package de.fhdw.wtf.persistence.meta;
   
   import de.fhdw.wtf.persistence.exception.NotValidInputException;
   
   /**
    * A class to represent a connection between three objects in the database. The UnidirectionalLink itself is an instance
    * of an association3.
    * 
    */
  public class MapLink extends Link {
  	
  	/**
  	 * The hashmap-key object.
  	 */
  	private final Object key;
  	
  	/**
  	 * Getter for the key of this UnidirectionalLink.
  	 * 
  	 * @return Provides an Object, which is the key of this link.
  	 */
  	public Object getKey() {
  		return this.key;
  	}
  	
  	/**
  	 * The type of this link.
  	 */
  	private final MapAssociation instanceOf;
  	
  	@Override
  	public MapAssociation getInstanceOf() {
  		return this.instanceOf;
  	}
  	
  	/**
  	 * Constructor for a new UnidirectionalLink, it should only be called by the Object Facade or Junit Test to
  	 * guarantee a valid consistency with the database.
  	 * 
  	 * @param id
  	 *            The Id of the UnidirectionalLink, determined by the database.
  	 * @param owner
  	 *            The owner of the this UnidirectionalLink. A User Object.
  	 * @param target
  	 *            The target of this link. An Object.
  	 * @param key
  	 *            The hashmap-key of this link. An Object.
  	 * @param instanceOf
  	 *            The type of this link.
  	 * @throws NotValidInputException
  	 */
  	public MapLink(final long id,
  			final UserObject owner,
  			final Object target,
  			final Object key,
  			final MapAssociation instanceOf) throws NotValidInputException {
  		super(id, owner, target);
  		this.key = key;
  		this.instanceOf = instanceOf;
  		
  	}
  	
  	@Override
  	public String toString() {
  		return "MapLink<" + this.getId() + ">";
  	}
  	
  	@Override
  	public boolean equals(final java.lang.Object other) {
  		if (!(other instanceof MapLink)) {
  			return false;
  		}
  		
  		final MapLink link = (MapLink) other;
  		return super.equals(link) && this.getInstanceOf().equals(link.getInstanceOf())
  				&& this.getKey().equals(link.getKey());
  	}
  	
  	@Override
  	public int hashCode() {
  		return super.hashCode() ^ this.instanceOf.hashCode() ^ this.key.hashCode();
  	}
  }