package org.lsst.ccs.config;
   
   import javax.persistence.*;
   import java.util.Collection;
   import java.util.Collections;
   import java.util.HashSet;
   import java.util.Set;
   
   /**
   * a "zombie" that represents subsystem description that can be alive (end timestamp is STILL_ALIVE)
   * or dead (end timestamp is a realistic date).
   * <P>
   *  "ghost" data is necessary because there can be references to subsystem description
   *  that becomes deprecated while the description is "alive"; when later this description "dies"
   *  it's not necessary to change the references to this data (only the end time stamp is changed).
   *  <P>
   *   so ghosts are created at the same time as the original "living" data and anticipate death;
   *   their id is the same as the "living" object.
   * @author bamade
   */
  // Date: 10/04/12
  
      @Entity
      // not immutable since endtime can be modified!
      //@Table(name="SubsystemHistory")
  class GhostSubsystemDescription  extends SubsystemDescription{
      private static final long serialVersionUID = -8567707918287105248L;
      @Id
      private long id ;
  
  
      // here the combination "name + tag" is not unique so is not a naturalId
      // TODO: a map<Path, XXX> instead
      // IMMUTABLE!
      @OneToMany(cascade = CascadeType.ALL, fetch= FetchType.EAGER)
      protected /*@NonNull*/ Set<GhostParameterDescription> paramDescriptions  ;
  
      //////////// CONSTRUCTORS
  
       GhostSubsystemDescription() {
      }
  
      /**
       * creates a ghost from a living subsystem description.
       * @param other
       * @throws IllegalArgumentException if argument is not registered in database
       */
      public GhostSubsystemDescription(ASubsystemDescription other) {
          super(other);
          this.id = other.getId();
          //post control
          if(this.id == 0 ){
              throw new IllegalArgumentException(
                      "cannot create ghost from non registered object (where id is not initialized by database)");
          }
          this.setStartTimestamp(other.getStartTimestamp());
          Set<GhostParameterDescription> set = new HashSet<GhostParameterDescription>();
          // copy the ParameterDescription
          for(ParameterDescription parmDesc: other.getParamDescriptions()) {
              AParameterDescription realDesc = (AParameterDescription) parmDesc ;
              set.add(new GhostParameterDescription(realDesc)) ;
          }
          this.paramDescriptions = Collections.unmodifiableSet(set) ;
          this.setPreviousDescriptionID(other.getPreviousDescriptionID());
      }
  
  
      /////////////////////// ACCESSORS/ MUTATORS
  
      @Override
      public long getId() {
          return id;
      }
  
      @Override
      void setId(long id) {
         this.id = id ;
      }
  
      /**
       * calls <TT>getParamDescriptions()</TT>
       * @return
       */
      @Override
      public Set<? extends ParameterDescription> getParamDescriptionSet() {
          return getParamDescriptions() ;
      }
  
  
      /**
       *
       * @return an immutable list of ghosts for Parameter descriptions
       */
      public Set<GhostParameterDescription> getParamDescriptions() {
          return paramDescriptions;
      }
  
       void setParamDescriptions(Set<GhostParameterDescription> paramDescriptions) {
          this.paramDescriptions = Collections.unmodifiableSet(paramDescriptions);
     }
 
     @Override
      void setEndTimestamp(long endTimestamp) {
         super.setEndTimestamp(endTimestamp);
     }
 
     @Override
     public void addParameterDescriptions(ParameterDescription... descriptions) {
         throw new UnsupportedOperationException("immutable description") ;
     }
 
     @Override
     public void addParameterDescriptions(Collection<ParameterDescription> descriptions) {
         throw new UnsupportedOperationException("immutable description") ;
     }
 
     @Override
     public void removeParameterDescriptions(ParameterDescription... descriptions) {
         throw new UnsupportedOperationException("immutable description") ;
     }
 
 
 }