#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
"""
Programa que implementa una calculadora científica básica
"""

import tkinter as tk
from math import factorial, sqrt, pi

def clic(tecla):
    '''Funcion que almacena los clics de cada tecla'''
    global cuenta
    cuenta = cuenta + str(tecla) #cuenta = "1+2" eval(1+2) --> 3
    resultado.set(cuenta)

def limpieza():
    global cuenta
    cuenta = ""
    resultado.set("0")

def hacer_cuenta():
    global cuenta
    try:
        total = str(eval(cuenta))
    except:
        limpieza()
        total = "ERROR"
    resultado.set(total)



###### programa principal #############################

ventana = tk.Tk()
ventana.config(width=392, height=600, bg="light steel blue")
ventana.title("Calculadora")
ventana.resizable(0,0)

# variable que almacena una cadena con los clics de cada tecla
cuenta = ""

# variable que muestra el resultado por pantalla
resultado = tk.StringVar()
resultado.set("0")

# ancho y alto de los teclas
ancho = 10
alto = 3

# primera fila : 1 2 3 +
boton1 = tk.Button(text="1", width=ancho, height=alto, command=lambda:clic(1))
boton1.place(x=17, y=180)
boton2 = tk.Button(text="2", width=ancho, height=alto, command=lambda:clic(2))
boton2.place(x=107, y=180)
boton3 = tk.Button(text="3", width=ancho, height=alto, command=lambda:clic(3))
boton3.place(x=197, y=180)
botonSuma = tk.Button(text="+", bg="white", width=ancho, height=alto, command=lambda:clic('+'))
botonSuma.place(x=287, y=180)

# segunda fila : 4 5 6 -
boton4 = tk.Button(text="4", width=ancho, height=alto, command=lambda:clic(4))
boton4.place(x=17, y=240)
boton5 = tk.Button(text="5", width=ancho, height=alto, command=lambda:clic(5))
boton5.place(x=107, y=240)
boton6 = tk.Button(text="6", width=ancho, height=alto, command=lambda:clic(6))
boton6.place(x=197, y=240)
botonResta = tk.Button(text="-", bg="white", width=ancho, height=alto, command=lambda:clic('-'))
botonResta.place(x=287, y=240)

# tercera fila : 7 8 9 x
boton7 = tk.Button(text="7", width=ancho, height=alto, command=lambda:clic(7))
boton7.place(x=17, y=300)
boton8 = tk.Button(text="8", width=ancho, height=alto, command=lambda:clic(8))
boton8.place(x=107, y=300)
boton9 = tk.Button(text="9", width=ancho, height=alto, command=lambda:clic(9))
boton9.place(x=197, y=300)
botonPor = tk.Button(text="x", width=ancho, bg="white", height=alto, command=lambda:clic('*'))
botonPor.place(x=287, y=300)

# cuarta fila : ( 0 ) /
botonParI = tk.Button(text="(", width=ancho, height=alto, command=lambda:clic('('))
botonParI.place(x=17, y=360)
botonCero = tk.Button(text="0", width=ancho, height=alto, command=lambda:clic(0))
botonCero.place(x=107, y=360)
botonParD = tk.Button(text=")", width=ancho, height=alto, command=lambda:clic(')'))
botonParD.place(x=197, y=360)
botonDiv = tk.Button(text="/", bg="white",width=ancho, height=alto, command=lambda:clic('/'))
botonDiv.place(x=287, y=360)

# quinta fila : Raiz punto decimal potencia resto
botonRaiz = tk.Button(text="RAIZ", width=ancho, height=alto, command=lambda:clic('sqrt('))
botonRaiz.place(x=17, y=420)
botonPunto = tk.Button(text=".", width=ancho, height=alto, command=lambda:clic('.'))
botonPunto.place(x=107, y=420)
botonPot = tk.Button(text="POWER", width=ancho, height=alto, command=lambda:clic('**'))
botonPot.place(x=197, y=420)
botonResto = tk.Button(text="%", bg="gainsboro",width=ancho, height=alto, command=lambda:clic('%'))
botonResto.place(x=287, y=420)

# sexta fila : clear factorial pi =
boton1 = tk.Button(text="CLEAR", width=ancho, height=alto, command=limpieza)
boton1.place(x=17, y=480)
boton2 = tk.Button(text="!", width=ancho, height=alto, command=lambda:clic('factorial('))
boton2.place(x=107, y=480)
boton3 = tk.Button(text="PI", width=ancho, height=alto, command=lambda:clic(pi))
boton3.place(x=197, y=480)
botonSuma = tk.Button(text="=", bg="light blue",width=ancho, height=alto, command=hacer_cuenta)
botonSuma.place(x=287, y=480)

pantalla = tk.Entry(
                font=['arial',20, 'bold'],
                width=22,
                textvariable = resultado,
                justify ="right",
                bd=20,
                bg="powder blue",
                state=tk.DISABLED
                )
pantalla.place(x=10, y=60)


ventana.mainloop()