/*
  This file is part of TALER
  (C) 2014 Christian Grothoff (and other contributing authors)

  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, If not, see <http://www.gnu.org/licenses/>
*/
/**
 * @file mint/mint_db.h
 * @brief Low-level (statement-level) database access for the mint
 * @author Florian Dold
 * @author Christian Grothoff
 */

#ifndef _NEURO_MINT_DB_H
#define _NEURO_MINT_DB_H

#include <libpq-fe.h>
#include <microhttpd.h>
#include <gnunet/gnunet_util_lib.h>
#include "taler_util.h"
#include "mint.h"



/**
 * FIXME.
 */
int
TALER_MINT_DB_prepare (PGconn *db_conn);


/**
 * Reserve row.  Corresponds to table 'reserves' in the mint's
 * database.  FIXME: not sure this is how we want to store this
 * information.  Also, may currently used in different ways in the
 * code, so we might need to separate the struct into different ones
 * depending on the context it is used in.
 */
struct Reserve
{
  /**
   * Signature over the purse.
   * Only valid if (blind_session_missing==GNUNET_YES).
   */
  struct GNUNET_CRYPTO_EddsaSignature status_sig;

  /**
   * Signature with purpose TALER_SIGNATURE_PURSE.
   * Only valid if (blind_session_missing==GNUNET_YES).
   */
  struct GNUNET_CRYPTO_EccSignaturePurpose status_sig_purpose;

  /**
   * Signing key used to sign the purse.
   * Only valid if (blind_session_missing==GNUNET_YES).
   */
  struct GNUNET_CRYPTO_EddsaPublicKey status_sign_pub;

  /**
   * Withdraw public key, identifies the purse.
   * Only the customer knows the corresponding private key.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey reserve_pub;

  /**
   * Remaining balance in the purse. // FIXME: do not use NBO here!
   */
  struct TALER_AmountNBO balance;

  /**
   * Expiration date for the purse.
   */
  struct GNUNET_TIME_AbsoluteNBO expiration;
};


int
TALER_MINT_DB_get_reserve (PGconn *db_conn,
                           const struct GNUNET_CRYPTO_EddsaPublicKey *reserve_pub,
                           struct Reserve *reserve_res);


/**
 * Update information about a reserve.
 *
 * @param db_conn
 * @param reserve current reserve status
 * @param fresh FIXME
 * @return #GNUNET_OK on success
 */
int
TALER_MINT_DB_update_reserve (PGconn *db_conn,
                              const struct Reserve *reserve,
                              int fresh);








int
TALER_MINT_DB_insert_refresh_order (PGconn *db_conn,
                                    uint16_t newcoin_index,
                                    const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub,
                                    const struct GNUNET_CRYPTO_rsa_PublicKey *denom_pub);

int
TALER_MINT_DB_get_refresh_session (PGconn *db_conn,
                                   const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
                                   struct RefreshSession *r_session);


/**
 * FIXME
 */
struct KnownCoin
{
  struct TALER_CoinPublicInfo public_info;

  /**
   * Refreshing session, only valid if
   * is_refreshed==1.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey refresh_session_pub;

  struct TALER_Amount expended_balance;

  int is_refreshed;

};


int
TALER_MINT_DB_get_known_coin (PGconn *db_conn,
                              const struct GNUNET_CRYPTO_EcdsaPublicKey *coin_pub,
                              struct KnownCoin *known_coin);

// FIXME: what does 'upsert' even mean!?
int
TALER_MINT_DB_upsert_known_coin (PGconn *db_conn,
                                 struct KnownCoin *known_coin);


int
TALER_MINT_DB_insert_known_coin (PGconn *db_conn,
                                 const struct KnownCoin *known_coin);


int
TALER_MINT_DB_create_refresh_session (PGconn *db_conn,
                                      const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub);


