package jalview.ws2.helpers;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import jalview.ws2.actions.BaseJob;
import jalview.ws2.actions.api.JobI;
import jalview.ws2.api.JobStatus;

/**
 * A property change listener to be used by web service tasks that delegates all
 * sub-job related events from {@link BaseJob} subclasses to
 * {@link TaskEventSupport}. Tasks can create one instance of this class with
 * their event handler as a delegate and add it as a property change listener to
 * each sub-job supporting property change listeners. It ensures that an
 * appropriate {@code fireSubJob*Changed} method of the delegate object will be
 * called whenever a {@link PropertyChagneEvent} is emitted by the sub-job.
 * 
 * @author mmwarowny
 *
 * @param <T>
 *          result type of the task
 */
public class DelegateJobEventListener<T> implements PropertyChangeListener
{
  private final TaskEventSupport<T> delegate;

  public DelegateJobEventListener(TaskEventSupport<T> delegate)
  {
    this.delegate = delegate;
  }

  @Override
  public void propertyChange(PropertyChangeEvent evt)
  {
    switch (evt.getPropertyName())
    {
    case "status":
      statusChanged(evt);
      break;
    case "log":
      logChanged(evt);
      break;
    case "errorLog":
      errorLogChanged(evt);
      break;
    default:
      throw new AssertionError(String.format(
          "illegal property name \"%s\"", evt.getPropertyName()));
    }
  }

  private void statusChanged(PropertyChangeEvent evt)
  {
    JobI job = (JobI) evt.getSource();
    JobStatus status = (JobStatus) evt.getNewValue();
    delegate.fireSubJobStatusChanged(job, status);
  }

  private void logChanged(PropertyChangeEvent evt)
  {
    JobI job = (JobI) evt.getSource();
    String log = (String) evt.getNewValue();
    delegate.fireSubJobLogChanged(job, log);
  }

  private void errorLogChanged(PropertyChangeEvent evt)
  {
    JobI job = (JobI) evt.getSource();
    String errorLog = (String) evt.getNewValue();
    delegate.fireSubJobErrorLogChanged(job, errorLog);
  }
}