import board
import busio
import digitalio
import time
import lcd
import i2c_pcf8574_interface

# -------------------------------------------------------------
# 1. HARDWARE SETUP 
# -------------------------------------------------------------
# I2C LCD (GP4 = SDA, GP5 = SCL)
i2c_bus = busio.I2C(scl=board.GP5, sda=board.GP4)
i2c_obj = i2c_pcf8574_interface.I2CPCF8574Interface(i2c_bus, 0x27)
display = lcd.LCD(i2c_obj, num_rows=2, num_cols=16)

# Switches (Active Low - Pull UP)
# SW1 = Motion (GP15), SW2 = Reset (GP14)
sw1 = digitalio.DigitalInOut(board.GP15)
sw1.direction = digitalio.Direction.INPUT
sw1.pull = digitalio.Pull.UP

sw2 = digitalio.DigitalInOut(board.GP14)
sw2.direction = digitalio.Direction.INPUT
sw2.pull = digitalio.Pull.UP

# Keypad Rows (Outputs - GP13 to GP10)
r1 = digitalio.DigitalInOut(board.GP13)
r2 = digitalio.DigitalInOut(board.GP12)
r3 = digitalio.DigitalInOut(board.GP11)
r4 = digitalio.DigitalInOut(board.GP10)
rows = [r1, r2, r3, r4]
for r in rows:
    r.direction = digitalio.Direction.OUTPUT
    r.value = True # Set idle to HIGH

# Keypad Columns (Inputs - GP9 to GP6)
c1 = digitalio.DigitalInOut(board.GP9)
c2 = digitalio.DigitalInOut(board.GP8)
c3 = digitalio.DigitalInOut(board.GP7)
c4 = digitalio.DigitalInOut(board.GP6)
cols = [c1, c2, c3, c4]
for c in cols:
    c.direction = digitalio.Direction.INPUT
    c.pull = digitalio.Pull.UP

# -------------------------------------------------------------
# 2. SYSTEM VARIABLES
# -------------------------------------------------------------
PASSWORD = "1234"
entered_pin = ""
system_active = False  
prev_sw1 = True        

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

# -------------------------------------------------------------
# 3. SCANNING FUNCTION 
# -------------------------------------------------------------
def scan_keypad():
    """Checks every row and column manually"""
    for r_idx in range(4):
        rows[r_idx].value = False  # Drive current row LOW
        
        for c_idx in range(4):
            if cols[c_idx].value == False: # If column reads LOW, key is pressed
                key = KEYMAP[r_idx][c_idx]
                time.sleep(0.2) # Basic Debounce
                while cols[c_idx].value == False: # Wait for finger to lift
                    pass
                rows[r_idx].value = True # Set row back to HIGH
                return key
                
        rows[r_idx].value = True # Set row back to HIGH
    return None

# -------------------------------------------------------------
# 4. MAIN LOOP
# -------------------------------------------------------------
display.set_backlight(False) # Start with screen OFF (SDG 11 - Energy Save)

while True:
    # --- SW1: MOTION SENSOR TOGGLE ---
    if sw1.value == False and prev_sw1 == True:
        system_active = not system_active
        time.sleep(0.2)
        
        if system_active:
            display.set_backlight(True)
            display.clear()
            display.set_cursor_pos(0, 0)
            display.print("Motion Detected")
            display.set_cursor_pos(1, 0)
            display.print("PIN: ____")
        else:
            display.set_backlight(False)
            display.clear()
            entered_pin = "" # Security reset
            
    prev_sw1 = sw1.value

    # --- KEYPAD & RESET (Only if Active) ---
    if system_active:
        
        # SW2: RESET INPUT
        if sw2.value == False:
            entered_pin = ""
            display.set_cursor_pos(1, 5)
            display.print("____") # Clear the underline area
            time.sleep(0.2)

        # KEYPAD SCAN
        kp = scan_keypad()
        if kp is not None:
            if len(entered_pin) < 4:
                entered_pin += kp
                # Update LCD with stars
                display.set_cursor_pos(1, 5)
                display.print("*" * len(entered_pin))
            
            # CHECK PASSWORD
            if len(entered_pin) == 4:
                time.sleep(0.4)
                display.clear()
                display.set_cursor_pos(0, 0)
                
                if entered_pin == PASSWORD:
                    display.print("ACCESS GRANTED")
                    display.set_cursor_pos(1, 0)
                    display.print("Welcome Home!")
                else:
                    display.print("ACCESS DENIED")
                    display.set_cursor_pos(1, 0)
                    display.print("Try Again")
                
                time.sleep(2.0)
                entered_pin = ""
                display.clear()
                display.set_cursor_pos(0, 0)
                display.print("Motion Detected")
                display.set_cursor_pos(1, 0)
                display.print("PIN: ____")

    time.sleep(0.01)