Trying to get filterable attributes of product collection

Question

I am trying to get filterable attributes of product collection after applying filter to it programmatically.

same as layered navigation idea after I apply filter to category, it just return attributes that I can filter with it. that's what I am trying to do here.

I need that to return filterable attributes after applying filter to collection to send it to mobile app via api.

$category = Mage::getModel('catalog/category')->setStoreId(1)->load(84);
$collection = $category->getProductCollection()
                        ->setOrder('position', 'ASC')
                        ->addAttributeToSelect('*')
                        ->addAttributeToFilter('status', 1)
                        ->addAttributeToFilter('visibility', 4)
                        ->setStoreId(1);


$filtringAttributes = Array
(
    (object) array
        (
            'label' => 'Ref Nav Doors',
            'code' => 'ref_nav_doors',
            'value' => 693
        ),

    (object) array
        (
            'label' => 'Color',
            'code' => 'color',
            'value' => 5
        )
);

if (!empty($filtringAttributes)) {

    foreach ($filtringAttributes as $attribute) {
        $key = $attribute->code;
        $value = $attribute->value;
        $collection->addAttributeToFilter($key, $value);
    }
}

Answer 1

I am not sure if this fits your needs exactly, but it will give you all of the columns added by your addAttributeToSelect('*') function, and all of those will be filterable in the collection.

$first = $collection
         ->getFirstItem()
         ->toArray();

$columns = array_keys($first);