/*
 *  Off-the-Record Messaging library
 *  Copyright (C) 2004-2009  Ian Goldberg, Chris Alexander, Willy Lew,
 *			     Nikita Borisov
 *                           <otr@cypherpunks.ca>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of version 2.1 of the GNU Lesser General
 *  Public License as published by the Free Software Foundation.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef __CONTEXT_PRIV_H__
#define __CONTEXT_PRIV_H__

#include <gcrypt.h>
#include <stdbool.h>

#include "dh.h"
#include "auth.h"
#include "sm.h"

// maximum number of file transfers
#define OTR_MAX_FT 256
// minimum value of allowed file transfer id
#define OTR_MIN_FT 1

typedef struct context_priv {
	/* The part of the fragmented message we've seen so far */
	char *fragment;

	/* The length of fragment */
	size_t fragment_len;

	/* The total number of fragments in this message */
	unsigned short fragment_n;

	/* The highest fragment number we've seen so far for this message */
	unsigned short fragment_k;

	/* current keyid used by other side; this is set to 0 if we get
	 * a OTRL_TLV_DISCONNECTED message from them. */
	unsigned int their_keyid;

	/* Y[their_keyid] (their DH pubkey) */
	gcry_mpi_t their_y;

	/* Y[their_keyid-1] (their prev DH pubkey) */
	gcry_mpi_t their_old_y;

	/* current keyid used by us */
	unsigned int our_keyid;

	/* DH key[our_keyid] */
	DH_keypair our_dh_key;

	/* DH key[our_keyid-1] */
	DH_keypair our_old_dh_key;

	/* sesskeys[i][j] are the session keys derived from DH
	 * key[our_keyid-i] and mpi Y[their_keyid-j] */
	DH_sesskeys sesskeys[2][2];

	/* saved mac keys to be revealed later */
	unsigned int numsavedkeys;
	unsigned char *saved_mac_keys;

	/* generation number: increment every time we go private, and never
	 * reset to 0 (unless we remove the context entirely) */
	unsigned int generation;

	/* The last time a Data Message was sent */
	time_t lastsent;

	/* The last time a Data Message was received */
	time_t lastrecv;

	/* The plaintext of the last Data Message sent */
	char *lastmessage;

	/* Is the last message eligible for retransmission? */
	int may_retransmit;
	
	// list of currently active file transfers
	int * file_transfers_recv;	// list of file descriptors (for writing received data)
	char ** file_transfers_send;	// list of mapped files (for reading send data)
	size_t * ft_send_len;		// size of each mapped region
	size_t * ft_send_offset;	// list of appropriate offset (data already sent)
} ConnContextPriv;

/* Create a new private connection context. */
ConnContextPriv * context_priv_new();

// check if file transfer with given id is active in this context
bool context_priv_ft_recv_id(const ConnContextPriv * context_priv, unsigned char id);
bool context_priv_ft_send_id(const ConnContextPriv * context_priv, unsigned char id);

// file transfer manipulation routines
unsigned char context_priv_ft_add_recv(ConnContextPriv * context_priv, char * filename);
unsigned char context_priv_ft_add_send(ConnContextPriv * context_priv, char * filename);

int context_priv_ft_del_recv(ConnContextPriv * context_priv, unsigned char id);
int context_priv_ft_del_send(ConnContextPriv * context_priv, unsigned char id);

// sending data: get next chunk and rewind offset accordingly
char * context_priv_ft_chunk(ConnContextPriv * context_priv, unsigned char id, size_t chunk_len);

// total number of file transfers in context
unsigned int context_priv_ft_get_total_id_recv(ConnContextPriv * context_priv);
unsigned int context_priv_ft_get_total_id_send(ConnContextPriv * context_priv);

/* Frees up memory that was used in context_priv_new */
void context_priv_force_finished(ConnContextPriv * context_priv);

#endif