package net.super_.rdp.bcel.transimpl;

import net.super_.rdp.bcel.ClassGenTransformer;
import net.super_.rdp.bcel.SignatureFilter;
import net.super_.rdp.bcel.Member;
import net.super_.rdp.bcel.InstructionSearcher;
import net.super_.rdp.util.Loggable;
import net.super_.rdp.util.Utils;
import net.super_.rdp.util.Logger;
import org.apache.bcel.generic.*;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.Constants;

import java.util.Iterator;

/**
 * Created by IntelliJ IDEA.
 * User: super_
 * Date: Nov 14, 2008
 * Time: 3:23:52 PM
 * To change this template use File | Settings | File Templates.
 */
public class ClassLoaderT implements ClassGenTransformer, Loggable {

    public boolean isApplicable(ClassGen classGen) {
        return classGen.getSuperclassName().equals("java.lang.ClassLoader");
    }

    public void applyTransformation(ClassGen classGen) {
        Utils.defineClass("ClassLoader", classGen);
        SignatureFilter sFilter = new SignatureFilter("Ljava/util/Hashtable;");
        Member[] results = Utils.runMemberFilter(classGen, sFilter);
        Member cachedClasses = results[0];
        Utils.defineMember("CachedClasses", cachedClasses);
        Member loadClassMethod = Utils.findMethod(classGen, "loadClass", "(Ljava/lang/String;Z)Ljava/lang/Class;");
        MethodGen mGen = Utils.getMethodGen(loadClassMethod);
        InstructionSearcher searcher = new InstructionSearcher(mGen.getInstructionList());
        String bufferPattern = "INVOKEVIRTUAL ASTORE ALOAD IFNULL";
        Iterator<InstructionHandle[]> result = searcher.search(bufferPattern);
        if (!result.hasNext()) {
            Logger.log(this, "Unable to find pattern: " + bufferPattern);
            return;
        }
        InstructionHandle[] classBufferPattern = result.next();
        InstructionHandle bufferAstore = classBufferPattern[1];
        int positionIdx = ((ASTORE) bufferAstore.getInstruction()).getIndex();
        Logger.log(this, "Class data buffer index: " + positionIdx);
        InstructionFactory instrFactory = new InstructionFactory(classGen, classGen.getConstantPool());
        InvokeInstruction modifyInvoke = instrFactory.createInvoke("ClassProxy", "modifyBuffer", new ArrayType(BasicType.BYTE, 1), new Type[] { new ArrayType(BasicType.BYTE, 1) }, Constants.INVOKESTATIC);
        searcher.getInstructionList().insert(bufferAstore, modifyInvoke);
        classGen.replaceMethod((Method) loadClassMethod.getFieldOrMethod(), mGen.getMethod());
    }
}