from machine import Pin, PWM, I2C
import time

# ==================== PIN CONFIGURATION ====================

PASSWORD = "21907894"

# Keypad: 4 rows and 4 columns
rows = [
    Pin(6, Pin.OUT),
    Pin(7, Pin.OUT),
    Pin(8, Pin.OUT),
    Pin(9, Pin.OUT)
]

cols = [
    Pin(10, Pin.IN, Pin.PULL_DOWN),
    Pin(11, Pin.IN, Pin.PULL_DOWN),
    Pin(12, Pin.IN, Pin.PULL_DOWN),
    Pin(13, Pin.IN, Pin.PULL_DOWN)
]

KEYS = [
    ["1", "2", "3", "A"],
    ["4", "5", "6", "B"],
    ["7", "8", "9", "C"],
    ["*", "0", "#", "D"]
]

# Servo
servo = PWM(Pin(15))
servo.freq(50)

# LEDs
red_led = Pin(2, Pin.OUT)
green_led = Pin(3, Pin.OUT)

# LCD: I2C address 0x27
i2c = I2C(0, sda=Pin(0), scl=Pin(1), freq=100000)
LCD_ADDR = 0x27

BL = 0x08
EN = 0x04
RS = 0x01

# ==================== LCD DRIVER ====================

def lcd_write_byte(data):
    i2c.writeto(LCD_ADDR, bytes([data | BL]))

def lcd_pulse(data):
    lcd_write_byte(data | EN)
    time.sleep_us(500)
    lcd_write_byte(data & ~EN)
    time.sleep_us(100)

def lcd_send(value, mode):
    high = value & 0xF0
    low = (value << 4) & 0xF0

    lcd_write_byte(high | mode)
    lcd_pulse(high | mode)

    lcd_write_byte(low | mode)
    lcd_pulse(low | mode)

def lcd_cmd(value):
    lcd_send(value, 0)

def lcd_char(value):
    lcd_send(ord(value), RS)

def lcd_init():
    time.sleep_ms(50)

    for _ in range(3):
        lcd_write_byte(0x30)
        lcd_pulse(0x30)
        time.sleep_ms(5)

    lcd_write_byte(0x20)
    lcd_pulse(0x20)

    lcd_cmd(0x28)
    lcd_cmd(0x0C)
    lcd_cmd(0x06)
    lcd_cmd(0x01)
    time.sleep_ms(5)

def lcd_clear():
    lcd_cmd(0x01)
    time.sleep_ms(3)

def lcd_line(row, text):
    lcd_cmd(0x80 if row == 0 else 0xC0)

    text = str(text)[:16].ljust(16)

    for character in text:
        lcd_char(character)

def lcd_message(line1, line2=""):
    lcd_clear()
    lcd_line(0, line1)
    lcd_line(1, line2)

# ==================== SERVO CONTROL ====================

def set_servo(angle):
    # Convert angle to a 50 Hz servo duty cycle
    duty = int(1638 + (angle / 180) * (8192 - 1638))
    servo.duty_u16(duty)

# ==================== KEYPAD SCAN ====================

def scan_keypad():
    for r in range(4):
        for row in rows:
            row.value(0)

        rows[r].value(1)
        time.sleep_us(50)

        for c in range(4):
            if cols[c].value():
                key = KEYS[r][c]

                # Wait for key release to avoid repeated input
                while cols[c].value():
                    time.sleep_ms(10)

                time.sleep_ms(30)
                return key

    return None

# ==================== LOCK STATE ====================

entered = ""
unlocked = False
wrong_attempts = 0

LOCKOUT_SECONDS = 10
lockout_until = 0

def show_locked():
    red_led.value(1)
    green_led.value(0)
    set_servo(0)
    lcd_message("LOCKED", "Enter PIN:")

def show_unlocked():
    red_led.value(0)
    green_led.value(1)
    set_servo(90)
    lcd_message("ACCESS GRANTED", "* to lock")

# ==================== MAIN PROGRAM ====================

print("Combination lock started")
print("LCD address:", hex(LCD_ADDR))

try:
    print("STEP 1: Starting LCD")
    lcd_init()
    print("STEP 2: LCD initialized")

    lcd_message("DIAGNOSTIC", "PLEASE WAIT")
    print("STEP 3: LCD message sent")

    time.sleep(3)

    print("STEP 4: Starting servo and LEDs")
    show_locked()
    print("STEP 5: Lock screen sent")

    while True:
        now = time.time()

        # Handle temporary lockout
        if now < lockout_until:
            remaining = lockout_until - now
            lcd_message("TOO MANY ERRORS", "Wait: {} sec".format(remaining))
            time.sleep_ms(200)
            continue

        key = scan_keypad()

        if key is None:
            time.sleep_ms(20)
            continue

        print("Key pressed:", key)

        # While unlocked, '*' locks the system again
        if unlocked:
            if key == "*":
                unlocked = False
                entered = ""
                wrong_attempts = 0
                show_locked()
                print("System locked")
            continue

        # Clear the currently entered PIN
        if key == "*":
            entered = ""
            lcd_message("LOCKED", "PIN cleared")
            time.sleep_ms(500)
            lcd_message("LOCKED", "Enter PIN:")
            continue

        # Submit the PIN
        if key == "#":
            if entered == PASSWORD:
                unlocked = True
                wrong_attempts = 0
                entered = ""
                show_unlocked()
                print("Correct PIN: unlocked")

            else:
                wrong_attempts += 1
                entered = ""

                print("Incorrect PIN. Attempts:", wrong_attempts)

                if wrong_attempts >= 3:
                    lockout_until = time.time() + LOCKOUT_SECONDS
                    lcd_message("TOO MANY ERRORS", "Wait: 10 sec")
                    print("Lockout for 10 seconds")

                else:
                    lcd_message(
                        "WRONG PIN",
                        "Attempts: {}/3".format(wrong_attempts)
                    )
                    time.sleep_ms(1200)
                    lcd_message("LOCKED", "Enter PIN:")

            continue

        # Accept numeric keys only
        if key.isdigit():
            if len(entered) < len(PASSWORD):
                entered += key

            # Show asterisks rather than revealing the PIN
            lcd_message("Enter PIN:", "*" * len(entered))

except Exception as error:
    print("ERROR:", error)
    try:
        lcd_message("SYSTEM ERROR", "Check console")
    except Exception:
        pass