/*
  This file is part of TALER
  Copyright (C) 2014-2017 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 include/taler_exchangedb_lib.h
 * @brief IO operations for the exchange's private keys
 * @author Florian Dold
 * @author Benedikt Mueller
 * @author Christian Grothoff
 */
#ifndef TALER_EXCHANGEDB_LIB_H
#define TALER_EXCHANGEDB_LIB_H

#include "taler_signatures.h"
#include "taler_exchangedb_plugin.h"
#include "taler_bank_service.h"

/**
 * Subdirectroy under the exchange's base directory which contains
 * the exchange's signing keys.
 */
#define TALER_EXCHANGEDB_DIR_SIGNING_KEYS "signkeys"

/**
 * Subdirectory under the exchange's base directory which contains
 * the exchange's denomination keys.
 */
#define TALER_EXCHANGEDB_DIR_DENOMINATION_KEYS "denomkeys"


/**
 * @brief Iterator over signing keys.
 *
 * @param cls closure
 * @param filename name of the file the key came from
 * @param ski the sign key
 * @return #GNUNET_OK to continue to iterate,
 *  #GNUNET_NO to stop iteration with no error,
 *  #GNUNET_SYSERR to abort iteration with error!
 */
typedef int
(*TALER_EXCHANGEDB_SigningKeyIterator)(
  void *cls,
  const char *filename,
  const struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP *ski);


/**
 * Call @a it for each signing key found in the @a exchange_base_dir.
 *
 * @param exchange_base_dir base directory for the exchange,
 *                      the signing keys must be in the #TALER_EXCHANGEDB_DIR_SIGNING_KEYS
 *                      subdirectory
 * @param it function to call on each signing key
 * @param it_cls closure for @a it
 * @return number of files found (may not match
 *         number of keys given to @a it as malformed
 *         files are simply skipped), -1 on error
 */
int
TALER_EXCHANGEDB_signing_keys_iterate (const char *exchange_base_dir,
                                       TALER_EXCHANGEDB_SigningKeyIterator it,
                                       void *it_cls);


/**
 * Exports a signing key to the given file.
 *
 * @param exchange_base_dir base directory for the keys
 * @param start start time of the validity for the key
 * @param ski the signing key
 * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure.
 */
int
TALER_EXCHANGEDB_signing_key_write (
  const char *exchange_base_dir,
  struct GNUNET_TIME_Absolute start,
  const struct TALER_EXCHANGEDB_PrivateSigningKeyInformationP *ski);


/**
 * @brief Iterator over denomination keys.
 *
 * @param cls closure
 * @param alias coin alias
 * @param dki the denomination key
 * @return #GNUNET_OK to continue to iterate,
 *  #GNUNET_NO to stop iteration with no error,
 *  #GNUNET_SYSERR to abort iteration with error!
 */
typedef int
(*TALER_EXCHANGEDB_DenominationKeyIterator)(
  void *cls,
  const char *alias,
  const struct TALER_EXCHANGEDB_DenominationKey *dki);


/**
 * @brief Iterator over revoked denomination keys.
 *
 * @param cls closure
 * @param denom_hash hash of the denomination public key
 * @param revocation_master_sig signature showing @a denom_hash was revoked
 * @return #GNUNET_OK to continue to iterate,
 *  #GNUNET_NO to stop iteration with no error,
 *  #GNUNET_SYSERR to abort iteration with error!
 */
typedef int
(*TALER_EXCHANGEDB_RevocationIterator)(
  void *cls,
  const struct GNUNET_HashCode *denom_hash,
  const struct TALER_MasterSignatureP *revocation_master_sig);


/**
 * Call @a it for each denomination key found in the @a exchange_base_dir.
 *
 * @param exchange_base_dir base directory for the exchange,
 *                      the signing keys must be in the #TALER_EXCHANGEDB_DIR_DENOMINATION_KEYS
 *                      subdirectory
 * @param it function to call on each denomination key found
 * @param it_cls closure for @a it
 * @return -1 on error, 0 if no files were found, otherwise
 *         a positive number (however, even with a positive
 *         number it is possible that @a it was never called
 *         as maybe none of the files were well-formed)
 */
int
TALER_EXCHANGEDB_denomination_keys_iterate (
  const char *exchange_base_dir,
  TALER_EXCHANGEDB_DenominationKeyIterator it,
  void *it_cls);


