from machine import Pin, ADC, time_pulse_us
import time
from lcd import lcd_init, lcd_print, lcd_clear

# source: https://wokwi.com/projects/462793394742436865

# -----------------------------
# Smart Safety Monitor System
# -----------------------------

# Ultrasonic Sensor
trig = Pin(12, Pin.OUT)
echo = Pin(14, Pin.IN)

# Gas Sensor
gas_sensor = ADC(Pin(34))
gas_sensor.atten(ADC.ATTN_11DB)

# -----------------------------
# Threshold Settings
# -----------------------------
SAFE_DISTANCE = 35
WARNING_DISTANCE = 20

SAFE_GAS = 1300
WARNING_GAS = 2200

# -----------------------------
# LCD Startup
# -----------------------------
lcd_init()
lcd_print("Safety System")
time.sleep(2)

# -----------------------------
# Functions
# -----------------------------

def get_distance():
    """Measure distance using ultrasonic sensor"""
    trig.value(0)
    time.sleep_us(2)

    trig.value(1)
    time.sleep_us(10)
    trig.value(0)

    duration = time_pulse_us(echo, 1, 30000)

    if duration < 0:
        return None

    distance = (duration * 0.0343) / 2
    return round(distance, 1)


def get_gas():
    """Read gas level"""
    return gas_sensor.read()


def check_status(distance, gas):
    """Determine system state"""

    if distance is None:
        return "NO SIGNAL"

    if distance < WARNING_DISTANCE or gas > WARNING_GAS:
        return "DANGER"

    elif distance < SAFE_DISTANCE or gas > SAFE_GAS:
        return "WARNING"

    else:
        return "SAFE"


def show_lcd(status):
    """Display status on LCD"""
    lcd_clear()

    if status == "SAFE":
        lcd_print("ALL SAFE")

    elif status == "WARNING":
        lcd_print("CHECK AREA")

    elif status == "DANGER":
        lcd_print("ALERT NOW!")

    else:
        lcd_print("NO SIGNAL")


def serial_output(status, distance, gas):
    """Print full data"""

    if distance is None:
        print("No Signal | Gas:", gas)

    else:
        print("Status:", status,
              "| Distance:", distance, "cm",
              "| Gas:", gas)


# -----------------------------
# Main Program
# -----------------------------
while True:

    distance_value = get_distance()
    gas_value = get_gas()

    system_status = check_status(distance_value, gas_value)

    show_lcd(system_status)

    serial_output(system_status, distance_value, gas_value)

    time.sleep(1)