/*
GanttProject is an opensource project management tool.
Copyright (C) 2011 GanttProject team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package net.sourceforge.ganttproject.task.dependency.constraint;

import java.util.Date;
import java.util.List;

import biz.ganttproject.core.time.CalendarFactory;
import biz.ganttproject.core.time.GanttCalendar;

import net.sourceforge.ganttproject.GPLogger;
import net.sourceforge.ganttproject.language.GanttLanguage;
import net.sourceforge.ganttproject.task.Task;
import net.sourceforge.ganttproject.task.TaskActivity;
import net.sourceforge.ganttproject.task.dependency.TaskDependency;
import net.sourceforge.ganttproject.task.dependency.TaskDependencyConstraint;
import net.sourceforge.ganttproject.task.dependency.TaskDependency.ActivityBinding;

/**
 * Dependent task finishes not earlier than dependee starts
 *
 * @author bard
 */
public class StartFinishConstraintImpl extends ConstraintImpl implements TaskDependencyConstraint {
  public StartFinishConstraintImpl() {
    super(TaskDependencyConstraint.Type.startfinish, GanttLanguage.getInstance().getText("startfinish"));
  }

  @Override
  public TaskDependencyConstraint.Collision getCollision() {
    Task dependee = getDependency().getDependee();
    Task dependant = getDependency().getDependant();
    final GanttCalendar dependeeStart = dependee.getStart();
    final GanttCalendar dependantEnd = dependant.getEnd();

    GanttCalendar acceptableEnd = CalendarFactory.createGanttCalendar(dependant.getManager().getCalendar().shiftDate(
        dependeeStart.getTime(), dependant.getManager().createLength(getDependency().getDifference())));

    boolean isActive = getDependency().getHardness() == TaskDependency.Hardness.RUBBER ? dependantEnd.compareTo(acceptableEnd) < 0
        : dependantEnd.compareTo(acceptableEnd) != 0;

    GanttCalendar acceptableStart = isActive ? CalendarFactory.createGanttCalendar(
        dependant.getManager().getCalendar().shiftDate(acceptableEnd.getTime(), dependant.getDuration().reverse())) : dependant.getStart();
    return new TaskDependencyConstraint.DefaultCollision(acceptableStart,
        TaskDependencyConstraint.Collision.START_LATER_VARIATION, isActive);
  }

  @Override
  public Collision getBackwardCollision(Date dependantStart) {
    Task dependee = getDependency().getDependee();
    GanttCalendar dependeeEnd = dependee.getEnd().clone();

    Date barrier = shift(dependantStart, getDependency().getDependant().getDuration().getLength()
        - getDependency().getDifference() + dependee.getDuration().getLength());
    boolean isActive = getDependency().getHardness() == TaskDependency.Hardness.RUBBER ? dependeeEnd.getTime().compareTo(
        barrier) > 0
        : dependeeEnd.getTime().compareTo(barrier) != 0;

    return new TaskDependencyConstraint.DefaultCollision(CalendarFactory.createGanttCalendar(barrier),
        TaskDependencyConstraint.Collision.START_EARLIER_VARIATION, isActive);
  }

  @Override
  public ActivityBinding getActivityBinding() {
    List<TaskActivity> dependantActivities = getDependency().getDependant().getActivities();
    List<TaskActivity> dependeeActivities = getDependency().getDependee().getActivities();
    if (dependantActivities.isEmpty()) {
      GPLogger.logToLogger("Task " + getDependency().getDependant() + " has no activities");
      return null;
    }
    if (dependeeActivities.isEmpty()) {
      GPLogger.logToLogger("Task " + getDependency().getDependee() + " has no activities");
      return null;
    }
    TaskActivity theDependant = dependantActivities.get(dependantActivities.size()- 1);
    TaskActivity theDependee = dependeeActivities.get(0);
    return new DependencyActivityBindingImpl(theDependant, theDependee, new Date[] { theDependant.getEnd(),
        theDependee.getStart() });
  }
}