from machine import Pin, PWM
import time

# --- INITIALIZATION ---
# Initialize 4 LEDs: GP0, GP1, GP2, GP3
led_pins = [0, 1, 2, 3]
leds = [Pin(pin, Pin.OUT) for pin in led_pins]

# Initialize Buzzer: GP15
buzzer = PWM(Pin(15))
buzzer.duty_u16(0) # Start with 0 volume (silent)

# Initialize Buttons
# GP18 is Active High: Connect to 3.3V, needs a Pull-down resistor 
btn1 = Pin(18, Pin.IN, Pin.PULL_DOWN)

# GP19 is Active Low: Connect to GND, needs a Pull-up resistor 
btn2 = Pin(19, Pin.IN, Pin.PULL_UP)

while True:
    # Task 1.1: GP18 pressed (Active High = 1)
    if btn1.value() == 1:
        for _ in range(6): # Blink 4-LEDs 6 times
            for led in leds: led.value(1)
            time.sleep(0.5)
            for led in leds: led.value(0)
            time.sleep(0.5)
            
        # Sound the buzzer
        buzzer.freq(1000)      # Set frequency (pitch) to 1000 Hz
        buzzer.duty_u16(32768) # Set duty cycle to 50% to turn the sound ON
        time.sleep(0.5)
        buzzer.duty_u16(0)     # Set duty cycle back to 0 to turn sound OFF

    # Task 1.2: GP19 pressed (Active Low = 0)
    elif btn2.value() == 0:
        for _ in range(4): # 4 cycles of shifting
            # Shifting Left to Right
            for led in leds:
                led.value(1)
                time.sleep(0.1)
                led.value(0)
            # Shifting Right to Left
            for led in reversed(leds):
                led.value(1)
                time.sleep(0.1)
                led.value(0)
    
    else:
        # "do nothing"
        pass
    
    time.sleep(0.01) # Small delay for stability