/*

 * Copied from Gentyref project http://code.google.com/p/gentyref/

 * Reformatted and moved to fit package structure

 */



package com.google.sitebricks.conversion.generics;



import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;



/**

 * Wrapper around {@link Type}.

 *

 * You can use this to create instances of Type for a type known at compile

 * time.

 *

 * For example, to get the Type that represents List<String>:

 * <code>Type listOfString = new TypeToken&lt;List&lt;String&gt;&gt;(){}.getType();</code>

 *

 * @author Wouter Coekaerts <wouter@coekaerts.be>

 *

 * @param <T>

 *            The type represented by this TypeToken.

 */

public abstract class TypeToken<T>

{

	private final Type type;



	/**

	 * Constructs a type token.

	 */

	protected TypeToken()

	{

		this.type = extractType();

	}



	private TypeToken(Type type)

	{

		this.type = type;

	}



	public Type getType()

	{

		return type;

	}



	private Type extractType()

	{

		Type t = getClass().getGenericSuperclass();

		if (!(t instanceof ParameterizedType))

		{

			throw new RuntimeException("Invalid TypeToken; must specify type parameters");

		}

		ParameterizedType pt = (ParameterizedType) t;

		if (pt.getRawType() != TypeToken.class)

		{

			throw new RuntimeException("Invalid TypeToken; must directly extend TypeToken");

		}

		return pt.getActualTypeArguments()[0];

	}



	/**

	 * Gets type token for the given {@code Class} instance.

	 */

	public static <T> TypeToken<T> get(Class<T> type)

	{

		return new SimpleTypeToken<T>(type);

	}



	/**

	 * Gets type token for the given {@code Type} instance.

	 */

	public static TypeToken<?> get(Type type)

	{

		return new SimpleTypeToken<Object>(type);

	}



	private static class SimpleTypeToken<T> extends TypeToken<T>

	{

		public SimpleTypeToken(Type type)

		{

			super(type);

		}

	}



	@Override

	public boolean equals(Object obj)

	{

		return (obj instanceof TypeToken<?>) && type.equals(((TypeToken<?>) obj).type);

	}



	@Override

	public int hashCode()

	{

		return type.hashCode();

	}

}