import machine
import utime
from machine import Pin

# ── Pin setup ──────────────────────────────────────
BTN       = Pin(9,  Pin.IN,  Pin.PULL_DOWN)
LED_GREEN = Pin(6,  Pin.OUT)
LED_RED   = Pin(7,  Pin.OUT)
BUZZER    = Pin(8,  Pin.OUT)

# ── LCD setup (4-bit) ──────────────────────────────
RS = Pin(0, Pin.OUT)
E  = Pin(1, Pin.OUT)
D4 = Pin(2, Pin.OUT)
D5 = Pin(3, Pin.OUT)
D6 = Pin(4, Pin.OUT)
D7 = Pin(5, Pin.OUT)

def pulse():
    E.value(1); utime.sleep_us(500)
    E.value(0); utime.sleep_us(500)

def send_nibble(n):
    D4.value((n >> 0) & 1)
    D5.value((n >> 1) & 1)
    D6.value((n >> 2) & 1)
    D7.value((n >> 3) & 1)
    pulse()

def lcd_cmd(cmd):
    RS.value(0)
    send_nibble(cmd >> 4)
    send_nibble(cmd & 0xF)
    utime.sleep_ms(2)

def lcd_char(ch):
    RS.value(1)
    send_nibble(ord(ch) >> 4)
    send_nibble(ord(ch) & 0xF)
    utime.sleep_us(200)

def lcd_print(text):
    for c in text:
        lcd_char(c)

def lcd_pos(row, col):
    lcd_cmd(0x80 | (col + (0x40 if row else 0)))

def lcd_clear():
    lcd_cmd(0x01); utime.sleep_ms(5)

def lcd_init():
    utime.sleep_ms(50)
    RS.value(0)
    for _ in range(3):
        send_nibble(0x3); utime.sleep_ms(5)
    send_nibble(0x2); utime.sleep_ms(1)
    lcd_cmd(0x28)
    lcd_cmd(0x0C)
    lcd_cmd(0x06)
    lcd_clear()

def beep(duration=0.2):
    BUZZER.value(1); utime.sleep(duration); BUZZER.value(0)

# ── Fake palm database (simulated) ─────────────────
REGISTERED_PALMS = ["PALM_001", "PALM_002"]

def scan_palm():
    return "PALM_001" if BTN.value() else None

def match_palm(scan_id):
    return scan_id in REGISTERED_PALMS

# ── Main loop ──────────────────────────────────────
lcd_init()
LED_GREEN.value(0)
LED_RED.value(0)

while True:
    lcd_clear()
    lcd_pos(0, 0); lcd_print("  PalmPay Ready ")
    lcd_pos(1, 0); lcd_print(" Press btn=scan ")
    utime.sleep(0.1)

    if BTN.value():
        lcd_clear()
        lcd_pos(0, 0); lcd_print("  Scanning Palm ")
        lcd_pos(1, 0); lcd_print("  Please wait.. ")
        utime.sleep(1.5)

        scan_id = scan_palm()

        if scan_id and match_palm(scan_id):
            LED_GREEN.value(1)
            LED_RED.value(0)
            beep(0.2)
            lcd_clear()
            lcd_pos(0, 0); lcd_print("Payment Approved")
            lcd_pos(1, 0); lcd_print("  Thank You!    ")
            utime.sleep(3)
            LED_GREEN.value(0)
        else:
            LED_RED.value(1)
            LED_GREEN.value(0)
            beep(0.6)
            lcd_clear()
            lcd_pos(0, 0); lcd_print(" Auth  Failed!  ")
            lcd_pos(1, 0); lcd_print(" Try Again...   ")
            utime.sleep(3)
            LED_RED.value(0)