/* 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.activiti.engine.impl.cmd;

import java.io.Serializable;

import org.activiti.engine.ActivitiException;
import org.activiti.engine.impl.context.Context;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandContext;
import org.activiti.engine.impl.persistence.entity.TaskEntity;

/**
 * An abstract superclass for {@link Command} implementations that 
 * want to verify the provided task is always active (ie. not suspended).
 * 
 * @author Joram Barrez
 */
public abstract class NeedsActiveTaskCmd<T> implements Command<T>, Serializable {
  
  private static final long serialVersionUID = 1L;
  
  protected String taskId;
  
  public NeedsActiveTaskCmd(String taskId) {
    this.taskId = taskId;
  }
  
  public T execute(CommandContext commandContext) {
    
    if(taskId == null) {
      throw new ActivitiException("taskId is null");
    }
    
    TaskEntity task = Context
      .getCommandContext()
      .getTaskManager()
      .findTaskById(taskId);
    
    if (task == null) {
      throw new ActivitiException("Cannot find task with id " + taskId);
    }
    
    if (task.isSuspended()) {
      throw new ActivitiException(getSuspendedTaskException());
    }
    
    return execute(commandContext, task);
  }
  
  /**
   * Subclasses must implement in this method their normal command logic.
   * The provided task is ensured to be active.
   */
  protected abstract T execute(CommandContext commandContext, TaskEntity task);
  
  /**
   * Subclasses can override this method to provide a customized exception message
   * that will be thrown when the task is suspended.
   */
  protected String getSuspendedTaskException() {
    return "Cannot execute operation: task is suspended";
  }

}