/*
  This file is part of TALER
  (C) 2020, 2021 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_private-post-instances.c
 * @brief implementing POST /instances request handling
 * @author Christian Grothoff
 */
#include "platform.h"
#include "taler-merchant-httpd_private-post-instances.h"
#include "taler-merchant-httpd_helper.h"
#include <taler/taler_json_lib.h>
#include <regex.h>

/**
 * How often do we retry the simple INSERT database transaction?
 */
#define MAX_RETRIES 3


/**
 * Check if the array of @a payto_uris contains exactly the same
 * URIs as those already in @a mi (possibly in a different order).
 *
 * @param mi a merchant instance with accounts
 * @param payto_uris a JSON array with accounts (presumably)
 * @return true if they are 'equal', false if not or of payto_uris is not an array
 */
static bool
accounts_equal (const struct TMH_MerchantInstance *mi,
                json_t *payto_uris)
{
  if (! json_is_array (payto_uris))
    return false;
  {
    unsigned int len = json_array_size (payto_uris);
    bool matches[GNUNET_NZL (len)];
    struct TMH_WireMethod *wm;

    memset (matches,
            0,
            sizeof (matches));
    for (wm = mi->wm_head;
         NULL != wm;
         wm = wm->next)
    {
      const char *uri = json_string_value (json_object_get (wm->j_wire,
                                                            "payto_uri"));

      GNUNET_assert (NULL != uri);
      for (unsigned int i = 0; i<len; i++)
      {
        const char *str = json_string_value (json_array_get (payto_uris,
                                                             i));

        GNUNET_assert (NULL != str);
        if (0 == strcasecmp (uri,
                             str))
        {
          if (matches[i])
          {
            GNUNET_break (0);
            return false; /* duplicate entry!? */
          }
          matches[i] = true;
          break;
        }
      }
    }
    for (unsigned int i = 0; i<len; i++)
      if (! matches[i])
        return false;
  }
  return true;
}


/**
 * Free memory used by @a wm
 *
 * @param wm wire method to free
 */
static void
free_wm (struct TMH_WireMethod *wm)
{
  json_decref (wm->j_wire);
  GNUNET_free (wm->wire_method);
  GNUNET_free (wm);
}


/**
 * Free memory used by @a mi.
 *
 * @param mi instance to free
 */
static void
free_mi (struct TMH_MerchantInstance *mi)
{
  struct TMH_WireMethod *wm;

  while (NULL != (wm = mi->wm_head))
  {
    GNUNET_CONTAINER_DLL_remove (mi->wm_head,
                                 mi->wm_tail,
                                 wm);
    free_wm (wm);
  }
  GNUNET_free (mi->settings.id);
  GNUNET_free (mi->settings.name);
  json_decref (mi->settings.address);
  json_decref (mi->settings.jurisdiction);
  GNUNET_free (mi);
}


/**
 * Generate an instance, given its configuration.
 *
 * @param rh context of the handler
 * @param connection the MHD connection to handle
 * @param[in,out] hc context with further information about the request
 * @return MHD result code
 */
MHD_RESULT
TMH_private_post_instances (const struct TMH_RequestHandler *rh,
                            struct MHD_Connection *connection,
                            struct TMH_HandlerContext *hc)
{
  struct TALER_MERCHANTDB_InstanceSettings is;
  struct TALER_MERCHANTDB_InstanceAuthSettings ias;
  json_t *payto_uris;
  const char *auth_token = NULL;
  struct TMH_WireMethod *wm_head = NULL;
  struct TMH_WireMethod *wm_tail = NULL;
  json_t *jauth;
  struct GNUNET_JSON_Specification spec[] = {
    GNUNET_JSON_spec_json ("payto_uris",
                           &payto_uris),
    GNUNET_JSON_spec_string ("id",
                             (const char **) &is.id),
    GNUNET_JSON_spec_string ("name",
                             (const char **) &is.name),
    GNUNET_JSON_spec_json ("auth",
                           &jauth),
    GNUNET_JSON_spec_json ("address",
                           &is.address),
    GNUNET_JSON_spec_json ("jurisdiction",
                           &is.jurisdiction),
    TALER_JSON_spec_amount ("default_max_wire_fee",
                            TMH_currency,
                            &is.default_max_wire_fee),
    GNUNET_JSON_spec_uint32 ("default_wire_fee_amortization",
                             &is.default_wire_fee_amortization),
    TALER_JSON_spec_amount ("default_max_deposit_fee",
                            TMH_currency,
                            &is.default_max_deposit_fee),
    TALER_JSON_spec_relative_time ("default_wire_transfer_delay",
                                   &is.default_wire_transfer_delay),
    TALER_JSON_spec_relative_time ("default_pay_delay",
                                   &is.default_pay_delay),
    GNUNET_JSON_spec_end ()
  };

