private func signIn() {
        self.view.endEditing(true)

        let messages = self.validationErrorMessages()
        self.validateErrorMessages(messages)
        if messages.count > 0 {
            return
        }

        let entry = FFEntry()
        entry.login = self.loginTextField.text
        entry.password = self.passwordTextField.text

        FFHUD.show()
        self.navigationController?.view.isUserInteractionEnabled = false
        FFNetworkAdapter.request(target: .login(entry: entry), success: { [weak self] (response) in
            FFHUD.dismiss()
            self?.navigationController?.view.isUserInteractionEnabled = true

            let token = try! response.mapObject(FFToken.self)
            let user = try! response.mapObject(FFUser.self)

            FFUserHolder.token = token.value!
            FFUserHolder.user = user

            self?.performSegue(withIdentifier: FFGlobalConstants.toMenuSegueIdentifier, sender: nil)
            }, failure: { [weak self] (messages) in
                FFHUD.dismiss()
                self?.navigationController?.view.isUserInteractionEnabled = true
                self?.validateErrorMessages(messages)
        })
    }

    private func validationErrorMessages() -> [FFErrorMessage] {
        var messages: [FFErrorMessage] = []

        if !(self.loginTextField.text?.isValideLogin)! {
            let message = FFErrorMessage()
            message.type = FFErrorMessageType.login
            message.text = NSLocalizedString("validation_login_length", comment: "")

            messages.append(message)
        }

        if !(self.passwordTextField.text?.isValidePassword)! {
            let message = FFErrorMessage()
            message.type = FFErrorMessageType.password
            message.text = NSLocalizedString("validation_password_length", comment: "")

            messages.append(message)
        }

        return messages
    }

    private func validateErrorMessages(_ messages: [FFErrorMessage]) {
        if let message = messages.first(where: {$0.type == FFErrorMessageType.login}) {
            self.loginTextField.borderColorTypeName = FFColorType.redOrange.rawValue

            self.loginErrorLabel.isHidden = false
            self.loginErrorImageView.isHidden = false
            self.loginErrorLabel.text = message.text
        }
        else {
            self.loginTextField.borderColorTypeName = FFColorType.alto.rawValue
            self.loginErrorLabel.isHidden = true
            self.loginErrorImageView.isHidden = true
        }

        if let message = messages.first(where: {$0.type == FFErrorMessageType.password}) {
            self.passwordTextField.borderColorTypeName = FFColorType.redOrange.rawValue

            self.passwordErrorLabel.isHidden = false
            self.passwordErrorImageView.isHidden = false
            self.passwordErrorLabel.text = message.text
        }
        else {
            self.passwordTextField.borderColorTypeName = FFColorType.alto.rawValue
            self.passwordErrorLabel.isHidden = true
            self.passwordErrorImageView.isHidden = true
        }

        if let message = messages.first(where: {$0.type == FFErrorMessageType.alert}) {
            FFAlertManager.showErrorMessage(message.text!)
        }
    }