package codechicken.lib.asm;

import org.objectweb.asm.tree.*;

import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;

import static org.objectweb.asm.tree.AbstractInsnNode.*;

public class InstructionComparator
{    
    public static class InsnListSection
    {
        public InsnListSection(AbstractInsnNode first, AbstractInsnNode last)
        {
            this.first = first;
            this.last = last;
        }
        
        public InsnListSection(InsnList haystack, int start, int end)
        {
            this(haystack.get(start), haystack.get(end));
        }
        
        public AbstractInsnNode first;
        public AbstractInsnNode last;
    }
    
    public static boolean varInsnEqual(VarInsnNode insn1, VarInsnNode insn2)
    {
        if(insn1.var == -1 || insn2.var == -1)
            return true;
        
        return insn1.var == insn2.var;
    }
    
    public static boolean methodInsnEqual(AbstractInsnNode absnode, int Opcode, ObfMapping method)
    {
        if(!(absnode instanceof MethodInsnNode) || absnode.getOpcode() != Opcode)
            return false;
        
        return method.matches((MethodInsnNode)absnode);
    }
    
    public static boolean methodInsnEqual(MethodInsnNode insn1, MethodInsnNode insn2)
    {
        return insn1.owner.equals(insn2.owner) && insn1.name.equals(insn2.name) && insn1.desc.equals(insn2.desc);
    }
    
    public static boolean fieldInsnEqual(FieldInsnNode insn1, FieldInsnNode insn2)
    {
        return insn1.owner.equals(insn2.owner) && insn1.name.equals(insn2.name) && insn1.desc.equals(insn2.desc);
    }
    
    public static boolean ldcInsnEqual(LdcInsnNode insn1, LdcInsnNode insn2)
    {
        if(insn1.cst.equals("~") || insn2.cst.equals("~"))
            return true;
        
        return insn1.cst.equals(insn2.cst);
    }
    
    public static boolean typeInsnEqual(TypeInsnNode insn1, TypeInsnNode insn2)
    {
        if(insn1.desc.equals("~") || insn2.desc.equals("~"))
            return true;
        
        return insn1.desc.equals(insn2.desc);
    }
    
    public static boolean iincInsnEqual(IincInsnNode node1, IincInsnNode node2)
    {
        return node1.var == node2.var && node1.incr == node2.incr;
    }
    
    public static boolean intInsnEqual(IntInsnNode node1, IntInsnNode node2)
    {
        if(node1.operand == -1 || node2.operand == -1)
            return true;
        
        return node1.operand == node2.operand;
    }
    
    public static boolean insnEqual(AbstractInsnNode node1, AbstractInsnNode node2)
    {
        if(node1.getOpcode() != node2.getOpcode())
            return false;
        
        switch(node2.getType())
        {
            case VAR_INSN:
                return varInsnEqual((VarInsnNode) node1, (VarInsnNode) node2);
            case TYPE_INSN:
                return typeInsnEqual((TypeInsnNode) node1, (TypeInsnNode) node2);
            case FIELD_INSN:
                return fieldInsnEqual((FieldInsnNode) node1, (FieldInsnNode) node2);
            case METHOD_INSN:
                return methodInsnEqual((MethodInsnNode) node1, (MethodInsnNode) node2);
            case LDC_INSN:
                return ldcInsnEqual((LdcInsnNode) node1, (LdcInsnNode) node2);
            case IINC_INSN:
                return iincInsnEqual((IincInsnNode) node1, (IincInsnNode) node2);
            case INT_INSN:
                return intInsnEqual((IntInsnNode)node1, (IntInsnNode)node2);
            default:
                return true;
        }
    }

    public static InsnList getImportantList(InsnList list)
    {
        if(list.size() == 0)
            return list;
        
        HashMap<LabelNode, LabelNode> labels = new HashMap<LabelNode, LabelNode>();
        for(AbstractInsnNode insn = list.getFirst(); insn != null; insn = insn.getNext())
        {
            if(insn instanceof LabelNode)
                labels.put((LabelNode)insn, (LabelNode)insn);
        }        
        
