/*
  This file is part of TALER
  (C) 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 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_contract.c
 * @brief shared logic for contract terms handling
 * @author Christian Blättler
 */
#include "platform.h"
#include <gnunet/gnunet_common.h>
#include <jansson.h>
#include <stdint.h>
#include "taler-merchant-httpd_contract.h"

enum TALER_MerchantContractInputType
TMH_contract_input_type_from_string (const char *str)
{
  /* For now, only 'token' is the only supported option. */
  if (0 == strcmp("token", str))
  {
    return TALER_MCIT_TOKEN;
  }

  return TALER_MCIT_INVALID;
}

enum TALER_MerchantContractOutputType
TMH_contract_output_type_from_string (const char *str)
{
  /* For now, only 'token' is the only supported option. */
  if (0 == strcmp("token", str))
  {
    return TALER_MCOT_TOKEN;
  }

  return TALER_MCOT_INVALID;
}

const char *
TMH_string_from_contract_input_type (enum TALER_MerchantContractInputType t)
{
  switch (t) {
  case TALER_MCIT_TOKEN:
    return "token";
  case TALER_MCIT_COIN:
    return "coin";
  default:
    return "invalid";
  }
}

const char *
TMH_string_from_contract_output_type (enum TALER_MerchantContractOutputType t)
{
  switch (t) {
  case TALER_MCOT_TOKEN:
    return "token";
  case TALER_MCOT_COIN:
    return "coin";
  case TALER_MCOT_TAX_RECEIPT:
    return "tax_receipt";
  default:
    return "invalid";
  }
}

/**
 * Parse given JSON object to choices array.
 *
 * @param cls closure, pointer to array length
 * @param root the json array representing the choices
 * @param[out] spec where to write the data
 * @return #GNUNET_OK upon successful parsing; #GNUNET_SYSERR upon error
 */
static enum GNUNET_GenericReturnValue
parse_choices (void *cls,
              json_t *root,
              struct GNUNET_JSON_Specification *spec)
{
  struct TALER_MerchantContractChoice **choices = spec->ptr;
  unsigned int *choices_len = cls;
  if (!json_is_array (root))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  GNUNET_array_grow (*choices,
                     *choices_len,
                     json_array_size (root));

  for (unsigned int i = 0; i<*choices_len; i++)
  {
    const json_t *jinputs;
    const json_t *joutputs;
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_array_const ("inputs",
                                    &jinputs),
      GNUNET_JSON_spec_array_const ("outputs",
                                    &joutputs),
      GNUNET_JSON_spec_end ()
    };
    const char *error_name;
    unsigned int error_line;
    struct TALER_MerchantContractChoice *choice = &(*choices)[i];

    if (GNUNET_OK !=
        GNUNET_JSON_parse (json_array_get (root, i),
                          spec,
                          &error_name,
                          &error_line))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Failed to parse %s at %u: %s\n",
                  spec[error_line].field,
                  error_line,
                  error_name);
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }

    {
      const json_t *jinput;
      size_t idx;
      json_array_foreach ((json_t *) jinputs, idx, jinput)
      {
        struct TALER_MerchantContractInput input = {.details.token.count = 1};
        const char *kind;
        struct GNUNET_JSON_Specification ispec[] = {
          GNUNET_JSON_spec_string ("kind",
                                    &kind),
          GNUNET_JSON_spec_string ("token_family_slug",
                                    &input.details.token.token_family_slug),
          GNUNET_JSON_spec_timestamp ("valid_after",
                                      &input.details.token.valid_after),
          GNUNET_JSON_spec_mark_optional (
            GNUNET_JSON_spec_uint32 ("count",
                                      &input.details.token.count),
            NULL),
          GNUNET_JSON_spec_end()
        };
        const char *ierror_name;
        unsigned int ierror_line;

        if (GNUNET_OK !=
            GNUNET_JSON_parse (jinput,
                                ispec,
                                &ierror_name,
                                &ierror_line))
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      "Failed to parse %s at %u: %s\n",
                      spec[ierror_line].field,
                      ierror_line,
                      ierror_name);
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }

        input.type = TMH_contract_input_type_from_string (kind);

        if (TALER_MCIT_INVALID == input.type)
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      "Field 'kind' invalid in input #%u\n",
                      (unsigned int) idx);
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }

        if (0 == input.details.token.count)
        {
          /* Ignore inputs with 'number' field set to 0 */
          continue;
        }

