/*
  This file is part of TALER
  Copyright (C) 2018, 2020 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 lib/merchant_api_wallet_get_order.c
 * @brief Implementation of the GET /orders/$ID request
 * @author Christian Grothoff
 * @author Marcello Stanisci
 * @author Florian Dold
 */
#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 <taler/taler_json_lib.h>
#include <taler/taler_signatures.h>


/**
 * @brief A GET /orders/$ID handle
 */
struct TALER_MERCHANT_OrderWalletGetHandle
{

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

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

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

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

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


/**
 * Convenience function to call the callback in @a owgh with an error code of
 * @a ec and the exchange body being set to @a reply.
 *
 * @param owgh handle providing callback
 * @param ec error code to return to application
 * @param reply JSON reply we got from the exchange, can be NULL
 */
static void
cb_failure (struct TALER_MERCHANT_OrderWalletGetHandle *owgh,
            enum TALER_ErrorCode ec,
            const json_t *reply)
{
  struct TALER_MERCHANT_HttpResponse hr = {
    .ec = TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
    .reply = reply
  };

  owgh->cb (owgh->cb_cls,
            &hr,
            GNUNET_SYSERR,
            GNUNET_SYSERR,
            NULL,
            NULL,
            NULL,
            NULL,
            0,
            NULL);
}


/**
 * Function called when we're done processing the GET /check-payment request.
 *
 * @param cls the `struct TALER_MERCHANT_OrderWalletGetHandle`
 * @param response_code HTTP response code, 0 on error
 * @param json response body, should be NULL
 */
static void
handle_wallet_get_order_finished (void *cls,
                                  long response_code,
                                  const void *response)
{
  struct TALER_MERCHANT_OrderWalletGetHandle *owgh = cls;
  const json_t *json = response;

  owgh->job = NULL;
  switch (response_code)
  {
  case MHD_HTTP_OK:
    {
      struct TALER_Amount refund_amount;
      json_t *refunds;
      bool refunded;
      struct TALER_MerchantPublicKeyP merchant_pub;
      unsigned int refund_len;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_bool ("refunded",
                               &refunded),
        GNUNET_JSON_spec_fixed_auto ("merchant_pub",
                                     &merchant_pub),
        TALER_JSON_spec_amount ("refund_amount",
                                &refund_amount),
        GNUNET_JSON_spec_json ("refunds",
                               &refunds),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json,
                             spec,
                             NULL, NULL))
      {
        GNUNET_break_op (0);
        cb_failure (owgh,
                    TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
                    json);
        TALER_MERCHANT_wallet_order_get_cancel (owgh);
        return;
      }

      if (! json_is_array (refunds))
      {
        GNUNET_break_op (0);
        cb_failure (owgh,
                    TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
                    json);
        GNUNET_JSON_parse_free (spec);
        TALER_MERCHANT_wallet_order_get_cancel (owgh);
        return;
      }

      refund_len = json_array_size (refunds);
      {
        struct TALER_MERCHANT_RefundDetail rds[refund_len];

        memset (rds,
                0,
                sizeof (rds));
        for (unsigned int i = 0; i<refund_len; i++)
        {
          struct TALER_MERCHANT_RefundDetail *rd = &rds[i];
          const json_t *jrefund = json_array_get (refunds,
                                                  i);
          const char *refund_status_type;
          uint32_t exchange_status;
          int ret;
          struct GNUNET_JSON_Specification espec[] = {
            GNUNET_JSON_spec_uint32 ("exchange_status",
                                     &exchange_status),
            GNUNET_JSON_spec_end ()
          };

          if (GNUNET_OK !=
              GNUNET_JSON_parse (jrefund,
                                 espec,
                                 NULL, NULL))
          {
            GNUNET_break_op (0);
            cb_failure (owgh,
                        TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
                        json);
            TALER_MERCHANT_wallet_order_get_cancel (owgh);
            return;
          }

          if (MHD_HTTP_OK == exchange_status)
          {
            struct GNUNET_JSON_Specification rspec[] = {
              GNUNET_JSON_spec_string ("type",
                                       &refund_status_type),
              GNUNET_JSON_spec_fixed_auto ("exchange_sig",
                                           &rd->exchange_sig),
              GNUNET_JSON_spec_fixed_auto ("exchange_pub",
                                           &rd->exchange_pub),
              GNUNET_JSON_spec_uint64 ("rtransaction_id",
                                       &rd->rtransaction_id),
              GNUNET_JSON_spec_fixed_auto ("coin_pub",
                                           &rd->coin_pub),
              TALER_JSON_spec_amount ("refund_amount",
                                      &rd->refund_amount),
              GNUNET_JSON_spec_end ()
            };

