Access page content from cms/page from head.phtml

Question

I have the following code in template/page/html/head.phtml which tries it best to supply facebook with an apropriate sharing image.(og:image)

Everything works, except for the part that I'm trying to get the content text of a cms/page. Logic dictates that if I use Mage::getSingleton('cms/page')->getContent() that I should get the HTML content of the cms page being viewed. However, 0 is returned to my function so I'm stuck with my default images on cms pages.

What am I doing wrong?

<?php
// viewing a product, get the image of the product for social sharing
if (Mage::registry('current_product'))
    {
    echo Mage::helper('catalog/image')->init(Mage::registry('current_product'), 'small_image')->resize(213);
    }
// this is where I get nothing returned from the content of the current page being viewed.
elseif($cms_content = Mage::getSingleton('cms/page')->getContent())
    {
    $src = array();
    $pos = 0;
    while(strpos($cms_content,'<img ',$pos)!== false)
        {
        // do a lot of complicated stuff here, not relevant for question
        }
    $theone = isset($src[0]) ? $src[0] : false;
    echo $theone;
    }
// show default image
else
    {
    echo 'default image url';
    }

Answer 1

You can get the current page like this:

$pageId = Mage::app()->getRequest()->getParam('page_id', Mage::app()->getRequest()->getParam('id', false));
$page = Mage::getModel('cms/page')->load($pageId);

To get the content use

$page->getContent();

but this will get you only the content in the database. So if you have directives like {{store}} or {{media}} they won't be parsed.
To get the parsed content use this:

$content = Mage::helper('cms')->getPageTemplateProcessor()->filter($page->getContent());