        GNUNET_array_append (choice->inputs,
                             choice->inputs_len,
                             input);
      }
    }

    {
      const json_t *joutput;
      size_t idx;
      json_array_foreach ((json_t *) joutputs, idx, joutput)
      {
        struct TALER_MerchantContractOutput output = {.details.token.count = 1};
        const char *kind;
        struct GNUNET_JSON_Specification ispec[] = {
          GNUNET_JSON_spec_string ("kind",
                                    &kind),
          GNUNET_JSON_spec_string ("token_family_slug",
                                    &output.details.token.token_family_slug),
          GNUNET_JSON_spec_timestamp ("valid_after",
                                      &output.details.token.valid_after),
          GNUNET_JSON_spec_mark_optional (
            GNUNET_JSON_spec_uint32 ("count",
                                      &output.details.token.count),
            NULL),
          GNUNET_JSON_spec_end()
        };
        const char *ierror_name;
        unsigned int ierror_line;

        if (GNUNET_OK !=
            GNUNET_JSON_parse (joutput,
                                ispec,
                                &ierror_name,
                                &ierror_line))
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      "Failed to parse %s at %u: %s\n",
                      spec[ierror_line].field,
                      ierror_line,
                      ierror_name);
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }

        output.type = TMH_contract_output_type_from_string (kind);

        if (TALER_MCOT_INVALID == output.type)
        {
          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                      "Field 'kind' invalid in output #%u\n",
                      (unsigned int) idx);
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }

        if (0 == output.details.token.count)
        {
          /* Ignore outputs with 'number' field set to 0 */
          continue;
        }

        GNUNET_array_append (choice->outputs,
                             choice->outputs_len,
                             output);
      }
    }
  }

  return GNUNET_OK;
}


struct GNUNET_JSON_Specification
TALER_JSON_spec_choices (const char *name,
                         struct TALER_MerchantContractChoice **choices,
                         unsigned int *choices_len)
{
  struct GNUNET_JSON_Specification ret = {
    .cls = (void *) choices_len,
    .parser = &parse_choices,
    .field = name,
    .ptr = choices,
  };

  return ret;
}


/**
 * Parse given JSON object to token families array.
 *
 * @param cls closure, pointer to array length
 * @param root the json object representing the token families. The keys are
 *             the token family slugs.
 * @param[out] spec where to write the data
 * @return #GNUNET_OK upon successful parsing; #GNUNET_SYSERR upon error
 */
static enum GNUNET_GenericReturnValue
parse_token_families (void *cls,
                      json_t *root,
                      struct GNUNET_JSON_Specification *spec)
{
  struct TALER_MerchantContractTokenFamily **families = spec->ptr;
  unsigned int *families_len = cls;
  json_t *jfamily;
  const char *slug;
  if (!json_is_object (root))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }

  json_object_foreach(root, slug, jfamily)
  {
    const json_t *keys;
    struct TALER_MerchantContractTokenFamily family = {
      .slug = slug
    };

    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_array_const ("keys",
                                     &keys),
      GNUNET_JSON_spec_bool ("critical",
                              &family.critical),
      GNUNET_JSON_spec_end ()
      /* TODO: Figure out if these fields should be 'const' */
      // GNUNET_JSON_spec_string ("description",
      //                          &family.description),
      // GNUNET_JSON_spec_object_const ("description_i18n",
      //                                &family.description_i18n),
    };
    const char *error_name;
    unsigned int error_line;

    if (GNUNET_OK !=
        GNUNET_JSON_parse (jfamily,
                          spec,
                          &error_name,
                          &error_line))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "Failed to parse %s at %u: %s\n",
                  spec[error_line].field,
                  error_line,
                  error_name);
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }

