# Step 1: Import necessary modules
from machine import SoftI2C, Pin
from utime import sleep
from i2c_lcd import I2cLcd
import time

# I2C address of the LCD
AddressOfLcd = 0x27

# Initialize I2C for the LCD
i2c = SoftI2C(scl=Pin(22), sda=Pin(21), freq=400000)  # connect scl to GPIO 22, sda to GPIO 21

# Initialize the LCD
lcd = I2cLcd(i2c, AddressOfLcd, 2, 16)

# Define GPIO pins for rows
row_pins = [Pin(15, Pin.OUT), Pin(2, Pin.OUT), Pin(4, Pin.OUT), Pin(5, Pin.OUT)]

# Define GPIO pins for columns (changed to 16 and 17)
column_pins = [Pin(18, Pin.IN, Pin.PULL_DOWN), Pin(19, Pin.IN, Pin.PULL_DOWN), Pin(26, Pin.IN, Pin.PULL_DOWN), Pin(27, Pin.IN, Pin.PULL_DOWN)]

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

# Function to read the keypad
def read_keypad():
    for row_num, row_pin in enumerate(row_pins):
        row_pin.on()
        for col_num, col_pin in enumerate(column_pins):
            if col_pin.value() == 1:
                row_pin.off()
                return keys[row_num][col_num]
        row_pin.off()
    return None

# Function to display text on the LCD
def display_text(line1, line2=""):
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr(line1)
    lcd.move_to(0, 1)
    lcd.putstr(line2)

# Function to get a number from the keypad
def get_number():
    num = ''
    while True:
        key = read_keypad()
        if key:
            if key in '0123456789':
                num += key
                display_text(num)
            elif key == '#':  # Confirm the number
                return int(num)
            elif key == '*':  # Clear the current number
                num = ''
                display_text(num)
            sleep(0.2)  # Debounce delay

# Main calculator logic
def calculator():
    while True:
        display_text('Enter a:')
        a = get_number()
        
        display_text('Enter b:')
        b = get_number()
        
        display_text('Op: + - * /')
        while True:
            op = read_keypad()
            if op in 'ABCD':
                break
        
        if op == 'A':  # Addition
            result = a + b
            op_str = '+'
        elif op == 'B':  # Subtraction
            result = a - b
            op_str = '-'
        elif op == 'C':  # Multiplication
            result = a * b
            op_str = '*'
        elif op == 'D':  # Division
            if b != 0:
                result = a / b
            else:
                result = 'Err'
            op_str = '/'
        
        display_text(f'{a}{op_str}{b}=', str(result))
        sleep(5)  # Display the result for 5 seconds

# Start the calculator
calculator()