/*
  This file is part of TALER
  Copyright (C) 2014-2023 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU 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 pq/pq_query_helper.c
 * @brief helper functions for Taler-specific libpq (PostGres) interactions
 * @author Sree Harsha Totakura <sreeharsha@totakura.in>
 * @author Florian Dold
 * @author Christian Grothoff
 */
#include "platform.h"
#include <gnunet/gnunet_common.h>
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_pq_lib.h>
#include "taler_pq_lib.h"
#include "pq_common.h"


/**
 * Function called to convert input amount into SQL parameter as tuple.
 *
 * @param cls closure
 * @param data pointer to input argument, here a `struct TALER_Amount`
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_amount_currency_tuple (void *cls,
                             const void *data,
                             size_t data_len,
                             void *param_values[],
                             int param_lengths[],
                             int param_formats[],
                             unsigned int param_length,
                             void *scratch[],
                             unsigned int scratch_length)
{
  struct GNUNET_PQ_Context *db = cls;
  const struct TALER_Amount *amount = data;
  size_t sz;

  GNUNET_assert (NULL != db);
  GNUNET_assert (NULL != amount);
  GNUNET_assert (1 == param_length);
  GNUNET_assert (1 <= scratch_length);
  GNUNET_assert (sizeof (struct TALER_Amount) == data_len);
  GNUNET_static_assert (sizeof(uint32_t) == sizeof(Oid));
  {
    char *out;
    Oid oid_v;
    Oid oid_f;
    Oid oid_c;
    struct TALER_PQ_AmountCurrencyP d;

    GNUNET_assert (GNUNET_OK ==
                   GNUNET_PQ_get_oid_by_name (db,
                                              "int8",
                                              &oid_v));
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_PQ_get_oid_by_name (db,
                                              "int4",
                                              &oid_f));
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_PQ_get_oid_by_name (db,
                                              "varchar",
                                              &oid_c));
    sz = TALER_PQ_make_taler_pq_amount_currency_ (amount,
                                                  oid_v,
                                                  oid_f,
                                                  oid_c,
                                                  &d);
    out = GNUNET_malloc (sz);
    memcpy (out,
            &d,
            sz);
    scratch[0] = out;
  }

  param_values[0] = scratch[0];
  param_lengths[0] = sz;
  param_formats[0] = 1;

  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_amount_with_currency (
  const struct GNUNET_PQ_Context *db,
  const struct TALER_Amount *amount)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv_cls = (void *) db,
    .conv = &qconv_amount_currency_tuple,
    .data = amount,
    .size = sizeof (*amount),
    .num_params = 1,
  };

  return res;
}


/**
 * Function called to convert input amount into SQL parameter as tuple.
 *
 * @param cls closure
 * @param data pointer to input argument, here a `struct TALER_Amount`
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_amount_tuple (void *cls,
                    const void *data,
                    size_t data_len,
                    void *param_values[],
                    int param_lengths[],
                    int param_formats[],
                    unsigned int param_length,
                    void *scratch[],
                    unsigned int scratch_length)
{
  struct GNUNET_PQ_Context *db = cls;
  const struct TALER_Amount *amount = data;
  size_t sz;

  GNUNET_assert (NULL != db);
  GNUNET_assert (NULL != amount);
  GNUNET_assert (1 == param_length);
  GNUNET_assert (1 <= scratch_length);
  GNUNET_assert (sizeof (struct TALER_Amount) == data_len);
  GNUNET_static_assert (sizeof(uint32_t) == sizeof(Oid));
  {
    char *out;
    Oid oid_v;
    Oid oid_f;

    GNUNET_assert (GNUNET_OK ==
                   GNUNET_PQ_get_oid_by_name (db,
                                              "int8",
                                              &oid_v));
    GNUNET_assert (GNUNET_OK ==
                   GNUNET_PQ_get_oid_by_name (db,
                                              "int4",
                                              &oid_f));

