/*
 * Copyright 2005 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.kie.api.event.process;

import java.util.EventListener;

/**
 * A listener for events related to process instance execution.
 */
public interface ProcessEventListener
    extends
    EventListener {

    /**
     * This listener method is invoked right before a process instance is being started.
     * @param event
     */
    void beforeProcessStarted(ProcessStartedEvent event);

    /**
     * This listener method is invoked right after a process instance has been started.
     * @param event
     */
    void afterProcessStarted(ProcessStartedEvent event);

    /**
     * This listener method is invoked right before a process instance is being completed (or aborted).
     * @param event
     */
    void beforeProcessCompleted(ProcessCompletedEvent event);

    /**
     * This listener method is invoked right after a process instance has been completed (or aborted).
     * @param event
     */
    void afterProcessCompleted(ProcessCompletedEvent event);

    /**
     * This listener method is invoked right before a node in a process instance is being triggered
     * (which is when the node is being entered, for example when an incoming connection triggers it).
     * @param event
     */
    void beforeNodeTriggered(ProcessNodeTriggeredEvent event);

    /**
     * This listener method is invoked right after a node in a process instance has been triggered
     * (which is when the node was entered, for example when an incoming connection triggered it).
     * @param event
     */
    void afterNodeTriggered(ProcessNodeTriggeredEvent event);

    /**
     * This listener method is invoked right before a node in a process instance is being left
     * (which is when the node is completed, for example when it has performed the task it was
     * designed for).
     * @param event
     */
    void beforeNodeLeft(ProcessNodeLeftEvent event);

    /**
     * This listener method is invoked right after a node in a process instance has been left
     * (which is when the node was completed, for example when it performed the task it was
     * designed for).
     * @param event
     */
    void afterNodeLeft(ProcessNodeLeftEvent event);

    /**
     * This listener method is invoked right before the value of a process variable is being changed.
     * @param event
     */
    void beforeVariableChanged(ProcessVariableChangedEvent event);

    /**
     * This listener method is invoked right after the value of a process variable has been changed.
     * @param event
     */
    void afterVariableChanged(ProcessVariableChangedEvent event);
    
    /**
     * This listener method is invoked right before a process/node instance's SLA has been violated.
     * @param event
     */
    default void beforeSLAViolated(SLAViolatedEvent event) {}

    /**
     * This listener method is invoked right after a process/node instance's SLA has been violated.
     * @param event
     */
    default void afterSLAViolated(SLAViolatedEvent event) {}

    /**
     * This listener method is invoked when a signal is sent
     * @param event
     */
    default void onSignal(SignalEvent event) {}

    /**
     * This listener method is invoked when a message is sent
     * @param event
     */
    default void onMessage(MessageEvent event) {}

    /**
     * This listener method is invoked when async node is entered triggering
     * a scheduled job for executing this node.
     * @param event
     */
    default void onAsyncNodeScheduledEvent(ProcessAsyncNodeScheduledEvent event) {}
}
