from machine import Pin, PWM
import utime
from time import time as now

# Pin definitions
pir = Pin(14, Pin.IN)
trig = Pin(27, Pin.OUT)
echo = Pin(26, Pin.IN)
led = Pin(33, Pin.OUT)
buzzer = PWM(Pin(25))
servo_pwm = PWM(Pin(13), freq=50)

from keypad import Keypad4x4
keys = [['1','2','3','A'],['4','5','6','B'],['7','8','9','C'],['*','0','#','D']]
keypad = Keypad4x4(keys, [19,18,5,17], [16,4,2,15])

correct_password = "1234"
TIMEOUT = 180

def get_distance_cm():
    trig.off(); utime.sleep_us(2)
    trig.on(); utime.sleep_us(10)
    trig.off()
    timeout = 10000
    start_time = utime.ticks_us()
    while echo.value() == 0:
        if utime.ticks_diff(utime.ticks_us(), start_time) > timeout:
            return 999
    start = utime.ticks_us()
    while echo.value() == 1:
        if utime.ticks_diff(utime.ticks_us(), start_time) > timeout:
            return 999
    end = utime.ticks_us()
    duration = utime.ticks_diff(end, start)
    return (duration / 2) / 29.1

def servo_move(pos):
    servo_pwm.duty(77 if pos=="unlock" else 25)

def stop_buzzer():
    buzzer.duty(0)
    try:
        buzzer.deinit()
    except:
        pass

def alert(times=3):
    for _ in range(times):
        led.on()
        buzzer.init()
        buzzer.freq(500); buzzer.duty(200)
        utime.sleep(0.3)
        led.off()
        buzzer.duty(0)
        utime.sleep(0.3)
    stop_buzzer()

def unlock_sequence():
    led.off()
    buzzer.init(); buzzer.freq(800); buzzer.duty(150)
    utime.sleep(0.2)
    stop_buzzer()
    servo_move("unlock")
    utime.sleep(5)
    servo_move("lock")
    led.on()

def check_password(timeout_s):
    start = now()
    typed = ""
    while now() - start < timeout_s:
        key = keypad.get_key()
        if key:
            typed += key
            print("*", end="", flush=True)
            if len(typed) == len(correct_password):
                print()
                return typed == correct_password
        utime.sleep(0.1)
    return None

servo_move("lock")
led.on()
stop_buzzer()
print("System ready – stand <100 cm from sensor to trigger")

while True:
    dist = get_distance_cm()
    print("Distance:", round(dist,1), "cm")
    if dist < 100:
        print("Presence detected – you have 3 minutes")
        start = now()
        while now() - start < TIMEOUT:
            if get_distance_cm() >= 100:
                print("Person left – resetting")
                break
            remaining = int(TIMEOUT - (now() - start))
            result = check_password(remaining)
            if result is True:
                print("Correct password!")
                unlock_sequence()
                break
            elif result is False:
                print("Wrong password!")
                alert()
                break
        else:
            print("Timeout – no password entered")
            alert(5)
    utime.sleep(0.5)