I need to build an associative array with the plugin name and the language file it uses in the following sequence:

/whatever/path/length/public_html/wp-content/plugins/adminimize/languages/adminimize-en_US.mo
/whatever/path/length/public_html/wp-content/plugins/audio-tube/lang/atp-en_US.mo
/whatever/path/length/public_html/wp-content/languages/en_US.mo
/whatever/path/length/public_html/wp-content/themes/twentyeleven/languages/en_US.mo 

Those are the language files WordPress is loading.
They are all inside /wp-content/, but with variable server paths.
I'm looking only for those inside the plugins folder, grab the plugin folder name and the filename.

Hipothetical case in PHP, where reg_extract_* functions are the parts I'm missing:

$plugins = array();

foreach( $big_array as $item ) 
{
    $folder = reg_extract_folder( $item );
    if( 'plugin' == $folder ) 
    {
        // "folder-name-after-plugins-folder"
        $plugin_name = reg_extract_pname( $item ); 

        // "ending-mo-file.mo"
        $file_name = reg_extract_fname( $item ); 

        $plugins[] = array( 'name' => $plugin_name, 'file' => $file_name );
    }
}

[update]

Ok, so I was missing quite a basic function, pathinfo... :/

No problem to detect if /plugins/ is contained in the array.

But what about the plugin folder name?