/* Messenger.c
 *
 * An implementation of a simple text chat only messenger on the tox network core.
 *
 *  Copyright (C) 2013 Tox project All Rights Reserved.
 *
 *  This file is part of Tox.
 *
 *  Tox 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.
 *
 *  Tox 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 Tox.  If not, see <http://www.gnu.org/licenses/>.
 *  
 */

#include "Messenger.h"
#define MIN(a,b) (((a)<(b))?(a):(b))
 
typedef struct
{
    uint8_t client_id[CLIENT_ID_SIZE];
    int crypt_connection_id;
    int friend_request_id; /* id of the friend request corresponding to the current friend request to the current friend. */
    uint8_t status; /* 0 if no friend, 1 if added, 2 if friend request sent, 3 if confirmed friend, 4 if online. */
    uint8_t info[MAX_DATA_SIZE]; /* the data that is sent during the friend requests we do */
    uint8_t name[MAX_NAME_LENGTH];
    uint8_t name_sent; /* 0 if we didn't send our name to this friend 1 if we have. */
    uint8_t *userstatus;
    uint16_t userstatus_length;
    uint8_t userstatus_sent;
    uint16_t info_size; /* length of the info */
}Friend;

uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];

static uint8_t self_name[MAX_NAME_LENGTH];
static uint8_t *self_userstatus;
static uint16_t self_userstatus_len;

#define MAX_NUM_FRIENDS 256

static Friend friendlist[MAX_NUM_FRIENDS];

static uint32_t numfriends;
 
/* 1 if we are online
   0 if we are offline
   static uint8_t online; */

/* return the friend id associated to that public key.
   return -1 if no such friend */
int getfriend_id(uint8_t * client_id)
{
    uint32_t i;
    for(i = 0; i < numfriends; ++i)
    {
        if(friendlist[i].status > 0)
        {
            if(memcmp(client_id, friendlist[i].client_id, crypto_box_PUBLICKEYBYTES) == 0)
            {
                return i;
            }
        }
    }
    return -1;
}

/* copies the public key associated to that friend id into client_id buffer.
   make sure that client_id is of size CLIENT_ID_SIZE.
   return 0 if success
   return -1 if failure. */
int getclient_id(int friend_id, uint8_t * client_id)
{
    if(friend_id >= numfriends || friend_id < 0)
    {
        return -1;
    }

    if(friendlist[friend_id].status > 0)
    {
        memcpy(client_id, friendlist[friend_id].client_id, CLIENT_ID_SIZE);
        return 0;
    }
    return -1;
}

/* add a friend
   set the data that will be sent along with friend request
   client_id is the client id of the friend
   data is the data and length is the length
   returns the friend number if success
   return -1 if failure. */
int m_addfriend(uint8_t * client_id, uint8_t * data, uint16_t length)
{
    if(length == 0 || length >=
            (MAX_DATA_SIZE - crypto_box_PUBLICKEYBYTES - crypto_box_NONCEBYTES - crypto_box_BOXZEROBYTES + crypto_box_ZEROBYTES))
    {
        return -1;
    }
    if(memcmp(client_id, self_public_key, crypto_box_PUBLICKEYBYTES) == 0)
    {
        return -1;
    }
    if(getfriend_id(client_id) != -1)
    {
        return -1;
    }
    uint32_t i;
    for(i = 0; i <= numfriends; ++i)
    {
        if(friendlist[i].status == 0)
        {
            DHT_addfriend(client_id);
            friendlist[i].status = 1;
            friendlist[i].crypt_connection_id = -1;
            friendlist[i].friend_request_id = -1;
            memcpy(friendlist[i].client_id, client_id, CLIENT_ID_SIZE);
            friendlist[i].userstatus = calloc(1, 1);
            friendlist[i].userstatus_length = 1;
            memcpy(friendlist[i].info, data, length);
            friendlist[i].info_size = length;
            
