const int buttonPin = 2; // Button pin
const int ledPin = 8;    // LED pin
const int blinkLed = 11; // Blink LED pin
const int testPin = A0;

const int debounceDelay = 50; // the debounce time; increase if the output flickers
// Variables will change:
bool ledState = 0;           // Current state of the LED
bool blinkState;             // Current stateo of blink LED
int lastButtonState = LOW;  // Previous reading from the input pin

unsigned long lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long tNow; // Used to measure blink time

void setup() {
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
  pinMode(testPin,OUTPUT);
  digitalWrite(testPin,HIGH);

  // set initial LED state
  digitalWrite(ledPin, ledState);
  Serial.begin(115200);
}

void loop() {
  // read the state of the switch into a local variable:
  if(isButtonPressed()){
    ledState = !ledState;
    digitalWrite(ledPin,ledState);
  }  

  if(millis()-tNow >=500){
    tNow = millis();
    blinkState = !blinkState;
    digitalWrite(blinkLed,blinkState);
  }
}

bool isButtonPressed(){
  static  bool buttonState;
  static  bool debouncedButtonState=1;
  bool isPressed = false;
  int reading = digitalRead(buttonPin);
  
  if (reading != buttonState) {
    // reset the debouncing timer
    //Serial.print(millis()-lastDebounceTime);Serial.print(":");
    //Serial.print(debouncedButtonState);Serial.print(" ");Serial.println(reading);
    digitalWrite(testPin,debouncedButtonState);
    buttonState = reading;
    lastDebounceTime = millis();
  }
  else{
    if ((millis() - lastDebounceTime) > debounceDelay) {
      //Serial.print(millis()-lastDebounceTime);Serial.print("\t");
      lastDebounceTime = millis();
      if(reading == 0 && debouncedButtonState == 1){
        isPressed = true;
      }
      debouncedButtonState = reading;
      //Serial.print(debouncedButtonState);Serial.print(" ");Serial.println(reading);
      digitalWrite(testPin,debouncedButtonState);
    }
  } 
  return isPressed; 
}