/*
   This file is part of TALER
   Copyright (C) 2022-2023 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 lib/exchange_api_purse_create_with_deposit.c
 * @brief Implementation of the client to create a purse with
 *        an initial set of deposits (and a contract)
 * @author Christian Grothoff
 */
#include "platform.h"
#include <jansson.h>
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_json_lib.h>
#include <gnunet/gnunet_curl_lib.h>
#include "taler_json_lib.h"
#include "taler_exchange_service.h"
#include "exchange_api_handle.h"
#include "exchange_api_common.h"
#include "taler_signatures.h"
#include "exchange_api_curl_defaults.h"


/**
 * Information we track per deposited coin.
 */
struct Deposit
{
  /**
   * Coin's public key.
   */
  struct TALER_CoinSpendPublicKeyP coin_pub;

  /**
   * Signature made with the coin.
   */
  struct TALER_CoinSpendSignatureP coin_sig;

  /**
   * Coin's denomination.
   */
  struct TALER_DenominationHashP h_denom_pub;

  /**
   * Age restriction hash for the coin.
   */
  struct TALER_AgeCommitmentHash ahac;

  /**
   * How much did we say the coin contributed.
   */
  struct TALER_Amount contribution;
};


/**
 * @brief A purse create with deposit handle
 */
struct TALER_EXCHANGE_PurseCreateDepositHandle
{

  /**
   * The keys of the exchange this request handle will use
   */
  struct TALER_EXCHANGE_Keys *keys;

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

  /**
   * The base URL of the exchange.
   */
  char *exchange_url;

  /**
   * Context for #TEH_curl_easy_post(). Keeps the data that must
   * persist for Curl to make the upload.
   */
  struct TALER_CURL_PostContext ctx;

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

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

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

  /**
   * Expected value in the purse after fees.
   */
  struct TALER_Amount purse_value_after_fees;

  /**
   * Our encrypted contract (if we had any).
   */
  struct TALER_EncryptedContract econtract;

  /**
   * Public key of the merge capability.
   */
  struct TALER_PurseMergePublicKeyP merge_pub;

  /**
   * Public key of the purse.
   */
  struct TALER_PurseContractPublicKeyP purse_pub;

  /**
   * Signature with the purse key on the request.
   */
  struct TALER_PurseContractSignatureP purse_sig;

  /**
   * Hash over the purse's contract terms.
   */
  struct TALER_PrivateContractHashP h_contract_terms;

  /**
   * When does the purse expire.
   */
  struct GNUNET_TIME_Timestamp purse_expiration;

  /**
   * Array of @e num_deposit deposits.
   */
  struct Deposit *deposits;

  /**
   * How many deposits did we make?
   */
  unsigned int num_deposits;

};


/**
 * Function called when we're done processing the
 * HTTP /deposit request.
 *
 * @param cls the `struct TALER_EXCHANGE_DepositHandle`
 * @param response_code HTTP response code, 0 on error
 * @param response parsed JSON result, NULL on error
 */
static void
handle_purse_create_deposit_finished (void *cls,
                                      long response_code,
                                      const void *response)
{
  struct TALER_EXCHANGE_PurseCreateDepositHandle *pch = cls;
  const json_t *j = response;
  struct TALER_EXCHANGE_PurseCreateDepositResponse dr = {
    .hr.reply = j,
    .hr.http_status = (unsigned int) response_code
  };
  const struct TALER_EXCHANGE_Keys *keys = pch->keys;

  pch->job = NULL;
  switch (response_code)
  {
  case 0:
    dr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
    break;
  case MHD_HTTP_OK:
    {
      struct GNUNET_TIME_Timestamp etime;
      struct TALER_Amount total_deposited;
      struct TALER_ExchangeSignatureP exchange_sig;
      struct TALER_ExchangePublicKeyP exchange_pub;
      struct GNUNET_JSON_Specification spec[] = {
        GNUNET_JSON_spec_fixed_auto ("exchange_sig",
                                     &exchange_sig),
        GNUNET_JSON_spec_fixed_auto ("exchange_pub",
                                     &exchange_pub),
        GNUNET_JSON_spec_timestamp ("exchange_timestamp",
                                    &etime),
        TALER_JSON_spec_amount ("total_deposited",
                                pch->purse_value_after_fees.currency,
                                &total_deposited),
        GNUNET_JSON_spec_end ()
      };

