using System;
using System.Collections.Generic;

namespace TLang.VM
{
    public class SubEnvironment : TLangEnvironment
    {
        public SubEnvironment(TLangEnvironment env)
        {
            this.pEnv=env;
        }
        TLangEnvironment pEnv;

        Dictionary<string,TObject> items = new Dictionary<string, TObject>();
        public override TObject GetObject(string key)
        {
            if(pEnv.HasObjectRecurse(key))
            {
                return pEnv.GetObject(key);
            }
            if(HasObject(key))
            {
                return items[key];
            }
            return new TUndefined();
        }

        public override bool HasObject(string key)
        {
            return items.ContainsKey(key);
        }
        public override bool HasObjectRecurse(string key)
        {
            return HasObject(key) || pEnv.HasObjectRecurse(key);
        }

        
        public override TLangEnvironment GetParentEnvironment()
        {
            return pEnv;
        }

        public override RootEnvironment GetRootEnvironment()
        {
            return pEnv.GetRootEnvironment();
        }

        public override void SetObject(string key, TObject value)
        {
            if(pEnv.HasObjectRecurse(key))
            {
                pEnv.SetObject(key,value);
            }
            else
            {
                items[key] = value;
            }
            
        }

        public override TLangEnvironment GetSubEnvironment()
        {
            return new SubEnvironment(this);
        }
    }
}