/*
  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 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 jkyc 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 *jkyc)
{
  unsigned int num_kycs = (unsigned int) json_array_size (jkyc);
  unsigned int num_limits = 0;
  unsigned int num_kycauths = 0;
  unsigned int pos_limits = 0;
  unsigned int pos_kycauths = 0;

  if ( (json_array_size (jkyc) != (size_t) num_kycs) ||
       (num_kycs > MAX_KYC) )
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }

  for (unsigned int i = 0; i<num_kycs; i++)
  {
    const json_t *jlimits = NULL;
    const json_t *jkycauths = NULL;
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_mark_optional (
        GNUNET_JSON_spec_array_const (
          "limits",
          &jlimits),
        NULL),
      GNUNET_JSON_spec_mark_optional (
        GNUNET_JSON_spec_array_const (
          "payto_kycauths",
          &jkycauths),
        NULL),
      GNUNET_JSON_spec_end ()
    };

    if (GNUNET_OK !=
        GNUNET_JSON_parse (json_array_get (jkyc,
                                           i),
                           spec,
                           NULL, NULL))
    {
      GNUNET_break (0);
      json_dumpf (json_array_get (jkyc,
                                  i),
                  stderr,
                  JSON_INDENT (2));
      return GNUNET_SYSERR;
    }
    num_limits += json_array_size (jlimits);
    num_kycauths += json_array_size (jkycauths);
  }


  {
    struct TALER_MERCHANT_AccountKycRedirectDetail kycs[
      GNUNET_NZL (num_kycs)];
    struct TALER_EXCHANGE_AccountLimit limits[
      GNUNET_NZL (num_limits)];
    struct TALER_FullPayto payto_kycauths[
      GNUNET_NZL (num_kycauths)];

    memset (kycs,
            0,
            sizeof (kycs));
    for (unsigned int i = 0; i<num_kycs; i++)
    {
      struct TALER_MERCHANT_AccountKycRedirectDetail *rd
        = &kycs[i];
      const json_t *jlimits = NULL;
      const json_t *jkycauths = NULL;
      uint32_t hs;
      struct GNUNET_JSON_Specification spec[] = {
        TALER_JSON_spec_full_payto_uri (
          "payto_uri",
          &rd->payto_uri),
        TALER_JSON_spec_web_url (
          "exchange_url",
          &rd->exchange_url),
        GNUNET_JSON_spec_uint32 (
          "exchange_http_status",
          &hs),
        GNUNET_JSON_spec_bool (
          "no_keys",
          &rd->no_keys),
        GNUNET_JSON_spec_bool (
          "auth_conflict",
          &rd->auth_conflict),
        GNUNET_JSON_spec_mark_optional (
          TALER_JSON_spec_ec (
            "exchange_code",
            &rd->exchange_code),
          NULL),
        GNUNET_JSON_spec_mark_optional (
          GNUNET_JSON_spec_fixed_auto (
            "access_token",
            &rd->access_token),
          &rd->no_access_token),
        GNUNET_JSON_spec_mark_optional (
          GNUNET_JSON_spec_array_const (
            "limits",
            &jlimits),
          NULL),
        GNUNET_JSON_spec_mark_optional (
          GNUNET_JSON_spec_array_const (
            "payto_kycauths",
            &jkycauths),
          NULL),
        GNUNET_JSON_spec_end ()
      };
      size_t j;
      json_t *jlimit;
      json_t *jkycauth;

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json_array_get (jkyc,
                                             i),
                             spec,
                             NULL, NULL))
      {
        GNUNET_break (0);
        json_dumpf (json_array_get (jkyc,
                                    i),
                    stderr,
                    JSON_INDENT (2));
        return GNUNET_SYSERR;
      }
      rd->exchange_http_status = (unsigned int) hs;
      rd->limits = &limits[pos_limits];
      rd->limits_length = json_array_size (jlimits);
      json_array_foreach (jlimits, j, jlimit)
      {
        struct TALER_EXCHANGE_AccountLimit *limit
          = &limits[pos_limits];
        struct GNUNET_JSON_Specification jspec[] = {
          TALER_JSON_spec_kycte (
            "operation_type",
            &limit->operation_type),
          GNUNET_JSON_spec_relative_time (
            "timeframe",
            &limit->timeframe),
          TALER_JSON_spec_amount_any (
            "threshold",
            &limit->threshold),
          GNUNET_JSON_spec_mark_optional (
            GNUNET_JSON_spec_bool (
              "soft_limit",
              &limit->soft_limit),
            NULL),
          GNUNET_JSON_spec_end ()
        };

        GNUNET_assert (pos_limits < num_limits);
        limit->soft_limit = false;
        if (GNUNET_OK !=
            GNUNET_JSON_parse (jlimit,
                               jspec,
                               NULL, NULL))
        {
          GNUNET_break (0);
          json_dumpf (json_array_get (jkyc,
                                      i),
                      stderr,
                      JSON_INDENT (2));
          return GNUNET_SYSERR;
        }
        pos_limits++;
      }
      rd->payto_kycauths = &payto_kycauths[pos_kycauths];
      rd->pkycauth_length = json_array_size (jkycauths);
      json_array_foreach (jkycauths, j, jkycauth)
      {
        GNUNET_assert (pos_kycauths < num_kycauths);
        payto_kycauths[pos_kycauths].full_payto
          = (char *) json_string_value (jkycauth);
        if (NULL == payto_kycauths[pos_kycauths].full_payto)
        {
          GNUNET_break (0);
          json_dumpf (json_array_get (jkyc,
                                      i),
                      stderr,
                      JSON_INDENT (2));
          return GNUNET_SYSERR;
        }
        pos_kycauths++;
      }
    }
    kr->details.ok.kycs = kycs;
    kr->details.ok.kycs_length = num_kycs;
    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_OK:
    {
      const json_t *jkyc;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_array_const ("kyc_data",
                                      &jkyc),
        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,
                     jkyc))
      {
        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_NO_CONTENT:
    break;
  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 lpt target for long polling
 * @param timeout how long to wait for a 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,
         enum TALER_EXCHANGE_KycLongPollTarget lpt,
         struct GNUNET_TIME_Relative timeout,
         TALER_MERCHANT_KycGetCallback cb,
         void *cb_cls)
{
  struct TALER_MERCHANT_KycGetHandle *kyc;
  CURL *eh;
  char timeout_ms[32];
  char lpt_str[32];
  unsigned long long tms;

  kyc = GNUNET_new (struct TALER_MERCHANT_KycGetHandle);
  kyc->ctx = ctx;
  kyc->cb = cb;
  kyc->cb_cls = cb_cls;
  GNUNET_snprintf (lpt_str,
                   sizeof (lpt_str),
                   "%d",
                   (int) lpt);
  tms = timeout.rel_value_us
        / GNUNET_TIME_UNIT_MILLISECONDS.rel_value_us;
  GNUNET_snprintf (timeout_ms,
                   sizeof (timeout_ms),
                   "%llu",
                   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,
        "lpt",
        TALER_EXCHANGE_KLPT_NONE == lpt
        ? NULL
        : lpt_str,
        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,
  enum TALER_EXCHANGE_KycLongPollTarget lpt,
  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,
                  lpt,
                  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,
  enum TALER_EXCHANGE_KycLongPollTarget lpt,
  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,
                  lpt,
                  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);
}