      if (GNUNET_OK !=
          GNUNET_JSON_parse (j,
                             spec,
                             NULL, NULL))
      {
        GNUNET_break_op (0);
        dr.hr.http_status = 0;
        dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
        break;
      }
      if (GNUNET_OK !=
          TALER_EXCHANGE_test_signing_key (keys,
                                           &exchange_pub))
      {
        GNUNET_break_op (0);
        dr.hr.http_status = 0;
        dr.hr.ec = TALER_EC_EXCHANGE_PURSE_CREATE_EXCHANGE_SIGNATURE_INVALID;
        break;
      }
      if (GNUNET_OK !=
          TALER_exchange_online_purse_created_verify (
            etime,
            pch->purse_expiration,
            &pch->purse_value_after_fees,
            &total_deposited,
            &pch->purse_pub,
            &pch->h_contract_terms,
            &exchange_pub,
            &exchange_sig))
      {
        GNUNET_break_op (0);
        dr.hr.http_status = 0;
        dr.hr.ec = TALER_EC_EXCHANGE_PURSE_CREATE_EXCHANGE_SIGNATURE_INVALID;
        break;
      }
    }
    break;
  case MHD_HTTP_BAD_REQUEST:
    /* This should never happen, either us or the exchange is buggy
       (or API version conflict); just pass JSON reply to the application */
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_FORBIDDEN:
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    /* Nothing really to verify, exchange says one of the signatures is
       invalid; as we checked them, this should never happen, we
       should pass the JSON reply to the application */
    break;
  case MHD_HTTP_NOT_FOUND:
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    /* Nothing really to verify, this should never
       happen, we should pass the JSON reply to the application */
    break;
  case MHD_HTTP_CONFLICT:
    {
      dr.hr.ec = TALER_JSON_get_error_code (j);
      switch (dr.hr.ec)
      {
      case TALER_EC_EXCHANGE_PURSE_CREATE_CONFLICTING_META_DATA:
        if (GNUNET_OK !=
            TALER_EXCHANGE_check_purse_create_conflict_ (
              &pch->purse_sig,
              &pch->purse_pub,
              j))
        {
          GNUNET_break_op (0);
          dr.hr.http_status = 0;
          dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
          break;
        }
        break;
      case TALER_EC_EXCHANGE_GENERIC_INSUFFICIENT_FUNDS:
        /* Nothing to check anymore here, proof needs to be
           checked in the GET /coins/$COIN_PUB handler */
        break;
      case TALER_EC_EXCHANGE_GENERIC_COIN_CONFLICTING_DENOMINATION_KEY:
        // FIXME #7267: write check (add to exchange_api_common! */
        break;
      case TALER_EC_EXCHANGE_PURSE_DEPOSIT_CONFLICTING_META_DATA:
        {
          struct TALER_CoinSpendPublicKeyP coin_pub;
          struct TALER_CoinSpendSignatureP coin_sig;
          struct TALER_DenominationHashP h_denom_pub;
          struct TALER_AgeCommitmentHash phac;
          bool found = false;

          if (GNUNET_OK !=
              TALER_EXCHANGE_check_purse_coin_conflict_ (
                &pch->purse_pub,
                pch->exchange_url,
                j,
                &h_denom_pub,
                &phac,
                &coin_pub,
                &coin_sig))
          {
            GNUNET_break_op (0);
            dr.hr.http_status = 0;
            dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
            break;
          }
          for (unsigned int i = 0; i<pch->num_deposits; i++)
          {
            struct Deposit *deposit = &pch->deposits[i];

