/*******************************************************************************
 *  Copyright (c) 2012 Google, Inc.
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  which accompanies this distribution, and is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *  
 *  Contributors:
 *  Google, Inc. - initial API and implementation
 *******************************************************************************/
package com.windowtester.internal.runtime;

import java.io.Serializable;

import com.windowtester.internal.debug.Logger;
import com.windowtester.internal.runtime.bundle.BundleClassReference;

/**
 * A class that stores the class information for a widget in the form of a 
 * string.
 */
public class ClassReference implements Serializable {


	public static BundleClassReference forBundleClass(Class<?> cls) {
		return BundleClassReference.forBundleClass(cls);
	}
	
	public static ClassReference forClass(Class<?> cls) {
		return new ClassReference(cls);
	}
	
	/**
	 * @since 3.8.1
	 */
	public static ClassReference forName(String className) {
		return new ClassReference(className);
	}
		
	/**
	 * A class that is used as a sentinel when class resolution in
	 * {@link ClassReference#getClassForName()} fails.
	 *
	 */
	public static final class UnresolvableClass{}
	
	private static final long serialVersionUID = -5522094418456665521L;
	
	/** name of the class **/
	private final String name;
	
	/** the class  -- transient to avoid serialization**/
	private transient Class<?> cls;
	
	
	/**
	 * Constructor 
	 * @param cls the class 
	 */
	public ClassReference(Class<?> cls){
		if (cls == null)
			throw new IllegalArgumentException("class must not be null");
		this.cls  = cls;
		this.name = cls.getName();
	}
	
	/**
	 * Constructor
	 * @param name the class name
	 */
	public ClassReference(String className){
		if (className == null)
			throw new IllegalArgumentException("class name must not be null");
		name = className;
	}
	
	/**
	 * @return the class corresponding to the name
	 */
	public Class<?> getClassForName(){
		if (!isResolved())
			cls = resolveClass();
		return cls;
	}

	private Class<?> resolveClass() {
		try {
			return Class.forName(getName());
		} catch (ClassNotFoundException e) {
			Logger.log(e);
			/*
			 * I'd like to throw an exception here but there are lots
			 * of clients that call this code and don't expect an exception...
			 * As a an interim solution, we return a sentinel value that indicates
			 * that the class could not be resolved.
			 */
			return UnresolvableClass.class;
		}
	}
	
	/* (non-Javadoc)
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	public boolean equals(Object obj) {
		if (obj == null)
			return false;
		if (!(obj instanceof ClassReference))
			return false;
		ClassReference other = (ClassReference)obj;
		//just test by string names
		return other.name.equals(this.name);
	}
	
		
	/**
	 * @return the name of the class
	 */
	public String getName(){
		return name;
	}

	/**
	 * Test whether this class reference refers to the given class.
	 * <p>
	 * Note: this test <b>will not</b> force the class to be resolved.
	 */
	public boolean refersTo(Class<?> cls) {
		if (cls == null)
			throw new IllegalArgumentException("class must not be null");
		if (isResolved())
			return getClassForName().equals(cls);
		return cls.getName().equals(getName());
	}

	private boolean isResolved() {
		return cls != null;
	}

	
	/* (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		return "ClassReference(" + getName() + ")";
	}

	
}