    GNUNET_array_grow (family.keys,
                       family.keys_len,
                       json_array_size (keys));

    for (unsigned int i = 0; i<family.keys_len; i++)
    {
      /* TODO: Move this to TALER_JSON_spec_token_issue_key */
      int64_t cipher;
      struct TALER_MerchantContractTokenFamilyKey *key;
      key = &family.keys[i];
      /* TODO: Free when not used anymore */
      key->pub.public_key = GNUNET_new (struct GNUNET_CRYPTO_BlindSignPublicKey);
      struct GNUNET_JSON_Specification key_spec[] = {
        GNUNET_JSON_spec_fixed_auto ("h_pub",
                                   &key->pub.public_key->pub_key_hash),
        GNUNET_JSON_spec_rsa_public_key ("rsa_pub",
                                         &key->pub.public_key->details.rsa_public_key),
        //   GNUNET_JSON_spec_fixed_auto ("cs_pub",
        //                               &key.pub.public_key->details.cs_public_key)),
        GNUNET_JSON_spec_int64 ("cipher",
                                &cipher),
        GNUNET_JSON_spec_timestamp ("valid_after",
                                    &key->valid_after),
        GNUNET_JSON_spec_timestamp ("valid_before",
                                    &key->valid_before),
        GNUNET_JSON_spec_end()
      };
      const char *ierror_name;
      unsigned int ierror_line;

      if (GNUNET_OK !=
          GNUNET_JSON_parse (json_array_get (keys, i),
                             key_spec,
                             &ierror_name,
                             &ierror_line))
      {
        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                    "Failed to parse %s at %u: %s\n",
                    key_spec[ierror_line].field,
                    ierror_line,
                    ierror_name);
        GNUNET_break_op (0);
        return GNUNET_SYSERR;
      }

      switch (cipher) {
      case GNUNET_CRYPTO_BSA_RSA:
        key->pub.public_key->cipher = GNUNET_CRYPTO_BSA_RSA;
        break;
      case GNUNET_CRYPTO_BSA_CS:
        key->pub.public_key->cipher = GNUNET_CRYPTO_BSA_CS;
        break;
      case GNUNET_CRYPTO_BSA_INVALID:
        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                    "Field 'cipher' invalid in key #%u\n",
                    i);
        GNUNET_break_op (0);
        return GNUNET_SYSERR;
      }
    }

    GNUNET_array_append (*families, *families_len, family);
  }

  return GNUNET_OK;
}


struct GNUNET_JSON_Specification
TALER_JSON_spec_token_families (const char *name,
                                struct TALER_MerchantContractTokenFamily **families,
                                unsigned int *families_len)
{
  struct GNUNET_JSON_Specification ret = {
    .cls = (void *) families_len,
    .parser = &parse_token_families,
    .field = name,
    .ptr = families,
  };

  return ret;
}

enum GNUNET_GenericReturnValue
TMH_find_token_family_key (const char *slug,
                           struct GNUNET_TIME_Timestamp valid_after,
                           struct TALER_MerchantContractTokenFamily *families,
                           unsigned int families_len,
                           struct TALER_MerchantContractTokenFamily *family,
                           struct TALER_MerchantContractTokenFamilyKey *key)
{
  for (unsigned int i = 0; i < families_len; i++)
  {
    if (0 != strcmp (families[i].slug, slug))
    {
      continue;
    }
    if (NULL != family)
    {
      *family = families[i];
    }
    for (unsigned int k = 0; k < family->keys_len; k++)
    {
      if (GNUNET_TIME_timestamp_cmp(family->keys[k].valid_after,
                                    ==,
                                    valid_after))
      {
        if (NULL != key)
        {
          *key = family->keys[k];
        }
        return GNUNET_OK;
      }
    }
    /* matching family found, but no key. */
    return GNUNET_NO;
  }

  /* no matching family found */
  return GNUNET_NO;
}