from machine import Pin
import utime

# ===================== SWITCH ======================
switch = Pin(2, Pin.IN, Pin.PULL_DOWN)

def wait_until_switch_on():
    while switch.value() == 0:
        utime.sleep(0.05)


# ===================== FORCE RESET KEYPAD ======================
def reset_keypad():
    for r in keypad_rows:
        r.low()
    utime.sleep(0.05)


# ===================== LCD ======================
class LCD:
    def __init__(self, rs, en, d4, d5, d6, d7):
        self.rs = Pin(rs, Pin.OUT)
        self.en = Pin(en, Pin.OUT)
        self.data_pins = [Pin(d4, Pin.OUT), Pin(d5, Pin.OUT), Pin(d6, Pin.OUT), Pin(d7, Pin.OUT)]
        self.init_lcd()

    def pulse_enable(self):
        self.en.value(1)
        utime.sleep_us(40)
        self.en.value(0)
        utime.sleep_us(40)

    def send_nibble(self, data):
        for i in range(4):
            self.data_pins[i].value((data >> i) & 1)
        self.pulse_enable()

    def send_byte(self, data, mode):
        self.rs.value(mode)
        self.send_nibble(data >> 4)
        self.send_nibble(data & 0x0F)
        utime.sleep_ms(2)

    def command(self, cmd):
        self.send_byte(cmd, 0)

    def write_char(self, char):
        self.send_byte(ord(char), 1)

    def clear(self):
        self.command(0x01)
        utime.sleep_ms(2)

    def move_to(self, col, row):
        pos = col + 0x40 * row
        self.command(0x80 | pos)

    def putstr(self, string):
        for char in string:
            self.write_char(char)

    def init_lcd(self):
        utime.sleep_ms(20)
        self.command(0x33)
        self.command(0x32)
        self.command(0x28)
        self.command(0x0C)
        self.command(0x06)
        self.command(0x01)
        utime.sleep_ms(5)


# ===================== LCD & KEYPAD ======================
lcd = LCD(rs=16, en=13, d4=19, d5=20, d6=21, d7=26)

keypad_rows = [Pin(pin, Pin.OUT) for pin in [28, 22, 27, 18]]
keypad_columns = [Pin(pin, Pin.IN, Pin.PULL_DOWN) for pin in [17, 15, 14, 4]]

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

password = "1234"
input_buffer = ""
is_unlocked = False


# ===================== READ KEYPAD ======================
def read_keypad():
    for row in range(4):
        keypad_rows[row].high()
        utime.sleep_us(400)

        for col in range(4):
            if keypad_columns[col].value() == 1:
                keypad_rows[row].low()
                return keys[row][col]

        keypad_rows[row].low()

    return None


# ===================== PASSWORD SCREEN ======================
def request_password():
    global input_buffer, is_unlocked
    is_unlocked = False
    input_buffer = ""

    lcd.clear()
    lcd.putstr("Enter Password:")

    while True:

        # --- SWITCH CHECK ---
        if switch.value() == 0:
            lcd.clear()
            reset_keypad()
            wait_until_switch_on()
            lcd.init_lcd()          # reinitialize LCD
            reset_keypad()
            lcd.putstr("Enter Password:")
            input_buffer = ""
            continue
        # ---------------------

        key = read_keypad()
        if key:

            if key == '#':   # ENTER
                if input_buffer == password:
                    lcd.clear()
                    lcd.putstr("Unlocked!")
                    utime.sleep(2)
                    return True
                else:
                    lcd.clear()
                    lcd.putstr("Wrong Password!")
                    utime.sleep(2)
                    lcd.clear()
                    lcd.putstr("Enter Password:")
                    input_buffer = ""

            elif key == '*':  # CLEAR
                input_buffer = ""
                lcd.clear()
                lcd.putstr("Enter Password:")

            else:
                input_buffer += key
                lcd.move_to(0, 1)
                lcd.putstr('*' * len(input_buffer))

            utime.sleep(0.25)


# ===================== TEXT ENTRY MODE ======================
def enter_text():
    global input_buffer
    input_buffer = ""

    lcd.clear()
    lcd.putstr("Enter Text:")

    while True:

        if switch.value() == 0:
            lcd.clear()
            reset_keypad()
            wait_until_switch_on()
            lcd.init_lcd()
            return   # go back to main loop → ask password again

        key = read_keypad()
        if key:
            if key == '#':
                lcd.clear()
                lcd.putstr(input_buffer)
                input_buffer = ""

            elif key == '*':
                input_buffer = ""
                lcd.clear()
                lcd.putstr("Enter Text:")

            else:
                input_buffer += key
                lcd.move_to(0, 1)
                lcd.putstr(input_buffer)

            utime.sleep(0.25)


# ======================= MAIN LOOP =========================
try:
    while True:
        wait_until_switch_on()
        reset_keypad()

        if request_password():   # when unlocked
            enter_text()

except KeyboardInterrupt:
    lcd.clear()
    print("Program interrupted.")