    {
      struct TALER_PQ_AmountP d
        = TALER_PQ_make_taler_pq_amount_ (amount,
                                          oid_v,
                                          oid_f);

      sz = sizeof(d);
      out = GNUNET_malloc (sz);
      scratch[0] = out;
      GNUNET_memcpy (out,
                     &d,
                     sizeof(d));
    }
  }

  param_values[0] = scratch[0];
  param_lengths[0] = sz;
  param_formats[0] = 1;

  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_amount (
  const struct GNUNET_PQ_Context *db,
  const struct TALER_Amount *amount)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv_cls = (void *) db,
    .conv = &qconv_amount_tuple,
    .data = amount,
    .size = sizeof (*amount),
    .num_params = 1,
  };

  return res;
}


/**
 * Function called to convert input argument into SQL parameters.
 *
 * @param cls closure
 * @param data pointer to input argument
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_denom_pub (void *cls,
                 const void *data,
                 size_t data_len,
                 void *param_values[],
                 int param_lengths[],
                 int param_formats[],
                 unsigned int param_length,
                 void *scratch[],
                 unsigned int scratch_length)
{
  const struct TALER_DenominationPublicKey *denom_pub = data;
  const struct GNUNET_CRYPTO_BlindSignPublicKey *bsp = denom_pub->bsign_pub_key;
  size_t tlen;
  size_t len;
  uint32_t be[2];
  char *buf;
  void *tbuf;

  (void) cls;
  (void) data_len;
  GNUNET_assert (1 == param_length);
  GNUNET_assert (scratch_length > 0);
  GNUNET_break (NULL == cls);
  be[0] = htonl ((uint32_t) bsp->cipher);
  be[1] = htonl (denom_pub->age_mask.bits);
  switch (bsp->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    tlen = GNUNET_CRYPTO_rsa_public_key_encode (
      bsp->details.rsa_public_key,
      &tbuf);
    break;
  case GNUNET_CRYPTO_BSA_CS:
    tlen = sizeof (bsp->details.cs_public_key);
    break;
  default:
    GNUNET_assert (0);
  }
  len = tlen + sizeof (be);
  buf = GNUNET_malloc (len);
  GNUNET_memcpy (buf,
                 be,
                 sizeof (be));
  switch (bsp->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    GNUNET_memcpy (&buf[sizeof (be)],
                   tbuf,
                   tlen);
    GNUNET_free (tbuf);
    break;
  case GNUNET_CRYPTO_BSA_CS:
    GNUNET_memcpy (&buf[sizeof (be)],
                   &bsp->details.cs_public_key,
                   tlen);
    break;
  default:
    GNUNET_assert (0);
  }

  scratch[0] = buf;
  param_values[0] = (void *) buf;
  param_lengths[0] = len;
  param_formats[0] = 1;
  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_denom_pub (
  const struct TALER_DenominationPublicKey *denom_pub)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv = &qconv_denom_pub,
    .data = denom_pub,
    .num_params = 1
  };

  return res;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_denom_sig (
  const struct TALER_DenominationSignature *denom_sig)
{
  return GNUNET_PQ_query_param_unblinded_sig (denom_sig->unblinded_sig);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_blinded_denom_sig (
  const struct TALER_BlindedDenominationSignature *denom_sig)
{
  return GNUNET_PQ_query_param_blinded_sig (denom_sig->blinded_sig);
}


/**
 * Function called to convert input argument into SQL parameters.
 *
 * @param cls closure
 * @param data pointer to input argument
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_blinded_planchet (void *cls,
                        const void *data,
                        size_t data_len,
                        void *param_values[],
                        int param_lengths[],
                        int param_formats[],
                        unsigned int param_length,
                        void *scratch[],
                        unsigned int scratch_length)
{
  const struct TALER_BlindedPlanchet *bp = data;
  const struct GNUNET_CRYPTO_BlindedMessage *bm = bp->blinded_message;
  size_t tlen;
  size_t len;
  uint32_t be[2];
  char *buf;

