/*
  This file is part of TALER
  (C) 2014-2020 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU Affero 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 taler-merchant-httpd_get-tips-ID.c
 * @brief implementation of GET /tips/$ID
 * @author Marcello Stanisci
 * @author Christian Grothoff
 */
#include "platform.h"
#include <jansson.h>
#include <taler/taler_signatures.h>
#include <taler/taler_json_lib.h>
#include "taler-merchant-httpd_get-tips-ID.h"
#include "taler-merchant-httpd_mhd.h"
#include "taler-merchant-httpd_qr.h"
#include "taler-merchant-httpd_templating.h"

char *
TMH_make_taler_tip_uri (struct MHD_Connection *con,
                        const struct GNUNET_HashCode *tip_id,
                        const char *instance_id)
{
  const char *host;
  const char *forwarded_host;
  const char *uri_path;
  struct GNUNET_Buffer buf = { 0 };

  host = MHD_lookup_connection_value (con,
                                      MHD_HEADER_KIND,
                                      "Host");
  forwarded_host = MHD_lookup_connection_value (con,
                                                MHD_HEADER_KIND,
                                                "X-Forwarded-Host");

  uri_path = MHD_lookup_connection_value (con,
                                          MHD_HEADER_KIND,
                                          "X-Forwarded-Prefix");
  if (NULL != forwarded_host)
    host = forwarded_host;

  if (NULL == host)
  {
    GNUNET_break (0);
    return NULL;
  }

  GNUNET_assert (NULL != instance_id);
  GNUNET_assert (NULL != tip_id);

  GNUNET_buffer_write_str (&buf,
                           "taler");
  if (GNUNET_NO == TALER_mhd_is_https (con))
    GNUNET_buffer_write_str (&buf,
                             "+http");
  GNUNET_buffer_write_str (&buf,
                           "://tip/");
  GNUNET_buffer_write_str (&buf,
                           host);
  if (NULL != uri_path)
    GNUNET_buffer_write_path (&buf,
                              uri_path);
  if (0 != strcmp ("default",
                   instance_id))
  {
    GNUNET_buffer_write_path (&buf,
                              "instances");
    GNUNET_buffer_write_path (&buf,
                              instance_id);
  }
  /* Ensure previous part is slash-terminated */
  GNUNET_buffer_write_path (&buf,
                            "");
  GNUNET_buffer_write_data_encoded (&buf,
                                    tip_id,
                                    sizeof (*tip_id));
  return GNUNET_buffer_reap_str (&buf);
}


char *
TMH_make_tip_status_url (struct MHD_Connection *con,
                         const struct GNUNET_HashCode *tip_id,
                         const char *instance_id)
{
  const char *host;
  const char *forwarded_host;
  const char *uri_path;
  struct GNUNET_Buffer buf = { 0 };

  host = MHD_lookup_connection_value (con,
                                      MHD_HEADER_KIND,
                                      "Host");
  forwarded_host = MHD_lookup_connection_value (con,
                                                MHD_HEADER_KIND,
                                                "X-Forwarded-Host");

  uri_path = MHD_lookup_connection_value (con,
                                          MHD_HEADER_KIND,
                                          "X-Forwarded-Prefix");
  if (NULL != forwarded_host)
    host = forwarded_host;

  if (NULL == host)
  {
    GNUNET_break (0);
    return NULL;
  }

  GNUNET_assert (NULL != instance_id);
  GNUNET_assert (NULL != tip_id);

  if (GNUNET_NO == TALER_mhd_is_https (con))
    GNUNET_buffer_write_str (&buf,
                             "http://");
  else
    GNUNET_buffer_write_str (&buf,
                             "https://");
  GNUNET_buffer_write_str (&buf,
                           host);
  if (NULL != uri_path)
    GNUNET_buffer_write_path (&buf,
                              uri_path);
  if (0 != strcmp ("default",
                   instance_id))
  {
    GNUNET_buffer_write_path (&buf,
                              "instances");
    GNUNET_buffer_write_path (&buf,
                              instance_id);
  }
  GNUNET_buffer_write_path (&buf,
                            "tips/");
  GNUNET_buffer_write_data_encoded (&buf,
                                    tip_id,
                                    sizeof (*tip_id));
  return GNUNET_buffer_reap_str (&buf);
}