/**
 * Store the commitment to the given (encrypted) refresh link data
 * for the given refresh session.
 *
 * @param db_conn database connection to use
 * @param refresh_session_pub public key of the refresh session this
 *        commitment belongs with
 * @param i
 * @param j
 * @param commit_link link information to store
 * @return #GNUNET_SYSERR on internal error, #GNUNET_OK on success
 */
int
TALER_MINT_DB_insert_refresh_commit_link (PGconn *db_conn,
                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
                                          int i, int j,
                                          const struct RefreshCommitLink *commit_link);


int
TALER_MINT_DB_get_refresh_commit_link (PGconn *db_conn,
                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
                                       int i, int j,
                                       struct RefreshCommitLink *cc);


int
TALER_MINT_DB_insert_refresh_commit_coin (PGconn *db_conn,
                                          const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
                                          int i,
                                          int j,
                                          const struct RefreshCommitCoin *commit_coin);


int
TALER_MINT_DB_get_refresh_commit_coin (PGconn *db_conn,
                                       const struct GNUNET_CRYPTO_EddsaPublicKey *refresh_session_pub,
                                       int i, int j,
                                       struct RefreshCommitCoin *commit_coin);


struct GNUNET_CRYPTO_rsa_PublicKey *
TALER_MINT_DB_get_refresh_order (PGconn *db_conn,
                                 uint16_t newcoin_index,
                                 const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub);


int
TALER_MINT_DB_insert_refresh_collectable (PGconn *db_conn,
                                          uint16_t newcoin_index,
                                          const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub,
                                          const struct GNUNET_CRYPTO_rsa_Signature *ev_sig);


struct GNUNET_CRYPTO_rsa_Signature *
TALER_MINT_DB_get_refresh_collectable (PGconn *db_conn,
                                       uint16_t newcoin_index,
                                       const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub);



int
TALER_MINT_DB_set_reveal_ok (PGconn *db_conn,
                             const struct GNUNET_CRYPTO_EddsaPublicKey *session_pub);




/**
 * FIXME: doc, name is bad, too.
 */
typedef int
(*LinkIterator) (void *cls,
                 const struct TALER_RefreshLinkEncrypted *link_data_enc,
                 const struct GNUNET_CRYPTO_rsa_PublicKey *denom_pub,
                 const struct GNUNET_CRYPTO_rsa_Signature *ev_sig);


int
TALER_db_get_link (PGconn *db_conn,
                   const struct GNUNET_CRYPTO_EcdsaPublicKey *coin_pub,
                   LinkIterator link_iter,
                   void *cls);


/**
 * Obtain shared secret from the transfer public key (?).
 *
 * @param shared_secret_enc[out] set to shared secret; FIXME: use other type
 *               to indicate this is the encrypted secret
 */
int
TALER_db_get_transfer (PGconn *db_conn,
                       const struct GNUNET_CRYPTO_EcdsaPublicKey *coin_pub,
                       struct GNUNET_CRYPTO_EcdsaPublicKey *transfer_pub,
                       struct GNUNET_HashCode *shared_secret_enc);


int
TALER_TALER_DB_extract_amount (PGresult *result,
                               unsigned int row,
                               int indices[3],
                               struct TALER_Amount *denom);

int
TALER_TALER_DB_extract_amount_nbo (PGresult *result,
                                   unsigned int row,
                                   int indices[3],
                                   struct TALER_AmountNBO *denom_nbo);





// Chaos
////////////////////////////////////////////////////////////////
// Order



/**
 * Initialize database subsystem.
 */
int
TALER_MINT_DB_init (const char *connection_cfg);


/**
 * Get the thread-local database-handle.
 * Connect to the db if the connection does not exist yet.
 *
 * @param the database connection, or NULL on error
 */
PGconn *
TALER_MINT_DB_get_connection (void);


/**
 * Start a transaction.
 *
 * @return #GNUNET_OK on success
 */
int
TALER_MINT_DB_transaction (PGconn *db_conn);


/**
 * Commit a transaction.
 *
 * @return #GNUNET_OK on success
 */
int
TALER_MINT_DB_commit (PGconn *db_conn);


/**
 * Abort/rollback a transaction.
 *
 * @return #GNUNET_OK on success
 */
int
TALER_MINT_DB_rollback (PGconn *db_conn);



/**
 * Information we keep for a withdrawn coin to reproduce
 * the /withdraw operation if needed, and to have proof
 * that a reserve was drained by this amount.
 */
struct CollectableBlindcoin
{

