package net.sourceforge.fenixedu.domain.accessControl;

import net.sourceforge.fenixedu.domain.DomainObject;
import net.sourceforge.fenixedu.domain.DomainReference;

public abstract class DomainBackedGroup<T extends DomainObject> extends LeafGroup {

    private static final long serialVersionUID = 1L;

    private final DomainReference<T> reference;

    public DomainBackedGroup(T object) {
	super();

	// if (object == null) {
	// throw new DomainException("accessControl.group.domainBacked.null");
	// }

	this.reference = new DomainReference<T>(object);
    }

    /**
     * Obtains the object that was passed in the constructor. This method uses
     * the {@link DomainReference} created to retrieve the object. As such you
     * must always consider that the target object may have been deleted and
     * thus the reference will point to <code>null</code>.
     * 
     * @return the object passed in the constructor or <code>null</code> if the
     *         object was deleted
     */
    public T getObject() {
	return this.reference.getObject();
    }

    @Override
    public String getExpression() {
	// HACK: when an object is deleted a domain reference starts pointing to
	// null;
	// most DomainBackedGroups, if not all, don't expect this
	if (getObject() == null) {
	    return new NoOneGroup().getExpression();
	} else {
	    return super.getExpression();
	}
    }

    @Override
    public boolean equals(Object other) {
	if (other == null) {
	    return false;
	}

	if (!this.getClass().isAssignableFrom(other.getClass())) {
	    return false;
	}

	DomainBackedGroup otherGroup = (DomainBackedGroup) other;
	return this.reference.equals(otherGroup.reference);
    }

    @Override
    public int hashCode() {
	return this.reference.hashCode();
    }
}