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OptaPlanner solves planning problems. This lightweight, embeddable planning engine implements powerful and scalable algorithms to optimize business resource scheduling and planning. This module contains the examples which demonstrate how to use it in a normal Java application.

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/*
 * Copyright 2016 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.optaplanner.examples.taskassigning.domain.solver;

import java.util.Objects;

import org.optaplanner.core.impl.domain.variable.listener.VariableListener;
import org.optaplanner.core.impl.score.director.ScoreDirector;
import org.optaplanner.examples.taskassigning.domain.Task;
import org.optaplanner.examples.taskassigning.domain.TaskOrEmployee;

public class StartTimeUpdatingVariableListener implements VariableListener {

    @Override
    public void beforeEntityAdded(ScoreDirector scoreDirector, Task task) {
        // Do nothing
    }

    @Override
    public void afterEntityAdded(ScoreDirector scoreDirector, Task task) {
        updateStartTime(scoreDirector, task);
    }

    @Override
    public void beforeVariableChanged(ScoreDirector scoreDirector, Task task) {
        // Do nothing
    }

    @Override
    public void afterVariableChanged(ScoreDirector scoreDirector, Task task) {
        updateStartTime(scoreDirector, task);
    }

    @Override
    public void beforeEntityRemoved(ScoreDirector scoreDirector, Task task) {
        // Do nothing
    }

    @Override
    public void afterEntityRemoved(ScoreDirector scoreDirector, Task task) {
        // Do nothing
    }

    protected void updateStartTime(ScoreDirector scoreDirector, Task sourceTask) {
        TaskOrEmployee previous = sourceTask.getPreviousTaskOrEmployee();
        Task shadowTask = sourceTask;
        Integer previousEndTime = (previous == null ? null : previous.getEndTime());
        Integer startTime = calculateStartTime(shadowTask, previousEndTime);
        while (shadowTask != null && !Objects.equals(shadowTask.getStartTime(), startTime)) {
            scoreDirector.beforeVariableChanged(shadowTask, "startTime");
            shadowTask.setStartTime(startTime);
            scoreDirector.afterVariableChanged(shadowTask, "startTime");
            previousEndTime = shadowTask.getEndTime();
            shadowTask = shadowTask.getNextTask();
            startTime = calculateStartTime(shadowTask, previousEndTime);
        }
    }

    private Integer calculateStartTime(Task task, Integer previousEndTime) {
        if (task == null || previousEndTime == null) {
            return null;
        }
        return Math.max(task.getReadyTime(), previousEndTime);
    }

}