            ++numfriends;
            return i;
        }
    }
    return -1;
}

int m_addfriend_norequest(uint8_t * client_id)
{
    if(getfriend_id(client_id) != -1)
    {
        return -1;
    }
    uint32_t i;
    for(i = 0; i <= numfriends; ++i)
    {
        if(friendlist[i].status == 0)
        {
            DHT_addfriend(client_id);
            friendlist[i].status = 2;
            friendlist[i].crypt_connection_id = -1;
            friendlist[i].friend_request_id = -1;
            memcpy(friendlist[i].client_id, client_id, CLIENT_ID_SIZE);
            friendlist[i].userstatus = calloc(1, 1);
            friendlist[i].userstatus_length = 1;
            numfriends++;
            return i;
        }
    }
    return -1;
}

/* remove a friend
   return 0 if success
   return -1 if failure */
int m_delfriend(int friendnumber)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }

    DHT_delfriend(friendlist[friendnumber].client_id);
    crypto_kill(friendlist[friendnumber].crypt_connection_id);
    free(friendlist[friendnumber].userstatus);
    memset(&friendlist[friendnumber], 0, sizeof(Friend));
    uint32_t i;
    for(i = numfriends; i != 0; --i)
    {
        if(friendlist[i].status != 0)
        {
            break;
        }
    }
    numfriends = i;
    return 0;
}

/* return 4 if friend is online
   return 3 if friend is confirmed
   return 2 if the friend request was sent
   return 1 if the friend was added
   return 0 if there is no friend with that number */
int m_friendstatus(int friendnumber)
{
    if(friendnumber < 0 || friendnumber >= MAX_NUM_FRIENDS)
    {
        return 0;
    }
    return friendlist[friendnumber].status;
}

/* send a text chat message to an online friend
   return 1 if packet was successfully put into the send queue
   return 0 if it was not */
int m_sendmessage(int friendnumber, uint8_t * message, uint32_t length)
{
    if(friendnumber < 0 || friendnumber >= MAX_NUM_FRIENDS)
    {
        return 0;
    }
    if(length >= MAX_DATA_SIZE || friendlist[friendnumber].status != 4)
    /* this does not mean the maximum message length is MAX_DATA_SIZE - 1, it is actually 17 bytes less. */
    {
        return 0;
    }
    uint8_t temp[MAX_DATA_SIZE];
    temp[0] = PACKET_ID_MESSAGE;
    memcpy(temp + 1, message, length);
    return write_cryptpacket(friendlist[friendnumber].crypt_connection_id, temp, length + 1);
}

/* send a name packet to friendnumber */
static int m_sendname(int friendnumber, uint8_t * name)
{
    uint8_t temp[MAX_NAME_LENGTH + 1];
    memcpy(temp + 1, name, MAX_NAME_LENGTH);
    temp[0] = PACKET_ID_NICKNAME;
    return write_cryptpacket(friendlist[friendnumber].crypt_connection_id, temp, MAX_NAME_LENGTH + 1);
}

/* set the name of a friend
   return 0 if success
   return -1 if failure */
static int setfriendname(int friendnumber, uint8_t * name)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }
    memcpy(friendlist[friendnumber].name, name, MAX_NAME_LENGTH);
    return 0;
}

/* Set our nickname
   name must be a string of maximum MAX_NAME_LENGTH length.
   return 0 if success
   return -1 if failure */
int setname(uint8_t * name, uint16_t length)
{
    if(length > MAX_NAME_LENGTH)
    {
        return -1;
    }
    memcpy(self_name, name, length);
    uint32_t i;
    for(i = 0; i < numfriends; ++i)
    {
        friendlist[i].name_sent = 0;
    }
    return 0;
}