            if (0 !=
                GNUNET_memcmp (&coin_pub,
                               &deposit->coin_pub))
              continue;
            if (0 !=
                GNUNET_memcmp (&deposit->h_denom_pub,
                               &h_denom_pub))
            {
              found = true;
              break;
            }
            if (0 !=
                GNUNET_memcmp (&deposit->ahac,
                               &phac))
            {
              found = true;
              break;
            }
            if (0 ==
                GNUNET_memcmp (&coin_sig,
                               &deposit->coin_sig))
            {
              GNUNET_break_op (0);
              continue;
            }
            found = true;
            break;
          }
          if (! found)
          {
            /* conflict is for a different coin! */
            GNUNET_break_op (0);
            dr.hr.http_status = 0;
            dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
            break;
          }
        }
      case TALER_EC_EXCHANGE_PURSE_ECONTRACT_CONFLICTING_META_DATA:
        if (GNUNET_OK !=
            TALER_EXCHANGE_check_purse_econtract_conflict_ (
              &pch->econtract.econtract_sig,
              &pch->purse_pub,
              j))
        {
          GNUNET_break_op (0);
          dr.hr.http_status = 0;
          dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
          break;
        }
        break;
      default:
        GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                    "Unexpected error code %d for conflcting deposit\n",
                    dr.hr.ec);
        GNUNET_break_op (0);
        dr.hr.http_status = 0;
        dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
      }
    }
    break;
  case MHD_HTTP_GONE:
    /* could happen if denomination was revoked */
    /* Note: one might want to check /keys for revocation
       signature here, alas tricky in case our /keys
       is outdated => left to clients */
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    break;
  case MHD_HTTP_INTERNAL_SERVER_ERROR:
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    /* Server had an internal issue; we should retry, but this API
       leaves this to the application */
    break;
  default:
    /* unexpected response code */
    dr.hr.ec = TALER_JSON_get_error_code (j);
    dr.hr.hint = TALER_JSON_get_error_hint (j);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unexpected response code %u/%d for exchange deposit\n",
                (unsigned int) response_code,
                dr.hr.ec);
    GNUNET_break_op (0);
    break;
  }
  pch->cb (pch->cb_cls,
           &dr);
  TALER_EXCHANGE_purse_create_with_deposit_cancel (pch);
}


struct TALER_EXCHANGE_PurseCreateDepositHandle *
TALER_EXCHANGE_purse_create_with_deposit (
  struct GNUNET_CURL_Context *ctx,
  const char *url,
  struct TALER_EXCHANGE_Keys *keys,
  const struct TALER_PurseContractPrivateKeyP *purse_priv,
  const struct TALER_PurseMergePrivateKeyP *merge_priv,
  const struct TALER_ContractDiffiePrivateP *contract_priv,
  const json_t *contract_terms,
  unsigned int num_deposits,
  const struct TALER_EXCHANGE_PurseDeposit deposits[static num_deposits],
  bool upload_contract,
  TALER_EXCHANGE_PurseCreateDepositCallback cb,
  void *cb_cls)
{
  struct TALER_EXCHANGE_PurseCreateDepositHandle *pch;
  json_t *create_obj;
  json_t *deposit_arr;
  CURL *eh;
  char arg_str[sizeof (pch->purse_pub) * 2 + 32];
  uint32_t min_age = 0;

  pch = GNUNET_new (struct TALER_EXCHANGE_PurseCreateDepositHandle);
  pch->cb = cb;
  pch->cb_cls = cb_cls;
  {
    struct GNUNET_JSON_Specification spec[] = {
      GNUNET_JSON_spec_timestamp ("pay_deadline",
                                  &pch->purse_expiration),
      TALER_JSON_spec_amount_any ("amount",
                                  &pch->purse_value_after_fees),
      GNUNET_JSON_spec_mark_optional (
        GNUNET_JSON_spec_uint32 ("minimum_age",
                                 &min_age),
        NULL),
      GNUNET_JSON_spec_end ()
    };

