// -------- PIN SETUP --------
#define BUTTON_PIN D8     // button input
#define LED_PIN D2        // yellow LED (active LOW or HIGH — we'll handle)


// -------- TIMING CONFIG --------
const unsigned long debounceDelay = 50;     // debounce time
const unsigned long longPressTime = 1000;   // long press threshold
const unsigned long doublePressGap = 400;   // max gap for double press


// -------- STATE VARIABLES --------
bool buttonState = LOW;          // current stable state
bool lastButtonReading = LOW;    // last raw reading

unsigned long lastDebounceTime = 0;

unsigned long pressStartTime = 0;
unsigned long lastReleaseTime = 0;

int pressCount = 0;

int totalAmount = 0;


// -------- SETUP --------
void setup() {
  Serial.begin(115200);

  pinMode(BUTTON_PIN, INPUT_PULLDOWN); // using your proven setup
  pinMode(LED_PIN, OUTPUT);

  digitalWrite(LED_PIN, LOW); // LED OFF initially
}


// -------- LOOP --------
void loop() {

  int reading = digitalRead(BUTTON_PIN);

  // -------- DEBOUNCE --------
  if (reading != lastButtonReading) {
    lastDebounceTime = millis(); // reset debounce timer
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {

    if (reading != buttonState) {
      buttonState = reading;

      // -------- BUTTON PRESSED --------
      if (buttonState == HIGH) {
        pressStartTime = millis(); // start timing
      }

      // -------- BUTTON RELEASED --------
      else {
        unsigned long pressDuration = millis() - pressStartTime;

        // -------- LONG PRESS --------
        if (pressDuration >= longPressTime) {

          handleLongPress();  // ₹5
          pressCount = 0;     // reset count (important)

        } else {
          // short press → count for single/double
          pressCount++;
          lastReleaseTime = millis();
        }
      }
    }
  }

  // -------- SINGLE / DOUBLE DECISION --------
  if (pressCount > 0 && (millis() - lastReleaseTime) > doublePressGap) {

    if (pressCount == 1) {
      handleSinglePress();   // ₹1
    }
    else if (pressCount == 2) {
      handleDoublePress();   // ₹2
    }

    pressCount = 0; // reset after handling
  }

  lastButtonReading = reading;
}


// -------- ACTIONS --------

// SINGLE PRESS → ₹1
void handleSinglePress() {
  totalAmount += 1;

  Serial.print("Single Press | +1 | Total: ");
  Serial.println(totalAmount);

  // single blink
  digitalWrite(LED_PIN, HIGH);
  delay(120);
  digitalWrite(LED_PIN, LOW);
}


// DOUBLE PRESS → ₹2
void handleDoublePress() {
  totalAmount += 2;

  Serial.print("Double Press | +2 | Total: ");
  Serial.println(totalAmount);

  // double blink
  for (int i = 0; i < 2; i++) {
    digitalWrite(LED_PIN, HIGH);
    delay(120);
    digitalWrite(LED_PIN, LOW);
    delay(120);
  }
}


// LONG PRESS → ₹5
void handleLongPress() {
  totalAmount += 5;

  Serial.print("Long Press | +5 | Total: ");
  Serial.println(totalAmount);

  // long glow
  digitalWrite(LED_PIN, HIGH);
  delay(400);
  digitalWrite(LED_PIN, LOW);
}