mod_rewrite prefix as a folder

I have this structure in my home directory:

• /index.php
• /.htaccess
• /folderx/
• /folderx/subfolder/
• /folderx/subfolder/file.php

What I need, is to mod_rewite all requests with the prefix "folderx_" to the real folderx directory. But additionally, I need to force redirection - the user should't be available to request /folderx/subfolder/subsubfolder/file.php directly. It should be redirected to the mod_rewrite url: /folderx_subfolder/subsubfolder/file.php

• /folderx_subfolder/ => /folderx/subfolder/
• /folderx_subfolder/file.php => /folderx/subfolder/file.php
• /folderx_subfolder/subsu开发者_如何学编程bfolder/ => /folderx/subfolder/subsubfolder/
• /folderx_subfolder/subsubfolder/file.php => /folderx/subfolder/subsubfolder/file.php

I've tried the code below, but the redirect is not working properly. When requesting the subfolder, it redirects to the prefix, but I don't know how to prevent looping( Please, help! /folderx/subfolder/subsubfolder/file.php

RewriteCond %{REQUEST_URI} ^/folderx/(.*)$
RedirectMatch ^/folderx/(.*)$ /folderx_$1
RewriteRule ^folderx_([a-z]{3,15})(/?)+$ /folderx/$1/ [NC]
RewriteRule ^folderx_([a-z]{3,15})/(.*)$ /folderx/$1/$2 [NC]

RewriteRule ^folderx/(.+)$ http://example.com/folder_$1 [nc,last,redirect]
RewriteRule ^folderx_(.+)$ /folderx/$1 [nc]