  /**
   * Our signature over the (blinded) coin.
   */
  struct GNUNET_CRYPTO_rsa_Signature *sig;

  /**
   * Denomination key (which coin was generated).
   */
  struct GNUNET_CRYPTO_rsa_PublicKey *denom_pub;

  /**
   * Public key of the reserve that was drained.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey reserve_pub;

  /**
   * Signature confirming the withdrawl, matching @e reserve_pub,
   * @e denom_pub and @e h_blind.
   */
  struct GNUNET_CRYPTO_EddsaSignature reserve_sig;
};


/**
 * Locate the response for a /withdraw request under the
 * key of the hash of the blinded message.
 *
 * @param db_conn database connection to use
 * @param h_blind hash of the blinded message
 * @param collectable corresponding collectable coin (blind signature)
 *                    if a coin is found
 * @return #GNUNET_SYSERR on internal error
 *         #GNUNET_NO if the collectable was not found
 *         #GNUNET_YES on success
 */
int
TALER_MINT_DB_get_collectable_blindcoin (PGconn *db_conn,
                                         const struct GNUNET_HashCode *h_blind,
                                         struct CollectableBlindcoin *collectable);


/**
 * Store collectable bit coin under the corresponding
 * hash of the blinded message.
 *
 * @param db_conn database connection to use
 * @param h_blind hash of the blinded message
 * @param collectable corresponding collectable coin (blind signature)
 *                    if a coin is found
 * @return #GNUNET_SYSERR on internal error
 *         #GNUNET_NO if the collectable was not found
 *         #GNUNET_YES on success
 */
int
TALER_MINT_DB_insert_collectable_blindcoin (PGconn *db_conn,
                                            const struct GNUNET_HashCode *h_blind,
                                            const struct CollectableBlindcoin *collectable);


/**
 * Specification for a /deposit operation.
 */
struct Deposit
{
  /**
   * Information about the coin that is being deposited.
   */
  struct TALER_CoinPublicInfo coin;

  /**
   * ECDSA signature affirming that the customer intends
   * this coin to be deposited at the merchant identified
   * by @e h_wire in relation to the contract identified
   * by @e h_contract.
   */
  struct GNUNET_CRYPTO_EcdsaSignature csig;

  /**
   * Public key of the merchant.  Enables later identification
   * of the merchant in case of a need to rollback transactions.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey merchant_pub;

  /**
   * Hash over the contract between merchant and customer
   * (remains unknown to the Mint).
   */
  struct GNUNET_HashCode h_contract;

  /**
   * Hash of the (canonical) representation of @e wire, used
   * to check the signature on the request.  Generated by
   * the mint from the detailed wire data provided by the
   * merchant.
   */
  struct GNUNET_HashCode h_wire;

  /**
   * Detailed wire information for executing the transaction.
   */
  const json_t *wire;

  /**
   * Merchant-generated transaction ID to detect duplicate
   * transactions.
   */
  uint64_t transaction_id;

  /**
   * Fraction of the coin's remaining value to be deposited.
   * The coin is identified by @e coin_pub.
   */
  struct TALER_Amount amount;

};


/**
 * Check if we have the specified deposit already in the database.
 *
 * @param db_conn database connection
 * @param deposit deposit to search for
 * @return #GNUNET_YES if we know this operation,
 *         #GNUNET_NO if this deposit is unknown to us,
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_have_deposit (PGconn *db_conn,
                            const struct Deposit *deposit);


/**
 * Insert information about deposited coin into the
 * database.
 *
 * @param db_conn connection to the database
 * @param deposit deposit information to store
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
 */
int
TALER_MINT_DB_insert_deposit (PGconn *db_conn,
                              const struct Deposit *deposit);


/**
 * Specification for a /refresh/melt operation.
 */
struct RefreshMelt
{
  /**
   * Information about the coin that is being melted.
   */
  struct TALER_CoinPublicInfo coin;

  /**
   * Public key of the melting session.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey session_pub;

  /**
   * Signature over the melting operation.
   */
  struct GNUNET_CRYPTO_EcdsaSignature coin_sig;

  /**
   * How much value is being melted?
   */
  struct TALER_Amount amount;

