pre_save post

function my_pre_save_post( $post_id ) {
    if ( !empty( $_POST['acf']['field_57e3ed6c92ec1'] ) ) {

        // if profile name is entered

        $entered_title      = $_POST['acf']['field_57e3ed6c92ea0'];
        $cleaned_title      = preg_replace( '/[^A-Za-z0-9\-\s]/', '', $entered_title ); // Removes special chars.
        $post_name          = sanitize_title( $cleaned_title );
        update_field( 'field_57e3ed6c92ea0', $cleaned_title, $post_id ); // update acf field

        // check if profile image has changed
        $submitted_photo    = $_POST['acf']['field_57e3ed6c9321c']; // array
        $stored_photo       = get_field( 'sd_profile_photo', $post_id );

        if ( $submitted_photo == $stored_photo ) {
            // do nothing
        } else {
            $send_mail      = true;
            add_post_meta( $submitted_photo, '_image_pending', true );
        }
        if ( $submitted_photo ) {
            // link image to post
            global $wpdb;
            $wpdb->update(
                $wpdb->posts,
                array(
                    'post_parent' => $post_id,
                ),
                array(
                    'ID' => $submitted_photo
                )
            );
        }

        // update post status + post title (if needed)
        global $wpdb;
        $wpdb->update(
            $wpdb->posts,
            array(
                'post_status'   => 'pending',
                'post_title'    => $cleaned_title,
                'post_name'     => $post_name
            ),
            array(
                'ID' => $post_id
            )
        );

        // check if new images are added
        $submitted_gallery  = $_POST['acf']['field_57e3ed6c93236']; // array
        $stored_gallery     = get_field( 'sd_gallery', $post_id );
        $gallery_id_array   = array();

        if ( $stored_gallery ) {
            foreach ( $stored_gallery as $gallery_item ) {
                $gallery_id_array[] = $gallery_item['ID'];
            }
        }

        if ( $submitted_gallery ) {
            foreach ( $submitted_gallery as $gallery ) {

                // link image to post
                $wpdb->update(
                    $wpdb->posts,
                    array(
                        'post_parent' => $post_id,
                    ),
                    array(
                        'ID' => $gallery
                    )
                );

                if ( in_array( $gallery, $gallery_id_array ) ) {
                    // if it exists in the array, do nothing
                } else {
                    // if it doesn't exist, update post meta
                    add_post_meta( $gallery, '_image_pending', true );
                }
            }
        }

        if ( $send_mail == true ) {
            $from_email     = get_field( 'sd_support_email', 'option' );
            if ( ! $from_email ) { $from_email = '[email protected]'; }
            $to             = get_option( 'admin_email' );
            $subject        = 'Ad waiting approval';
            $message        = 'An add is submitted and is <a href="#">awaiting approval</a>.';
            $headers[]      = 'From: Site <' . $from_email . '>';
            $headers[]      = 'Content-Type: text/html; charset=UTF-8';
            wp_mail( $to, $subject, $message, $headers );
        }

        clean_post_cache( $post_id );

        // Trigger all transition hooks in wordpress (in case other functions hook into those to do things.
        $old_status         = $post->post_status;
        $post->post_status  = 'pending';
        wp_transition_post_status( 'publish', $old_status, $post );

    }
    // return the same ID
    return $post_id;
}
add_filter( 'acf/pre_save_post' , 'my_pre_save_post', 10, 1 );