# ESP32 LED Control Program with Push Buttons
# MicroPython Implementation with Detailed Comments

# Import required libraries
from machine import Pin  # For GPIO pin control
import time             # For time delays

# ========== HARDWARE CONFIGURATION ==========
# Define GPIO pins connected to LEDs (adjust to your wiring)
# Note: ESP32 GPIO numbers may differ from physical pin numbers
LED = [14, 15, 16, 17]  # Array of 4 LED pins (GPIO14 to GPIO17)

# Define GPIO pins connected to push buttons
# Buttons should be wired between these pins and GND (active-low)
SW = [18, 19, 21]       # Array of 3 switch pins (GPIO18, GPIO19, GPIO21)

# ========== GPIO INITIALIZATION ==========
# Initialize all LED pins as outputs using list comprehension
# Creates a list of Pin objects in output mode
led_pins = [Pin(pin, Pin.OUT) for pin in LED]

# Initialize all switch pins as inputs with internal pull-up resistors
# This means:
# - Button not pressed: pin reads HIGH (1)
# - Button pressed: pin reads LOW (0) because connected to GND
sw_pins = [Pin(pin, Pin.IN, Pin.PULL_UP) for pin in SW]

# Initialize all LEDs to OFF state (LOW)
for led in led_pins:
    led.value(0)  # Set to LOW voltage (0 = OFF)

# ========== LED EFFECT FUNCTIONS ==========
def blink_all(delay_ms=1000):
    """
    Blink all LEDs simultaneously
    Args:
        delay_ms: Duration in milliseconds for both ON and OFF states
    """
    # Turn ON all LEDs
    for led in led_pins:
        led.value(1)  # Set HIGH (1 = ON)
    time.sleep_ms(delay_ms)  # Keep ON for specified time
    
    # Turn OFF all LEDs
    for led in led_pins:
        led.value(0)
    time.sleep_ms(delay_ms)  # Keep OFF for specified time

def run_right_to_left(delay_ms=2000):
    """
    Light LEDs sequentially from first to last (right to left)
    Args:
        delay_ms: Time each LED stays ON in milliseconds
    """
    for led in led_pins:      # Loop in order: LED[0], LED[1], etc.
        led.value(1)          # Turn ON current LED
        time.sleep_ms(delay_ms)  # Hold ON state
        led.value(0)          # Turn OFF before moving to next

def run_left_to_right(delay_ms=4000):
    """
    Light LEDs sequentially from last to first (left to right)
    Args:
        delay_ms: Time each LED stays ON in milliseconds
    """
    for led in reversed(led_pins):  # Loop in reverse order
        led.value(1)
        time.sleep_ms(delay_ms)
        led.value(0)

# ========== MAIN PROGRAM LOOP ==========
try:
    print("Program started. Press buttons to control LEDs.")
    
    while True:  # Run forever until KeyboardInterrupt (Ctrl+C)
        time.sleep_ms(10)  # Small delay to reduce CPU usage
        
        # ----- Button 0 (SW0) Pressed -----
        if sw_pins[0].value() == 0:  # Active-low check
            print("Button 0: All LEDs blinking (1s interval)")
            while sw_pins[0].value() == 0:  # While button is held
                blink_all(1000)  # Blink with 1000ms (1s) delay
        
        # ----- Button 1 (SW1) Pressed -----
        elif sw_pins[1].value() == 0:
            print("Button 1: Left-to-right chase (2s delay)")
            while sw_pins[1].value() == 0:
                run_right_to_left(2000)  # 2000ms (2s) per LED
        
        # ----- Button 2 (SW2) Pressed -----
        elif sw_pins[2].value() == 0:
            print("Button 2:  Right-to-left chase (4s delay)")
            while sw_pins[2].value() == 0:
                run_left_to_right(4000)  # 4000ms (4s) per LED
        
        # ----- No Buttons Pressed -----
        else:
            # Ensure all LEDs are OFF when no buttons pressed
            for led in led_pins:
                led.value(0)
            time.sleep_ms(10)  # Small delay to prevent busy-waiting

# ========== CLEANUP ON EXIT ==========
except KeyboardInterrupt:
    # Turn OFF all LEDs when program is stopped (Ctrl+C)
    for led in led_pins:
        led.value(0)
    print("\nProgram stopped. All LEDs turned OFF.")