using ln.json;
using ln.json.mapping;
using ln.objects.collections;
using System;
using System.Collections.Generic;
using System.Runtime.Serialization;
using System.Text;

namespace ln.objects.serialization.json
{
    public class LazyListMapping<T> : JSONMapping where T:class
    {
        ObjectStore ObjectStore;
        Type ElementType;

        public LazyListMapping(ObjectStore objectStore)
            :base(typeof(IList<>))
        {
            ObjectStore = objectStore;
            ElementType = typeof(T);
        }

        public override JSONValue ToJson(JSONMapper mapper, object value)
        {
            if (!(value is IList<T> ilist))
                throw new ArgumentException(nameof(value));
            JSONArray jsonArray = new JSONArray();

            foreach (T item in ilist)
                if (mapper.Serialize(item, out JSONValue jsonItem))
                    jsonArray.Add(jsonItem);
                else
                    throw new SerializationException();
                
            return jsonArray;
        }

        public override object FromJson(JSONMapper mapper, JSONValue json)
        {
            IList<T> ilist = new LazyList<T>(ObjectStore);

            JSONArray jsonArray = json as JSONArray;

            foreach (JSONValue item in jsonArray.Children)
                ilist.Add((T)mapper.FromJson(item, ElementType));

            return ilist;
        }

    }
}