/* get name of friendnumber
   put it in name
   name needs to be a valid memory location with a size of at least MAX_NAME_LENGTH bytes.
   return 0 if success
   return -1 if failure */
int getname(int friendnumber, uint8_t * name)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }
    memcpy(name, friendlist[friendnumber].name, MAX_NAME_LENGTH);
    return 0;
}

int m_set_userstatus(uint8_t *status, uint16_t length)
{
    if(length > MAX_USERSTATUS_LENGTH)
    {
        return -1;
    }
    uint8_t *newstatus = calloc(length, 1);
    memcpy(newstatus, status, length);
    free(self_userstatus);
    self_userstatus = newstatus;
    self_userstatus_len = length;

    uint32_t i;
    for(i = 0; i < numfriends; ++i)
    {
        friendlist[i].userstatus_sent = 0;
    }
    return 0;
}

/*  return the size of friendnumber's user status
    guaranteed to be at most MAX_USERSTATUS_LENGTH */
int m_get_userstatus_size(int friendnumber)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }
    return friendlist[friendnumber].userstatus_length;
}

/*  copy the user status of friendnumber into buf, truncating if needed to maxlen
    bytes, use m_get_userstatus_size to find out how much you need to allocate */
int m_copy_userstatus(int friendnumber, uint8_t * buf, uint32_t maxlen)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }
    memset(buf, 0, maxlen);
    memcpy(buf, friendlist[friendnumber].userstatus, MIN(maxlen, MAX_USERSTATUS_LENGTH) - 1);
    return 0;
}

static int send_userstatus(int friendnumber, uint8_t * status, uint16_t length)
{
    uint8_t *thepacket = malloc(length + 1);
    memcpy(thepacket + 1, status, length);
    thepacket[0] = PACKET_ID_USERSTATUS;
    int written = write_cryptpacket(friendlist[friendnumber].crypt_connection_id, thepacket, length + 1);
    free(thepacket);
    return written;
}

static int set_friend_userstatus(int friendnumber, uint8_t * status, uint16_t length)
{
    if(friendnumber >= numfriends || friendnumber < 0)
    {
        return -1;
    }
    uint8_t *newstatus = calloc(length, 1);
    memcpy(newstatus, status, length);
    free(friendlist[friendnumber].userstatus);
    friendlist[friendnumber].userstatus = newstatus;
    friendlist[friendnumber].userstatus_length = length;
    return 0;
}

/*
static void (*friend_request)(uint8_t *, uint8_t *, uint16_t);
static uint8_t friend_request_isset = 0;
*/
/* set the function that will be executed when a friend request is received. */
void m_callback_friendrequest(void (*function)(uint8_t *, uint8_t *, uint16_t))
{
    callback_friendrequest(function);
}

static void (*friend_message)(int, uint8_t *, uint16_t);
static uint8_t friend_message_isset = 0;

/* set the function that will be executed when a message from a friend is received. */
void m_callback_friendmessage(void (*function)(int, uint8_t *, uint16_t))
{
    friend_message = function;
    friend_message_isset = 1;
}

static void (*friend_namechange)(int, uint8_t *, uint16_t);
static uint8_t friend_namechange_isset = 0;
void m_callback_namechange(void (*function)(int, uint8_t *, uint16_t))
{
    friend_namechange = function;
    friend_namechange_isset = 1;
}

static void (*friend_statuschange)(int, uint8_t *, uint16_t);
static uint8_t friend_statuschange_isset = 0;
void m_callback_userstatus(void (*function)(int, uint8_t *, uint16_t))
{
    friend_statuschange = function;
    friend_statuschange_isset = 1;
}