  (void) cls;
  (void) data_len;
  GNUNET_assert (1 == param_length);
  GNUNET_assert (scratch_length > 0);
  GNUNET_break (NULL == cls);
  be[0] = htonl ((uint32_t) bm->cipher);
  be[1] = htonl (0x0100); /* magic marker: blinded */
  switch (bm->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    tlen = bm->details.rsa_blinded_message.blinded_msg_size;
    break;
  case GNUNET_CRYPTO_BSA_CS:
    tlen = sizeof (bm->details.cs_blinded_message);
    break;
  default:
    GNUNET_assert (0);
  }
  len = tlen + sizeof (be);
  buf = GNUNET_malloc (len);
  GNUNET_memcpy (buf,
                 &be,
                 sizeof (be));
  switch (bm->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    GNUNET_memcpy (&buf[sizeof (be)],
                   bm->details.rsa_blinded_message.blinded_msg,
                   tlen);
    break;
  case GNUNET_CRYPTO_BSA_CS:
    GNUNET_memcpy (&buf[sizeof (be)],
                   &bm->details.cs_blinded_message,
                   tlen);
    break;
  default:
    GNUNET_assert (0);
  }
  scratch[0] = buf;
  param_values[0] = (void *) buf;
  param_lengths[0] = len;
  param_formats[0] = 1;
  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_blinded_planchet (
  const struct TALER_BlindedPlanchet *bp)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv = &qconv_blinded_planchet,
    .data = bp,
    .num_params = 1
  };

  return res;
}


/**
 * Function called to convert input argument into SQL parameters.
 *
 * @param cls closure
 * @param data pointer to input argument
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_exchange_withdraw_values (void *cls,
                                const void *data,
                                size_t data_len,
                                void *param_values[],
                                int param_lengths[],
                                int param_formats[],
                                unsigned int param_length,
                                void *scratch[],
                                unsigned int scratch_length)
{
  const struct TALER_ExchangeWithdrawValues *alg_values = data;
  const struct GNUNET_CRYPTO_BlindingInputValues *bi =
    alg_values->blinding_inputs;
  size_t tlen;
  size_t len;
  uint32_t be[2];
  char *buf;

  (void) cls;
  (void) data_len;
  GNUNET_assert (1 == param_length);
  GNUNET_assert (scratch_length > 0);
  GNUNET_break (NULL == cls);
  be[0] = htonl ((uint32_t) bi->cipher);
  be[1] = htonl (0x010000); /* magic marker: EWV */
  switch (bi->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    tlen = 0;
    break;
  case GNUNET_CRYPTO_BSA_CS:
    tlen = sizeof (struct GNUNET_CRYPTO_CSPublicRPairP);
    break;
  default:
    GNUNET_assert (0);
  }
  len = tlen + sizeof (be);
  buf = GNUNET_malloc (len);
  GNUNET_memcpy (buf,
                 &be,
                 sizeof (be));
  switch (bi->cipher)
  {
  case GNUNET_CRYPTO_BSA_RSA:
    break;
  case GNUNET_CRYPTO_BSA_CS:
    GNUNET_memcpy (&buf[sizeof (be)],
                   &bi->details.cs_values,
                   tlen);
    break;
  default:
    GNUNET_assert (0);
  }
  scratch[0] = buf;
  param_values[0] = (void *) buf;
  param_lengths[0] = len;
  param_formats[0] = 1;
  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_exchange_withdraw_values (
  const struct TALER_ExchangeWithdrawValues *alg_values)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv = &qconv_exchange_withdraw_values,
    .data = alg_values,
    .num_params = 1
  };

  return res;
}


/**
 * Function called to convert input argument into SQL parameters.
 *
 * @param cls closure
 * @param data pointer to input argument, here a `json_t *`
 * @param data_len number of bytes in @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_json (void *cls,
            const void *data,
            size_t data_len,
            void *param_values[],
            int param_lengths[],
            int param_formats[],
            unsigned int param_length,
            void *scratch[],
            unsigned int scratch_length)
{
  const json_t *json = data;
  char *str;

