/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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.opencastproject.editor;
  
  import org.opencastproject.editor.api.EditorServiceException;
  import org.opencastproject.editor.api.ErrorStatus;
  import org.opencastproject.editor.api.LockData;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  
  import java.util.concurrent.TimeUnit;
  
  public class EditorLock {
  
    private static LoadingCache <String,LockData> lockedPackages;
  
    public EditorLock(int timeout) {
      lockedPackages = CacheBuilder.newBuilder().expireAfterWrite(timeout, TimeUnit.SECONDS).build(
        new CacheLoader<String, LockData>() {
          // NB, this is not used but the abstract class needs a concrete implementaton
          @Override
          public LockData load(String mediapackageId) throws Exception {
            return lockedPackages.getIfPresent(mediapackageId);
          }
        });
    }
  
    public void lock(String mediaPackage, LockData lockRequest) throws EditorServiceException {
      LockData lockData = lockedPackages.getIfPresent(mediaPackage);
  
      if (null != lockData) {
        if (lockRequest.getUUID().equals(lockData.getUUID())) {
          lockedPackages.refresh(mediaPackage);
        } else {
          String lockMessage = lockData.toString();
          throw new EditorServiceException(lockMessage,ErrorStatus.MEDIAPACKAGE_LOCKED);
        }
      } else {
        lockedPackages.put(mediaPackage, lockRequest);
      }
    }
  
    public void unlock(String mediaPackage, LockData lockRequest) throws EditorServiceException {
      LockData lockData = lockedPackages.getIfPresent(mediaPackage);
  
      if (null != lockData) {
        if (lockRequest.getUUID().equals(lockData.getUUID())) {
          lockedPackages.invalidate(mediaPackage);
        } else {
          String lockMessage = "MediaPackage " + mediaPackage + lockData.toString();
          throw new EditorServiceException(lockMessage,ErrorStatus.MEDIAPACKAGE_LOCKED);
        }
      }
    }
  
    public boolean isLocked(String mediaPackage) {
      return (null != getLockData(mediaPackage));
    }
  
    public LockData getLockData(String mediaPackage) {
      return lockedPackages.getIfPresent(mediaPackage);
    }
  }