import tkinter as tk

def call_convert():
    tem = numberInput.get()

    try:
        value = float(tem)
        option = var.get()

        if option == "Litro":
            gal = value * 0.264172
            result_label1.config(text=f"{gal:.3f} Galão (EUA)")

        elif option == "Galão(EUA)":
            lit = value * 3.78541
            result_label1.config(text=f"{lit:.3f} Litros")

    except ValueError:
        result_label1.config(text="Digite um número válido")

# janela
root = tk.Tk()
root.geometry('400x150+100+200')
root.title('Converter medidas de líquidos')
root.configure(background='#09A3BA')
root.resizable(width=False, height=False)

numberInput = tk.StringVar()

# label e entrada
input_label = tk.Label(root, text="Digite Valor:", bg='#09A3BA', fg="#FFFFFF")
input_entry = tk.Entry(root, textvariable=numberInput)

input_label.grid(row=1, column=0)
input_entry.grid(row=1, column=1)

# resultado
result_label1 = tk.Label(root, bg='#09A3BA', fg="#FFFFFF")
result_label1.grid(row=3, columnspan=4)

# dropdown
var = tk.StringVar()
dropDownList = ["Litro", "Galão(EUA)"]

dropdown = tk.OptionMenu(root, var, *dropDownList)
var.set(dropDownList[0])
dropdown.grid(row=1, column=3)

dropdown.config(bg='#09A3BA', fg="#FFFFFF")
dropdown["menu"].config(bg='#09A3BA', fg="#FFFFFF")

# botão
result_button = tk.Button(root, text="Converter",
                          command=call_convert,
                          bg='#09A3BA', fg="#FFFFFF")

result_button.grid(row=2, columnspan=4)

root.mainloop()