/*
 *     file: CollectionConstraint.java
 *  package: oreilly.hcj.datamodeling.constraints
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
########## DO NOT EDIT ABOVE THIS LINE ########## */

package oreilly.hcj.datamodeling.constraints;

import java.util.Collection;
import java.util.Iterator;

/**  
 * Models a constraint on Collection objects.
 * 
 * <p>
 * Objects of this class are immutable.
 * </p>
 *
 * @author <a href="mailto:worderisor@yahoo.com">Robert Simmons jr.</a>
 * @version $Revision: 1.1 $
 */
public class CollectionConstraint extends ObjectConstraint {
	/** Holds value of property containedType. */
	private Class containedType;

	/** 
	 * Creates a new instance of CollectionConstraint.
	 *
	 * @param name Contains the name of the constraint.
	 * @param optional Indicates if the property is optional.
	 * @param dataType The data type of the object being constrained.
	 * @param containedType The type of values in the container; null if it doesnt
	 *        matter.
	 *
	 * @throws IllegalArgumentException If dataType isn't a subclass of Collection.
	 *
	 * @see mirror.datamodel.constraints.Constraint
	 */
	public CollectionConstraint(final String name, final boolean optional,
	                            final Class dataType, final Class containedType) {
		super(name, optional, dataType);

		if (!Collection.class.isAssignableFrom(dataType)) {
			throw new IllegalArgumentException("The dataType must be a Collection");  //$NON-NLS-1$
		}

		this.containedType = containedType;
	}

	/** 
	 * Getter for property containedType.
	 *
	 * @return Value of property containedType.
	 */
	public Class getContainedType() {
		return this.containedType;
	}

	/** 
	 * Validate the given object against the constraint.  Checks to make sure the
	 * collection is not null if not allowed. If a non-null collection is passed then
	 * the members of the collection are tested to be of the type given for the set
	 * contents. Passing null for a data type allows all data types.
	 *
	 * @param obj The object to validate.
	 *
	 * @throws ConstraintException If the constraint is violated.
	 */
	public void validate(final Object obj) {
		if (obj == null) {
			throw new ConstraintException(ConstraintExceptionType.NULL_NOT_ALLOWED);
		}
		if (!getDataType()
		         .isAssignableFrom(obj.getClass())) {
			throw new ConstraintException(ConstraintExceptionType.INVALID_DATA_TYPE);
		}
		Collection coll = (Collection)obj;
		if (coll.isEmpty()) {
			if (!isOptional()) {
				throw new ConstraintException(ConstraintExceptionType.COLLECTION_CANNOT_BE_EMPTY);
			}
		}
		if (containedType != null) {
			Iterator iter = coll.iterator();
			while (iter.hasNext()) {
				if (!containedType.isAssignableFrom(iter.next().getClass())) {
					throw new ConstraintException(ConstraintExceptionType.INVALID_COLLECTION_MEMBER);
				}
			}
		}
	}
}

/* ########## End of File ########## */