/**
 * Call @a it for each revoked denomination key found in the @a revocation_dir.
 *
 * @param revocation_dir base directory where revocations are stored
 * @param master_pub master public key (used to check revocations)
 * @param it function to call on each revoked denomination key found
 * @param it_cls closure for @a it
 * @return -1 on error, 0 if no files were found, otherwise
 *         a positive number (however, even with a positive
 *         number it is possible that @a it was never called
 *         as maybe none of the files were well-formed)
 */
int
TALER_EXCHANGEDB_revocations_iterate (
  const char *revocation_dir,
  const struct TALER_MasterPublicKeyP *master_pub,
  TALER_EXCHANGEDB_RevocationIterator it,
  void *it_cls);


/**
 * Mark the given denomination key as revoked and request the wallets
 * to initiate recoup.
 *
 * @param revocation_dir where to write the revocation certificate
 * @param denom_hash hash of the denomination key to revoke
 * @param mpriv master private key to sign with
 * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure.
 */
int
TALER_EXCHANGEDB_denomination_key_revoke (
  const char *revocation_dir,
  const struct GNUNET_HashCode *denom_hash,
  const struct TALER_MasterPrivateKeyP *mpriv);


/**
 * Exports a denomination key to the given file.
 *
 * @param filename the file where to write the denomination key
 * @param dki the denomination key
 * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure.
 */
int
TALER_EXCHANGEDB_denomination_key_write (
  const char *filename,
  const struct TALER_EXCHANGEDB_DenominationKey *dki);


/**
 * Import a denomination key from the given file.
 *
 * @param filename the file to import the key from
 * @param[out] dki set to the imported denomination key
 * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure
 */
int
TALER_EXCHANGEDB_denomination_key_read (
  const char *filename,
  struct TALER_EXCHANGEDB_DenominationKey *dki);


/**
 * @brief Iterator over auditor information.
 *
 * @param cls closure
 * @param apub the auditor's public key
 * @param auditor_url URL of the auditor
 * @param mpub the exchange's public key (as expected by the auditor)
 * @param dki_len length of @a asig and @a dki arrays
 * @param asigs array of the auditor's signatures over the @a dks, of length @a dki_len
 * @param dki array of denomination coin data signed by the auditor, of length @a dki_len
 * @return #GNUNET_OK to continue to iterate,
 *  #GNUNET_NO to stop iteration with no error,
 *  #GNUNET_SYSERR to abort iteration with error!
 */
typedef int
(*TALER_EXCHANGEDB_AuditorIterator)(
  void *cls,
  const struct TALER_AuditorPublicKeyP *apub,
  const char *auditor_url,
  const struct TALER_MasterPublicKeyP *mpub,
  unsigned int dki_len,
  const struct TALER_AuditorSignatureP *asigs,
  const struct TALER_DenominationKeyValidityPS *dki);


/**
 * Call @a it with information for each auditor found in the
 * directory with auditor information as specified in @a cfg.
 *
 * @param cfg configuration to use
 * @param it function to call with auditor information
 * @param it_cls closure for @a it
 * @return -1 on error, 0 if no files were found, otherwise
 *         a positive number (however, even with a positive
 *         number it is possible that @a it was never called
 *         as maybe none of the files were well-formed)
 */
int
TALER_EXCHANGEDB_auditor_iterate (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                  TALER_EXCHANGEDB_AuditorIterator it,
                                  void *it_cls);


