package jalview.ws2.actions;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.List;

import jalview.datamodel.SequenceI;
import jalview.util.MathUtils;
import jalview.ws2.actions.api.JobI;
import jalview.ws2.actions.api.TaskEventListener;
import jalview.ws2.api.JobStatus;
import jalview.ws2.api.WebServiceJobHandle;

/**
 * Basic implementation of the {@link JobI} interface which stores internal job
 * id, status, log and error log and provides getters to those fields.
 * Additionally, it stores sequences that will be submitted as job input and the
 * handle to the job on the server. Extending classes can add extra fields in
 * order to associate additional data with the job.
 * 
 * Observers can be registered with this bean-like object to listen to changes
 * to {@code status}, {@code log}, and {@code errorLog} properties. Typically,
 * the events are delegated to the {@link TaskEventListener} objects observing
 * the task that created this job.
 * 
 * @author mmwarowny
 */
// TODO: make class non-abstract by removing isInputValid()
public abstract class BaseJob implements JobI
{
  protected final long internalId = MathUtils.getUID();

  protected final List<SequenceI> inputSeqs;

  protected JobStatus status = null;

  protected String log = "";

  protected String errorLog = "";

  /* FIXME: server job is not specific to the BaseJob and should preferably
   * be managed by classes using clients (tasks). */
  protected WebServiceJobHandle serverJob;

  public BaseJob(List<SequenceI> inputSeqs)
  {
    this.inputSeqs = inputSeqs;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public final long getInternalId()
  {
    return internalId;
  }

  /**
   * Return the list of input sequences associated with this job.
   * 
   * @return input sequences
   */
  public List<SequenceI> getInputSequences()
  {
    return inputSeqs;
  }

  /**
   * Check if inputs make a valid job.
   * 
   * @return {@code true} if the input is valid.
   */
  // FIXME: method not necessary, may incorporate into task#prepare()
  public abstract boolean isInputValid();

  /**
   * Check if the job is completed, This includes jobs with invalid input,
   * successful and unsuccessful termination.
   * 
   * @return {@code true} if job is completed successfully or not
   */
  public boolean isCompleted()
  {
    return !isInputValid() || getStatus().isDone();
  }

  @Override
  public final JobStatus getStatus()
  {
    return status;
  }

  /**
   * Set new status of the job and notify listeners of the change. Job status is
   * managed internally by tasks and should not be modified outside the task
   * which created this job.
   * 
   * @param status
   *          new job status
   */
  public final void setStatus(JobStatus status)
  {
    JobStatus oldStatus = this.status;
    this.status = status;
    pcs.firePropertyChange("status", oldStatus, status);
  }

  @Override
  public final String getLog()
  {
    return log;
  }

  /**
   * Set log text and notify listeners of the change. Log is managed by tasks
   * which created the job and should not be modified by other classes.
   * 
   * @param log
   *          new log
   */
  public final void setLog(String log)
  {
    String oldLog = this.log;
    this.log = log;
    pcs.firePropertyChange("log", oldLog, log);
  }

  @Override
  public final String getErrorLog()
  {
    return errorLog;
  }

  /**
   * Set error log text and notify listeners of the change. Error log is managed
   * by tasks which created the job and should not be modified by other classes.
   * 
   * @param errorLog
   */
  public final void setErrorLog(String errorLog)
  {
    String oldLog = this.errorLog;
    this.errorLog = errorLog;
    pcs.firePropertyChange("errorLog", oldLog, errorLog);
  }

  /**
   * Return the job handle that identifies this job running on the server or
   * {@code null} if the job was not submitted.
   * 
   * @return server job handle
   */
  public final WebServiceJobHandle getServerJob()
  {
    return serverJob;
  }

  /**
   * Set the server job handle once the job was submitted to the server. The
   * handler is managed by the task which created this job and should not be
   * modified by other classes.
   * 
   * @param job
   */
  public final void setServerJob(WebServiceJobHandle job)
  {
    this.serverJob = job;
  }

  private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);

  /**
   * Register an observer that will be notified of changes to status, log and
   * error log.
   * 
   * @param listener
   *          property change listener
   */
  public final void addPropertyChagneListener(PropertyChangeListener listener)
  {
    pcs.addPropertyChangeListener(listener);
  }

  /**
   * Remove the property listener from this object.
   * 
   * @param listener
   *          listener to remove
   */
  public final void removePropertyChangeListener(PropertyChangeListener listener)
  {
    pcs.removePropertyChangeListener(listener);
  }
}