  (void) cls;
  (void) data_len;
  GNUNET_assert (1 == param_length);
  GNUNET_assert (scratch_length > 0);
  str = json_dumps (json, JSON_COMPACT);
  if (NULL == str)
    return -1;
  scratch[0] = str;
  param_values[0] = (void *) str;
  param_lengths[0] = strlen (str);
  param_formats[0] = 1;
  return 1;
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_json (const json_t *x)
{
  struct GNUNET_PQ_QueryParam res = {
    .conv = &qconv_json,
    .data = x,
    .num_params = 1
  };

  return res;
}


/** ------------------- Array support  -----------------------------------**/

/**
 * Closure for the array type handlers.
 *
 * May contain sizes information for the data, given (and handled) by the
 * caller.
 */
struct qconv_array_cls
{
  /**
   * If not null, contains the array of sizes (the size of the array is the
   * .size field in the ambient GNUNET_PQ_QueryParam struct). We do not free
   * this memory.
   *
   * If not null, this value has precedence over @a sizes, which MUST be NULL */
  const size_t *sizes;

  /**
   * If @a size and @a c_sizes are NULL, this field defines the same size
   * for each element in the array.
   */
  size_t same_size;

  /**
   * If true, the array parameter to the data pointer to the qconv_array is a
   * continuous byte array of data, either with @a same_size each or sizes
   * provided bytes by @a sizes;
   */
  bool continuous;

  /**
   * Type of the array elements
   */
  enum TALER_PQ_ArrayType typ;

  /**
   * Oid of the array elements
   */
  Oid oid;

  /**
   * db context, needed for OID-lookup of basis-types
   */
  struct GNUNET_PQ_Context *db;
};

/**
 * Callback to cleanup a qconv_array_cls to be used during
 * GNUNET_PQ_cleanup_query_params_closures
 */
static void
qconv_array_cls_cleanup (void *cls)
{
  GNUNET_free (cls);
}


/**
 * Function called to convert input argument into SQL parameters for arrays
 *
 * Note: the format for the encoding of arrays for libpq is not very well
 * documented.  We peeked into various sources (postgresql and libpqtypes) for
 * guidance.
 *
 * @param cls Closure of type struct qconv_array_cls*
 * @param data Pointer to first element in the array
 * @param data_len Number of _elements_ in array @a data (if applicable)
 * @param[out] param_values SQL data to set
 * @param[out] param_lengths SQL length data to set
 * @param[out] param_formats SQL format data to set
 * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
 * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
 * @param scratch_length number of entries left in @a scratch
 * @return -1 on error, number of offsets used in @a scratch otherwise
 */
static int
qconv_array (
  void *cls,
  const void *data,
  size_t data_len,
  void *param_values[],
  int param_lengths[],
  int param_formats[],
  unsigned int param_length,
  void *scratch[],
  unsigned int scratch_length)
{
  struct qconv_array_cls *meta = cls;
  size_t num = data_len;
  size_t total_size;
  const size_t *sizes;
  bool same_sized;
  void *elements = NULL;
  bool noerror = true;
  /* needed to capture the encoded rsa signatures */
  void **buffers = NULL;
  size_t *buffer_lengths = NULL;

  (void) (param_length);
  (void) (scratch_length);

  GNUNET_assert (NULL != meta);
  GNUNET_assert (num < INT_MAX);

  sizes = meta->sizes;
  same_sized = (0 != meta->same_size);

#define RETURN_UNLESS(cond) \
  do { \
    if (! (cond)) \
    { \
      GNUNET_break ((cond)); \
      noerror = false; \
      goto DONE; \
    } \
  } while (0)