  {
    enum GNUNET_GenericReturnValue res;

    res = TALER_MHD_parse_json_data (connection,
                                     hc->request_body,
                                     spec);
    if (GNUNET_OK != res)
      return (GNUNET_NO == res)
             ? MHD_YES
             : MHD_NO;
  }

  {
    enum GNUNET_GenericReturnValue ret;

    ret = TMH_check_auth_config (connection,
                                 jauth,
                                 &auth_token);
    if (GNUNET_OK != ret)
      return (GNUNET_NO == ret) ? MHD_YES : MHD_NO;
  }

  /* check payto_uris for well-formedness */
  if (! TMH_payto_uri_array_valid (payto_uris))
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PAYTO_URI_MALFORMED,
                                       NULL);

  /* check 'id' well-formed */
  {
    static bool once;
    static regex_t reg;
    bool id_wellformed = true;

    if (! once)
    {
      GNUNET_assert (0 ==
                     regcomp (&reg,
                              "^[A-Za-z0-9][A-Za-z0-9_.@-]+$",
                              REG_EXTENDED));
    }

    if (0 != regexec (&reg,
                      is.id,
                      0, NULL, 0))
      id_wellformed = false;
    if (! id_wellformed)
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_BAD_REQUEST,
                                         TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                         "id");
  }

  if (! TMH_location_object_valid (is.address))
  {
    GNUNET_break_op (0);
    GNUNET_JSON_parse_free (spec);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                       "address");
  }

  if (! TMH_location_object_valid (is.jurisdiction))
  {
    GNUNET_break_op (0);
    GNUNET_JSON_parse_free (spec);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_BAD_REQUEST,
                                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                                       "jurisdiction");
  }

  {
    /* Test if an instance of this id is known */
    struct TMH_MerchantInstance *mi;

    mi = TMH_lookup_instance (is.id);
    if (NULL != mi)
    {
      if (mi->deleted)
      {
        GNUNET_JSON_parse_free (spec);
        return TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_CONFLICT,
                                           TALER_EC_MERCHANT_PRIVATE_POST_INSTANCES_PURGE_REQUIRED,
                                           is.id);
      }
      /* Check for idempotency */
      if ( (0 == strcmp (mi->settings.id,
                         is.id)) &&
           (0 == strcmp (mi->settings.name,
                         is.name)) &&
           ( ( (NULL != auth_token) &&
               (GNUNET_OK ==
                TMH_check_auth (auth_token,
                                &mi->auth.auth_salt,
                                &mi->auth.auth_hash)) ) ||
             ( (NULL == auth_token) &&
               (GNUNET_YES ==
                GNUNET_is_zero (&mi->auth.auth_hash))) ) &&
           (1 == json_equal (mi->settings.address,
                             is.address)) &&
           (1 == json_equal (mi->settings.jurisdiction,
                             is.jurisdiction)) &&
           (GNUNET_OK == TALER_amount_cmp_currency (
              &mi->settings.default_max_deposit_fee,
              &is.default_max_deposit_fee)) &&
           (0 == TALER_amount_cmp (&mi->settings.default_max_deposit_fee,
                                   &is.default_max_deposit_fee)) &&
           (GNUNET_OK == TALER_amount_cmp_currency (
              &mi->settings.default_max_wire_fee,
              &is.default_max_wire_fee)) &&
           (0 == TALER_amount_cmp (&mi->settings.default_max_wire_fee,
                                   &is.default_max_wire_fee)) &&
           (mi->settings.default_wire_fee_amortization ==
            is.default_wire_fee_amortization) &&
           (mi->settings.default_wire_transfer_delay.rel_value_us ==
            is.default_wire_transfer_delay.rel_value_us) &&
           (mi->settings.default_pay_delay.rel_value_us ==
            is.default_pay_delay.rel_value_us) &&
           (accounts_equal (mi,
                            payto_uris)) )
      {
        GNUNET_JSON_parse_free (spec);
        return TALER_MHD_reply_static (connection,
                                       MHD_HTTP_NO_CONTENT,
                                       NULL,
                                       NULL,
                                       0);
      }
      else
      {
        GNUNET_JSON_parse_free (spec);
        return TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_CONFLICT,
                                           TALER_EC_MERCHANT_PRIVATE_POST_INSTANCES_ALREADY_EXISTS,
                                           is.id);
      }
    }
  }