MHD_RESULT
TMH_get_tips_ID (const struct TMH_RequestHandler *rh,
                 struct MHD_Connection *connection,
                 struct TMH_HandlerContext *hc)
{
  struct GNUNET_HashCode tip_id;
  enum GNUNET_DB_QueryStatus qs;
  struct TALER_Amount total_authorized;
  struct TALER_Amount total_picked_up;
  struct GNUNET_TIME_Absolute expiration;
  char *exchange_url;
  struct TALER_ReservePrivateKeyP reserve_priv;

  if (GNUNET_OK !=
      GNUNET_CRYPTO_hash_from_string (hc->infix,
                                      &tip_id))
  {
    /* tip_id has wrong encoding */
    GNUNET_break_op (0);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                       hc->infix);
  }

  TMH_db->preflight (TMH_db->cls);
  qs = TMH_db->lookup_tip (TMH_db->cls,
                           hc->instance->settings.id,
                           &tip_id,
                           &total_authorized,
                           &total_picked_up,
                           &expiration,
                           &exchange_url,
                           &reserve_priv);
  if (0 > qs)
  {
    /* single, read-only SQL statements should never cause
       serialization problems */
    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR != qs);
    /* Always report on hard error as well to enable diagnostics */
    GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                                       TALER_EC_GENERIC_DB_FETCH_FAILED,
                                       NULL);
  }
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Unknown tip id given: `%s'\n",
                hc->infix);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_NOT_FOUND,
                                       TALER_EC_MERCHANT_GENERIC_TIP_ID_UNKNOWN,
                                       hc->infix);
  }

  /* Build response */
  {
    struct TALER_Amount remaining;
    struct GNUNET_TIME_Absolute expiration_round = expiration;
    MHD_RESULT ret;

    GNUNET_break (0 <=
                  TALER_amount_subtract (&remaining,
                                         &total_authorized,
                                         &total_picked_up));

    GNUNET_TIME_round_abs (&expiration_round);
    if (TMH_MHD_test_html_desired (connection))
    {
      char *qr;
      char *uri;
      char *tip_status_url;

      uri = TMH_make_taler_tip_uri (connection,
                                    &tip_id,
                                    hc->instance->settings.id);
      tip_status_url = TMH_make_tip_status_url (connection,
                                                &tip_id,
                                                hc->instance->settings.id);
      qr = TMH_create_qrcode (uri);
      if (NULL == qr)
      {
        GNUNET_break (0);
        GNUNET_free (uri);
        ret = TALER_MHD_reply_with_error (connection,
                                          MHD_HTTP_INTERNAL_SERVER_ERROR,
                                          TALER_EC_GENERIC_ALLOCATION_FAILURE,
                                          "during QR code generation");
      }
      else
      {
        json_t *context;
        context = json_pack ("{s:s, s:s, s:s}",
                             "remaining_tip",
                             TALER_amount2s (&remaining),
                             "taler_tip_uri",
                             uri,
                             "taler_tip_qrcode_svg",
                             qr);
        GNUNET_assert (NULL != context);

        ret = TMH_return_from_template (connection,
                                        ( (0 == remaining.value) &&
                                          (0 == remaining.fraction) )
                                        ? MHD_HTTP_GONE
                                        : MHD_HTTP_OK,
                                        ( (0 == remaining.value) &&
                                          (0 == remaining.fraction) )
                                        ? "depleted_tip"
                                        : "offer_tip",
                                        uri,
                                        context);
        json_decref (context);
      }
      GNUNET_free (tip_status_url);
      GNUNET_free (uri);
      GNUNET_free (qr);
    }
    else
    {
      ret = TALER_MHD_reply_json_pack (connection,
                                       ( (0 == remaining.value) &&
                                         (0 == remaining.fraction) )
                                       ? MHD_HTTP_GONE
                                       : MHD_HTTP_OK,
                                       "{s:s, s:o, s:o}",
                                       "exchange_url",
                                       exchange_url,
                                       "tip_amount",
                                       TALER_JSON_from_amount (&remaining),
                                       "expiration",
                                       GNUNET_JSON_from_time_abs (
                                         expiration_round));
    }
    GNUNET_free (exchange_url);
    return ret;
  }
}


/* end of taler-merchant-httpd_get-tips-ID.c */