GF Addon Snippet using gform_post_payment_action

gfaddon.php

<?php

class GFDonorPerfectAddon extends GFFeedAddOn {
    public function init() {

        parent::init();

        add_action( 'gform_post_payment_action', array( $this, 'post_payment_action_hook' ), 10, 2 );
    }
    
    public function post_payment_action_hook( $entry, $action ) {
        $this->log_debug( __METHOD__ . "(): called." );
        $this->log_debug( __METHOD__ . ": \n" . print_r( array( 'action' => $action ), true) );
        if ( in_array( $action['type'], array( 'add_subscription_payment', 'complete_payment') ) ) {            
            $form = GFAPI::get_form( $entry['form_id'] );
            
            $feed = $this->get_single_submission_feed( $entry, $form );

            $entry['transaction_id_actual'] = $action['transaction_id'];
        
            $this->process_feed( $feed, $entry, $form );
        }
    }

    public function process_feed( $feed, $entry, $form ) {        
        /* If DPO instance is not initialized, exit. */
        if ( ! $this->initialize_api() ) {
            $this->log_error( __METHOD__ . '(): DonorPerfect API not configured; feed not processed.' );
        }
        $this->log_debug( __METHOD__ . ": \n" . print_r( array( 
            'feed'  => $feed,
            'entry' => $entry,
        ), true) );

        $values = $this->get_feed_values( $feed, $entry );
        $feed_type = $feed['meta']['feed_type'];

        if ( $feed_type === 'donate' ) {
            $this->process_donate_feed( $values );
        } elseif ( $feed_type === 'membership' ) {
            $this->process_membership_feed( $values );
        } else {
            $this->log_error( __METHOD__ .': Error processing feed (Invalid feed type).' );
        }
    }
}