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/* This file is part of libbrandt.
 * (C) 2016 Markus Teich
 *
 * libbrandt 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 of the License, or (at your option) any later
 * version.
 *
 * libbrandt 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
 * libbrandt.  If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @file brandt.h
 * @brief This Header defines the external interface of libbrandt.
 */

#ifndef _BRANDT_BRANDT_H
#define _BRANDT_BRANDT_H

struct BRANDT_auction;

/**
 * Functions of this type are called by libbrandt to broadcast messages to the
 * blackboard of a specific auction.
 *
 * TODO: how must the message be handled? (encryption, auth, reliability, …)
 *
 * @param[in] auction_closure Closure pointer representing the respective
 * auction. This is the Pointer given to BRANDT_join().
 * @param[in] msg The message to be broadcast to all participants of
 * @a auction_closure.
 * @param[in] msg_len The length of the message @a msg in bytes.
 * @return 1 on success, 0 on failure.
 */
typedef int (*BRANDT_cb_broadcast) (void *auction_closure, const void *msg, size_t msg_len);

/**
 * Functions of this type are called by libbrandt to unicast messages to the
 * seller of a specific auction.
 *
 * TODO: how must the message be handled? (encryption, auth, reliability, …)
 *
 * @param[in] auction_closure Closure pointer representing the respective
 * auction. This is the Pointer given to BRANDT_join().
 * @param[in] msg The message to be sent to the seller of @a auction_closure.
 * @param[in] msg_len The length of the message @a msg in bytes.
 * @return 1 on success, 0 on failure.
 */
typedef int (*BRANDT_cb_unicast_seller) (void *auction_closure, const void *msg, size_t msg_len);

/**
 * Functions of this type are called by libbrandt to report the auction outcome
 * to the user.
 *
 * TODO: update price type. Don't do this notification as a callback?
 *
 * @param[in] auction_closure Closure pointer representing the respective
 * auction. This is the Pointer given to BRANDT_join().
 * @param[in] won 1 if the user has won the auction, 0 otherwise.
 * @param[in] price The price, the winner has to pay or 0 if the auction result
 * is private and the user did not win.
 */
typedef void (*BRANDT_cb_report_result) (void *auction_closure, int won, uint16_t price);

/**
 * Join an auction described by the @a auction_data parameter.
 * @param[in] broadcast Pointer to the broadcast callback function
 * @param[in] unicast Pointer to the unicast callback function
 * @param[in] report Pointer to the report callback function
 * @param[in] auction_closure Closure pointer representing the auction. This
 * will not be touched by libbrandt. It is only passed to the callbacks.
 * @param[in] auction_data The auction information data a an opaque data
 * structure. It will be parsed and checked by BRANDT_join().
 * @param[in] auction_data_len The length in bytes of the @a auction_data
 * structure.
 * @return A pointer, which should only be remembered and passed to
 * libbrandt functions when the client needs to refer to this auction. This is a
 * black-box pointer, do NOT access/change it or the data it points to!
 */
const struct BRANDT_auction *BRANDT_join (BRANDT_cb_broadcast broadcast,
                                          BRANDT_cb_unicast_seller unicast,
                                          BRANDT_cb_report_result report,
                                          const void *auction_closure,
                                          const void *auction_data,
                                          size_t auction_data_len);

/**
 * Create a new auction described by the @a auction_data parameter.
 * @param[in] broadcast Pointer to the broadcast callback function
 * @param[in] report Pointer to the report callback function
 * @param[in] auction_closure Closure pointer representing the auction. This
 * will not be touched by libbrandt. It is only passed to the callbacks.
 * @param[out] auction_data The auction information data a an opaque data
 * structure. It will be generated by BRANDT_new() and should be distributed to
 * all possibly interested bidders.
 * @param[out] auction_data_len The length in bytes of the @a auction_data
 * structure. Will be filled by BRANDT_new().
 * @param[in] num_prices The amount of possible valuations for the sold item(s).
 * If 0, a default of 256 will be used. TODO: what about 1, does it work with
 * second price auctions?
 * @param[in] m The mode of the auction. If 0, it will be a first price auction
 * where the winner has to pay the price of his bid. If >0 it will be a second
 * price auction selling exactly that amount of items and each winner has to pay
 * the price of the highest loosing bid. TODO: what if bidders < m?
 * @param[in] outcome_public If 1, the auction winner and price will be public
 * to all participants, if 0, this information will only be revealed to the
 * winner and the seller.
 * @return A pointer, which should only be remembered and passed to
 * libbrandt functions when the client needs to refer to this auction. This is a
 * black-box pointer, do NOT access/change it or the data it points to!
 */
const struct BRANDT_auction *BRANDT_new (BRANDT_cb_broadcast broadcast,
                                         BRANDT_cb_report_result report,
                                         const void *auction_closure,
                                         const void **auction_data,
                                         size_t *auction_data_len,
                                         uint16_t num_prices,
                                         uint16_t m,
                                         int outcome_public);

/**
 * Receive a broadcast message related to a specific auction.
 * @param[in] auction The pointer returned by BRANDT_join() or BRANDT_new() from
 * which message @a msg was received.
 * @param[in] msg The message that was received.
 * @param[in] msg_len The length in bytes of @a msg.
 */
void BRANDT_got_broadcast (struct BRANDT_auction *auction, void *msg, size_t msg_len);

/**
 * Receive a unicast message from a bidder related to a specific auction.
 * @param[in] auction The pointer returned by BRANDT_new() from which message
 * @a msg was received.
 * @param[in] msg The message that was received.
 * @param[in] msg_len The length in bytes of @a msg.
 * TODO: how to link message to sender id within auction?
 */
void BRANDT_got_unicast (struct BRANDT_auction *auction, void *msg, size_t msg_len);

///TODO: Error handling functions?

#endif