  /* Calculate sizes and check bounds */
  {
    /* num * length-field */
    size_t x = sizeof(uint32_t);
    size_t y = x * num;
    RETURN_UNLESS ((0 == num) || (y / num == x));

    /* size of header */
    total_size  = x = sizeof(struct GNUNET_PQ_ArrayHeader_P);
    total_size += y;
    RETURN_UNLESS (total_size >= x);

    /* sizes of elements */
    if (same_sized)
    {
      x = num * meta->same_size;
      RETURN_UNLESS ((0 == num) || (x / num == meta->same_size));

      y = total_size;
      total_size += x;
      RETURN_UNLESS (total_size >= y);
    }
    else  /* sizes are different per element */
    {
      switch (meta->typ)
      {
      case TALER_PQ_array_of_amount_currency:
        {
          const struct TALER_Amount *amounts = data;
          Oid oid_v;
          Oid oid_f;
          Oid oid_c;

          buffer_lengths  = GNUNET_new_array (num, size_t);
          /* hoist out of loop? */
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int8",
                                                    &oid_v));
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int4",
                                                    &oid_f));
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "varchar",
                                                    &oid_c));
          for (size_t i = 0; i<num; i++)
          {
            struct TALER_PQ_AmountCurrencyP am;
            size_t len;

            len = TALER_PQ_make_taler_pq_amount_currency_ (
              &amounts[i],
              oid_v,
              oid_f,
              oid_c,
              &am);
            buffer_lengths[i] = len;
            y = total_size;
            total_size += len;
            RETURN_UNLESS (total_size >= y);
          }
          sizes = buffer_lengths;
          break;
        }
      case TALER_PQ_array_of_blinded_denom_sig:
        {
          const struct TALER_BlindedDenominationSignature *denom_sigs = data;
          size_t len;

          buffers  = GNUNET_new_array (num, void *);
          buffer_lengths  = GNUNET_new_array (num, size_t);

          for (size_t i = 0; i<num; i++)
          {
            const struct GNUNET_CRYPTO_BlindedSignature *bs =
              denom_sigs[i].blinded_sig;

            switch (bs->cipher)
            {
            case GNUNET_CRYPTO_BSA_RSA:
              len = GNUNET_CRYPTO_rsa_signature_encode (
                bs->details.blinded_rsa_signature,
                &buffers[i]);
              RETURN_UNLESS (len != 0);
              break;
            case GNUNET_CRYPTO_BSA_CS:
              len = sizeof (bs->details.blinded_cs_answer);
              break;
            default:
              GNUNET_assert (0);
            }

            /* for the cipher and marker */
            len += 2 * sizeof(uint32_t);
            buffer_lengths[i] = len;

            y = total_size;
            total_size += len;
            RETURN_UNLESS (total_size >= y);
          }
          sizes = buffer_lengths;
          break;
        }
      default:
        GNUNET_assert (0);
      }
    }

    RETURN_UNLESS (INT_MAX > total_size);
    RETURN_UNLESS (0 != total_size);

    elements = GNUNET_malloc (total_size);
  }

  /* Write data */
  {
    char *out = elements;
    struct GNUNET_PQ_ArrayHeader_P h = {
      .ndim = htonl (1),        /* We only support one-dimensional arrays */
      .has_null = htonl (0),    /* We do not support NULL entries in arrays */
      .lbound = htonl (1),      /* Default start index value */
      .dim = htonl (num),
      .oid = htonl (meta->oid),
    };

    /* Write header */
    GNUNET_memcpy (out,
                   &h,
                   sizeof(h));
    out += sizeof(h);

    /* Write elements */
    for (size_t i = 0; i < num; i++)
    {
      size_t sz = same_sized ? meta->same_size : sizes[i];

