/*
 * Hibernate Validator, declare and validate application constraints
 *
 * License: Apache License, Version 2.0
 * See the license.txt file in the root directory or <http://www.apache.org/licenses/LICENSE-2.0>.
 */
package org.hibernate.validator.internal.util.annotationfactory;

import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.Map;

/**
 * Encapsulates the data you need to create an annotation. In
 * particular, it stores the type of an <code>Annotation</code> instance
 * and the values of its elements.
 * The "elements" we're talking about are the annotation attributes,
 * not its targets (the term "element" is used ambiguously
 * in Java's annotations documentation).
 *
 * @author Paolo Perrotta
 * @author Davide Marchignoli
 * @author Hardy Ferentschik
 * @author Gunnar Morling
 */
public class AnnotationDescriptor<T extends Annotation> {

	private final Class<T> type;

	private final Map<String, Object> elements = new HashMap<String, Object>();

	/**
	 * Returns a new descriptor for the given annotation type.
	 *
	 * @param <S> The type of the annotation.
	 * @param annotationType The annotation's class.
	 *
	 * @return A new descriptor for the given annotation type.
	 */
	public static <S extends Annotation> AnnotationDescriptor<S> getInstance(Class<S> annotationType) {
		return new AnnotationDescriptor<S>( annotationType );
	}

	/**
	 * Returns a new descriptor for the given annotation type.
	 *
	 * @param <S> The type of the annotation.
	 * @param annotationType The annotation's class.
	 * @param elements A map with attribute values for the annotation to be created.
	 *
	 * @return A new descriptor for the given annotation type.
	 */
	public static <S extends Annotation> AnnotationDescriptor<S> getInstance(Class<S> annotationType, Map<String, Object> elements) {
		return new AnnotationDescriptor<S>( annotationType, elements );
	}

	public AnnotationDescriptor(Class<T> annotationType) {
		this.type = annotationType;
	}

	public AnnotationDescriptor(Class<T> annotationType, Map<String, Object> elements) {
		this.type = annotationType;
		for ( Map.Entry<String, Object> entry : elements.entrySet() ) {
			this.elements.put( entry.getKey(), entry.getValue() );
		}
	}

	public void setValue(String elementName, Object value) {
		elements.put( elementName, value );
	}

	public Object valueOf(String elementName) {
		return elements.get( elementName );
	}

	public boolean containsElement(String elementName) {
		return elements.containsKey( elementName );
	}

	public int numberOfElements() {
		return elements.size();
	}

	/**
	 * Returns a map with the elements contained in this descriptor keyed by name. This map is a copy
	 * of the internally used map, so it can safely be modified without altering this descriptor.
	 *
	 * @return A map with this descriptor's elements.
	 */
	public Map<String, Object> getElements() {
		return new HashMap<String, Object>( elements );
	}

	public Class<T> type() {
		return type;
	}
}