUNET_free (url);
  if (NULL == kyc->url)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    GNUNET_free (kyc);
    return NULL;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Requesting URL '%s'\n",
              kyc->url);
  eh = TALER_MERCHANT_curl_easy_get_ (kyc->url);
  if (0 != tms)
  {
    GNUNET_break (CURLE_OK ==
                  curl_easy_setopt (eh,
                                    CURLOPT_TIMEOUT_MS,
                                    (long) (tms + 100L)));
  }
  kyc->job = GNUNET_CURL_job_add (ctx,
                                  eh,
                                  &handle_get_kyc_finished,
                                  kyc);
  return kyc;
}


struct TALER_MERCHANT_KycGetHandle *
TALER_MERCHANT_kyc_get (struct GNUNET_CURL_Context *ctx,
                        const char *backend_url,
                        const struct TALER_MerchantWireHashP *h_wire,
                        const char *exchange_url,
                        struct GNUNET_TIME_Relative timeout,
                        TALER_MERCHANT_KycGetCallback cb,
                        void *cb_cls)
{
  char *url;

  GNUNET_asprintf (&url,
                   "%sprivate/",
                   backend_url);
  return kyc_get (ctx,
                  url, /* consumed! */
                  h_wire,
                  exchange_url,
                  timeout,
                  cb,
                  cb_cls);
}


struct TALER_MERCHANT_KycGetHandle *
TALER_MERCHANT_management_kyc_get (struct GNUNET_CURL_Context *ctx,
                                   const char *backend_url,
                                   const char *instance_id,
                                   const struct TALER_MerchantWireHashP *h_wire,
                                   const char *exchange_url,
                                   struct GNUNET_TIME_Relative timeout,
                                   TALER_MERCHANT_KycGetCallback cb,
                                   void *cb_cls)
{
  char *url;

  GNUNET_asprintf (&url,
                   "%smanagement/instances/%s/",
                   backend_url,
                   instance_id);
  return kyc_get (ctx,
                  url, /* consumed! */
                  h_wire,
                  exchange_url,
                  timeout,
                  cb,
                  cb_cls);
}


void
TALER_MERCHANT_kyc_get_cancel (
  struct TALER_MERCHANT_KycGetHandle *kyc)
{
  if (NULL != kyc->job)
    GNUNET_CURL_job_cancel (kyc->job);
  GNUNET_free (kyc->url);
  GNUNET_free (kyc);
}