#define PORT 33445
/* run this at startup */
int initMessenger()
{
    new_keys();
    m_set_userstatus((uint8_t*)"Online", sizeof("Online"));
    initNetCrypto();
    IP ip;
    ip.i = 0;

    if(init_networking(ip,PORT) == -1)
        return -1;

    return 0;
}

static void doFriends()
{/* TODO: add incoming connections and some other stuff. */
    uint32_t i;
    int len;
    uint8_t temp[MAX_DATA_SIZE];
    for(i = 0; i < numfriends; ++i)
    {
        if(friendlist[i].status == 1)
        {
            int fr = send_friendrequest(friendlist[i].client_id, friendlist[i].info, friendlist[i].info_size);
            if(fr == 0)/*TODO: This needs to be fixed so that it sends the friend requests a couple of times in case
                                of packet loss*/
            {
                friendlist[i].status = 2;
            }
            else 
            if(fr > 0)
            {
                friendlist[i].status = 2;
            }
        }
        if(friendlist[i].status == 2 || friendlist[i].status == 3) /* friend is not online */
        {
            if(friendlist[i].status == 2)
            {
                if(friendlist[i].friend_request_id + 10 < unix_time()) /*I know this is hackish but it should work.*/
                {
                    send_friendrequest(friendlist[i].client_id, friendlist[i].info, friendlist[i].info_size);
                    friendlist[i].friend_request_id = unix_time();
                    
                }
            }
            IP_Port friendip = DHT_getfriendip(friendlist[i].client_id);
            switch(is_cryptoconnected(friendlist[i].crypt_connection_id))
            {
                case 0:
                    if (friendip.ip.i > 1)
                        friendlist[i].crypt_connection_id = crypto_connect(friendlist[i].client_id, friendip);
                    break;
                case 3: /*  Connection is established */
                    friendlist[i].status = 4;
                    break;
                case 4:
                    crypto_kill(friendlist[i].crypt_connection_id);
                    friendlist[i].crypt_connection_id = -1;
                    break;
                default:
                    break;
            }
        }
        while(friendlist[i].status == 4) /* friend is online */
        {
            if(friendlist[i].name_sent == 0)
            {
                if(m_sendname(i, self_name))
                {
                    friendlist[i].name_sent = 1;
                }
            }
            if(friendlist[i].userstatus_sent == 0)
            {
                if(send_userstatus(i, self_userstatus, self_userstatus_len))
                {
                    friendlist[i].userstatus_sent = 1;
                }
            }
            len = read_cryptpacket(friendlist[i].crypt_connection_id, temp);
            if(len > 0)
            {
                switch(temp[0]) {
                    case PACKET_ID_NICKNAME: {
                        if (len != MAX_NAME_LENGTH + 1) break;
                        if(friend_namechange_isset)
                        {
                            friend_namechange(i, temp + 1, MAX_NAME_LENGTH); /* TODO: use the actual length */
                        }
                        memcpy(friendlist[i].name, temp + 1, MAX_NAME_LENGTH);
                        friendlist[i].name[MAX_NAME_LENGTH - 1] = 0; /* make sure the NULL terminator is present. */
                        break;
                    }
                    case PACKET_ID_USERSTATUS: {
                        uint8_t *status = calloc(MIN(len - 1, MAX_USERSTATUS_LENGTH), 1);
                        memcpy(status, temp + 1, MIN(len - 1, MAX_USERSTATUS_LENGTH));
                        if(friend_statuschange_isset)
                        {
                            friend_statuschange(i, status, MIN(len - 1, MAX_USERSTATUS_LENGTH));
                        }
                        set_friend_userstatus(i, status, MIN(len - 1, MAX_USERSTATUS_LENGTH));
                        free(status);
                        break;
                    }
                    case PACKET_ID_MESSAGE: {
                        if(friend_message_isset)
                        {
                            (*friend_message)(i, temp + 1, len - 1);
                        }
                        break;
                    }
                }
            }
            else
            {
                 if(is_cryptoconnected(friendlist[i].crypt_connection_id) == 4) /* if the connection timed out, kill it */
                 {
                         crypto_kill(friendlist[i].crypt_connection_id);
                         friendlist[i].crypt_connection_id = -1;
                         friendlist[i].status = 3;
                 }
                 break;
            }
        }
    }
}

