#include <Windows.h>
#include <chrono>
#include <fstream>
#include <iostream>
#include <pthread.h>
#include <stdlib.h>
#include <string>
#include <vector>
#include <iomanip>

std::chrono::steady_clock::time_point keyTime;
std::vector<double> deltaTimes;
bool spacePressed = false;

//function for writing a string to a csv file
int writeTextToCsv(std::string text, std::string filename) {
    std::ofstream fileStream;
    fileStream.open(filename + ".csv");
    fileStream << text;
    fileStream.close();
    return 0;
}

//saves the time in a global variable when the space bar is pressed
void *keyPressedTime(void *) {
    while (!(GetKeyState(VK_SPACE) & 0x8000)) {
        Sleep(1);
    }
    spacePressed = true;
    keyTime = std::chrono::steady_clock::now();
    return 0;
}

int main() {
    std::cout << "Try to hit 'space' when '5' is showing, the output will be written in a csv file\nit will now run ten times" << std::endl;

    //the pc time measure systematic error
    std::chrono::steady_clock::time_point pcTimeBegin = std::chrono::steady_clock::now();
    std::chrono::steady_clock::time_point pcTimEnd = std::chrono::steady_clock::now();
    int pcTimeDiff = std::chrono::duration_cast<std::chrono::microseconds>(pcTimEnd - pcTimeBegin).count();

    pthread_t keyThread;

    for (int i = 0; i < 10; i++) {
        Sleep(1000);
        std::cout << std::endl;

        spacePressed = false;

        //start time measure for space press
        pthread_create(&keyThread, NULL, &keyPressedTime, NULL);

        std::chrono::steady_clock::time_point begin;

        //counter
        for (int num = 1; num <= 1000; num++) {
            Sleep(10);
            std::cout << "\r" << std::setprecision(2) << std::fixed << num / 100.0;
            if (num == 500) {
                //reference time point
                begin = std::chrono::steady_clock::now();
            }
            if (num >= 500 && spacePressed) {
                break;
            }
        }

        //wait till space pressed
        void *status;
        pthread_join(keyThread, &status);

        //calculate time diff
        double deltaTime = (std::chrono::duration_cast<std::chrono::microseconds>(keyTime - begin).count() - pcTimeDiff) * 1.0e-6;
        deltaTimes.push_back(deltaTime);

        std::cout << "\r" << 5 + deltaTime << std::endl;

        //printout time diff
        std::cout << "Time difference = " << deltaTime << " s" << std::endl;
    }

    //output writing
    std::string deltaTimesStr = "reaction times in s\tmean absolute reaction time in s\n";
    for (int i = 0; i < deltaTimes.size(); i++) {
        deltaTimesStr += std::to_string(deltaTimes[i]);
        if (i == 0) {
            deltaTimesStr += "\t";
            double sum = 0;
            for (auto data : deltaTimes) {
                sum += abs(data);
            }
            deltaTimesStr += std::to_string(sum / deltaTimes.size());
        }
        deltaTimesStr += "\n";
    }
    writeTextToCsv(deltaTimesStr, "reaction_times");
    return 0;
}