#define SERVER_IP_ADDRESS "127.0.0.1"       // IPv4 address of server
#define SERVER_PORT 15000                   // Port number of server that will be used for communication with clients
#define BUFFER_SIZE 512                     // Size of buffer that will be used for sending and receiving messages to client
#define CLIENT_PORT 15011

int main()
{
    // Server address structure
    sockaddr_in serverAddress;
    sockaddr_in clientAddress;

    // Size of server address structure
    int sockAddrLen = sizeof(serverAddress);

    // Buffer that will be used for sending and receiving messages to client
    char dataBuffer[BUFFER_SIZE];

    // WSADATA data structure that is used to receive details of the Windows Sockets implementation
    WSADATA wsaData;

    // Initialize windows sockets for this process
    int iResult = WSAStartup(MAKEWORD(2,2), &wsaData);

    // Check if library is succesfully initialized
    if (iResult != 0)
    {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

   // Initialize memory for address structure
    memset((char*)&serverAddress, 0, sizeof(serverAddress));

     // Initialize address structure of server
    serverAddress.sin_family = AF_INET;                             // IPv4 address famly
    serverAddress.sin_addr.s_addr = inet_addr(SERVER_IP_ADDRESS);   // Set server IP address using string
    serverAddress.sin_port = htons(SERVER_PORT);// Set server port

    memset((char*)&clientAddress, 0, sizeof(clientAddress));
    clientAddress.sin_family = AF_INET;             // set server address protocol family
    clientAddress.sin_addr.s_addr = INADDR_ANY;     // use all available addresses of server
    clientAddress.sin_port = htons(SERVER_PORT);

    // Create a socket
    SOCKET clientSocket = socket(AF_INET,      // IPv4 address famly
                                 SOCK_DGRAM,   // Datagram socket
                                 IPPROTO_UDP); // UDP protocol

    // Check if socket creation succeeded
    if (clientSocket == INVALID_SOCKET)
    {
        printf("Creating socket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }
    iResult = bind(clientSocket,(SOCKADDR*)&clientAddress,sizeof(clientAddress));
    if (iResult == SOCKET_ERROR)
    {
        printf("bind failed with error: %d\n", WSAGetLastError());
        closesocket(clientSocket);
        WSACleanup();
        return 1;
    }
    unsigned long mode = 1;
    iResult = ioctlsocket(clientSocket, FIONBIO, &mode);
    if (iResult != NOERROR)
        printf("ioctlsocket failed with error: %ld", iResult);

    while (1) {

        iResult = recvfrom(clientSocket,
            dataBuffer,
            BUFFER_SIZE,
            0,
            (SOCKADDR*)&serverAddress,
            &sockAddrLen);
        if (iResult != SOCKET_ERROR)
        {
            dataBuffer[iResult] = '\0';
            printf("server sent: %s.\n", dataBuffer);
        }
        else {
            if (WSAGetLastError() == WSAEWOULDBLOCK)
            {
                printf("Enter message to send:\n");

                // Read string from user into outgoing buffer
                gets_s(dataBuffer, BUFFER_SIZE);

                // Send message to server
                iResult = sendto(clientSocket,                      // Own socket
                    dataBuffer,                     // Text of message
                    strlen(dataBuffer),             // Message size
                    0,                                  // No flags
                    (SOCKADDR *)&serverAddress,     // Address structure of server (type, IP address and port)
                    sizeof(serverAddress));         // Size of sockadr_in structure

        // Check if message is succesfully sent. If not, close client application
                if (iResult == SOCKET_ERROR)
                {
                    printf("sendto failed with error: %d\n", WSAGetLastError());
                    closesocket(clientSocket);
                    WSACleanup();
                    return 1;
                }
            }
            else
            {
                printf("recvfrom failed with error: %d\n", WSAGetLastError());
                continue;
            }
        }
    }
    // Only for demonstration purpose
    printf("Press any key to exit: ");
    _getch();

    // Close client application
    iResult = closesocket(clientSocket);
    if (iResult == SOCKET_ERROR)
    {
        printf("closesocket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // Close Winsock library
    WSACleanup();

    // Client has succesfully sent a message
    return 0;
}