main.py

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import ObjectProperty
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from database import DataBase


class CreateAccountWindow(Screen):
    namee = ObjectProperty(None)
    email = ObjectProperty(None)
    password = ObjectProperty(None)
    
    def submit(self):
        if self.namee.text != "" and self.email.text != "" and self.email.text.count("@") == 1 and self.email.text.count(".") > 0:
            if self.password != "":
                db.add_user(self.email.text, self.password.text, self.namee.text)
                self.reset()
                sm.current = "login"
            else:
                invalidForm()
        else:
            invalidForm()
                
                
    def login(self):
        self.reset()
        sm.current = "login"
        
        
    def reset(self):
        self.email.text = ""
        self.password.text = ""
        self.namee.text = ""
        
        
class LoginWindow(Screen):
    email = ObjectProperty(None)
    password = ObjectProperty(None)
    
    def loginBtn(self):
        if db.validate(self.email.text, self.password.text):
            MainWindow.current = self.email.text
            self.reset()
            sm.current = "main"
        else:
            invalidLogin()
            
            
    def createBtn(self):
        self.reset()
        sm.current = "create"
        
        
    def reset(self):
        self.email.text = ""
        self.password.text = ""
        
        
class MainWindow(Screen):
    n = ObjectProperty(None)
    created = ObjectProperty(None)
    email = ObjectProperty(None)
    current = ""
    
    
    def logOut(self):
        sm.current = "login"
        
        
    def on_enter(self, *args):
        password, name, created = db.get_user(self.current)
        self.n.text = "Nome da conta: " + name
        self.email.text = "Email: " + self.current
        self.created.text = "Criado em: " + created
            
            
class WindowManager(ScreenManager):
    pass


def invalidLogin():
    pop = Popup(title='Login Invalido',
    content=Label(text='Usuario ou senha invalidos.'),
    size_hint=(None, None), size=(400, 400))
    pop.open()
    
    
def invalidForm():
    pop = Popup(title='Invalid Form', content=Label(text='Por favor preencha todos os campos com informações validas!.'), size_hint=(None, None), size=(400, 400))
    pop.open()
    
    
kv = Builder.load_file("my.kv")
sm = WindowManager()
db = DataBase("users.txt")
screens = [LoginWindow(name="login"), CreateAccountWindow(name="create"), MainWindow(name="main")]
for screen in screens:
    sm.add_widget(screen)
    sm.current = "login"
        
            
class MyMainApp(App):
    def build(self):
        return sm
    
    
if __name__ == "__main__":
    MyMainApp().run()