/*
 * SonarQube
 * Copyright (C) 2009-2017 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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 org.sonar.core.issue.tracking;

import java.util.Collection;
import java.util.List;

public abstract class LazyInput<ISSUE extends Trackable> implements Input<ISSUE> {

  private List<ISSUE> issues;
  private LineHashSequence lineHashSeq;
  private BlockHashSequence blockHashSeq;

  @Override
  public LineHashSequence getLineHashSequence() {
    if (lineHashSeq == null) {
      lineHashSeq = loadLineHashSequence();
    }
    return lineHashSeq;
  }

  @Override
  public BlockHashSequence getBlockHashSequence() {
    if (blockHashSeq == null) {
      blockHashSeq = BlockHashSequence.create(getLineHashSequence());
    }
    return blockHashSeq;
  }

  @Override
  public Collection<ISSUE> getIssues() {
    if (issues == null) {
      issues = loadIssues();
    }
    return issues;
  }

  protected abstract LineHashSequence loadLineHashSequence();

  protected abstract List<ISSUE> loadIssues();
}