    if (GNUNET_OK !=
        GNUNET_JSON_parse (contract_terms,
                           spec,
                           NULL, NULL))
    {
      GNUNET_break (0);
      return NULL;
    }
  }
  if (GNUNET_OK !=
      TALER_JSON_contract_hash (contract_terms,
                                &pch->h_contract_terms))
  {
    GNUNET_break (0);
    return NULL;
  }
  GNUNET_CRYPTO_eddsa_key_get_public (&purse_priv->eddsa_priv,
                                      &pch->purse_pub.eddsa_pub);
  {
    char pub_str[sizeof (pch->purse_pub) * 2];
    char *end;

    end = GNUNET_STRINGS_data_to_string (
      &pch->purse_pub,
      sizeof (pch->purse_pub),
      pub_str,
      sizeof (pub_str));
    *end = '\0';
    GNUNET_snprintf (arg_str,
                     sizeof (arg_str),
                     "purses/%s/create",
                     pub_str);
  }
  GNUNET_CRYPTO_eddsa_key_get_public (&merge_priv->eddsa_priv,
                                      &pch->merge_pub.eddsa_pub);
  pch->url = TALER_url_join (url,
                             arg_str,
                             NULL);
  if (NULL == pch->url)
  {
    GNUNET_break (0);
    GNUNET_free (pch);
    return NULL;
  }
  pch->num_deposits = num_deposits;
  pch->deposits = GNUNET_new_array (num_deposits,
                                    struct Deposit);
  deposit_arr = json_array ();
  GNUNET_assert (NULL != deposit_arr);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Signing with URL `%s'\n",
              url);
  for (unsigned int i = 0; i<num_deposits; i++)
  {
    const struct TALER_EXCHANGE_PurseDeposit *deposit = &deposits[i];
    const struct TALER_AgeCommitmentProof *acp = deposit->age_commitment_proof;
    struct Deposit *d = &pch->deposits[i];
    json_t *jdeposit;
    struct TALER_AgeCommitmentHash *aghp = NULL;
    struct TALER_AgeAttestation attest;
    struct TALER_AgeAttestation *attestp = NULL;

