Calculator

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout


class Container(BoxLayout):
    def update_label(self):
        self.formula = self.formula
        self.lbl.text = self.formula

    def add_number(self, instance):
        if self.res == 10:
            self.res = 0
            self.formula = ""
        if self.formula == "0":
            self.formula = ""

        self.formula += str(instance)
        for i in self.formula:
            if i in "1234567890.":
                self.num += i
            if i in "-+*/":
                self.fin += f"{float(self.num):,}".replace(",", " ")
                self.num = ""
                self.fin += i
        self.formula = self.fin + f"{float(self.num):,}".replace(",", " ")
        self.num = ""
        self.fin = ""
        self.formula = self.formula.replace(".0", "")
        self.update_label()

    def add_operation(self, instance):
        check = str(instance).lower()

        if self.res == 10:
            self.res = 0
            pass
        if self.formula == "0":
            self.formula = ""
            if (str(instance).lower() == "."):
                self.formula += "0"
            else:
                if (check == "-"):
                    self.formula += str(instance)
                    self.update_label()
                    return
                if (check == "+") or (check == "*") or (check == "/"):
                    self.lbl.text = '0'
                    self.formula = "0"
                    return self.formula
        # if (check == "×"):
        #     self.formula += "*"
        if (self.formula[-1] == "+") or (self.formula[-1] == "*") or (self.formula[-1] == "/") \
                or (self.formula[-1] == "-"):
            if (self.formula[0] == "-"):
                return
            self.formula = self.formula[:-1]
            self.formula += str(instance)

            self.update_label()
            return
        else:
            self.formula += str(instance)

        self.update_label()

    def calculate(self):
        try:
            self.lbl.text = str(eval(self.lbl.text.replace(" ", "")))
            self.formula = "{0:,.2f}".format(float(self.lbl.text)).replace(",", " ")
            self.update_label()
            self.res = 10

        except:
            self.lbl.text = '0'
            self.formula = "0"

    def backspace(self):
        if self.res == 10:
            self.res = 0
            self.lbl.text = '0'
            self.formula = "0"
            self.update_label()
            return

        self.formula = self.formula[:-1]
        self.lbl.text = self.formula
        if self.formula == "":
            self.lbl.text = '0'
            self.formula = "0"


class CalculatorApp(App):
    def build(self):
        return Container()


if __name__ == "__main__":
    CalculatorApp().run()