            ret = GNUNET_JSON_parse (jrefund,
                                     rspec,
                                     NULL, NULL);
            if (GNUNET_OK == ret)
            {
              /* check that type field is correct */
              if (0 != strcmp ("success", refund_status_type))
              {
                GNUNET_break_op (0);
                ret = GNUNET_SYSERR;
              }
            }
          }
          else
          {
            struct GNUNET_JSON_Specification rspec[] = {
              GNUNET_JSON_spec_string ("type",
                                       &refund_status_type),
              GNUNET_JSON_spec_fixed_auto ("coin_pub",
                                           &rd->coin_pub),
              GNUNET_JSON_spec_uint64 ("rtransaction_id",
                                       &rd->rtransaction_id),
              TALER_JSON_spec_amount ("refund_amount",
                                      &rd->refund_amount),
              GNUNET_JSON_spec_end ()
            };

            ret = GNUNET_JSON_parse (jrefund,
                                     rspec,
                                     NULL, NULL);
            if (GNUNET_OK == ret)
            {
              /* parse optional arguments */
              json_t *jec;

              jec = json_object_get (jrefund,
                                     "exchange_code");
              if (NULL != jec)
              {
                if (! json_is_integer (jec))
                {
                  GNUNET_break_op (0);
                  ret = GNUNET_SYSERR;
                }
                else
                {
                  rd->hr.ec = (enum TALER_ErrorCode) json_integer_value (jec);
                }
              }
              rd->hr.reply = json_object_get (jrefund,
                                              "exchange_reply");
              /* check that type field is correct */
              if (0 != strcmp ("failure", refund_status_type))
              {
                GNUNET_break_op (0);
                ret = GNUNET_SYSERR;
              }
            }
          }
          if (GNUNET_OK != ret)
          {
            GNUNET_break_op (0);
            cb_failure (owgh,
                        TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
                        json);
            TALER_MERCHANT_wallet_order_get_cancel (owgh);
            return;
          }
          rd->hr.http_status = exchange_status;
        }

        {
          struct TALER_MERCHANT_HttpResponse hr = {
            .reply = json,
            .http_status = MHD_HTTP_OK
          };

          owgh->cb (owgh->cb_cls,
                    &hr,
                    GNUNET_YES,
                    refunded ? GNUNET_YES : GNUNET_NO,
                    refunded ? &refund_amount : NULL,
                    NULL, /* paid! */
                    NULL, /* paid! */
                    &merchant_pub,
                    refund_len,
                    rds);
        }
      }
      GNUNET_JSON_parse_free (spec);
      break;
    }
  case MHD_HTTP_PAYMENT_REQUIRED:
    {
      /* Status is: unpaid */
      const char *taler_pay_uri = json_string_value (json_object_get (json,
                                                                      "taler_pay_uri"));
      const char *already_paid = json_string_value (json_object_get (json,
                                                                     "already_paid_order_id"));
      if (NULL == taler_pay_uri)
      {
        GNUNET_break_op (0);
        cb_failure (owgh,
                    TALER_EC_CHECK_PAYMENT_RESPONSE_MALFORMED,
                    json);
      }
      else
      {
        struct TALER_MERCHANT_HttpResponse hr = {
          .reply = json,
          .http_status = MHD_HTTP_OK
        };

        owgh->cb (owgh->cb_cls,
                  &hr,
                  GNUNET_NO,
                  GNUNET_NO,
                  NULL,
                  taler_pay_uri,
                  already_paid,
                  NULL,
                  0,
                  NULL);
      }
      break;
    }
  default:
    {
      struct TALER_MERCHANT_HttpResponse hr;

      TALER_MERCHANT_parse_error_details_ (response,
                                           response_code,
                                           &hr);
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Checking order status failed with HTTP status code %u/%d\n",
                  (unsigned int) response_code,
                  (int) hr.ec);
      GNUNET_break_op (0);
      owgh->cb (owgh->cb_cls,
                &hr,
                GNUNET_SYSERR,
                GNUNET_SYSERR,
                NULL,
                NULL,
                NULL,
                NULL,
                0,
                NULL);
      break;
    }
  }
  TALER_MERCHANT_wallet_order_get_cancel (owgh);
}