/**
 * Write auditor information to the given file.
 *
 * @param filename the file where to write the auditor information to
 * @param apub the auditor's public key
 * @param auditor_url the URL of the auditor
 * @param asigs the auditor's signatures, array of length @a dki_len
 * @param mpub the exchange's public key (as expected by the auditor)
 * @param dki_len length of @a dki and @a asigs arrays
 * @param dki array of denomination coin data signed by the auditor
 * @return #GNUNET_OK upon success; #GNUNET_SYSERR upon failure.
 */
int
TALER_EXCHANGEDB_auditor_write (
  const char *filename,
  const struct TALER_AuditorPublicKeyP *apub,
  const char *auditor_url,
  const struct TALER_AuditorSignatureP *asigs,
  const struct TALER_MasterPublicKeyP *mpub,
  uint32_t dki_len,
  const struct TALER_DenominationKeyValidityPS *dki);


/**
 * Initialize the plugin.
 *
 * @param cfg configuration to use
 * @return NULL on failure
 */
struct TALER_EXCHANGEDB_Plugin *
TALER_EXCHANGEDB_plugin_load (const struct GNUNET_CONFIGURATION_Handle *cfg);


/**
 * Shutdown the plugin.
 *
 * @param plugin plugin to unload
 */
void
TALER_EXCHANGEDB_plugin_unload (struct TALER_EXCHANGEDB_Plugin *plugin);


/**
 * Sorted list of fees to be paid for aggregate wire transfers.
 * Sorted by @e start_date or @e end_date --- both work fine as
 * the resulting order must be the same.
 */
struct TALER_EXCHANGEDB_AggregateFees
{
  /**
   * This is a linked list.
   */
  struct TALER_EXCHANGEDB_AggregateFees *next;

  /**
   * Fee to be paid for wire transfers to a merchant.
   */
  struct TALER_Amount wire_fee;

  /**
   * Fee to be paid when we close a reserve and send funds back.
   */
  struct TALER_Amount closing_fee;

  /**
   * Time when this fee goes into effect (inclusive)
   */
  struct GNUNET_TIME_Absolute start_date;

  /**
   * Time when this fee stops being in effect (exclusive).
   */
  struct GNUNET_TIME_Absolute end_date;

  /**
   * Signature affirming the above fee structure.
   */
  struct TALER_MasterSignatureP master_sig;
};


/**
 * Read the current fee structure from disk.
 *
 * @param cfg configuration to use
 * @param wireplugin name of the wire plugin to read fees for
 * @return sorted list of aggregation fees, NULL on error
 */
struct TALER_EXCHANGEDB_AggregateFees *
TALER_EXCHANGEDB_fees_read (const struct GNUNET_CONFIGURATION_Handle *cfg,
                            const char *wireplugin);


/**
 * Convert @a af to @a wf.
 *
 * @param wiremethod name of the wire method the fees are for
 * @param[in,out] af aggregate fees, host format (updated to round time)
 * @param[out] wf aggregate fees, disk / signature format
 */
void
TALER_EXCHANGEDB_fees_2_wf (const char *wiremethod,
                            struct TALER_EXCHANGEDB_AggregateFees *af,
                            struct TALER_MasterWireFeePS *wf);


/**
 * Write given fee structure to disk.
 *
 * @param filename where to write the fees
 * @param wireplugin name of the plugin for which we write the fees
 * @param af fee structure to write
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
TALER_EXCHANGEDB_fees_write (const char *filename,
                             const char *wireplugin,
                             struct TALER_EXCHANGEDB_AggregateFees *af);


/**
 * Free @a af data structure
 *
 * @param af list to free
 */
void
TALER_EXCHANGEDB_fees_free (struct TALER_EXCHANGEDB_AggregateFees *af);


/**
 * Information about an account from the configuration.
 */
struct TALER_EXCHANGEDB_AccountInfo
{
  /**
   * Section in the configuration file that specifies the
   * account. Must start with "exchange-account-".
   */
  const char *section_name;

  /**
   * Name of the wire method used by this account.
   */
  const char *method;

  /**
   * payto://-URL of the account.
   */
  const char *payto_uri;

  /**
   * Filename containing the signed /wire response, or NULL
   * if not given.
   */
  const char *wire_response_filename;

  /**
   * #GNUNET_YES if this account is enabed to be debited
   * by the taler-exchange-aggregator.
   */
  int debit_enabled;