  /**
   * What is the index of this coin in the melting session?
   */
  uint16_t oldcoin_index;

};


/**
 * Test if the given /refresh/melt request is known to us.
 *
 * @param db_conn database connection
 * @param melt melt operation
 * @return #GNUNET_YES if known,
 *         #GNUENT_NO if not,
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_have_refresh_melt (PGconn *db_conn,
                                 const struct RefreshMelt *melt);


/**
 * Store the given /refresh/melt request in the database.
 *
 * @param db_conn database connection
 * @param melt melt operation
 * @return #GNUNET_OK on success
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_insert_refresh_melt (PGconn *db_conn,
                                   const struct RefreshMelt *melt);


/**
 * Get information about melted coin details from the database.
 *
 * @param db_conn database connection
 * @param session session key of the melt operation
 * @param oldcoin_index index of the coin to retrieve
 * @param melt melt data to fill in
 * @return #GNUNET_OK on success
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_get_refresh_melt (PGconn *db_conn,
                                const struct GNUNET_CRYPTO_EddsaPublicKey *session,
                                uint16_t oldcoin_index,
                                struct RefreshMelt *melt);


/**
 * Specification for a /lock operation.
 */
struct Lock
{
  /**
   * Information about the coin that is being melted.
   */
  struct TALER_CoinPublicInfo coin;

  /**
   * Signature over the melting operation.
   */
  const struct GNUNET_CRYPTO_EcdsaSignature coin_sig;

  /**
   * How much value is being melted?
   */
  struct TALER_Amount amount;

  // FIXME: more needed...
};


/**
 * Test if the given /lock request is known to us.
 *
 * @param db_conn database connection
 * @param lock lock operation
 * @return #GNUNET_YES if known,
 *         #GNUENT_NO if not,
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_have_lock (PGconn *db_conn,
                         const struct Lock *lock);


/**
 * Store the given /lock request in the database.
 *
 * @param db_conn database connection
 * @param lock lock operation
 * @return #GNUNET_OK on success
 *         #GNUNET_SYSERR on internal error
 */
int
TALER_MINT_DB_insert_lock (PGconn *db_conn,
                           const struct Lock *lock);


/**
 * Enumeration to classify the different types of transactions
 * that can be done with a coin.
 */
enum TALER_MINT_DB_TransactionType
{
  /**
   * /deposit operation.
   */
  TALER_MINT_DB_TT_DEPOSIT = 0,

  /**
   * /refresh/melt operation.
   */
  TALER_MINT_DB_TT_REFRESH_MELT = 1,

  /**
   * /lock operation.
   */
  TALER_MINT_DB_TT_LOCK = 2
};


/**
 * List of transactions we performed for a particular coin.
 */
struct TALER_MINT_DB_TransactionList
{

  /**
   * Next pointer in the NULL-terminated linked list.
   */
  struct TALER_MINT_DB_TransactionList *next;

  /**
   * Type of the transaction, determines what is stored in @e details.
   */
  enum TALER_MINT_DB_TransactionType type;

  /**
   * Details about the transaction, depending on @e type.
   */
  union
  {

    /**
     * Details if transaction was a /deposit operation.
     */
    struct Deposit *deposit;

    /**
     * Details if transaction was a /refresh/melt operation.
     */
    struct RefreshMelt *melt;

    /**
     * Details if transaction was a /lock operation.
     */
    struct Lock *lock;

  } details;

};


/**
 * Compile a list of all (historic) transactions performed
 * with the given coin (/refresh/melt and /deposit operations).
 *
 * @param db_conn database connection
 * @param coin_pub coin to investigate
 * @return list of transactions, NULL if coin is fresh
 */
struct TALER_MINT_DB_TransactionList *
TALER_MINT_DB_get_coin_transactions (PGconn *db_conn,
                                     const struct GNUNET_CRYPTO_EcdsaPublicKey *coin_pub);


/**
 * Free linked list of transactions.
 *
 * @param list list to free
 */
void
TALER_MINT_DB_free_coin_transaction_list (struct TALER_MINT_DB_TransactionList *list);






#endif /* _NEURO_MINT_DB_H */