static void doInbound()
{
    uint8_t secret_nonce[crypto_box_NONCEBYTES];
    uint8_t public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t session_key[crypto_box_PUBLICKEYBYTES];
    int inconnection = crypto_inbound(public_key, secret_nonce, session_key);
    if(inconnection != -1)
    {
        int friend_id = getfriend_id(public_key);
        if(friend_id != -1)
        {
             crypto_kill(friendlist[friend_id].crypt_connection_id);
             friendlist[friend_id].crypt_connection_id =
             accept_crypto_inbound(inconnection, public_key, secret_nonce, session_key);
             
             friendlist[friend_id].status = 3;
        }
    }
}

/* the main loop that needs to be run at least 200 times per second. */
void doMessenger()
{
    IP_Port ip_port;
    uint8_t data[MAX_UDP_PACKET_SIZE];
    uint32_t length;
    while(receivepacket(&ip_port, data, &length) != -1)
    {
#ifdef DEBUG
        /* if(rand() % 3 != 1) //simulate packet loss */
        /* { */
        if(DHT_handlepacket(data, length, ip_port) && LosslessUDP_handlepacket(data, length, ip_port) && friendreq_handlepacket(data, length, ip_port))
        {
            /* if packet is discarded */
            printf("Received unhandled packet with length: %u\n", length);
        }
        else
        {
            printf("Received handled packet with length: %u\n", length);
        }
        /* } */
        printf("Status: %u %u %u\n",friendlist[0].status ,is_cryptoconnected(friendlist[0].crypt_connection_id),  friendlist[0].crypt_connection_id);
#else
        DHT_handlepacket(data, length, ip_port);
        LosslessUDP_handlepacket(data, length, ip_port);
        friendreq_handlepacket(data, length, ip_port);
#endif

    }
    doDHT();
    doLossless_UDP();
    doNetCrypto();
    doInbound();
    doFriends();
}

/* returns the size of the messenger data (for saving) */
uint32_t Messenger_size()
{
    return crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES
                                     + sizeof(uint32_t) + DHT_size() + sizeof(uint32_t) + sizeof(Friend) * numfriends;
}

/* save the messenger in data of size Messenger_size() */
void Messenger_save(uint8_t * data)
{
    save_keys(data);
    data += crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES;
    uint32_t size = DHT_size();
    memcpy(data, &size, sizeof(size));
    data += sizeof(size);
    DHT_save(data);
    data += size;
    size = sizeof(Friend) * numfriends;
    memcpy(data, &size, sizeof(size));
    data += sizeof(size);
    memcpy(data, friendlist, sizeof(Friend) * numfriends);
}

/* load the messenger from data of size length. */
int Messenger_load(uint8_t * data, uint32_t length)
{
    if(length == ~0)
    {
        return -1;
    }
    if(length < crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES + sizeof(uint32_t) * 2)
    {
        return -1;
    }
    length -= crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES + sizeof(uint32_t) * 2;
    load_keys(data);
    data += crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES;
    uint32_t size;
    memcpy(&size, data, sizeof(size));
    data += sizeof(size);
    
    if(length < size)
    {
        return -1;
    }
    length -= size;
    if(DHT_load(data, size) == -1)
    {
        return -1;
    }
    data += size;
    memcpy(&size, data, sizeof(size));
    data += sizeof(size);
    if(length != size || length % sizeof(Friend) != 0)
    {
        return -1;
    }
    
    Friend * temp = malloc(size);
    memcpy(temp, data, size);
    
    uint16_t num = size / sizeof(Friend);
    
    uint32_t i;
    for(i = 0; i < num; ++i)
    {
        if(temp[i].status != 0)
        {
            int fnum = m_addfriend_norequest(temp[i].client_id);
            setfriendname(fnum, temp[i].name);
            /* set_friend_userstatus(fnum, temp[i].userstatus, temp[i].userstatus_length); */
        }
    }
    free(temp);
    return 0;
}