      *(uint32_t *) out = htonl (sz);
      out += sizeof(uint32_t);
      switch (meta->typ)
      {
      case TALER_PQ_array_of_amount:
        {
          const struct TALER_Amount *amounts = data;
          Oid oid_v;
          Oid oid_f;

          /* hoist out of loop? */
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int8",
                                                    &oid_v));
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int4",
                                                    &oid_f));
          {
            struct TALER_PQ_AmountP am
              = TALER_PQ_make_taler_pq_amount_ (
                  &amounts[i],
                  oid_v,
                  oid_f);

            GNUNET_memcpy (out,
                           &am,
                           sizeof(am));
          }
          break;
        }
      case TALER_PQ_array_of_amount_currency:
        {
          const struct TALER_Amount *amounts = data;
          Oid oid_v;
          Oid oid_f;
          Oid oid_c;

          /* hoist out of loop? */
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int8",
                                                    &oid_v));
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "int4",
                                                    &oid_f));
          GNUNET_assert (GNUNET_OK ==
                         GNUNET_PQ_get_oid_by_name (meta->db,
                                                    "varchar",
                                                    &oid_c));
          {
            struct TALER_PQ_AmountCurrencyP am;
            size_t len;

            len = TALER_PQ_make_taler_pq_amount_currency_ (
              &amounts[i],
              oid_v,
              oid_f,
              oid_c,
              &am);
            GNUNET_memcpy (out,
                           &am,
                           len);
          }
          break;
        }
      case TALER_PQ_array_of_blinded_denom_sig:
        {
          const struct TALER_BlindedDenominationSignature *denom_sigs = data;
          const struct GNUNET_CRYPTO_BlindedSignature *bs =
            denom_sigs[i].blinded_sig;
          uint32_t be[2];

          be[0] = htonl ((uint32_t) bs->cipher);
          be[1] = htonl (0x01);     /* magic margker: blinded */
          GNUNET_memcpy (out,
                         &be,
                         sizeof(be));
          out += sizeof(be);
          sz -= sizeof(be);

          switch (bs->cipher)
          {
          case GNUNET_CRYPTO_BSA_RSA:
            /* For RSA, 'same_sized' must have been false */
            GNUNET_assert (NULL != buffers);
            GNUNET_memcpy (out,
                           buffers[i],
                           sz);
            break;
          case GNUNET_CRYPTO_BSA_CS:
            GNUNET_memcpy (out,
                           &bs->details.blinded_cs_answer,
                           sz);
            break;
          default:
            GNUNET_assert (0);
          }
          break;
        }
      case TALER_PQ_array_of_blinded_coin_hash:
        {
          const struct TALER_BlindedCoinHashP *coin_hs = data;

          GNUNET_memcpy (out,
                         &coin_hs[i],
                         sizeof(struct TALER_BlindedCoinHashP));

          break;
        }
      case TALER_PQ_array_of_denom_hash:
        {
          const struct TALER_DenominationHashP *denom_hs = data;

          GNUNET_memcpy (out,
                         &denom_hs[i],
                         sizeof(struct TALER_DenominationHashP));
          break;
        }
      case TALER_PQ_array_of_hash_code:
        {
          const struct GNUNET_HashCode *hashes = data;

          GNUNET_memcpy (out,
                         &hashes[i],
                         sizeof(struct GNUNET_HashCode));
          break;
        }
      default:
        {
          GNUNET_assert (0);
          break;
        }
      }
      out += sz;
    }
  }
  param_values[0] = elements;
  param_lengths[0] = total_size;
  param_formats[0] = 1;
  scratch[0] = elements;

DONE:
  if (NULL != buffers)
  {
    for (size_t i = 0; i<num; i++)
      GNUNET_free (buffers[i]);
    GNUNET_free (buffers);
  }
  GNUNET_free (buffer_lengths);
  if (noerror)
    return 1;
  return -1;
}


