from machine import Pin, ADC, time_pulse_us
import time as t


# CONSTANTS
# =========

# ultrasonic
echo = Pin(18, Pin.IN)
trig = Pin(19, Pin.OUT, value=0)

# other sensors
ldr = ADC(Pin(35, Pin.IN))
gas = ADC(Pin(25, Pin.IN))

# leds
light = Pin(15, Pin.OUT, value=0)
danger_light = Pin(2, Pin.OUT, value=0)

# thresholds
VEHICLE_DIST = 30
DANGER_DIST = 15
GAS_LIMIT = 3000
LIGHT_THRES = 1500

# FUNCTIONS
# =========
def get_distance() -> float:
    """
    return the ultrasonic sensor reading in centimeters
    note: return None if no data was returned by the sensor
    """
    trig.value(0)
    t.sleep_us(2)

    trig.value(1)
    t.sleep_us(10)

    trig.value(0)

    duration = time_pulse_us(echo, 1, 30000)

    if duration < 0:
        return None
    
    return duration / 58

def handle_distance(d) -> str:
    """process the distance reading and return a string representing the current state"""
    if d is None:
        return "No Signal"
    elif d < DANGER_DIST:
        return "Danger"
    elif d < VEHICLE_DIST:
        return "Vehicle"
    else:
        return "Clear"

def handle_gas(g) -> str:
    """process the gas reading and return a string representing the current state"""
    if g > GAS_LIMIT:
        return "Danger"
    else:
        return "Clear"

def handle_light(l) -> str:
    """process the light reading and return a string representing the current state"""
    if l > LIGHT_THRES: # not enough light
        return "Dark"
    else:
        return "Light"

# MAIN LOOP
# =========
while True:
    d_state = handle_distance(get_distance())
    g_state = handle_gas(gas.read())
    l_state = handle_light(ldr.read())

    if d_state.lower() == "danger" or g_state.lower() == "danger":
        danger_light.value(1)
    else:
        danger_light.value(0)
    
    if l_state.lower() == "dark":
        light.value(1)
    else:
        light.value(0)

    print(f"[{t.time()}s]:")
    print(f"\tDistance => {d_state}")
    print(f"\tGas      => {g_state}")
    print(f"\tLight    => {l_state}")

    t.sleep(2)