package com.walker.infrastructure.utils;

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

public class GenericTypeUtils {

    /**
     * 返回给定对象的泛型类型，默认返回第一个泛型(可能存在多个)。
     * @param clazz
     * @return
     * @date 2022-11-16
     */
    public static Class getSuperClassGenericType(Class clazz){
        return getSuperClassGenericType(clazz, 0);
    }

    public static Class getSuperClassGenericType(Class clazz, int index){
        Type genType = clazz.getGenericSuperclass();

        if (!(genType instanceof ParameterizedType)) {
//	      log.warn(clazz.getSimpleName() + "'s superclass not ParameterizedType");
            return Object.class;
        }

        Type[] params = ((ParameterizedType)genType).getActualTypeArguments();

        if ((index >= params.length) || (index < 0)) {
//	      log.warn("Index: " + index + ", Size of " + clazz.getSimpleName() + "'s Parameterized Type: " + params.length);
            return Object.class;
        }
        if (!(params[index] instanceof Class)) {
//	      log.warn(clazz.getSimpleName() + " not set the actual class on superclass generic parameter");
            return Object.class;
        }
        return (Class)params[index];
    }
}