/* 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.
//returns 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
//returns 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.
//returns 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);

//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))
{
    friend_request = function;
}


static void (*friend_message)(int, uint8_t *, uint16_t);

//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;
}


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

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

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

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)
        {
             IP_Port friendip = DHT_getfriendip(friendlist[i].client_id);
             int request = check_friendrequest(friendlist[i].friend_request_id);
             //printf("\n%u %u %u\n", friendip.ip.i, request, friendlist[i].friend_request_id);
             if(friendip.ip.i > 1 && request == -1)
             {
                  friendlist[i].friend_request_id = send_friendrequest(friendlist[i].client_id,
                                               friendip, friendlist[i].info, friendlist[i].info_size);
                  friendlist[i].status = 2;
             }
        }
        if(friendlist[i].status == 2 || friendlist[i].status == 3) //friend is not online
        {
            check_friendrequest(friendlist[i].friend_request_id);//for now this is used to kill the friend request
            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;
                        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));
                        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: {
                        (*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 doFriendRequest()
{
    uint8_t public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t temp[MAX_DATA_SIZE];
    
    int len = handle_friendrequest(public_key, temp);
    if(len >= 0)
    {
        (*friend_request)(public_key, temp, len);
    }
}



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))
        {
            //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);
#endif

    }
    doDHT();
    doLossless_UDP();
    doNetCrypto();
    doInbound();
    doFriendRequest();
    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++)
    {
        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;
}