GUI app using Tkinter

#----------------
# --- main.py ---
#----------------

import tkinter as tk
from tkinter import ttk, messagebox
import re
import locale
from businesslogic import BusinessLogic
from dataaccesslayer import DataAccessLayer

def main():

    # create main window
    window = tk.Tk()
    window.title('Create new account...')
    window.geometry('600x225')
    window.minsize(600, 225)

    # create an instance of the BusinessLogic & DataAccessLayer classes
    bl = BusinessLogic(window)
    dal = DataAccessLayer(window)

    def createAccount():    #routingNumber, accountNumber, openingDeposit):
        routingNumber = txtRoutingNumber.get()
        accountNumber = txtAccountNumber.get()
        openingDeposit = formatAsCurrency(float(txtOpeningDeposit.get()))

        # dal.insertNewAccount()

        print(f"\nCreating new account...\n"
              f"\tRouting #: {routingNumber}\n"
              f"\tAccount #: {accountNumber}\n"
              f"\t  Deposit: {formatAsCurrency(openingDeposit)}\n\n")

        return True

    def formatAsCurrency(amount):
        return '{:.2f}'.format(float(amount))

    # create label/prompt for the routing number
    lblRoutingNumber = ttk.Label(window,
                                text="ABA routing number: ",
                                justify="right",
                                borderwidth=0,
                                font="Tahoma 12",
                                relief="solid")

    lblRoutingNumber.place(x=85, y=42)

    # create entry box for routing number
    txtRoutingNumber = ttk.Entry(
        window,
        validate="key",
        width=10,
        justify="left",
        name="routingNumber",
        font="Tahoma 12",
        validatecommand=(window.register(bl.validateRoutingNumber),
                        '%S',  # character(s) just entered or deleted
                        '%s',  # text already in the textbox, before any changes
                        '%P',  # text in the textbox if the insertion/deletion is allowed
                        '%d',  # action code, see above
                        "txtRoutingNumber",
                        9  # maximum number of digits allowed
                        )
    )

    txtRoutingNumber.place(x=307, y=40)

    # create label/prompt for the account number
    lblAcctNumber = ttk.Label(window,
                            text="Account number: ",
                            justify="right",
                            borderwidth=0,
                            font="Tahoma 12",
                            relief="solid")

    lblAcctNumber.place(x=124, y=82)

    # create entry object for the account number
    txtAccountNumber = ttk.Entry(window,
                                validate="key",
                                width=19,
                                justify="left",
                                name="accountNumber",
                                font="Tahoma 12",
                                validatecommand=(window.register(bl.validateInputIsDigit), '%S', False)  #, '%W', 9, 18)
                                )

    txtAccountNumber.place(x=307, y=80)

    # create label/prompt for the opening deposit
    lblOpeningDeposit = ttk.Label(window,
                                text="Opening deposit: $",
                                justify="right",
                                borderwidth=0,
                                font="Tahoma 12",
                                relief="solid")

    lblOpeningDeposit.place(x=111, y=122)

    # create entry object for the opening deposit
    txtOpeningDeposit = ttk.Entry(window,
                                validate="key",
                                width=10,
                                justify="left",
                                name="openingDeposit",
                                font="Tahoma 12",
                                validatecommand=(window.register(bl.validateIsCurrency), '%S', '%s', '%P', True)
                                )

    txtOpeningDeposit.place(x=307, y=120)

    # create "Submit" button
    btnOK = ttk.Button(window,
                    name="btnOK",
                    text="Submit",
                    width=10,
                    command=createAccount(),    #createAccount())
                    ).place(x=80, y=180)

    # create "Cancel" button
    btnCancel = ttk.Button(window,
                        name="btnCancel",
                        text="Cancel",
                        width=10,
                        command=window.destroy
                        ).place(x=400, y=180)

    # set initial focus to the ABA routing number Entry() widget
    txtRoutingNumber.focus()

    # run ininite loop
    window.mainloop()

# EOFunc main()

if __name__ == "__main__":
    main()

