package com.profiler;

import java.lang.instrument.ClassFileTransformer;

import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;

import javassist.ByteArrayClassPath;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;

@Deprecated
public class TomcatTracer implements ClassFileTransformer {
    protected String agentArgString = "";
    protected Instrumentation instrumentation;
    ClassPool classPool;

    public static void premain(String agentArgs, Instrumentation inst) {
        new TomcatTracer(agentArgs, inst);
    }

    public TomcatTracer(String agentArgs, Instrumentation inst) {
        agentArgString = agentArgs;
        instrumentation = inst;
        instrumentation.addTransformer(this);
        classPool = ClassPool.getDefault();
    }

    @Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
        String javassistClassName = className.replace('/', '.');

        if (javassistClassName.startsWith("javax.servlet.") || javassistClassName.startsWith("org.apache.tomcat")) {
            if (!javassistClassName.startsWith("org.apache.tomcat.util")) {
                byte[] result = changeCode(javassistClassName, classfileBuffer);
                if (result != null)
                    return result;
            }
        }

        return null;
    }

    private byte[] changeCode(String javassistClassName, byte[] classfileBuffer) {
        boolean insertFlag = false;
        // 아래 코드 필요없음.
//		classPool.insertClassPath(new ByteArrayClassPath(javassistClassName, classfileBuffer));

        try {
            if (classPool == null) {
                System.out.println("NULL");
                classPool = ClassPool.getDefault();
            }

            CtClass cc = classPool.get(javassistClassName);
            CtMethod[] methodList = cc.getDeclaredMethods();

            for (CtMethod method : methodList) {
                String methodName = method.getLongName();

                if (!method.isEmpty()) {
                    System.out.println("***inserted instrument code at " + methodName);
                    method.insertBefore("{ System.out.println(\"--- " + methodName + "  is called. \");}");
                    insertFlag = true;
                }
            }

            if (insertFlag) {
                byte[] newClassfileBuffer = cc.toBytecode();
                System.out.println("@@@" + javassistClassName + "class's new Buffer generated !!!");

                return newClassfileBuffer;
            }
        } catch (Exception e) {
            System.err.println("!!!!! " + e.getMessage());
        }
        return null;
    }
}