/*
   ESP32 Interrupt Driven User Interface
   Wokwi Compatible

   Features:
   - Single Press
   - Double Press
   - Long Press

   Button  -> GPIO 2
   LED     -> GPIO 13
*/

#define BUTTON_PIN 2
#define LED_PIN    13

// Timing values
const unsigned long debounceDelay = 50;
const unsigned long doubleClickTime = 400;
const unsigned long longPressTime = 1000;

// Interrupt variables
volatile bool interruptFlag = false;
volatile bool buttonLevel = HIGH;
volatile unsigned long interruptMillis = 0;

// UI variables
bool waitingForSecondPress = false;

unsigned long pressStart = 0;
unsigned long lastRelease = 0;


// =====================================================
// ISR
// =====================================================
void IRAM_ATTR buttonISR() {

  interruptMillis = millis();
  buttonLevel = digitalRead(BUTTON_PIN);

  interruptFlag = true;
}


// =====================================================
// SETUP
// =====================================================
void setup() {

  Serial.begin(115200);

  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);

  digitalWrite(LED_PIN, LOW);

  // Interrupt on both edges
  attachInterrupt(
    digitalPinToInterrupt(BUTTON_PIN),
    buttonISR,
    CHANGE
  );

  Serial.println("ESP32 Interrupt UI Started");
}


// =====================================================
// LOOP
// =====================================================
void loop() {

  static unsigned long lastDebounceTime = 0;

  // Process interrupt event
  if (interruptFlag) {

    noInterrupts();

    bool currentState = buttonLevel;
    unsigned long eventTime = interruptMillis;

    interruptFlag = false;

    interrupts();

    // Debounce
    if ((eventTime - lastDebounceTime) > debounceDelay) {

      lastDebounceTime = eventTime;

      // ==========================================
      // BUTTON PRESSED
      // ==========================================
      if (currentState == LOW) {

        pressStart = eventTime;
      }

      // ==========================================
      // BUTTON RELEASED
      // ==========================================
      else {

        unsigned long pressDuration =
          eventTime - pressStart;

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

          waitingForSecondPress = false;

          Serial.println("LONG PRESS");

          // Slow blinking
          for (int i = 0; i < 3; i++) {

            digitalWrite(LED_PIN, HIGH);
            delay(300);

            digitalWrite(LED_PIN, LOW);
            delay(300);
          }
        }

        // ======================================
        // SHORT PRESS
        // ======================================
        else {

          // DOUBLE PRESS
          if (waitingForSecondPress &&
              (eventTime - lastRelease)
              <= doubleClickTime) {

            waitingForSecondPress = false;

            Serial.println("DOUBLE PRESS");

            // Toggle LED
            digitalWrite(
              LED_PIN,
              !digitalRead(LED_PIN)
            );
          }

          // Possible SINGLE PRESS
          else {

            waitingForSecondPress = true;
            lastRelease = eventTime;
          }
        }
      }
    }
  }

  // ==========================================
  // SINGLE PRESS DETECTION
  // ==========================================
  if (waitingForSecondPress &&
      (millis() - lastRelease)
      > doubleClickTime) {

    waitingForSecondPress = false;

    Serial.println("SINGLE PRESS");

    // Blink LED once
    digitalWrite(LED_PIN, HIGH);
    delay(200);

    digitalWrite(LED_PIN, LOW);
  }
}