using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace MoonTools.ECS
{
	// for saving and loading component storage
    public class ComponentStorageState
    {
		public int Count;
		public Dictionary<int, int> EntityIdToStorageIndex;
		public byte[] EntityIDs;
		public byte[] Components;

        public static ComponentStorageState Create<TComponent>(int count)
        {
			return new ComponentStorageState(
                count,
                count * Marshal.SizeOf<int>(),
                count * Marshal.SizeOf<TComponent>()
            );
		}

        private ComponentStorageState(int count, int entityIDSize, int componentSize)
        {
			Count = count;
			EntityIdToStorageIndex = new Dictionary<int, int>(count);
			EntityIDs = new byte[entityIDSize];
			Components = new byte[componentSize];
		}
	}
}