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package org.jaxws.stub2html.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

/**
 * Get a variable's java type, or a collection's generic type 
 *  For Example, 
 *  "String a" => String.class, and "List<Integer> b" => Integer.class 
 * 
 * @author chenjianjx (Basically copied from Internet)
 * 
 */
public class GenericsUtils {

	public static Class getFieldGenericType(Field field) {
		return chooseOneType(field.getType(), field.getGenericType());
	}

	public static Class getMethodGenericReturnType(Method method) {
		return chooseOneType(method.getReturnType(), method.getGenericReturnType());
	}

	public static Class getMethodGenericParameterTypes(Method method, int paramIndex) {
		Class literalType = method.getParameterTypes()[paramIndex];
		Type genericType = method.getGenericParameterTypes()[paramIndex];
		return chooseOneType(literalType, genericType);

	}

	static Class chooseOneType(Class literalType, Type genericType) {
		if (genericType instanceof ParameterizedType) {
			return digFromGenericType(genericType);
		}
		return literalType;
	}

	static Class digFromGenericType(Type genericType) {
		Type[] typeArguments = ((ParameterizedType) genericType).getActualTypeArguments();
		Type type = typeArguments[0];
		if (type instanceof ParameterizedType) {
			return digFromGenericType(type);
		}

		if (type instanceof Class) {
			return (Class) type;
		}

		return Object.class;

	}
}