# Simple Calculator using Keypad & I2C LCD with Raspberry Pi Pico

from machine import Pin, I2C
import utime
from pico_i2c_lcd import I2cLcd

debug = True

# I2C setup
i2c = I2C(0, scl=Pin(1), sda=Pin(0), freq=200000)

I2C_ADDR = i2c.scan()[0]
lcd = I2cLcd(i2c, I2C_ADDR, 2, 16)

# Keypad layout
keyName = [['1','2','3','+'],
           ['4','5','6','-'],
           ['7','8','9','*'],
           ['c','0','=','/']]

keypadRowPins = [13,12,11,10]
keypadColPins = [9,8,7,6]

row = []
col = []
keypadState = []

for i in keypadRowPins:
    row.append(Pin(i, Pin.IN, Pin.PULL_UP))
    keypadState.append([0,0,0,0])

for i in keypadColPins:
    col.append(Pin(i, Pin.OUT))

# ---------------- CALCULATOR LOGIC ---------------- #

def solve(oprt, oprdA, oprdB):

    if oprt == "+":
        return oprdA + oprdB
    elif oprt == "-":
        return oprdA - oprdB
    elif oprt == "*":
        return oprdA * oprdB
    elif oprt == "/":
        return round(oprdA / oprdB, 6)


def calc(lst):

    operand = []
    operator = []

    for i in lst:

        if debug:
            print(i)

        if i == '+':

            while (len(operator)!=0 and
                   (operator[-1] in ['*','/','-','+'])):

                b = operand.pop(-1)
                a = operand.pop(-1)
                c = operator.pop(-1)

                operand.append(solve(c,a,b))

            operator.append(i)

        elif i == '-':

            while (len(operator)!=0 and
                   (operator[-1] in ['*','/','-','+'])):

                b = operand.pop(-1)
                a = operand.pop(-1)
                c = operator.pop(-1)

                operand.append(solve(c,a,b))

            operator.append(i)

        elif i == '*':

            while (len(operator)!=0 and
                   (operator[-1] in ['*','/'])):

                b = operand.pop(-1)
                a = operand.pop(-1)
                c = operator.pop(-1)

                operand.append(solve(c,a,b))

            operator.append(i)

        elif i == '/':

            while (len(operator)!=0 and
                   (operator[-1] in ['*','/'])):

                b = operand.pop(-1)
                a = operand.pop(-1)
                c = operator.pop(-1)

                operand.append(solve(c,a,b))

            operator.append(i)

        elif i == '(':

            operator.append(i)

        elif i == ')':

            while operator[-1] != '(':

                b = operand.pop(-1)
                a = operand.pop(-1)
                c = operator.pop(-1)

                operand.append(solve(c,a,b))

            operator.pop(-1)

        else:
            operand.append(i)

    while len(operator) != 0:

        b = operand.pop(-1)
        a = operand.pop(-1)
        c = operator.pop(-1)

        operand.append(solve(c,a,b))

    return operand[0]


# ---------------- KEYPAD READING ---------------- #

def keypadRead():

    global row

    j_ifPressed = -1
    i_ifPressed = -1

    for i in range(len(col)):

        col[i].low()

        utime.sleep(0.005)

        for j in range(len(row)):

            pressed = not row[j].value()

            if pressed and (keypadState[j][i] != pressed):

                keypadState[j][i] = pressed

            elif not pressed and (keypadState[j][i] != pressed):

                keypadState[j][i] = pressed

                j_ifPressed = j
                i_ifPressed = i

        col[i].high()

    if j_ifPressed != -1 and i_ifPressed != -1:

        return keyName[j_ifPressed][i_ifPressed]

    else:

        return -1


# ---------------- LCD DISPLAY ---------------- #

def printLCD(lst):

    lcd.clear()

    string = ""

    for i in lst:
        string += str(i)

    lcd.move_to(0,0)
    lcd.putstr(string[:16])

    lcd.move_to(0,1)
    lcd.putstr(string[16:32])


# ---------------- START SCREEN ---------------- #

lcd.clear()

lcd.move_to(0,0)
lcd.putstr("Simple")

lcd.move_to(0,1)
lcd.putstr("Calculator")

utime.sleep(2)

lcd.clear()


# ---------------- MAIN PROGRAM ---------------- #

shiftFlag = False
signFlag = False
inputList = ['']


if __name__ == '__main__':

    while True:

        key = keypadRead()

        if key != -1:

            if ((key <= '9' and key >= '0') or key == '.'):

                inputList[-1] = inputList[-1] + key


            elif key in ['+','-','*','/']:

                if inputList != ['']:

                    if (inputList[-1] == '' and
                       inputList[-2] in ['+','-','*','/']):

                        inputList[-2] = key

                    elif inputList[-1] == '':

                        inputList[-1] = key
                        inputList.append('')

                    else:

                        inputList[-1] = float(inputList[-1])
                        inputList.append(key)
                        inputList.append('')


            elif key == 'c':

                if inputList == ["error"]:
                    inputList = ['']

                if inputList != ['']:

                    if inputList[-1] == '':

                        inputList.pop()
                        inputList[-1] = str(inputList[-1])[:-1]

                    else:

                        inputList[-1] = str(inputList[-1])[:-1]


            elif key == '=':

                if inputList[-1] == '':

                    inputList.pop(-1)

                elif inputList[-1] != ')':

                    inputList[-1] = float(inputList[-1])

                try:

                    ans = calc(inputList)

                    inputList = [str(ans)]

                except:

                    inputList = ["error"]


            printLCD(inputList)

            print(inputList)