        InsnList importantNodeList = new InsnList();
        for(AbstractInsnNode insn = list.getFirst(); insn != null; insn = insn.getNext())
        {
            if(insn instanceof LabelNode || insn instanceof LineNumberNode)
                continue;
            
            importantNodeList.add(insn.clone(labels));
        }
        return importantNodeList;
    }
    
    public static boolean insnListMatches(InsnList haystack, InsnList needle, int start)
    {
        if(haystack.size()-start < needle.size())
            return false;
        
        for(int i = 0; i < needle.size(); i++)
        {
            if(!insnEqual(haystack.get(i+start), needle.get(i)))
                return false;
        }
        return true;
    }
    
    public static List<Integer> insnListFind(InsnList haystack, InsnList needle)
    {
        LinkedList<Integer> list = new LinkedList<Integer>();
        for(int start = 0; start <= haystack.size()-needle.size(); start++)
            if(insnListMatches(haystack, needle, start))
                list.add(start);
        
        return list;
    }
    
    public static List<AbstractInsnNode> insnListFindStart(InsnList haystack, InsnList needle)
    {
        LinkedList<AbstractInsnNode> callNodes = new LinkedList<AbstractInsnNode>();
        for(int callPoint : insnListFind(haystack, needle))
            callNodes.add(haystack.get(callPoint));
        return callNodes;
    }
    
    public static List<AbstractInsnNode> insnListFindEnd(InsnList haystack, InsnList needle)
    {
        LinkedList<AbstractInsnNode> callNodes = new LinkedList<AbstractInsnNode>();
        for(int callPoint : insnListFind(haystack, needle))
            callNodes.add(haystack.get(callPoint+needle.size()-1));
        return callNodes;
    }
    
    public static List<InsnListSection> insnListFindL(InsnList haystack, InsnList needle)
    {
        HashSet<LabelNode> controlFlowLabels = new HashSet<LabelNode>();
        
        for(AbstractInsnNode insn = haystack.getFirst(); insn != null; insn = insn.getNext())
        {
            switch(insn.getType())
            {
                case 8:
                case 15:
                    break;
                case 7:
                    JumpInsnNode jinsn = (JumpInsnNode)insn;
                    controlFlowLabels.add(jinsn.label);
                    break;
                case 11:
                    TableSwitchInsnNode tsinsn = (TableSwitchInsnNode)insn;
                    for(LabelNode label : tsinsn.labels)
                        controlFlowLabels.add(label);
                    break;
                case 12:
                    LookupSwitchInsnNode lsinsn = (LookupSwitchInsnNode)insn;
                    for(LabelNode label : lsinsn.labels)
                        controlFlowLabels.add(label);
                    break;
            }
        }
        
        LinkedList<InsnListSection> list = new LinkedList<InsnListSection>();
        nextsection: for(int start = 0; start <= haystack.size()-needle.size(); start++)
        {
            InsnListSection section = insnListMatchesL(haystack, needle, start, controlFlowLabels);
            if(section != null)
            {
                for(InsnListSection asection : list)
                    if(asection.last == section.last)
                        continue nextsection;
                
                list.add(section);
            }
        }
        
        return list;
    }

    private static InsnListSection insnListMatchesL(InsnList haystack, InsnList needle, int start, HashSet<LabelNode> controlFlowLabels)
    {
        int h = start, n = 0; 
        for(;h < haystack.size() && n < needle.size(); h++)
        {
            AbstractInsnNode insn = haystack.get(h);
            if(insn.getType() == 15)
                continue;
            if(insn.getType() == 8 && !controlFlowLabels.contains(insn))
                continue;
            
            if(!insnEqual(haystack.get(h), needle.get(n)))
                return null;
            n++;
        }
        if(n != needle.size())
            return null;
        
        return new InsnListSection(haystack, start, h-1);
    }
}