/**
 * Checks the status of a payment.  Issue a GET /orders/$ID request to the
 * backend.  The @a h_contract serves as identification of the wallet and is
 * used to authorize the request.
 *
 * @param ctx execution context
 * @param backend_url base URL of the merchant backend
 * @param order_id order id to identify the payment
 * @param h_contract hash of the contract to authenticate the wallet
 * @param timeout timeout to use in long polling (how long may the server wait to reply
 *        before generating an unpaid response). Note that this is just provided to
 *        the server, we as client will block until the response comes back or until
 *        #TALER_MERCHANT_order_get_cancel() is called.
 * @param session_id for which session should the payment status be checked
 * @param min_refund long poll for the service to approve a refund exceeding this value;
 *        use NULL to not wait for any refund (only for payment). Only makes sense
 *        with a non-zero @a timeout. Can be NULL.
 * @param cb callback which will work the response gotten from the backend
 * @param cb_cls closure to pass to @a cb
 * @return handle for this operation, NULL upon errors
 */
struct TALER_MERCHANT_OrderWalletGetHandle *
TALER_MERCHANT_wallet_order_get (struct GNUNET_CURL_Context *ctx,
                                 const char *backend_url,
                                 const char *order_id,
                                 const struct GNUNET_HashCode *h_contract,
                                 struct GNUNET_TIME_Relative timeout,
                                 const char *session_id,
                                 const struct TALER_Amount *min_refund,
                                 TALER_MERCHANT_OrderWalletGetCallback cb,
                                 void *cb_cls)
{
  struct TALER_MERCHANT_OrderWalletGetHandle *owgh;
  unsigned long long tms;
  long tlong;

  GNUNET_assert (NULL != backend_url);
  GNUNET_assert (NULL != order_id);
  owgh = GNUNET_new (struct TALER_MERCHANT_OrderWalletGetHandle);
  owgh->ctx = ctx;
  owgh->cb = cb;
  owgh->cb_cls = cb_cls;
  tms = (unsigned long long) (timeout.rel_value_us
                              / GNUNET_TIME_UNIT_MILLISECONDS.rel_value_us);
  /* set curl timeout to *our* long poll timeout plus one minute
     (for network latency and processing delays) */
  tlong = (long) (GNUNET_TIME_relative_add (timeout,
                                            GNUNET_TIME_UNIT_MINUTES).
                  rel_value_us
                  / GNUNET_TIME_UNIT_MILLISECONDS.rel_value_us);
  {
    char timeout_ms[32];
    struct GNUNET_CRYPTO_HashAsciiEncoded h_contract_s;
    char *path;

    GNUNET_CRYPTO_hash_to_enc (h_contract,
                               &h_contract_s);
    GNUNET_snprintf (timeout_ms,
                     sizeof (timeout_ms),
                     "%llu",
                     tms);
    GNUNET_asprintf (&path,
                     "orders/%s",
                     order_id);
    owgh->url = TALER_url_join (backend_url,
                                path,
                                "h_contract",
                                h_contract_s.encoding,
                                "session_id",
                                session_id,
                                (0 != tms)
                                ? "timeout_ms"
                                : NULL,
                                timeout_ms,
                                (NULL != min_refund)
                                ? "refund"
                                : NULL,
                                (NULL != min_refund)
                                ? TALER_amount2s (min_refund)
                                : NULL,
                                NULL);
    GNUNET_free (path);
  }
  if (NULL == owgh->url)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Could not construct request URL.\n");
    GNUNET_free (owgh);
    return NULL;
  }

  {
    CURL *eh;

    eh = curl_easy_init ();
    if (NULL == eh)
    {
      GNUNET_break (0);
      GNUNET_free (owgh->url);
      GNUNET_free (owgh);
      return NULL;
    }
    if (CURLE_OK !=
        curl_easy_setopt (eh,
                          CURLOPT_URL,
                          owgh->url))
    {
      GNUNET_break (0);
      curl_easy_cleanup (eh);
      GNUNET_free (owgh->url);
      GNUNET_free (owgh);
      return NULL;
    }
    if (CURLE_OK !=
        curl_easy_setopt (eh,
                          CURLOPT_TIMEOUT_MS,
                          tlong))
    {
      GNUNET_break (0);
      curl_easy_cleanup (eh);
      GNUNET_free (owgh->url);
      GNUNET_free (owgh);
      return NULL;
    }

    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Checking order status at %s\n",
                owgh->url);
    if (NULL == (owgh->job =
                   GNUNET_CURL_job_add (ctx,
                                        eh,
                                        &handle_wallet_get_order_finished,
                                        owgh)))
    {
      GNUNET_break (0);
      GNUNET_free (owgh->url);
      GNUNET_free (owgh);
      return NULL;
    }
  }
  return owgh;
}


/**
 * Cancel a GET /orders/$ID request.
 *
 * @param owgh handle to the request to be canceled
 */
void
TALER_MERCHANT_wallet_order_get_cancel (
  struct TALER_MERCHANT_OrderWalletGetHandle *owgh)
{
  if (NULL != owgh->job)
  {
    GNUNET_CURL_job_cancel (owgh->job);
    owgh->job = NULL;
  }
  GNUNET_free (owgh->url);
  GNUNET_free (owgh);
}


/* end of merchant_api_wallet_get_order.c */