package pickandcraftSkin;

import static org.objectweb.asm.Opcodes.ALOAD;
import static org.objectweb.asm.Opcodes.ARETURN;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;

import java.io.File;
import java.io.InputStream;
import java.util.Iterator;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.InsnNode;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.VarInsnNode;


public class SkinClassTransformer implements net.minecraft.launchwrapper.IClassTransformer {
	@Override
	public byte[] transform(String arg0, String arg1, byte[] arg2) {

		//on cherche la classe qui nous interressent. On gere les deux cas: si elle est "obscurcie" ou pas
		if (arg0.equals("beu")) {
			System.out.println("********* INSIDE OBFUSCATED AbstractClientPlayer TRANSFORMER ABOUT TO PATCH: " + arg0);
			return patchClassASM(arg0, arg2, true);
        }

		if (arg0.equals("net.minecraft.client.entity.AbstractClientPlayer")) {
			System.out.println("********* INSIDE AbstractClientPlayer TRANSFORMER ABOUT TO PATCH: " + arg0);
			return patchClassASM(arg0, arg2, false);
        }

		//Check if the JVM is about to process the te.class or the EntityCreeper.class
		if (arg0.equals("bfn")
				|| arg0.equals("net.minecraft.client.renderer.ImageBufferDownload")) {
			System.out
					.println("********* INSIDE ImageBufferDownload TRANSFORMER ABOUT TO PATCH: "
							+ arg0);
			arg2 = patchClassInJar(arg0, arg2, arg0,
					SkinFMLLoadingPlugin.location);
		}

		return arg2;
	}

	//a small helper method that takes the class name we want to replace and our jar file.
	//It then uses the java zip library to open up the jar file and extract the classes.
	//Afterwards it serializes the class in bytes and pushes it on to the JVM.
	//with the original bytes that JVM was about to process ignored completly

	public byte[] patchClassInJar(String name, byte[] bytes, String ObfName,
			File location) {
		try {
			// open the jar as zip
			ZipFile zip = new ZipFile(location);
			// find the file inside the zip that is called te.class or
			// net.minecraft.entity.monster.EntityCreeper.class
			// replacing the . to / so it would look for
			// net/minecraft/entity/monster/EntityCreeper.class
			ZipEntry entry = zip.getEntry(name.replace('.', '/') + ".class");

			if (entry == null) {
				System.out
						.println(name + " not found in " + location.getName());
			} else {

				// serialize the class file into the bytes array
				InputStream zin = zip.getInputStream(entry);
				bytes = new byte[(int) entry.getSize()];
				zin.read(bytes);
				zin.close();
				System.out.println("[" + "SkinCustomHD" + "]: " + "Class "
						+ name + " patched!");
			}
			zip.close();
		} catch (Exception e) {
			throw new RuntimeException("Error overriding " + name + " from "
					+ location.getName(), e);
		}

		// return the new bytes
		return bytes;
	}

	public byte[] patchClassASM(String name, byte[] bytes, boolean obfuscated) {

		 	String targetMethod1Name = "", targetMethod2Name = "";
		 	boolean ok1 = false, ok2 = false;

	        if(obfuscated == true) {
	        	targetMethod1Name ="d";
			 	targetMethod2Name = "e";
	        }
	        else {
	        	targetMethod1Name ="getSkinUrl";
			 	targetMethod2Name = "getCapeUrl";
	        }


	      //on prepare la manipulation
		    ClassNode classNode = new ClassNode();
	        ClassReader classReader = new ClassReader(bytes);
	        classReader.accept(classNode, 0);


	      //Maintenant, on boucle sur toutes les methodes declarees dans la classe jusqu'a trouver la/les methode(s) cible(s)
	        Iterator<MethodNode> methods = classNode.methods.iterator();
	        while(methods.hasNext())
	        {
	            MethodNode m = methods.next();
	            System.out.println("********* Method Name: "+m.name + " Desc:" + m.desc);


	          //On verifie si il s'agit de la methode cible et si elle a la meme signature (plus de detail ici: http://journals.ecs.soton.ac.uk/java/tutorial/native1.1/implementing/method.html)
	            if ((m.name.equals(targetMethod1Name) && m.desc.equals("(Ljava/lang/String;)Ljava/lang/String;")))
	            {
	                System.out.println("********* Inside target method1!");

	                	//on creer une liste d'instruction pour invoquer une methode statique
	                	InsnList toInject = new InsnList();
	                	toInject.add(new VarInsnNode(ALOAD, 0));
	                				//new MethodInsnNode(on declare le type de la methode, "le chemin de la classe", "le nom de la methode", "sa signature")
	                	toInject.add(new MethodInsnNode(INVOKESTATIC, "pickandcraftSkin/PlayerCustom", "getURLSkinCustom", "(Ljava/lang/String;)Ljava/lang/String;"));
	                	toInject.add(new InsnNode(ARETURN));

	                   // on remplace les instructions deja presente dans la methode par notre liste d'instruction
	                   m.instructions = toInject;
	                   ok1 = true;
	                System.out.println("Patching Method1 Complete!");
	            }
	            else if ((m.name.equals(targetMethod2Name) && m.desc.equals("(Ljava/lang/String;)Ljava/lang/String;")))
	            {
	                System.out.println("********* Inside target2 method!");
	                   InsnList toInject = new InsnList();

	                   toInject.add(new VarInsnNode(ALOAD, 0));
	                   toInject.add(new MethodInsnNode(INVOKESTATIC, "pickandcraftSkin/PlayerCustom", "getURLCapeCustom", "(Ljava/lang/String;)Ljava/lang/String;"));
	                   toInject.add(new InsnNode(ARETURN));

	                   // on remplace les instructions deja presente dans la methode par notre liste d'instruction
	                   m.instructions = toInject;
	                   ok2 = true;
	                System.out.println("Patching Method2 Complete!");
	            }

	            if(ok1 && ok2)
	            	break;
	        }

	      //on finit la manipulation
	        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
	        classNode.accept(writer);
	        return writer.toByteArray();
      }

}