package mod.sin.wyvern.mastercraft;

import javassist.ClassPool;
import javassist.*;
import javassist.bytecode.*;

import java.io.IOException;

public class TitleInjector {
    private final CtClass titleCls;
    private final ConstPool constPool;
    private final CodeIterator codeIterator;
    private int insertPos = -1;
    private int lastOrd = -1;
    private int arraySizePos = -1;


    public TitleInjector(ClassPool classPool) throws NotFoundException, BadBytecode {
        titleCls = classPool.getCtClass("com.wurmonline.server.players.Titles$Title");
        CtConstructor initializer = titleCls.getClassInitializer();
        CodeAttribute codeAttr = initializer.getMethodInfo().getCodeAttribute();
        constPool = codeAttr.getConstPool();
        codeIterator = codeAttr.iterator();

        BytecodeTools b = new BytecodeTools(constPool);

        // My code needs a bit more stack space than javac-generated one
        codeAttr.setMaxStack(codeAttr.getMaxStack() + 3);

        while (codeIterator.hasNext()) {
            int pos = codeIterator.next();
            int op = codeIterator.byteAt(pos);
            if (op == Bytecode.AASTORE) {
                insertPos = codeIterator.next();
            } else if (op == Bytecode.ANEWARRAY) {
                arraySizePos = pos - 2;
            } else if (op == Bytecode.NEW) {
                pos = codeIterator.next(); // dup
                pos = codeIterator.next(); // ldc of ident
                pos = codeIterator.next(); // here's the ordinal
                lastOrd = BytecodeTools.getInteger(constPool, codeIterator, pos);
            }
        }

        if (insertPos == -1) throw new RuntimeException("Failed to find AASTORE");
        if (lastOrd == -1) throw new RuntimeException("Failed to find ordinals");
        if (arraySizePos == -1) throw new RuntimeException("Failed to array size position");
    }

    public void saveDebug() throws IOException, CannotCompileException, NotFoundException {
        titleCls.writeFile();
    }


    public void addTitle(String ident, int id, String name, String femaleName, int skillId, String type) throws BadBytecode, CannotCompileException {
        int ordinal = ++lastOrd;
        Bytecode code = new Bytecode(constPool);

        // When starting the values array is on stack, dup it for later use
        code.add(Bytecode.DUP);

        // Put out ordinal, will be used by AASTORE
        BytecodeTools.putInteger(constPool, code, ordinal);

        // Make new instance, and dupe that too
        code.addNew("com.wurmonline.server.players.Titles$Title");
        code.add(Bytecode.DUP);

        // Put constructor parameters into stack
        code.addLdc(ident);
        BytecodeTools.putInteger(constPool, code, ordinal);
        BytecodeTools.putInteger(constPool, code, id);
        code.addLdc(name);
        code.addLdc(femaleName);
        BytecodeTools.putInteger(constPool, code, skillId);
        code.addGetstatic("com.wurmonline.server.players.Titles$TitleType", type, "Lcom/wurmonline/server/players/Titles$TitleType;");

        // Call constructor, this will use one copy of our instance duped above, we need 2 more so dup it again
        code.addInvokespecial("com.wurmonline.server.players.Titles$Title", "<init>", "(Ljava/lang/String;IILjava/lang/String;Ljava/lang/String;ILcom/wurmonline/server/players/Titles$TitleType;)V");
        code.add(Bytecode.DUP);

        // Put instance into static field - this will use the second copy of our instance
        code.addPutstatic("mod.sin.wyvern.mastercraft.CustomTitles", ident, "Lcom/wurmonline/server/players/Titles$Title;");

        // And finally stick it into values array, this will use the duped array, ordinal and the final copy of our instance
        code.add(Bytecode.AASTORE);

        // End of bytecode gen, insert it into the initializer
        byte[] bytes = code.get();
        codeIterator.insertAt(insertPos, bytes);
        insertPos += bytes.length;

        // And increase array size
        codeIterator.write16bit(codeIterator.u16bitAt(arraySizePos) + 1, arraySizePos);
    }
}