from random import randint, choice
from tkinter import Tk, messagebox, Text, Button

def encode(string):
	#Pasamos a binario el mensaje original:
	binMSG = ""
	i = 0
	while i < len(string):
		caracter_MSG_binario = bin(ord(string[i])).replace("0b", "").zfill(8)
		binMSG = binMSG + caracter_MSG_binario
		i += 1
	#Dividimos el mensaje binario en dos cadenas de igual largo.
	Segmento1 = binMSG[:(int(len(binMSG)/2))]
	Segmento2 = binMSG[(int(len(binMSG)/2)):]
	#A cada segmento agregamos una cadena aleotoria inicial para generar encriptaciones diferentes para un mismo mensaje.
	Segmento1 = random_bin_chain(8) + Segmento1
	Segmento2 = random_bin_chain(8) + Segmento2	
	# (0 = @), (1 = $), (1 = &), (2 = *)
	i = 0
	cadena_final = ""
	while i < len(Segmento1):
		if Segmento1[i] == Segmento2[i] == "0":
			cadena_final += "@"
		elif Segmento1[i] == Segmento2[i] == "1":
			cadena_final += "$"
		elif Segmento1[i] == "1" and Segmento2[i] == "0":
			cadena_final += "&"
		elif Segmento1[i] == "0" and Segmento2[i] == "1":
			cadena_final += "*"
		i += 1
	#Transformamos los simbolos en caracteres normales (letras y numeros) y acortamos la cadena a la mitad.
	simbolos = ["@", "$", "&", "*"]
	valores = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.="
	i = k = 0
	while i < 4:
		for elemento in simbolos:
			match = elemento + simbolos[i]
			coincidencias = cadena_final.count(match)
			j = 1
			while j <= coincidencias:
				cadena_final = cadena_final.replace(match, choice(valores[k:k+4]), 1)
				j += 1
			k += 4
		i += 1
	return cadena_final
	#El largo de la cadena final es siempre mayor a 2*(string + 2)
	#El largo de la cadena final es siempre menor a (8/3)*(string + 2)

def decode(string):
	simbolos = ["@", "$", "&", "*"]
	valores = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.="
	#Lo primero es obtener la cadena de simbolos ["@", "$", "&", "*"]
	#Para ello transformamos las letras en simbolos.
	listavalores = []
	k = 0
	while (k+4) <= len(valores):
		listavalores.append(valores[k:k+4])
		k += 4
	
	i = k = 0
	while i < 4:
		for elemento in simbolos:
			match = elemento + simbolos[i]
			for caracter in listavalores[k]:
				string = string.replace(caracter, match)
			k += 1
		i += 1
	cadena_simbolos = string[8:]
	#La cadena de simbolos representa la suma de los dos segmentos del mensaje
	segmento1 = segmento2 = ""
	for elemento in cadena_simbolos:
		if elemento == "@":
			segmento1 = segmento1 + "0"
			segmento2 = segmento2 + "0"
		elif elemento == "$":
			segmento1 = segmento1 + "1"
			segmento2 = segmento2 + "1"
		elif elemento == "&":
			segmento1 = segmento1 + "1"
			segmento2 = segmento2 + "0"
		elif elemento == "*":
			segmento1 = segmento1 + "0"
			segmento2 = segmento2 + "1"
	cadena_binaria = segmento1 + segmento2
	#Ahora queda transformar la cadena binaria a texto plano.
	if (len(cadena_binaria) % 8) == 0:
		repeticiones = (len(cadena_binaria) // 8)
		j = k = 0
		valor_original = ""
		while k <= (repeticiones - 1):
			segmento_8 = cadena_binaria[j:j + 8]
			ascii_value = bin_to_ascii(segmento_8)
			str_value = chr(ascii_value)
			valor_original = valor_original + str(str_value)
			j += 8
			k += 1
	else:
		return ("Invalid text to decode.")
	return valor_original

def random_bin_chain(large):	
	binary_chain = ""
	for i in range(0, large):
		binary_chain = binary_chain + str(randint(0, 1))
	return binary_chain
	
def bin_to_ascii(bin_number):
    bin_number_str = str(bin_number)
    if len(bin_number_str) == 8:
        i = 0
        dec_number = 0
        while i <= 7:
            dec_number = dec_number + (int(bin_number_str[i]) * (2 ** (7 - i))) 
            i += 1
        return dec_number
    else:
        return "Error decoding."
		
def load_GUI():
	def EncodeClicked():
		string = txtInput.get('1.0', 'end').strip()
		if len(string) > 0:
			result = encode(string)
			txtInput.delete('1.0', 'end')
			txtInput.insert('1.0', result)
		else:
			messagebox.showwarning("Azav Cipher","The plain text must contain at least 1 character.")
	
	def DecodeClicked():
		string = txtInput.get('1.0', 'end').strip()
		if len(string) >= 4:
			if decode(string) != "Invalid text to decode.":
				result = decode(string)
				txtInput.delete('1.0', 'end')
				txtInput.insert('1.0', result)
			else:
				messagebox.showwarning("Azav Cipher","The encoded text is not valid to decode.")
		else:
			messagebox.showwarning("Azav Cipher","The encoded text must contain at least 4 characters.")

	#Main Window
	mainWindow = Tk()
	mainWindow.geometry("520x270")
	mainWindow.title("Azav Cipher")
	#TextBox
	txtInput = Text(mainWindow, height="12", width="60", relief = 'flat')
	txtInput.place(x=20, y=20)
	#Encode & Decode Buttons
	cmdEncode = Button(mainWindow,  text = 'Encode', width = 30, command = lambda:EncodeClicked()).place(x=20, y = 230)
	cmdEncode = Button(mainWindow,  text = 'Decode', width = 30, command = lambda:DecodeClicked()).place(x=285, y = 230)
	#Start
	mainWindow.mainloop()

		
load_GUI()