#include <iostream>
#include <cstdlib>
#include <time.h>
#include <thread>
#include <curses.h>
#include <termios.h>

void SleepForNumberOfSeconds(const int & numberofSeconds,bool & timesUp);
void WaitForTimeoutOrInterrupt(int const& numberofSeconds);
int keypress(void);
void nonblock(const bool state);

int main(){

    std::cout << "waiting for 3 seconds or until a key is pressed" << std::endl;
    WaitForTimeoutOrInterrupt(3);

    return EXIT_SUCCESS;
}

void SleepForNumberOfSeconds(const int & numberofSeconds,bool & timesUp){

    timespec delay = {numberofSeconds,0}; //500,000 = 1/2 milliseconds
    timespec delayrem;

    nanosleep(&delay, &delayrem);
    timesUp = true;

    return;
}
void WaitForTimeoutOrInterrupt(int const& numberofSeconds){

    bool timesUp = false;

    std::thread t(SleepForNumberOfSeconds, numberofSeconds, std::ref(timesUp));
    nonblock(1);
    while (!timesUp && !keypress()){

    }

    if (t.joinable()){
        t.detach();
    }
    nonblock(0);

    return;
}
int keypress(void){
    struct timeval tv;
    fd_set fds;
    tv.tv_sec = 0;
    tv.tv_usec = 0;
    FD_ZERO(&fds);
    FD_SET(STDIN_FILENO, &fds); //STDIN_FILENO is 0
    select(STDIN_FILENO+1, &fds, NULL, NULL, &tv);
    return FD_ISSET(STDIN_FILENO, &fds);
}
void nonblock(const bool state){

    struct termios ttystate;

    //get the terminal state
    tcgetattr(STDIN_FILENO, &ttystate);

    if (state){
        //turn off canonical mode
        ttystate.c_lflag &= ~ICANON;
        //minimum of number input read.
        ttystate.c_cc[VMIN] = 1;
    }
    else{
        //turn on canonical mode
        ttystate.c_lflag |= ICANON;
    }

    //set the terminal attributes.
    tcsetattr(STDIN_FILENO, TCSANOW, &ttystate);
}