import flet as ft


class Test(ft.TextField):
    def __init__(self, page: ft.Page):
        super().__init__()
        self.page = page
        self.len_date = 0
        self.on_change = self.scadenza

    def scadenza(self, e):
        text = e.control.value
        if len(text) > self.len_date:
            if len(text) == 2:
                e.control.value = text + "-"
            if len(text) == 5:
                e.control.value = text + "-"
            if len(text) > 10:
                e.control.value = text[0:10]
        else:
            if len(text) == 5:
                e.control.value = text[0:4]
            if len(text) == 2:
                e.control.value = text[0:1]

        self.len_date = len(e.control.value)
        self.page.update()


def main(page: ft.Page):
    page.theme_mode = ft.ThemeMode.LIGHT
    test = Test(page)
    page.add(test)


ft.app(target=main)