#-------------------------
# --- businesslogic.py ---
#-------------------------

import tkinter as tk
from tkinter import ttk, messagebox
import re
import locale

class BusinessLogic:

    def __init__(self, parentGUI):
        self.parent = parentGUI

    def validateRoutingNumber(self,
                            inputText,    # text that was entered or deleted
                            currentText,  # text that currently in the textbox, *before* any change
                            proposedText, # text that will be in the textbox, *if* the change is allowed
                            actionCode,   # see block comment abovew
                            widgetName,   # name of the widget object
                            maxLength):   # maximum number of digits

        # if number of digits currently in the textbox is less than the maximum length...
        if (len(proposedText) < int(maxLength)):

            # make sure text entered is a digit, not a character
            if (inputText.isdigit()):
                return True
            else:
                return False

        # length of text currently in the textbox is -eq or -gt the maximum length
        else:

            if (len(proposedText) > int(maxLength)):
                return False

            if (self.isValidRoutingNumber(proposedText)):
                return True   # accept the input
            else:
                return False  # reject it

        return

    def isValidRoutingNumber(self, routingNumber):
        n = 0

        for i in range(0, len(str(routingNumber)), 3):

            n += int(str(routingNumber)[i]) * 3 + \
                 int(str(routingNumber)[i+1]) * 7 + \
                 int(str(routingNumber)[i+2])

        if (n != 0 and n % 10 == 0):
            #print(f"{routingNumber} is a valid ABA routing number.")
            # messagebox.showinfo("Information", f"\"{routingNumber}\" is a valid ABA routing number.")
            # print(f"Routing number {routingNumber} is valid")
            return True
        else:
            print(f"{routingNumber} is *not* a valid ABA routing number!")
            # messagebox.showerror("Error", f"\"{routingNumber}\" is not a valid ABA routing number!")
            return False

        return

    def validateInputIsDigit(self,
                            insertText,
                            acceptDecimalPoint):

        if (acceptDecimalPoint and insertText == "."):
            return True
        else:
            if insertText.isdigit():
                return True
            else:
                return False

    def isValidAccountNumber(accountNumber):
        if accountNumber is None:
            return False
        else:
            regEx = r'^[0-9]{9,18}$'  # account number must be contain between 9 and 18 digits

            if re.match(regEx, accountNumber):
                return True
            else:
                return False

        return

    def validateIsCurrency( self,
                            userInput,              # amount that was entered or deleted
                            currentAmount,          # amount that's currently in the textbox, *before* any change
                            proposedAmount,         # amount that will be in the textbox, *if* the change is allowed
                            acceptDecimal = True,   # accept a decimal point?
                            acceptMinus = False):   # accept a minus sign?

        charsToReject = [",", "$", "."]

        if not acceptMinus:
            charsToReject.append("-")

        if acceptDecimal:
            charsToReject.remove(".")

        # TODO: add currency symbol for the user's locale

        if (userInput in charsToReject):
            return False

        # if the *proposed* amount already contains a decimal point...
        if ("." in proposedAmount):

            # and it would have more than 2 decimal places should the insertion/deletion be accepted
            if (len(str(proposedAmount).split(".")[1]) > 2):
                return False

        if (acceptDecimal and userInput == "."):

            # if the proposed amount would contain more than 1 decimal point
            if (proposedAmount.count(".") > 1):
                return False

            return True

        else:

            if (self.isValidCurrency(proposedAmount)):
                return True
            else:
                return False

    def isValidCurrency(self, amount):
        rePattern = r'^[1-9]\d*(\.\d{1,2})?$'

        try:
            if re.match(rePattern, "{:.2f}".format(float(amount))):
                return True
            else:
                return False
        except:
            return False

        return

#---------------------------
# --- dataaccesslayer.py ---
#---------------------------

#import re
#import locale

# TODO: Implement Sqlite
class DataAccessLayer:

    def __init__(self, parentGUI):
        self.parent = parentGUI
        pass

    # stub function until Sqlite is implemented
    def insertNewAccount(self):
        routingNumber = self.parent.txtRoutingNumber.get(),
        accountNumber = self.parent.txtAccountNumber.get()
        openingDeposit = self.parent.txtOpeningDeposit.get()

        print(f"\nCreating new account...\n"
        f"\tRouting #: {routingNumber}\n"
        f"\tAccount #: {accountNumber}\n"
        f"\t  Deposit: ${openingDeposit}\n\n")