const int interruptPin2 = 2;   // Interrupt pin D2
const int interruptPin3 = 3;   // Interrupt pin D3
const int interruptPin18 = 18;  // Interrupt pin D18
const int interruptPin19 = 19;  // Interrupt pin D19
const int interruptPin20 = 20;  // Interrupt pin D20
const int interruptPin21 = 21;  // Interrupt pin D21

volatile bool interruptTriggered = false;
volatile int triggeredPin = -1; // Store which pin triggered the interrupt

void setup() {
    Serial.begin(9600);
    
    // Set interrupt pins as input with pull-up resistors
    pinMode(interruptPin2, INPUT_PULLUP);
    pinMode(interruptPin3, INPUT_PULLUP);
    pinMode(interruptPin18, INPUT_PULLUP);
    pinMode(interruptPin19, INPUT_PULLUP);
    pinMode(interruptPin20, INPUT_PULLUP);
    pinMode(interruptPin21, INPUT_PULLUP);

    // Attach interrupts
    attachInterrupt(digitalPinToInterrupt(interruptPin2), handleInterrupt2, FALLING);
    attachInterrupt(digitalPinToInterrupt(interruptPin3), handleInterrupt3, FALLING);
    attachInterrupt(digitalPinToInterrupt(interruptPin18), handleInterrupt18Func, FALLING);
    attachInterrupt(digitalPinToInterrupt(interruptPin19), handleInterrupt19Func, FALLING);
    attachInterrupt(digitalPinToInterrupt(interruptPin20), handleInterrupt20Func, FALLING);
    attachInterrupt(digitalPinToInterrupt(interruptPin21), handleInterrupt21Func, FALLING);
}

void loop() {
    static unsigned long previousMillis = 0; // Store last time
    unsigned long currentMillis = millis(); // Get the current time
    
    if (currentMillis - previousMillis >= 1000) { // Check for 1 second interval
        previousMillis = currentMillis; // Update last time
        Serial.println("Non-blocking delay - Loop continues.");
    }

    // Print which pin triggered the interrupt if set
    if (interruptTriggered) {
        interruptTriggered = false; // Reset the flag
        printTriggeredPin();
 
    }
    delay(5000);
}

// Interrupt handler functions for each pin
void handleInterrupt2() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin2; // Store the pin that triggered the interrupt
    Serial.println("2");
}

void handleInterrupt3() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin3; // Store the pin that triggered the interrupt
}

void handleInterrupt18Func() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin18; // Store the pin that triggered the interrupt
}

void handleInterrupt19Func() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin19; // Store the pin that triggered the interrupt
}

void handleInterrupt20Func() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin20; // Store the pin that triggered the interrupt
}

void handleInterrupt21Func() {
    interruptTriggered = true; // Set interrupt flag
    triggeredPin = interruptPin21; // Store the pin that triggered the interrupt
    Serial.println("21");
}

void printTriggeredPin() {
    switch (triggeredPin) {
        case 2:
            Serial.println("Interrupt triggered on Pin D2");
            break;
        case 3:
            Serial.println("Interrupt triggered on Pin D3");
            break;
        case 18:
            Serial.println("Interrupt triggered on Pin D18");
            break;
        case 19:
            Serial.println("Interrupt triggered on Pin D19");
            break;
        case 20:
            Serial.println("Interrupt triggered on Pin D20");
            break;
        case 21:
            Serial.println("Interrupt triggered on Pin D21");
            break;
        default:
            Serial.println("Unknown interrupt pin");
            break;
    }
}