minecraft-kajetans-text-core-mod/src/main/java/me/ktcm/KajetansTransformer.java

package me.ktcm;

import net.minecraft.launchwrapper.IClassTransformer;
import net.minecraft.launchwrapper.Launch;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.FieldInsnNode;
import org.objectweb.asm.tree.FrameNode;
import org.objectweb.asm.tree.InsnList;
import org.objectweb.asm.tree.InsnNode;
import org.objectweb.asm.tree.LineNumberNode;
import org.objectweb.asm.tree.MethodInsnNode;
import org.objectweb.asm.tree.MethodNode;
import org.objectweb.asm.tree.VarInsnNode;

public class KajetansTransformer implements IClassTransformer
{
    private final boolean obfuscated;
    
    public KajetansTransformer() 
    {
        Boolean ldev = (Boolean) Launch.blackboard.get("fml.deobfuscatedEnvironment");
        if(ldev == null)
        {
            obfuscated = true;
        }
        else
        {
            obfuscated = !ldev;
        }
    }
    
    @Override
    public byte[] transform(String old, String searge, byte[] bytes)
    {
        if(searge.equals("net.minecraft.client.gui.FontRenderer"))
        {
            //net.minecraft.client.gui.FontRenderer;
            System.out.println("|‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾");
            System.out.println("| Patching net.minecraft.client.gui.FontRenderer");
            System.out.println("|___________________________________________________");
            return patchColorHook(old, bytes);
        }
        return bytes;
    }

    public byte[] patchColorHook(String c, byte[] bytes)
    {
        try
        {
            ClassNode classNode = new ClassNode();
            ClassReader classReader = new ClassReader(bytes);
            classReader.accept(classNode, 0);
            
            // net/minecraft/client/gui/FontRenderer bip
            // func_78255_a renderStringAtPos  Render a single line string at the current (posX,posY) and update posX
            // MD: net/minecraft/client/gui/FontRenderer/renderStringAtPos (Ljava/lang/String;Z)V bip/a (Ljava/lang/String;Z)V
            MethodNode mn;
            if(obfuscated)
            {
                mn = classNode.methods.stream().filter(me -> me.name.equals("a")).filter(me -> "(Ljava/lang/String;Z)V".equals(me.desc)).findAny().get();
            }
            else
            {
                mn = classNode.methods.stream().filter(me -> me.name.equals("renderStringAtPos")).findAny().get();
            }
            
            InsnList ins = mn.instructions;
            int index = 0; 
            boolean found = false;
            AbstractInsnNode next;
            while(index < ins.size())
            {
                next = ins.get(index);
                if(next instanceof MethodInsnNode)
                {
                    MethodInsnNode mnode = (MethodInsnNode) next;
                    if(mnode.name.equals("valueOf") && mnode.desc.equals("(C)Ljava/lang/String;"))
                    {
                        found = true;
            
                        // LdcInsnNode  18  9  - loading of string constant "0123456789abcdefklmnor", must be removed
                        // VarInsnNode  25  2  1
                        // VarInsnNode  21  2  3
                        // InsnNode  4  0  
                        // InsnNode  96  0  
                        // MethodInsnNode  182  5  (I)C false charAt java/lang/String
                        // insert new instruction here
                        // MethodInsnNode  184  5  (C)Ljava/lang/String; false valueOf java/lang/String - search for this instruction, its not obfuscated
                        // FieldInsnNode  178  4  Ljava/util/Locale; ROOT java/util/Locale - must be removed
                        // MethodInsnNode  182  5  (Ljava/util/Locale;)Ljava/lang/String; false toLowerCase java/lang/String - must be removed
                        // InsnNode  3  0  - must be removed
                        // MethodInsnNode  182  5  (I)C false charAt java/lang/String - must be removed
                        // MethodInsnNode  182  5  (I)I false indexOf java/lang/String - must be removed
                        // VarInsnNode  54  2  5
                        // LabelNode  -1  8  
            
                        index--;
                        ins.remove(ins.get(index - 5)); // remove "0123456789abcdefklmnor"
                        ins.remove(ins.get(index));
                        ins.remove(ins.get(index));
                        ins.remove(ins.get(index));
                        ins.remove(ins.get(index));
                        ins.remove(ins.get(index));
                        ins.remove(ins.get(index));
                        ins.insert(ins.get(index - 1), new MethodInsnNode(Opcodes.INVOKESTATIC, "me/ktcm/events/Hooks", "onColorCodeChosen", "(CZ)I", false));
                        ins.insert(ins.get(index - 1), new VarInsnNode(Opcodes.ILOAD, 2)); // push boolean shadow on the stack, inverted order
                        break;
                    }
                }
                index++;
            }
            
            if(!found)
            {
                System.out.println("Start of color hook was not found");
                return bytes;
            }
            
            /*java.util.ListIterator<AbstractInsnNode> list = ins.iterator();
            while(list.hasNext())
            {
                System.out.println(getString(list.next()));
            }*/

            ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
            classNode.accept(writer);
            return writer.toByteArray();
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }       
        return bytes;
    }
    
    public String getString(AbstractInsnNode node)
    {
        StringBuilder sb = new StringBuilder();
        sb.append(node.getClass().getSimpleName());
        sb.append("  ");
        sb.append(node.getOpcode());
        sb.append("  ");
        sb.append(node.getType());
        sb.append("  ");
        if(node instanceof LineNumberNode)
        {
            LineNumberNode n = (LineNumberNode) node;
            sb.append(n.line);
            sb.append(" ");
            sb.append(n.start);
        }
        else if(node instanceof VarInsnNode)
        {
            VarInsnNode n = (VarInsnNode) node;
            sb.append(n.var);
        }
        else if(node instanceof MethodInsnNode)
        {
            MethodInsnNode n = (MethodInsnNode) node;
            sb.append(n.desc);
            sb.append(" ");
            sb.append(n.itf);
            sb.append(" ");
            sb.append(n.name);
            sb.append(" ");
            sb.append(n.owner);
        }
        else if(node instanceof FrameNode)
        {
            FrameNode n = (FrameNode) node;
            if(n.local != null)
            {
                n.local.forEach(s -> {sb.append(s); sb.append(" ");});
            }
            if(n.stack != null)
            {
                n.stack.forEach(s -> {sb.append(s); sb.append(" ");});
            }
        }
        else if(node instanceof InsnNode)
        {
        }
        else if(node instanceof FieldInsnNode)
        {
            FieldInsnNode n = (FieldInsnNode) node;
            sb.append(n.desc);
            sb.append(" ");
            sb.append(n.name);
            sb.append(" ");
            sb.append(n.owner);
        }
        return sb.toString();
    }
}