package net.gdface.utils;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import net.gdface.utils.Assert;

import org.apache.bytecode.ChainedParamReader;

/**
 * 基于解析类数据实现获取构造函数或方法的参数名<br>
 * @author guyadong
 *
 */
public class ParameterNames extends BaseParameterNames {
	private final Map<Class<?>, ChainedParamReader> readers = new HashMap<Class<?>, ChainedParamReader>();
	/**
	 * @param clazz 要构造函数或方法的参数名的类,为{@code null}时所有getParameterNames方法返回{@code null}
	 */
	public ParameterNames(Class<?> clazz) {
		super(clazz);
		if(null != clazz){
			try {
				Class<?> c = clazz;
				do {
					readers.put(c, new ChainedParamReader(c));
				} while (null != (c = c.getSuperclass()));
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
	}

	@Override
	protected String[] doGetParameterNames(Member member) {
		if(null == clazz){
			return null;
		}
		Assert.notNull(member, "member");
		Class<?> declaringClass = member.getDeclaringClass();
		ChainedParamReader reader;
		if (null == (reader = readers.get(declaringClass))) {
			throw new IllegalArgumentException(String.format("%s is not member of %s", member.toString(),
					declaringClass.getName()));
		}
		String [] parameterNames = null;
		if (member instanceof Method){
			parameterNames = reader.getParameterNames((Method) member);
		} else if (member instanceof Constructor){
			parameterNames = reader.getParameterNames((Constructor<?>) member);
		} 
		return parameterNames;
	}
}