Python:ExampleProgramLoginSystem

import tkinter
from tkinter import*
import os
import random
from random import randint

def register_user(): ## Register User data save function
    username_info = username.get()
    password_info = password.get()
    email_info = email.get()

    file=open(username_info, 'w')
    file.write(username_info+'\n')
    file.write(password_info+'\n')
    file.write(email_info)
    file.close()
    file=open(email_info, 'w')
    file.write(email_info+'\n')
    file.write(username_info)
    file.close()


    username_entry.delete(0, END)
    password_entry.delete(0, END)
    email_entry.delete(0, END)

    Label(screen1, text = 'Registration Susccesful', fg = 'green', font = ('calibri', 11)).pack()

def login_verify(): ## Login Function
    username1 = username_verify.get()
    password1 = password_verify.get()

    username_entry1.delete(0, END)
    password_entry1.delete(0, END)

    list_of_files = os.listdir()

    if username1 in list_of_files:
        file1 = open(username1, 'r')
        verify = file1.read().splitlines()
        if password1 in verify:
            print('Logged in')
        else:
            print('Password incorrect')
    else:
        print('Username not found')

def codeP(): ## Generate code for reset password
    global code
    code = randint(1000, 9999)

def codeU(): ## Generate code to find username
    global code2
    code2 = randint(1000, 9999)

def submit_code():
    code1 = code_verify.get()

    password_code.delete(0, END)

    if int(code1) == code:
        Label(screen4, text='Code Correct', bg='green').pack()
    else:
        Label(screen4, text='Wrong Code', bg='red').pack()

def change_password(): ## Password reset function
    global code_verify
    global password_code

    username2 = username_verify1.get()

    username_entry2.delete(0, END)

    list_of_files1 = os.listdir()

    if username2 in list_of_files1:
        file2 = open(username2, 'r')
        verify1 = file2.read().splitlines()
        codeP()
        print(code)
        Label(screen4, text='Reset code sent').pack()
        password_code = Entry(screen4, textvariable=code_verify)
        password_code.pack()
        Label(screen4, text='').pack()
        Button(screen4, text='Submit code', width=10, height=2, command=submit_code).pack()
    else:
        Label(screen4, text='').pack()
        Label(screen4, text='No matching username').pack()

def find_username(): ## find forgoten username

    username3 = username_verify3.get()

    username_entry3.delete(0, END)

    list_of_files2 = os.listdir()

    if username3 in list_of_files2:
        file3 = open(username3, 'r')
        verify2 = file3.read().splitlines()
        Label(screen5, text='').pack()
        Label(screen5, text='Email Found', bg='green').pack()
    else:
        Label(screen5, text='').pack()
        Label(screen5, text='Email Not Found', bg='red').pack()

def register(): ## Register user / input from user
    global screen1
    screen1 = Toplevel(screen)
    screen1.title('Register')
    screen1.geometry('300x250')

    global username
    global password
    global email
    global username_entry
    global password_entry
    global email_entry

    username = StringVar()
    password = StringVar()
    email = StringVar()

    Label(screen1, text = 'Please enter details bellow').pack()
    Label(screen1, text='').pack()
    Label(screen1, text = 'Username* ').pack()
    username_entry = Entry(screen1, textvariable = username)
    username_entry.pack()
    Label(screen1, text = 'Password *').pack()
    password_entry = Entry(screen1, textvariable = password)
    password_entry.pack()
    Label(screen1, text = 'Email *').pack()
    email_entry = Entry(screen1, textvariable = email)
    email_entry.pack()
    Label(screen1, text='').pack()
    Button(screen1, text = 'Register', width=10,height=1, command = register_user).pack()

def reset_password(): ## Reset password / User input
    global screen4
    screen4 = Toplevel(screen)
    screen4.title('Reset Password')
    screen4.geometry('300x250')
    Label(screen4, text='Enter username *', height=2, width=30).pack()

    global username_entry2
    global username_verify1

    username_verify1 = StringVar()

    username_entry2 = Entry(screen4, textvariable= username_verify1)
    username_entry2.pack()

    Label(screen4, text='').pack()

    Button(screen4, text='Reset Password', command=change_password).pack()

def forgot_user(): ## Forgot user / User input
    global screen5
    screen5 = Toplevel(screen)
    screen5.title('Find username')
    screen5.geometry('300x250')
    Label(screen5, text='Enter Email *', height=2, width=30).pack()

    global username_entry3
    global username_verify3

    username_verify3 = StringVar()

    username_entry3 = Entry(screen5, textvariable=username_verify3, width=30)
    username_entry3.pack()

    Label(screen5, text='').pack()

    Button(screen5, text='Find Username', command=find_username).pack()

def login_issue(): ## Ask if user has forgot details
    global screen3
    screen3 = Toplevel(screen)
    screen3.title('Login Issues')
    screen3.geometry('300x250')
    Label(screen3, text='Have you forgot your Username or Password?', bg='grey', width='350', height='2', font=('calibri', 13)).pack()

    Button(screen3, text = 'USERNAME',  width=30, height=2, command=forgot_user).pack()
    Label(screen3, text='').pack()
    Button(screen3, text = 'PASSWORD',  width=30, height=2, command=reset_password).pack()

def login(): ## LOGIN PAGE FOR USER INPUT
    global screen2
    screen2 = Toplevel(screen)
    screen2.title('Login')
    screen2.geometry('300x250')
    Label(screen2, text = 'Please enter details bellow to login').pack()
    Label(screen2, text = '').pack()

    global username_verify
    global password_verify

    username_verify = StringVar()
    password_verify = StringVar()

    global username_entry1
    global password_entry1

    Label(screen2, text = 'Username * ').pack()
    username_entry1 = Entry(screen2, textvariable = username_verify)
    username_entry1.pack()
    Label(screen2, text = '').pack()
    Label(screen2, text = 'Password * ').pack()
    password_entry1 = Entry(screen2, textvariable = password_verify)
    password_entry1.pack()
    Label(screen2, text = '').pack()
    Button(screen2, text = 'Login', width = 10, height = 1, command = login_verify).pack()
    Label(screen2, text = '').pack()
    Button(screen2, text = 'Login issue?', width = 10, height = 1, command=login_issue).pack()

def main_screen(): ## Main screen
    global screen
    screen = Tk()
    screen.geometry('300x250')
    screen.title('Login API 1.2.1')
    Label(text = 'Login 1.2.1', bg = 'grey', width = '300', height = '2', font = ('Calibri', 13)).pack()
    Label(text = '').pack()
    Button(text = 'Login', height = '2', width = '30', command=login).pack()
    Label(text = '').pack()
    Button(text = 'Register', height = '2', width = '30', command=register).pack()

    screen.mainloop()
main_screen()