Preselect configurable product options by simple product URL

Question

How to show configurable product with preselected options if requested url is for simple product?

For example:

Simple product #1 has:
Color: Red
URL: /simple-red.html

Simple product #2 has:
Color: Green
URL: /simple-green.html

Configurable product has:
URL: /config.html

If user visits /simple-red.html it should be loaded configurable product with pre-selected option Color: Red

If user visits /simple-green.html it should be loaded configurable product with pre-selected option Color: Green

Answer 1

Successfully solved the problem:

1. Extended ProductController, to replace product id of simple product by product id of parent configurable product. Used SO Answer:
   Magento Catalog ProductController rewrite
   
   Code in custom ProductController:
   

   ...
   $productId  = (int) $this->getRequest()->getParam('id');
   
   // Get parent configurable product
   $_product = Mage::getModel('catalog/product')->load($productId);
   if ($_product->getTypeId() == "simple") {
       $parentIds = Mage::getModel('catalog/product_type_configurable')->getParentIdsByChild($_product->getId());
   
       // If parent exists
       if (isset($parentIds[0])) {
           $productId = $parentIds[0];
       }
   }
   ...
   

2. PreSelect configurable product options depending on simple product. Used link to tutorial given by Vishal Sharma
   

Result (sorry can't post images): Screenshot