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;

/**
 * èŽ·å–æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°å<br>
 * 当不能获取参数名的情况下,
 * {@link returnFakeNameIfFail}为{@code false}时返回{@code null},否则返回返回arg,arg2...æ ¼å¼çš„æ›¿ä»£å<br>
 * {@link returnFakeNameIfFail}默认为{@code true}
 * @author guyadong
 *
 */
public class ParameterNames {
        private final Map<Class<?>, ChainedParamReader> readers = new HashMap<Class<?>, ChainedParamReader>();
        private final Class<?> clazz;
        /** å½“èŽ·å–æ— æ³•å‚æ•°åæ—¶æ˜¯å¦è¿”å›žarg,arg2...æ ¼å¼çš„æ›¿ä»£åå­— */
        private boolean returnFakeNameIfFail = true;
        public ParameterNames setReturnFakeNameIfFail(boolean returnFakeNameIfFail) {
                this.returnFakeNameIfFail = returnFakeNameIfFail;
                return this;
        }

        /**
         * @param clazz è¦æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°åçš„ç±»,为{@code null}时所有getParameterNames方法返回{@code null}
         */
        public ParameterNames(Class<?> clazz) {
                this.clazz = 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);
                        }
                }
        }

        /**
         * èŽ·å–æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°å
         * @param reader
         * @param member æž„é€ å‡½æ•°æˆ–æ–¹æ³•å¯¹è±¡
         * @return
         */
        private final String[] getParameterNames(ChainedParamReader reader, Member member) {
                String [] parameterNames = null;
                int paramCount ;
                if (member instanceof Method){
                        parameterNames = reader.getParameterNames((Method) member);
                        paramCount = ((Method) member).getParameterTypes().length;
                } else if (member instanceof Constructor){
                        parameterNames = reader.getParameterNames((Constructor<?>) member);
                        paramCount = ((Constructor<?>) member).getParameterTypes().length;
                } else {
                        throw new IllegalArgumentException("member type must be Method or Constructor");
                }
                if(this.returnFakeNameIfFail){
                        if (null == parameterNames) {
                                parameterNames = new String[paramCount];
                                for (int i = 0; i < parameterNames.length; i++)
                                        parameterNames[i] = String.format("arg%d", i);
                        }
                }
                return parameterNames;
        }

        /**
         * èŽ·å–æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°å
         * @param member æž„é€ å‡½æ•°æˆ–æ–¹æ³•å¯¹è±¡
         * @return
         * @see #getParameterNames(ChainedParamReader, Member)
         */
        public final String[] getParameterNames(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()));
                }
                return getParameterNames(reader, member);
        }
        
        /**
         * èŽ·å–æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°å<br>
         * {@code name}为{@code null}æ—¶,èŽ·å–æž„é€ å‡½æ•°çš„å‚æ•°å
         * @param name 方法名
         * @param parameterTypes æž„é€ å‡½æ•°æˆ–æ–¹æ³•çš„å‚æ•°ç±»åž‹
         * @return
         * @throws NoSuchMethodException
         * @see #getParameterNames(String, Class)
         */
        public final String[] getParameterNames(String name, Class<?>[] parameterTypes) throws NoSuchMethodException {
                if(null == clazz){
                        return null;
                }
                try {
                        Member member = null == name ? clazz.getConstructor(parameterTypes) : clazz.getMethod(name, parameterTypes);
                        return getParameterNames(member);
                } catch (SecurityException e) {
                        throw new IllegalArgumentException(e);
                }
        }
        /**
         * {@link #getParameterNames(String, Class[])}不显式抛出异常版本
         * @param name
         * @param parameterTypes
         * @return
         */
        public final String[] getParameterNamesUnchecked(String name, Class<?>[] parameterTypes)  {
                try {
                        return getParameterNames(name, parameterTypes);
                } catch (NoSuchMethodException e) {
                        throw new RuntimeException(e);
                }
        }
}