/**
 * Function to generate a typ specific query parameter and corresponding closure
 *
 * @param num Number of elements in @a elements
 * @param continuous If true, @a elements is an continuous array of data
 * @param elements Array of @a num elements, either continuous or pointers
 * @param sizes Array of @a num sizes, one per element, may be NULL
 * @param same_size If not 0, all elements in @a elements have this size
 * @param typ Supported internal type of each element in @a elements
 * @param oid Oid of the type to be used in Postgres
 * @param[in,out] db our database handle for looking up OIDs
 * @return Query parameter
 */
static struct GNUNET_PQ_QueryParam
query_param_array_generic (
  unsigned int num,
  bool continuous,
  const void *elements,
  const size_t *sizes,
  size_t same_size,
  enum TALER_PQ_ArrayType typ,
  Oid oid,
  struct GNUNET_PQ_Context *db)
{
  struct qconv_array_cls *meta = GNUNET_new (struct qconv_array_cls);

  meta->typ = typ;
  meta->oid = oid;
  meta->sizes = sizes;
  meta->same_size = same_size;
  meta->continuous = continuous;
  meta->db = db;

  {
    struct GNUNET_PQ_QueryParam res = {
      .conv = qconv_array,
      .conv_cls = meta,
      .conv_cls_cleanup = qconv_array_cls_cleanup,
      .data = elements,
      .size = num,
      .num_params = 1,
    };

    return res;
  }
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_blinded_denom_sig (
  size_t num,
  const struct TALER_BlindedDenominationSignature *denom_sigs,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db,
                                            "bytea",
                                            &oid));
  return query_param_array_generic (num,
                                    true,
                                    denom_sigs,
                                    NULL,
                                    0,
                                    TALER_PQ_array_of_blinded_denom_sig,
                                    oid,
                                    NULL);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_blinded_coin_hash (
  size_t num,
  const struct TALER_BlindedCoinHashP *coin_hs,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db,
                                            "bytea",
                                            &oid));
  return query_param_array_generic (num,
                                    true,
                                    coin_hs,
                                    NULL,
                                    sizeof(struct TALER_BlindedCoinHashP),
                                    TALER_PQ_array_of_blinded_coin_hash,
                                    oid,
                                    NULL);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_denom_hash (
  size_t num,
  const struct TALER_DenominationHashP *denom_hs,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db,
                                            "bytea",
                                            &oid));
  return query_param_array_generic (num,
                                    true,
                                    denom_hs,
                                    NULL,
                                    sizeof(struct TALER_DenominationHashP),
                                    TALER_PQ_array_of_denom_hash,
                                    oid,
                                    NULL);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_hash_code (
  size_t num,
  const struct GNUNET_HashCode *hashes,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db, "gnunet_hashcode", &oid));
  return query_param_array_generic (num,
                                    true,
                                    hashes,
                                    NULL,
                                    sizeof(struct GNUNET_HashCode),
                                    TALER_PQ_array_of_hash_code,
                                    oid,
                                    NULL);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_amount (
  size_t num,
  const struct TALER_Amount *amounts,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db,
                                            "taler_amount",
                                            &oid));
  return query_param_array_generic (
    num,
    true,
    amounts,
    NULL,
    sizeof(struct TALER_PQ_AmountP),
    TALER_PQ_array_of_amount,
    oid,
    db);
}


struct GNUNET_PQ_QueryParam
TALER_PQ_query_param_array_amount_with_currency (
  size_t num,
  const struct TALER_Amount *amounts,
  struct GNUNET_PQ_Context *db)
{
  Oid oid;

  GNUNET_assert (GNUNET_OK ==
                 GNUNET_PQ_get_oid_by_name (db,
                                            "taler_amount_currency",
                                            &oid));
  return query_param_array_generic (
    num,
    true,
    amounts,
    NULL,
    0, /* currency is technically variable length */
    TALER_PQ_array_of_amount_currency,
    oid,
    db);
}


/* end of pq/pq_query_helper.c */