int input_pin = 2;       // Pin for the switch
volatile int value;
volatile int state_flag = 0;  // Tracks button presses and the mode of operation

// LED control frequencies
const unsigned long pulse_0_5Hz = 1000;  // 0.5 Hz -> 1000ms (on + off)
const unsigned long pulse_1Hz = 500;    // 1 Hz -> 500ms (on + off)

void setupTimer3() {
    noInterrupts();
    // Clear registers
    TCCR3A = 0;
    TCCR3B = 0;
    TCNT3 = 0;

    // 1 Hz (16000000 / ((15624+1)*1024))
    OCR3A = 15624;
    // CTC mode
    TCCR3B |= (1 << WGM32);
    // Prescaler 1024
    TCCR3B |= (1 << CS32) | (1 << CS30);
    // Output Compare Match A Interrupt Enable
    TIMSK3 |= (1 << OCIE3A);
    interrupts();
}

void setup() {
    pinMode(input_pin, INPUT);
    attachInterrupt(digitalPinToInterrupt(input_pin), state, FALLING);  // FALLING edge for switch press
    DDRC = 0xFF;  // Set PORTC pins (PC0 to PC7) as output for LEDs
    setupTimer3();
    Serial.begin(9600);
}

void loop() {
    // Green LED (PC0) blinking to indicate the program is running
    if (state_flag == 0) {
        PORTC = (1 << PC0);  // Turn on green LED
        delay(500);
        PORTC = (0 << PC0);  // Turn off green LED
        delay(500);
    }
    // Handle the different states based on button presses
    else if (state_flag == 1) {
        // 3 LEDs (PC1, PC2, PC3) blinking at 0.5Hz
        PORTC = (1 << PC1) | (1 << PC2) | (1 << PC3);  // Turn on LEDs
        delay(pulse_0_5Hz);  // Wait 1 second (0.5 Hz)
        PORTC = (0 << PC1) | (0 << PC2) | (0 << PC3);  // Turn off LEDs
        delay(pulse_0_5Hz);
    }
    else if (state_flag == 2) {
        // 4 LEDs (PC4, PC5, PC6, PC7) blinking at 1Hz
        PORTC = (1 << PC4) | (1 << PC5) | (1 << PC6) | (1 << PC7);  // Turn on LEDs
        delay(pulse_1Hz);  // Wait 0.5 second (1 Hz)
        PORTC = (0 << PC4) | (0 << PC5) | (0 << PC6) | (0 << PC7);  // Turn off LEDs
        delay(pulse_1Hz);
    }
    else if (state_flag == 3) {
        // Turn off all LEDs
        PORTC = 0x00;
    }
}

// Interrupt Service Routine for the button press
void state() {
    value = digitalRead(input_pin);  // Read the switch state
    Serial.print("Input reading: ");
    Serial.println(value);

    // Debounce: Wait for 200ms before processing the next press
    delay(200);

    // Switch state based on the current state_flag
    if (value == HIGH) {
        // Increment state and loop back to 0 after state 3
        state_flag++;
        if (state_flag > 3) {
            state_flag = 0;
        }
    }
}

// Timer interrupt service routine for LED control
ISR(TIMER3_COMPA_vect) {
    // This ISR runs every time Timer3 reaches OCR3A value
    // For now, this isn't changing behavior as the LED timing is handled in the loop() based on state_flag
}