  /* convert provided payto URIs into internal data structure with salts */
  {
    unsigned int len = json_array_size (payto_uris);

    for (unsigned int i = 0; i<len; i++)
    {
      json_t *payto_uri = json_array_get (payto_uris,
                                          i);
      struct TMH_WireMethod *wm;

      wm = TMH_setup_wire_account (json_string_value (payto_uri));
      GNUNET_CONTAINER_DLL_insert (wm_head,
                                   wm_tail,
                                   wm);
    }
  }

  /* handle authentication token setup */
  if (NULL == auth_token)
  {
    memset (&ias.auth_salt,
            0,
            sizeof (ias.auth_salt));
    memset (&ias.auth_hash,
            0,
            sizeof (ias.auth_hash));
  }
  else
  {
    /* Sets 'auth_salt' and 'auth_hash' */
    TMH_compute_auth (auth_token,
                      &ias.auth_salt,
                      &ias.auth_hash);
  }

  /* create in-memory data structure */
  {
    struct TMH_MerchantInstance *mi;
    enum GNUNET_DB_QueryStatus qs;

    mi = GNUNET_new (struct TMH_MerchantInstance);
    mi->wm_head = wm_head;
    mi->wm_tail = wm_tail;
    mi->settings = is;
    mi->settings.address = json_incref (mi->settings.address);
    mi->settings.jurisdiction = json_incref (mi->settings.jurisdiction);
    mi->settings.id = GNUNET_strdup (is.id);
    mi->settings.name = GNUNET_strdup (is.name);
    mi->auth = ias;
    GNUNET_CRYPTO_eddsa_key_create (&mi->merchant_priv.eddsa_priv);
    GNUNET_CRYPTO_eddsa_key_get_public (&mi->merchant_priv.eddsa_priv,
                                        &mi->merchant_pub.eddsa_pub);

    for (unsigned int i = 0; i<MAX_RETRIES; i++)
    {
      if (GNUNET_OK !=
          TMH_db->start (TMH_db->cls,
                         "post /instances"))
      {
        GNUNET_JSON_parse_free (spec);
        free_mi (mi);
        return TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GENERIC_DB_START_FAILED,
                                           NULL);
      }
      qs = TMH_db->insert_instance (TMH_db->cls,
                                    &mi->merchant_pub,
                                    &mi->merchant_priv,
                                    &mi->settings,
                                    &mi->auth);
      if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
      {
        MHD_RESULT ret;

        TMH_db->rollback (TMH_db->cls);
        if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
          goto retry;
        ret = TALER_MHD_reply_with_error (connection,
                                          MHD_HTTP_CONFLICT,
                                          TALER_EC_MERCHANT_PRIVATE_POST_INSTANCES_ALREADY_EXISTS,
                                          is.id);
        GNUNET_JSON_parse_free (spec);
        free_mi (mi);
        return ret;
      }
      for (struct TMH_WireMethod *wm = wm_head;
           NULL != wm;
           wm = wm->next)
      {
        struct TALER_MERCHANTDB_AccountDetails ad;
        struct GNUNET_JSON_Specification spec[] = {
          GNUNET_JSON_spec_string ("payto_uri",
                                   &ad.payto_uri),
          GNUNET_JSON_spec_fixed_auto ("salt",
                                       &ad.salt),
          GNUNET_JSON_spec_end ()
        };

        GNUNET_assert (GNUNET_OK ==
                       TALER_MHD_parse_json_data (NULL,
                                                  wm->j_wire,
                                                  spec));
        ad.h_wire = wm->h_wire;
        ad.active = wm->active;
        qs = TMH_db->insert_account (TMH_db->cls,
                                     mi->settings.id,
                                     &ad);
        if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
          break;
      }
      if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
      {
        GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
        TMH_db->rollback (TMH_db->cls);
        if (GNUNET_DB_STATUS_HARD_ERROR == qs)
          break;
        goto retry;
      }
      qs = TMH_db->commit (TMH_db->cls);
      if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
        qs = GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
retry:
      if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
        break; /* success! -- or hard failure */
    } /* for .. MAX_RETRIES */
    if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
    {
      GNUNET_JSON_parse_free (spec);
      free_mi (mi);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GENERIC_DB_COMMIT_FAILED,
                                         NULL);
    }
    /* Finally, also update our running process */
    GNUNET_assert (GNUNET_OK ==
                   TMH_add_instance (mi));
    TMH_reload_instances (mi->settings.id);
  }
  GNUNET_JSON_parse_free (spec);
  GNUNET_free (TMH_default_auth); /* clear it: user just either created default
                                     instance or it should already be NULL */
  return TALER_MHD_reply_static (connection,
                                 MHD_HTTP_NO_CONTENT,
                                 NULL,
                                 NULL,
                                 0);
}


/* end of taler-merchant-httpd_private-post-instances.c */