Filter related products, crossell and configurable options in observer

Question

I'm trying to filter these collections without any change to the template, I had no problems with the up-sell (not tested), but the other two doesn't have an event.
Note: The dom structure is unknown
Up-sell
Event: catalog_product_upsell

public function checkUpsell(Varien_Event_Observer $observer){
    if(!self::isModuleEnabled()){
        return;
    }

    $upsell =$observer->getEvent()->getCollection();
    $ids =array();
    foreach($upsell as $item){
        $ids[]=$item->getId();
    }
    $collection = Mage::getModel('country/product') ->getCollection()
                                                    ->addAttributeToFilter('active', 1)
                                                    ->addAttributeToFilter('product_id', array('in' => $ids));
    if($collection->length >0){
        $country = Mage::getSingleton('core/session')->getRazorphynCountry;
        foreach($collection as $res){
            if(($res->allowed==0 && strpos($countries, $country) !== false) || ($res->allowed==1 && strpos($countries, $country) === false)){
                $upsell->removeItemByKey($res->product_id);
            }
        }
    }
 }

Configurable options
Note: Horrible, can cause eye-bleeding
Event: core_block_abstract_to_html_after

...
if( Mage::registry('current_product')->getTypeId()=='configurable'){ //to be checked
                //Retrieve all options ids
                $childIds = Mage::getModel('catalog/product_type_configurable')->getChildrenIds($productId);

                //Retrieve rules to remove  for all options
                $collection = Mage::getModel('country/product')->getCollection()
                                                               ->addFieldToFilter('active', 1)
                                                               ->addFieldToFilter('product_id', $childIds)
                                                               ->limit(count($childIds));

                if($collection->length >0){
                    //Create an array with the items that will be removed
                    $removable=array();
                    foreach($collection as $res){
                        if(($res->allowed==0 && strpos($countries, $visitorCountry) !== false) || ($res->allowed==1 && strpos($countries, $visitorCountry) === false)){
                            $removable[$res->product_id]=true;
                        }
                    }

                    //Retrieve json with the product options (will be printed in the frontend
                    $json = Mage::createBlock('Mage_Catalog_Block_Product_View')->setProduct($productId)->getJsonConfig();
                    $arr=json_decode($json);
                    //I would like to print all the removed options
                    //each line is combination of removed options for the same product id
                    //label1: option - label2: option - label3:option
                    $removedOpt= array();
                    //Loop through options
                    foreach($arr['attribute'] as $element){
                        foreach($element['options'] as &$option){
                            foreach($option['products'] as &$productId){
                                if(in_array($productId,$removable)){
                                    $removedOpt[$productId][]=$element['label'].': '.$option['label'];
                                    unset($productId);
                                }
                            }
                            //Remove options if there is no associated product
                            if(count($option) == 0)
                                unset($option);
                        }
                    }

                    //Create final string with removed options
                    foreach($removedOpt as $o){
                        $o=implode(' - ',$o);
                    }
                    $removedOpt=implode("\n",$removedOpt);

                    $results  = $xpath->query('//script');

                    foreach($results as $res){
                        //Ugh...ehm...replace the already printed json with the new one...
                        preg_replace('/new\s*Product\.Config\((.*)\)/',$json,$html);
                    }
                    Mage::getSingleton('core/session')->addNotice(Mage::helper('country')->__("The following options are not available in your country:")."\n".$removedOpt);

                }
            }
...

So my question are:

• is there a smart way to limit the configurable options?
• is there a way to achieve the same results for cross-sells and related product?

config.xml:

...
<frontend>
        <events>

            <!-- Page Rendering event -->
            <core_block_abstract_to_html_after>
                <observers>
                    <razorphyn_country_core_block_abstract_to_html_after>
                        <type>singleton</type>
                        <class>Razorphyn_Country_Model_Observer</class>
                        <method>checkMerchantable</method>
                    </razorphyn_country_core_block_abstract_to_html_after>
                </observers>
            </core_block_abstract_to_html_after>

            <!-- Remove up-sell items -->
            <catalog_product_upsell>
                <observers>
                    <razorphyn_country_catalog_product_upsell>
                        <type>singleton</type>
                        <class>Razorphyn_Country_Model_Observer</class>
                        <method>checkUpsell</method>
                    </razorphyn_country_catalog_product_upsell>
                </observers>
            </catalog_product_upsell>

        </events>
...

Answer 1

Using type Wrong event:

As per my concept,

It really bad Idea to use core_block_abstract_to_html_after for collection filter.That is too horrible .

Wrong collection filter process:

It bad to use a loop and make a collection again and that it too hurt for site speed.

Solution: Better idea to use magento joining with you custom module model table Mage::getModel('country/product')

[Edit:]

For case of upsell you can do like this:

   public function checkUpsell(Varien_Event_Observer $observer){


    $upsell =$observer->getEvent()->getCollection();


        /* $table=Mage::getSingleton('core/resource')->getTableName('country/country');*/
        /* $Filter=Mage::getSingleton('core/resource')->getConnection('core_read')->select()
            ->from(array('d'=>$table), array('d.product_id'))  ->where('d.active = ?',1 );
            */
            //echo $upsell->getSelect()->where('`e`.`entity_id` IN (?)',new Zend_Db_Expr($Filter));
            $table=Mage::getSingleton('core/resource')->getTableName('country/product');
            echo $upsell->getSelect()
                  ->join(array('countryTable' => $table),
                'countryTable.product_id =e.entity_id And  countryTable.active=1',
                array('countryTable' => 'countryTable.product_id'));        


return $upsell;

    }
}

Note: as load() function before fire run observer then the joing query should not run