Upload generated images into external directory

[Immolare]

Original request by @CarloLupo.

Replace the content of add_to_media() function in admin/class-artist-image-generator-admin.php l.600 by this one :

   public function add_to_media(): mixed
    {
        require_once ABSPATH . "/wp-admin/includes/image.php";
        require_once ABSPATH . "/wp-admin/includes/file.php";
        require_once ABSPATH . "/wp-admin/includes/media.php";

        $url = sanitize_url($_POST['url']);
        $alt = sanitize_text_field($_POST['description']);

        // Download url to a temp file
        $tmp = download_url($url);
        if (is_wp_error($tmp)) {
            return false;
        }

        // Get the filename and extension ("photo.png" => "photo", "png")
        $filename = pathinfo($url, PATHINFO_FILENAME);
        $extension = pathinfo($url, PATHINFO_EXTENSION);

        // An extension is required or else WordPress will reject the upload
        if (!$extension) {
            // Look up mime type, example: "/photo.png" -> "image/png"
            $mime = mime_content_type($tmp);
            $mime = is_string($mime) ? sanitize_mime_type($mime) : false;

            // Only allow certain mime types because mime types do not always end in a valid extension (see the .doc example below)
            $mime_extensions = array(
                'image/jpg'  => 'jpg',
                'image/jpeg' => 'jpeg',
                'image/gif'  => 'gif',
                'image/png'  => 'png'
            );

            $extension = $mime_extensions[$mime] ?? false;

            if (!$extension) {
                // Could not identify extension
                @unlink($tmp);
                return false;
            }
        }

        // Define the path of the third-party folder where you want to save files
        $upload_dir = ABSPATH . 'custom_images/'; // REPLACE BY YOUR PATH HERE
        // Maybe you should add uniqid() to avoid same filenames in the directory 
        $file_name = sanitize_title($alt, $filename) . /*'_' . uniqid() .*/ ".$extension";
        
        $target_file = $upload_dir . $file_name;

        if (!rename($tmp, $target_file)) {
            wp_send_json_error('Error renaming file');
        }
        
        @unlink($tmp);

        // Success, return attachment ID (int). In this code, will return 0 anyway
        wp_send_json_success(['attachment_id' => 0]);

        if (defined('DOING_AJAX') && DOING_AJAX) {
            wp_die();
        }
    }

Note : make your own path by customizing $upload_dir var. This code will not store images into Wordpress Media Library. Feel free to adapt the code to your needs.