package org.simantics.scl.compiler.internal.types.effects;

import java.util.ArrayList;
import java.util.Collection;

import org.simantics.scl.compiler.types.TCon;
import org.simantics.scl.compiler.types.TMetaVar;
import org.simantics.scl.compiler.types.TUnion;
import org.simantics.scl.compiler.types.Type;
import org.simantics.scl.compiler.types.Types;

import gnu.trove.map.hash.TObjectIntHashMap;

public class EffectIdMap {

    public static final int MIN = 0;
    public static final int MAX = 0xffffffff;
    private static final int FIRST_FREE_EFFECT_ID = 16;
    
    private static ArrayList<TCon> effectCons = new ArrayList<TCon>(); 
    private static TObjectIntHashMap<TCon> effectCodes = new TObjectIntHashMap<TCon>();
    
    private static void add(String module, String name, int code) {
        TCon con = Types.con(module, name);
        effectCodes.put(con, code);
        effectCons.add(con);
    }
    
    static {
        add("Simantics/DB", "WriteGraph", 12);
        add("Simantics/DB", "ReadGraph",  4);
        add(Types.BUILTIN, "Proc",       1);
    }
    
    private ArrayList<Type> localCons = new ArrayList<Type>(); 
    private TObjectIntHashMap<Type> localCodes = new TObjectIntHashMap<Type>();
    private int freshId = FIRST_FREE_EFFECT_ID;
    
    public int toId(Type type, Collection<TMetaVar> metaVars) {
        type = Types.canonical(type);
        if(type instanceof TUnion) {
            int id = 0;
            for(Type e : ((TUnion)type).effects)
                id |= toId(e, metaVars);
            return id;
        }
        else if(effectCodes.contains(type)) {
            return effectCodes.get(type);
        }
        else if(type instanceof TMetaVar) {
            metaVars.add((TMetaVar)type);
            return 0;
        }
        else if(localCodes.contains(type)) {
            return localCodes.get(type);
        }
        else {
            int id = freshId;
            localCons.add(type);
            localCodes.put(type, id);
            freshId *= 2;
            return id;
        }
    }
    
    public Type toType(int id) {
        if(id == 0)
            return Types.NO_EFFECTS;
        ArrayList<Type> components = new ArrayList<Type>();
        for(TCon con : effectCons) {
            int conId = effectCodes.get(con);
            if((id&conId) == conId) {
                components.add(con);
                id ^= conId;
            }
        }
        for(Type con : localCons) {
            int conId = localCodes.get(con);
            if((id&conId) == conId) {
                components.add(con);
                id ^= conId;
            }
        }
        if(components.size() == 1)
            return components.get(0);
        else
            return Types.union(components);
    }

}