//https://forum.arduino.cc/t/arduino-debounce-button-logic-controlling-servos/1154479
//https://europe1.discourse-cdn.com/arduino/original/4X/7/e/0/7e0ee1e51f1df32e30893550c85f0dd33244fb0e.jpeg
#define ProjectName "Small Button Manager"
// make names
enum Mode {One, Two};
// make variables
const char* modes[] {"ModeOne", "ModeTwo"};
uint8_t mode = Two;
// make structures
struct MODESELECTOR
{
  uint8_t buttonPin;
  uint8_t stateOld;
  uint8_t mode;
  uint32_t debounceMillis;
  uint32_t intervalMillis;
}
modeSelector {A0, LOW, mode, 0, 20};
// make support
void heartBeat(int LedPin, uint32_t currentMillis)
{
  static bool setUp = false;
  if (!setUp) pinMode (LedPin, OUTPUT), setUp = !setUp;
  digitalWrite(LedPin, (currentMillis / 500) % 2);
}
// make application
void setup()
{
  Serial.begin(115200);
  Serial.println(ProjectName);
  pinMode(modeSelector.buttonPin, INPUT_PULLUP);
  Serial.print("start mode selected "), Serial.println(modes[modeSelector.mode]);
}
void loop()
{
  uint32_t currentMillis = millis();
  heartBeat(LED_BUILTIN, currentMillis);
  if (currentMillis - modeSelector.debounceMillis >= modeSelector.intervalMillis)
  {
    modeSelector.debounceMillis = currentMillis;
    uint8_t stateNew = digitalRead(modeSelector.buttonPin) ? LOW : HIGH;
    if (modeSelector.stateOld != stateNew)
    {
      modeSelector.stateOld = stateNew;
      if (stateNew == HIGH)
      {
        modeSelector.mode = modeSelector.mode ? LOW : HIGH;
        Serial.print("mode selected "), Serial.println(modes[modeSelector.mode]);
      }
    }
  }
}