from machine import Pin
import utime
from neopixel import Neopixel

# Constants for Pins
TRIGGER_PIN = 0
ECHO_PIN = 1

# Constants for LED Gauge
MIN_DISTANCE = 50
MAX_DISTANCE = 200
MIN_LEDS = 0
MAX_LEDS = 16

# Constants for LED Colors
GREEN_COLOR = (0, 255, 0)
RED_COLOR = (255, 0, 0)
OFF_COLOR = (0, 0, 0)  # Black, for turning off LEDs

# Brightness factor (between 0.0 and 1.0)
BRIGHTNESS = 0.5  # Adjust this value to set the desired brightness

# Constants for Flashing
FLASH_INTERVALS = {0: 0.2, 1: 0.3, 2: 0.4, 3: 0.5}

# Constants for timeout
DISTANCE_TIMEOUT = 5 * 1000  # Set the timeout period in milliseconds
HYSTERESIS_THRESHOLD = 10.0  # Set the hysteresis threshold in distance units

# Initialize Ultrasonic Sensor
trigger = Pin(TRIGGER_PIN, Pin.OUT)
echo = Pin(ECHO_PIN, Pin.IN)

def get_distance():
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(5)
    trigger.low()
    
    signaloff = utime.ticks_us() # Initialize with default values
    while echo.value() == 0:
        signaloff = utime.ticks_us()
    
    signalon = utime.ticks_us() # Initialize with default values
    while echo.value() == 1:
        signalon = utime.ticks_us()
    
    timepassed = signalon - signaloff
    distance = (timepassed * 0.0343) / 2
    return distance

# Initialize Neopixel
pixels = Neopixel(16, 0, 6, "GRB")

# Initialize the time of the last distance change
last_distance_change_time = utime.ticks_ms()

# Initialize the last_distance variable
last_distance = None

# Initialize LED state (on or off)
leds_on = False

while True:
    distance = get_distance()
    
    # Ensure distance is within the specified range
    if MIN_DISTANCE <= distance <= MAX_DISTANCE:
        # Calculate the number of LEDs to turn green based on the distance range
        leds_to_turn_green = int((distance - MIN_DISTANCE) / (MAX_DISTANCE - MIN_DISTANCE) * (MAX_LEDS - MIN_LEDS)) + MIN_LEDS
        
        # Determine the flashing interval based on the number of green LEDs
        flash_interval = FLASH_INTERVALS.get(leds_to_turn_green, 0.2)
        
        # LED Gauge Display
        if leds_on:  # Check if LEDs should be on
            if leds_to_turn_green <= 3:
                for i in range(16):
                    if i < leds_to_turn_green:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in GREEN_COLOR))
                    else:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in RED_COLOR))
                pixels.show()
                utime.sleep(flash_interval)
                for i in range(16):
                    if i < leds_to_turn_green:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in GREEN_COLOR))
                    else:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in OFF_COLOR))
                pixels.show()
                utime.sleep(flash_interval)
            else:
                # Delay for the normal display
                for i in range(16):
                    if i < leds_to_turn_green:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in GREEN_COLOR))
                    else:
                        pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in RED_COLOR))
                pixels.show()
                utime.sleep(0.1)  # Adjust this value to change the duration of the normal display
        
        # Check if the distance has changed and update the last change time and last_distance
        if last_distance is None or abs(distance - last_distance) > HYSTERESIS_THRESHOLD:
            last_distance_change_time = utime.ticks_ms()
            last_distance = distance
            leds_on = True  # Distance changed, turn LEDs on
    else:
        # Distance is outside the range
        leds_on = False  # Distance is outside the range, turn LEDs off
        
        # Turn off all LEDs
        for i in range(16):
            pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in OFF_COLOR))
        pixels.show()
    
    # Check if the distance has remained unchanged for the timeout period
    if leds_on and utime.ticks_diff(utime.ticks_ms(), last_distance_change_time) > DISTANCE_TIMEOUT:
        for i in range(16):
            pixels.set_pixel(i, tuple(int(c * BRIGHTNESS) for c in OFF_COLOR))
        pixels.show()
        leds_on = False  # LEDs turned off due to timeout