TCPClient.cpp

#include <bits/stdc++.h>
#include <unistd.h>
#include <cstring>      // Needed for memset
#include <sys/socket.h> // Needed for the socket functions
#include <netdb.h>      // Needed for the socket functions
#include <netinet/in.h>
#include <arpa/inet.h>
#include "common_utils.hpp"

using namespace std;

string user_id;
bool loggedin = false;
bool available = true;

template<typename T>
T cli_input(){
    T var;
    cout << "#> ";
    cin >> var;
    return var;
}

string Question::ask() {
    cout << "#> " << question << endl;
    for (int i = 0; i < options.size(); i++)
        printf("  %c : %s\n", 'A'+i, options[i].c_str());
    return cli_input<string>();
}

string make_header(string type, string data) { // type = "get_ques:T" , "post_ans"
    string header = user_id + "|" + type +"|"+ data;
    return header;
}

class ClientSocket {
    private:
    struct sockaddr_in client_address, server_address;
    int socket_fd;
    socklen_t client_address_length, server_address_length;
    char *recieve_buffer;
    char *send_buffer;
    int buffer_size;
    char read_header[16];
    char write_header[16];

    public:
    ClientSocket(string ip_address, int port, int buffer_size){
        recieve_buffer = (char*)malloc(sizeof(char)*buffer_size);
        send_buffer = (char*)malloc(sizeof(char)*buffer_size);
        this->buffer_size = buffer_size;
        server_address.sin_family = AF_INET;
        server_address.sin_port = htons(port);
        if (inet_pton(AF_INET, ip_address.c_str(), &server_address.sin_addr) <= 0)
            cerr << "Cannot connnect : Invalid IP Address\n";
        socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    }
    int _connect(){
        int connect_result = connect(socket_fd, (struct sockaddr *)&server_address,
                                     sizeof(server_address));
        return connect_result;
    }

    int get_socket_fd() {return socket_fd;}

    int _send(string message) {
        memset(write_header, 0, sizeof(write_header));
        string s = to_string(message.length());
        copy(s.begin(),s.end(), write_header);
        int write_result = write(socket_fd, write_header, 16);
        if (write_result > 0)
            write_result = write(socket_fd, message.c_str(), message.length());
        if (write_result <=0) cerr << "Unable to send message : "<< message  << endl;
        return write_result;
    }

    string _recieve(){
        memset(read_header, 0, sizeof(read_header));
        int read_result = read(socket_fd, read_header, 16);
        if (read_result >0) {
            int read_size = stoi(string(read_header));
            memset(recieve_buffer, 0, sizeof(recieve_buffer));
            read_result = read(socket_fd, recieve_buffer, read_size);
        }
        if ( read_result > 0) return string(recieve_buffer);
        cerr << "Unable to read from server." << endl;
        return "";
    }
    void _close(){
        close(socket_fd);
    }
    ~ClientSocket(){
        close(socket_fd);
    }
};

int login(ClientSocket client_socket) {
    if (client_socket._connect() >= 0) {
        cout << "Enter User id: ";
        user_id = cli_input<string> ();
        client_socket._send(make_header("user_id", user_id));
    }
    else {
        cerr << "Unable to connect to the server" << endl;
        return -1;
    }
    return 0;
}

void cli_init(ClientSocket client_socket){
    cout << "Welcome to Quizar, An online quizzing platform." << endl;
    if (!loggedin) {
        if (login(client_socket)) return;
        loggedin = true;
    }
    cout << "Select mode:\n G for group\n I for individual\n A for Admin\n";
    string mode = cli_input<string>();
    if (mode == "A") {
        cout << "Select topic:\n T for threads\n O for OS\n N for networks\n";
        string topic = cli_input<string>();
        client_socket._send(make_header("get_ques",mode+"|"+topic)); // unable to send aa rha hai
        cout << "Visited" << endl;
        string message = client_socket._recieve();
        while (message != "stream-end") {
            Question ques = deserialize_question(message);
            string answered = ques.ask();
            client_socket._send(answered);
            int ans; string explaination;
            deserialize_answer(client_socket._recieve(), &ans, &explaination);
            if (ans == answered[0]-'A') cout << "Correct ";
            else cout << "Wrong ";
            cout << "Correct answer : " << ques.get_option(ans) << endl;
            cout << "Explaintaion :" << explaination << endl;
            message = client_socket._recieve();
        }
    }
}

int main()
{
    ClientSocket client_socket = ClientSocket(IP_ADDRESS, PORT, BUFFER_SIZE);
    /**
    pid_t pid;
    pid = fork();
    if (pid == 0) {
        while (available) {
            available = (client_socket._send("available"));
        }
    }
    **/
    cli_init(client_socket);
    client_socket._close();
}