Refactor product loading logic and update URL routing

- Refactored the product loading logic in the ShopProduct class to improve performance and readability.
- Updated the URL routing in the index.php file to handle redirects and routes based on the request URI.
- Added a new method in the S class to check if adding a redirect will create a cycle in the redirect map.
- Updated the S class to use the new method for adding redirects and generating URL routes.
- Removed unnecessary code related to generating .htaccess rules.

index.php

@@ -79,6 +79,44 @@ if ( \S::get( 'action' ) == 'htaccess' )
   exit;
 }
 
+// check redirects
+$request_uri = substr( $_SERVER[ 'REQUEST_URI' ], 1, strlen( $_SERVER[ 'REQUEST_URI' ] ) );
+if ( $request_uri != '' )
+{
+  $new_url = $mdb -> get( 'pp_redirects', 'to', [ 'from' => $request_uri ], [ 'ORDER' => [ 'date_add' => 'DESC' ] ] );
+  if ( $new_url['to'] )
+  {
+    header( 'Location: ' . $new_url[ 'to' ], true, 301 );
+    exit;
+  }
+}
+
+// check routes
+$request_uri = ltrim( $_SERVER['REQUEST_URI'], '/' );
+if ( $request_uri != '' )
+{
+  $matched = false;
+
+  $routes = $mdb -> select( 'pp_routes', '*' );
+  foreach ( $routes as $route )
+  {
+    $pattern = $route['pattern'];
+    $destination = $route['destination'];
+
+    if ( preg_match("#^" . $pattern . "#", $request_uri, $matches ) )
+    {
+      // Replace placeholders in the destination with matches from the request URI
+      $destination = preg_replace( "#^" . $pattern . "#", $destination, $request_uri );
+
+      // Parse the destination string to extract GET parameters
+      parse_str(parse_url($destination, PHP_URL_QUERY), $_GET);
+
+      $matched = true;
+      break;
+    }
+  }
+}
+
 if ( \S::get( 'a' ) == 'page' and \S::get( 'id' ) )
 {
   $page = \front\factory\Pages::page_details( \S::get( 'id' ) );