[WP] Rename files in custom upload folder

wp_rename_upload_files.php

<?php

/* ----------------------------------------------------------------------------------------------------------------------------
*	PREFACE for this script	
*
* 	A frontend custom form, allowing registered users to create a custom post type + upload images to ACF Gallery custom field,
*	in a custom uploads folder, had a bug where it would replace any symbol with -,
*	including replacing the file extensions (eg. .jpg and .png, in -jpg and -png).
*	That resulted in various issues, even though browsers could still read the file as image.
*	After fixing the form itself, this script was made, to fix all the uploads that had already been uploaded and their path.
---------------------------------------------------------------------------------------------------------------------------- */

function replace_filenames() {

    $wp_upload = wp_upload_dir();
    $wp_upload_dir = trailingslashit($wp_upload["basedir"]);
    $wp_upload_url = trailingslashit($wp_upload["baseurl"]);
    $folder_name = trailingslashit('progetti'); // this is the custom folder name, inside the uploads folder
    $uploads_dir = trailingslashit($wp_upload_dir.$folder_name);

    $directories = glob($uploads_dir . '*' , GLOB_ONLYDIR);
	
	// Replace Settings
    $change_1 = '-jpg';
    $replace_1 = '.jpg';
    $change_2 = '-png';
    $replace_2 = '.png';
    $remove_1 = '-jpg-';
    $remove_2 = '-png-';

    foreach($directories as $dir) {
        if ($handle = opendir($dir)) {
            while (false !== ($fileName = readdir($handle))) {

                // skip weird stuff
                if($fileName == '.' || $fileName == '..')
                    continue;

                // Get img GUI & ID
				$dirname = str_replace('/absolute_path_to_/'.$folder_name.'/','',$dir);
                $guid = $wp_upload_url.$folder_name.$dirname.'/'.$fileName;
				$img_id = attachment_url_to_postid($guid);

				// Alternative to the attach to post id function - SQL query for ID  & skip if array is empty
				/*global $wpdb;
            	$attachment = $wpdb->get_col($wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE post_type='attachment' AND guid='%s';", $guid));
				if(empty($attachment))
					continue;*/

				// skip if no ID
				if($img_id == '' || $img_id == null)
					continue;

                // skip if file already has the extension in place
                $ext = substr($fileName, -4);
                if($ext == $replace_1 || $ext == $replace_2)
                    continue;

                // cleanup - remove the wrong stuff from automatically created thumbs
                if(preg_match('/'.$remove_1.'/',$fileName)) {
                    $newName = str_replace($remove_1,'-',$fileName);
                    rename($dir.'/' . $fileName, $dir.'/' . $newName.$replace_1);
                } elseif(preg_match('/'.$remove_2.'/',$fileName)) {
                    $newName = str_replace($remove_2,'-',$fileName);
                    rename($dir.'/' . $fileName, $dir.'/' . $newName.$replace_2);
                }

                // first replacement - jpg
                elseif (preg_match('/'.$change_1.'/',$fileName)) {
                    $newName = str_replace($change_1,$replace_1,$fileName);
                    rename($dir.'/' . $fileName, $dir.'/' . $newName);
					// Replace attachments GUI in database
					$new_guid = $wp_upload_url.$folder_name.$dirname.'/'.$newName;
					update_attached_file( $img_id, $newName );
                }
                // second replacement - png
                elseif(preg_match('/'.$change_2.'/',$fileName)) {
                    $newName = str_replace($change_2,$replace_2,$fileName);
                    rename($dir.'/' . $fileName, $dir.'/' . $newName);
					// Replace attachments GUI in database
					$new_guid = $wp_upload_url.$folder_name.$dirname.'/'.$newName;
					update_attached_file( $img_id, $newName );
                }

            }
            closedir($handle);
        }
    }
}

// Only run this ONCE, then comment this part out
if(current_user_can('manage_options') && !is_admin()) {
    replace_filenames();
}

?>