/*
 * Copyright 2019 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.kogito.uow;

import java.util.function.Consumer;

/**
 * Defines individual work unit that can be associated with unit of work
 *
 */
public interface WorkUnit<T> {

    int HIGH_PRIORITY = 10;
    int DEFAULT_PRIORITY = 100;
    int LOW_PRIORITY = 1000;

    /**
     * Returns data attached to the work unit
     * 
     * @return actual data of the work unit
     */
    T data();

    /**
     * Performs action associated with the work unit usually consuming data
     */
    void perform();

    /**
     * Optional abort logic associated with the work unit
     */
    default void abort() {

    }

    /**
     * Returns desired priority for the work unit execution order
     * 
     * @return property as positive number
     */
    default Integer priority() {
        return DEFAULT_PRIORITY;
    }

    /**
     * Creates new WorkUnit that has only action invoked upon completion of the unit of work
     * 
     * @param data data associated with the work
     * @param action work to be executed on given data
     * @return WorkUnit populated with data and action
     */
    static <S> WorkUnit<S> create(S data, Consumer<S> action) {
        return new WorkUnit<S>() {

            @Override
            public S data() {
                return data;
            }

            @Override
            public void perform() {
                action.accept(data());
            }

        };
    }

    /**
     * Creates new WorkUnit that has both action invoked upon completion of the unit of work
     * and compensation invoked in case of unit of work cancellation.
     * 
     * @param data data associated with the work
     * @param action work to be executed on given data
     * @param compensation revert action to be performed upon cancellation
     * @return WorkUnit populated with data, action and compensation
     */
    static <S> WorkUnit<S> create(S data, Consumer<S> action, Consumer<S> compensation) {
        return new WorkUnit<S>() {

            @Override
            public S data() {
                return data;
            }

            @Override
            public void perform() {
                action.accept(data());
            }

            @Override
            public void abort() {
                compensation.accept(data());
            }
        };
    }
}
