#include <iostream>
#include <unordered_set>
#include <Windows.h>

int main()
{
    DWORD                    Count;
    INPUT_RECORD             Reply;
    std::unordered_set<WORD> State;

    auto Input = GetStdHandle(STD_INPUT_HANDLE);

    while (WAIT_OBJECT_0 == WaitForSingleObject(Input, INFINITE))
    {
        ReadConsoleInput(Input, &Reply, 1, &Count);
        switch (Reply.EventType)
        {
            case KEY_EVENT:
            {
                //std::cout
                //    << " Down: "     << Reply.Event.KeyEvent.bKeyDown
                //    << " Repeat: "   << Reply.Event.KeyEvent.wRepeatCount
                //    << " KeyCode: "  << Reply.Event.KeyEvent.wVirtualKeyCode
                //    << " ScanCode: " << Reply.Event.KeyEvent.wVirtualScanCode
                //    << " Char: "     << Reply.Event.KeyEvent.uChar.UnicodeChar
                //    << " KeyState: " << Reply.Event.KeyEvent.dwControlKeyState
                //    << std::endl << std::flush;

                auto ScanCode = Reply.Event.KeyEvent.wVirtualScanCode;
                auto KeyDown = Reply.Event.KeyEvent.bKeyDown;
                auto Changed = KeyDown ? State.emplace(ScanCode).second
                                       : State.erase(ScanCode);
                if (Changed)
                {
                    std::cout << "chord:";
                    for (auto Key : State) std::cout << " " << Key;
                    std::cout << std::endl << std::flush;
                }
                break;
            }
            default:
                break;
        }
    }
}