    if (NULL != acp)
    {
      TALER_age_commitment_hash (&acp->commitment,
                                 &d->ahac);
      aghp = &d->ahac;
      if (GNUNET_OK !=
          TALER_age_commitment_attest (acp,
                                       min_age,
                                       &attest))
      {
        GNUNET_break (0);
        GNUNET_array_grow (pch->deposits,
                           pch->num_deposits,
                           0);
        GNUNET_free (pch->url);
        json_decref (deposit_arr);
        GNUNET_free (pch);
        return NULL;
      }
    }
    d->contribution = deposit->amount;
    d->h_denom_pub = deposit->h_denom_pub;
    GNUNET_CRYPTO_eddsa_key_get_public (&deposit->coin_priv.eddsa_priv,
                                        &d->coin_pub.eddsa_pub);
    TALER_wallet_purse_deposit_sign (
      url,
      &pch->purse_pub,
      &deposit->amount,
      &d->h_denom_pub,
      &d->ahac,
      &deposit->coin_priv,
      &d->coin_sig);
    jdeposit = GNUNET_JSON_PACK (
      GNUNET_JSON_pack_allow_null (
        GNUNET_JSON_pack_data_auto ("h_age_commitment",
                                    aghp)),
      GNUNET_JSON_pack_allow_null (
        GNUNET_JSON_pack_data_auto ("age_attestation",
                                    attestp)),
      TALER_JSON_pack_amount ("amount",
                              &deposit->amount),
      GNUNET_JSON_pack_data_auto ("denom_pub_hash",
                                  &deposit->h_denom_pub),
      TALER_JSON_pack_denom_sig ("ub_sig",
                                 &deposit->denom_sig),
      GNUNET_JSON_pack_data_auto ("coin_sig",
                                  &d->coin_sig),
      GNUNET_JSON_pack_data_auto ("coin_pub",
                                  &d->coin_pub));
    GNUNET_assert (0 ==
                   json_array_append_new (deposit_arr,
                                          jdeposit));
  }
  TALER_wallet_purse_create_sign (pch->purse_expiration,
                                  &pch->h_contract_terms,
                                  &pch->merge_pub,
                                  min_age,
                                  &pch->purse_value_after_fees,
                                  purse_priv,
                                  &pch->purse_sig);
  if (upload_contract)
  {
    TALER_CRYPTO_contract_encrypt_for_merge (&pch->purse_pub,
                                             contract_priv,
                                             merge_priv,
                                             contract_terms,
                                             &pch->econtract.econtract,
                                             &pch->econtract.econtract_size);
    GNUNET_CRYPTO_ecdhe_key_get_public (&contract_priv->ecdhe_priv,
                                        &pch->econtract.contract_pub.ecdhe_pub);
    TALER_wallet_econtract_upload_sign (pch->econtract.econtract,
                                        pch->econtract.econtract_size,
                                        &pch->econtract.contract_pub,
                                        purse_priv,
                                        &pch->econtract.econtract_sig);
  }
  create_obj = GNUNET_JSON_PACK (
    TALER_JSON_pack_amount ("amount",
                            &pch->purse_value_after_fees),
    GNUNET_JSON_pack_uint64 ("min_age",
                             min_age),
    GNUNET_JSON_pack_allow_null (
      TALER_JSON_pack_econtract ("econtract",
                                 upload_contract
                                 ? &pch->econtract
                                 : NULL)),
    GNUNET_JSON_pack_data_auto ("purse_sig",
                                &pch->purse_sig),
    GNUNET_JSON_pack_data_auto ("merge_pub",
                                &pch->merge_pub),
    GNUNET_JSON_pack_data_auto ("h_contract_terms",
                                &pch->h_contract_terms),
    GNUNET_JSON_pack_timestamp ("purse_expiration",
                                pch->purse_expiration),
    GNUNET_JSON_pack_array_steal ("deposits",
                                  deposit_arr));
  GNUNET_assert (NULL != create_obj);
  eh = TALER_EXCHANGE_curl_easy_get_ (pch->url);
  if ( (NULL == eh) ||
       (GNUNET_OK !=
        TALER_curl_easy_post (&pch->ctx,
                              eh,
                              create_obj)) )
  {
    GNUNET_break (0);
    if (NULL != eh)
      curl_easy_cleanup (eh);
    json_decref (create_obj);
    GNUNET_free (pch->econtract.econtract);
    GNUNET_array_grow (pch->deposits,
                       pch->num_deposits,
                       0);
    GNUNET_free (pch->url);
    GNUNET_free (pch);
    return NULL;
  }
  json_decref (create_obj);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "URL for purse create with deposit: `%s'\n",
              pch->url);
  pch->keys = TALER_EXCHANGE_keys_incref (keys);
  pch->exchange_url = GNUNET_strdup (url);
  pch->job = GNUNET_CURL_job_add2 (ctx,
                                   eh,
                                   pch->ctx.headers,
                                   &handle_purse_create_deposit_finished,
                                   pch);
  return pch;
}


void
TALER_EXCHANGE_purse_create_with_deposit_cancel (
  struct TALER_EXCHANGE_PurseCreateDepositHandle *pch)
{
  if (NULL != pch->job)
  {
    GNUNET_CURL_job_cancel (pch->job);
    pch->job = NULL;
  }
  GNUNET_free (pch->econtract.econtract);
  GNUNET_free (pch->exchange_url);
  GNUNET_free (pch->url);
  GNUNET_array_grow (pch->deposits,
                     pch->num_deposits,
                     0);
  TALER_EXCHANGE_keys_decref (pch->keys);
  TALER_curl_easy_post_finished (&pch->ctx);
  GNUNET_free (pch);
}


/* end of exchange_api_purse_create_with_deposit.c */