/*

 * Hedgewars, a free turn based strategy game

 * Copyright (C) 2012 Simeon Maxein <smaxein@googlemail.com>

 *

 * This program 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 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */

#include "socket.h"

#include "util/logging.h"

#include "util/util.h"

#include <stdlib.h>

#include <SDL_net.h>

#include <time.h>

struct _flib_tcpsocket {

    TCPsocket sock;

    SDLNet_SocketSet sockset;

};

struct _flib_acceptor {

    TCPsocket sock;

    uint16_t port;

};

static uint32_t getPeerIp(TCPsocket sock) {

    IPaddress *addr = SDLNet_TCP_GetPeerAddress(sock);

    return SDLNet_Read32(&addr->host);

}

static bool connectionIsLocal(TCPsocket sock) {

    return getPeerIp(sock) == (uint32_t)((127UL<<24)+1); // 127.0.0.1

}

static flib_tcpsocket *createSocket(TCPsocket sdlsock) {

    flib_tcpsocket *result = flib_calloc(1, sizeof(flib_tcpsocket));

    if(result) {

        result->sock = sdlsock;

        result->sockset = SDLNet_AllocSocketSet(1);

        if(!result->sockset) {

            flib_log_e("Can't allocate socket: Out of memory!");

            SDLNet_FreeSocketSet(result->sockset);

            free(result);

            result = NULL;

        } else {

            SDLNet_AddSocket(result->sockset, (SDLNet_GenericSocket)result->sock);

        }

    }

    return result;

}

TCPsocket listen(uint16_t port) {

    IPaddress addr;

    addr.host = INADDR_ANY;

    SDLNet_Write16(port, &addr.port);

    TCPsocket sock = SDLNet_TCP_Open(&addr);

    if(!sock) {

        flib_log_w("Unable to listen on port %u: %s", (unsigned)port, SDLNet_GetError());

    }

    return sock;

}

flib_acceptor *flib_acceptor_create(uint16_t port) {

    flib_acceptor *result = flib_calloc(1, sizeof(flib_acceptor));

    if(result) {

        if(port > 0) {

            result->port = port;

            result->sock = listen(result->port);

        } else {

            /* SDL_net does not seem to have a way to listen on a random unused port

               and find out which port that is, so let's try to find one ourselves. */

            srand(time(NULL));

            for(int i=0; !result->sock && i<1000; i++) {

                // IANA suggests using ports in the range 49152-65535 for things like this

                result->port = 49152+(rand()%(65536-49152));

                result->sock = listen(result->port);

            }

        }

        if(!result->sock) {

            flib_log_e("Failed to create acceptor.");

            free(result);

            result = NULL;

        }

    }

    return result;

}

uint16_t flib_acceptor_listenport(flib_acceptor *acceptor) {

    if(!acceptor) {

        flib_log_e("Call to flib_acceptor_listenport with acceptor==null");

        return 0;

    }

    return acceptor->port;

}

void flib_acceptor_close(flib_acceptor *acceptor) {

    if(acceptor) {

        SDLNet_TCP_Close(acceptor->sock);

        free(acceptor);

    }

}

flib_tcpsocket *flib_socket_accept(flib_acceptor *acceptor, bool localOnly) {

    flib_tcpsocket *result = NULL;

    if(!acceptor) {

        flib_log_e("Call to flib_socket_accept with acceptor==null");

    } else {

        TCPsocket sock = NULL;

        while(!result && (sock = SDLNet_TCP_Accept(acceptor->sock))) {

            if(localOnly && !connectionIsLocal(sock)) {

                flib_log_i("Rejected nonlocal connection attempt from %s", flib_format_ip(getPeerIp(sock)));

            } else {

                result = createSocket(sock);

            }

            if(!result) {

                SDLNet_TCP_Close(sock);

            }

        }

    }

    return result;

}

flib_tcpsocket *flib_socket_connect(const char *host, uint16_t port) {

    flib_tcpsocket *result = NULL;

    if(!host || port==0) {

        flib_log_e("Invalid parameter in flib_socket_connect");

    } else {

        IPaddress ip;

        if(SDLNet_ResolveHost(&ip,host,port)==-1) {

           flib_log_e("SDLNet_ResolveHost: %s\n", SDLNet_GetError());

        } else {

            TCPsocket sock=SDLNet_TCP_Open(&ip);

            if(!sock) {

                flib_log_e("SDLNet_TCP_Open: %s\n", SDLNet_GetError());

            } else {

                result = createSocket(sock);

                if(result) {

                    sock = NULL;

                }

            }

            SDLNet_TCP_Close(sock);

        }

    }

    return result;

}

void flib_socket_close(flib_tcpsocket *sock) {

    if(sock) {

        SDLNet_DelSocket(sock->sockset, (SDLNet_GenericSocket)sock->sock);

        SDLNet_TCP_Close(sock->sock);

        SDLNet_FreeSocketSet(sock->sockset);

        free(sock);

    }

}

int flib_socket_nbrecv(flib_tcpsocket *sock, void *data, int maxlen) {

    if(!sock || (maxlen>0 && !data)) {

        flib_log_e("Call to flib_socket_nbrecv with sock==null or data==null");

        return -1;

    }

    int readySockets = SDLNet_CheckSockets(sock->sockset, 0);

    if(readySockets>0) {

        int size = SDLNet_TCP_Recv(sock->sock, data, maxlen);

        return size>0 ? size : -1;

    } else if(readySockets==0) {

        return 0;

    } else {

        flib_log_e("Error in select system call: %s", SDLNet_GetError());

        return -1;

    }

}

int flib_socket_send(flib_tcpsocket *sock, const void *data, int len) {

    if(!sock || (len>0 && !data)) {

        flib_log_e("Call to flib_socket_send with sock==null or data==null");

        return -1;

    }

    return SDLNet_TCP_Send(sock->sock, data, len);

}