  /**
   * #GNUNET_YES if this account is enabed to be credited by wallets
   * and needs to be watched by the taler-exchange-wirewatch.
   * Also, the account will only be included in /wire if credit
   * is enabled.
   */
  int credit_enabled;
};


/**
 * Function called with information about a wire account.
 *
 * @param cls closure
 * @param ai account information
 */
typedef void
(*TALER_EXCHANGEDB_AccountCallback)(
  void *cls,
  const struct TALER_EXCHANGEDB_AccountInfo *ai);

/**
 * Parse the configuration to find account information.
 *
 * @param cfg configuration to use
 * @param cb callback to invoke
 * @param cb_cls closure for @a cb
 */
void
TALER_EXCHANGEDB_find_accounts (const struct GNUNET_CONFIGURATION_Handle *cfg,
                                TALER_EXCHANGEDB_AccountCallback cb,
                                void *cb_cls);


/**
 * Calculate the total value of all transactions performed.
 * Stores @a off plus the cost of all transactions in @a tl
 * in @a ret.
 *
 * @param tl transaction list to process
 * @param off offset to use as the starting value
 * @param[out] ret where the resulting total is to be stored
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
 */
int
TALER_EXCHANGEDB_calculate_transaction_list_totals (
  struct TALER_EXCHANGEDB_TransactionList *tl,
  const struct TALER_Amount *off,
  struct TALER_Amount *ret);


/* ***************** convenience functions ******** */

/**
 * Information we keep for each supported account of the exchange.
 */
struct TALER_EXCHANGEDB_WireAccount
{
  /**
   * Accounts are kept in a DLL.
   */
  struct TALER_EXCHANGEDB_WireAccount *next;

  /**
   * Plugins are kept in a DLL.
   */
  struct TALER_EXCHANGEDB_WireAccount *prev;

  /**
   * Authentication data.
   */
  struct TALER_BANK_AuthenticationData auth;

  /**
   * Wire transfer fee structure.
   */
  struct TALER_EXCHANGEDB_AggregateFees *af;

  /**
   * Name of the section that configures this account.
   */
  char *section_name;

  /**
   * Name of the wire method underlying the account.
   */
  char *method;

};


/**
 * Update wire transfer fee data structure in @a wa.
 *
 * @param cfg configuration to use
 * @param db_plugin database plugin to use
 * @param wa wire account data structure to update
 * @param now timestamp to update fees to
 * @param session DB session to use
 * @return fee valid at @a now, or NULL if unknown
 */
struct TALER_EXCHANGEDB_AggregateFees *
TALER_EXCHANGEDB_update_fees (const struct GNUNET_CONFIGURATION_Handle *cfg,
                              struct TALER_EXCHANGEDB_Plugin *db_plugin,
                              struct TALER_EXCHANGEDB_WireAccount *wa,
                              struct GNUNET_TIME_Absolute now,
                              struct TALER_EXCHANGEDB_Session *session);


/**
 * Find the wire plugin for the given payto:// URL.
 * Only useful after the accounts have been loaded
 * using #TALER_EXCHANGEDB_load_accounts().
 *
 * @param method wire method we need an account for
 * @return NULL on error
 */
struct TALER_EXCHANGEDB_WireAccount *
TALER_EXCHANGEDB_find_account_by_method (const char *method);


/**
 * Find the wire plugin for the given payto:// URL
 * Only useful after the accounts have been loaded
 * using #TALER_EXCHANGEDB_load_accounts().
 *
 * @param url wire address we need an account for
 * @return NULL on error
 */
struct TALER_EXCHANGEDB_WireAccount *
TALER_EXCHANGEDB_find_account_by_payto_uri (const char *url);


/**
 * Load account information opf the exchange from
 * @a cfg.
 *
 * @param cfg configuration to load from
 * @return #GNUNET_OK on success, #GNUNET_NO if no accounts are configured
 */
int
TALER_EXCHANGEDB_load_accounts (const struct GNUNET_CONFIGURATION_Handle *cfg);


/**
 * Free resources allocated by
 * #TALER_EXCHANGEDB_load_accounts().
 */
void
TALER_EXCHANGEDB_unload_accounts (void);

#endif