import tkinter as tk

calculation = ""

def add_to_calculation(symbol):
    global calculation
    calculation += str(symbol)
    text_result.delete(1.0, "end")
    text_result.insert(1.0, calculation)

def evaluate_calculation():
    global calculation
    try:
        calculation = str(eval(calculation))
        text_result.delete(1.0, "end")
        text_result.insert(1.0, calculation)
    except:
        clear_field()
        text_result.insert(1.0, "Error")

def clear_field():
    global calculation
    calculation = ""
    text_result.delete(1.0,"end")

def backspace():
    global calculation
    if len(calculation) == 0:
        pass
    else:
        calculation = calculation[:-1]
        text_result.delete(1.0, "end")
        text_result.insert(1.0, calculation)

def percentage():
    global calculation
    pass

def calculation_overx():
    global calculation
    try:
        calculation = str(eval("1/" + calculation))
        text_result.delete(1.0, "end")
        text_result.insert(1.0, calculation)
    except:
        clear_field()
        text_result.insert(1.0, "Error")

root = tk.Tk()
root.geometry("300x320")
root.title("Calculadora")

text_result = tk.Text(root,height=2, width=16, font=("Arial", 24))
text_result.grid(columnspan=5)

btn_clear = tk.Button(root, text="C", command=lambda: clear_field(), width=5, font=("Arial", 14))
btn_clear.grid(row=2, column=1)

btn_open_bracket = tk.Button(root, text="(", command=lambda: add_to_calculation("("), width=5, font=("Arial", 14))
btn_open_bracket.grid(row=2, column=2)

btn_close_bracket = tk.Button(root, text=")", command=lambda: add_to_calculation(")"), width=5, font=("Arial", 14))
btn_close_bracket.grid(row=2, column=3)

btn_backspace = tk.Button(root, text="<-", command=lambda: backspace(), width=5, font=("Arial", 14))
btn_backspace.grid(row=2, column=4)

btn_power = tk.Button(root, text="^", command=lambda: add_to_calculation("**"), width=5, font=("Arial", 14))
btn_power.grid(row=3, column=2)

btn_one_over = tk.Button(root, text="1/x", command=lambda: calculation_overx(), width=5, font=("Arial", 14))
btn_one_over.grid(row=3, column=1)

btn_percentage = tk.Button(root, text="%", command=lambda: percentage(), width=5, font=("Arial", 14))
btn_percentage.grid(row=3, column=3)

btn_1 = tk.Button(root, text="1", command=lambda: add_to_calculation(1), width=5, font=("Arial", 14))
btn_1.grid(row=4, column=1)

btn_2 = tk.Button(root, text="2", command=lambda: add_to_calculation(2), width=5, font=("Arial", 14))
btn_2.grid(row=4, column=2)

btn_3 = tk.Button(root, text="3", command=lambda: add_to_calculation(3), width=5, font=("Arial", 14))
btn_3.grid(row=4, column=3)

btn_4 = tk.Button(root, text="4", command=lambda: add_to_calculation(4), width=5, font=("Arial", 14))
btn_4.grid(row=5, column=1)

btn_5 = tk.Button(root, text="5", command=lambda: add_to_calculation(5), width=5, font=("Arial", 14))
btn_5.grid(row=5, column=2)

btn_6 = tk.Button(root, text="6", command=lambda: add_to_calculation(6), width=5, font=("Arial", 14))
btn_6.grid(row=5, column=3)

btn_7 = tk.Button(root, text="7", command=lambda: add_to_calculation(7), width=5, font=("Arial", 14))
btn_7.grid(row=6, column=1)

btn_8 = tk.Button(root, text="8", command=lambda: add_to_calculation(8), width=5, font=("Arial", 14))
btn_8.grid(row=6, column=2)

btn_9 = tk.Button(root, text="9", command=lambda: add_to_calculation(9), width=5, font=("Arial", 14))
btn_9.grid(row=6, column=3)

btn_0 = tk.Button(root, text="0", command=lambda: add_to_calculation(0), width=11, font=("Arial", 14))
btn_0.grid(row=7, column=1, columnspan=2)

btn_dot = tk.Button(root, text=".", command=lambda: add_to_calculation("."), width=5, font=("Arial", 14))
btn_dot.grid(row=7, column=3)

btn_plus = tk.Button(root, text="+", command=lambda: add_to_calculation("+"), width=5, font=("Arial", 14))
btn_plus.grid(row=6, column=4)

btn_minus = tk.Button(root, text="-", command=lambda: add_to_calculation("-"), width=5, font=("Arial", 14))
btn_minus.grid(row=5, column=4)

btn_times = tk.Button(root, text="x", command=lambda: add_to_calculation("*"), width=5, font=("Arial", 14))
btn_times.grid(row=4, column=4)

btn_division = tk.Button(root, text="/", command=lambda: add_to_calculation("/"), width=5, font=("Arial", 14))
btn_division.grid(row=3, column=4)

btn_enter = tk.Button(root, text="=", command=lambda: evaluate_calculation(), width=5, font=("Arial", 14))
btn_enter.grid(row=7, column=4)

root.mainloop()