package myorg.relex.many2many;
   
   import java.util.HashSet;
   import java.util.Set;
   import java.util.UUID;
   
   import javax.persistence.*;
   
   /**
   * This class provides an example of a many-to-many, bi-directional relationship that just
   * happens to be recursive. Both ends of the relationship reference an instance of this class. 
   */
  @Entity
  @Table(name="RELATIONEX_NODE")
  public class Node {
  	@Id
  	@Column(length=36, nullable=false)
  	private String id;
  	
  	@ManyToMany(cascade={CascadeType.PERSIST}, fetch=FetchType.LAZY)
  	@JoinTable(name="RELATIONEX_NODE_REL",
  			joinColumns=@JoinColumn(name="PARENT_ID"),
  			inverseJoinColumns=@JoinColumn(name="CHILD_ID"))
  	private Set<Node> children;
  	
  	@ManyToMany(mappedBy="children", fetch=FetchType.EAGER)
  	private Set<Node> parents;
  	
  	@Column(length=32, nullable=false)
  	private String name;
  	
  	public Node() { id=UUID.randomUUID().toString(); }
  	public Node(String name) {
  		this();
  		this.name = name;
  	}
  	public Node(Node parent, String name) {
  		this();
  		this.name = name;
  		parent.getChildren().add(this);
  		getParents().add(parent);
  	}
  
  	public String getId() { return id; }
  	public String getName() { return name; }
  	public void setName(String name) {
  		this.name = name;
  	}
  
  	public Set<Node> getChildren() {
  		if (children==null) {
  			children = new HashSet<Node>();
  		}
  		return children;
  	}
  	
  	public Set<Node> getParents() {
  		if (parents == null) {
  			parents = new HashSet<Node>();
  		}
  		return parents;
  	}
  	
  	@Override
  	public int hashCode() {
  		return id==null?0:id.hashCode();
  	}	
  	@Override
  	public boolean equals(Object obj) {
  		try {
  			if (this == obj) { return true; }
  			Node rhs = (Node)obj;
  			if (id==null && rhs.id != null) { return false; }
  			return id.equals(rhs.id);
  		} catch (Exception ex) { return false; }
  	}
  }