Magento – Redirect to previous page after log in

I want to redirect customer to last visiting page after loggedin.
My code as far looks like:
Config.xml

<?xml version="1.0"?>
<config>
<modules>
    <Virtua_Vcategory>
        <version>1.0.0</version>
    </Virtua_Vcategory>
</modules>
<global>
    <models>
        <virtua_vcategory>
            <class>Virtua_Vcategory_Model</class>
        </virtua_vcategory>
    </models>
    <helpers>
        <virtua_vcategory>
            <class>Virtua_Vcategory_Helper</class>
        </virtua_vcategory>
    </helpers>

    <blocks>
        <virtua_vcategory>
            <class>Virtua_Vcategory_Block</class>
        </virtua_vcategory>
    </blocks>

</global>
<frontend>
    <events>

        <catalog_controller_category_init_after>
            <observers>
                <virtua_vcategory>
                    <type>singleton</type>
                    <class>virtua_vcategory/observer</class>
                    <method>catalogControllerLoadAfter</method>
                </virtua_vcategory>
            </observers>
        </catalog_controller_category_init_after>

        <customer_login>
            <observers>
                <virtua_vcategory>
                    <class>virtua_vcategory/observer</class>
                    <method>customerLogin</method>
                </virtua_vcategory>
            </observers>
        </customer_login>
  </events>
</frontend>
</config>

Observer:

 <?php

 class Virtua_Vcategory_Model_Observer extends Mage_Core_Model_Abstract
 {
   public function catalogControllerLoadAfter(Varien_Event_Observer $observer)
{
    ...

    if (Mage::getSingleton('customer/session')->isLoggedIn()) {

        ...
    }
    else
    {
        $beforeurl = Mage::getSingleton('customer/session')->setBeforeAuthUrl(Mage::helper('core/url')->getCurrentUrl());

        MAGE::log($beforeurl );     /****first log*****/

        $route = 'customer/account/login';
        $url = Mage::getUrl($route);
        Mage::app()->getResponse()->setRedirect($url);
    }
}
     public function customerLogin(Varien_Event_Observer $observer)
    {

    $url = Mage::getSingleton('customer/session')->getBeforeAuthUrl();

    MAGE::log($url." after log in");     /*****second log*****/

    Mage::app()->getResponse()->setRedirect($url);
    }
}

And my first log (in catalogControllerLoadAfter() ) showing properly urlin object, but in second log url is overwritting. How can i fix it?