using System.Collections;
using System.Reflection;

using Syntriax.Engine.Core;

namespace Syntriax.Engine.Serialization;

public class EntityFinder
{
    private readonly HashSet<IEntity> _entities = [];

    public IReadOnlyCollection<IEntity> Entities => _entities;

    public void FindEntitiesUnder(object @object)
    {
        TypeData typeData = Utils.GetTypeData(@object.GetType());

        if (@object is not IEntity entity)
        {
            if (@object is IEnumerable enumerable && @object.GetType() != typeof(string))
                foreach (object? listObject in enumerable)
                    FindEntitiesUnder(listObject);
            return;
        }

        if (!_entities.Add(entity))
            return;

        foreach (PropertyInfo propertyInfo in typeData.Properties)
        {
            if (propertyInfo.PropertyType?.IsPrimitive ?? true || propertyInfo.PropertyType == typeof(string))
                continue;

            if (propertyInfo.HasAttribute<IgnoreSerializationAttribute>())
                continue;

            if (propertyInfo.GetValue(@object) is object propertyObject)
                FindEntitiesUnder(propertyObject);
        }

        foreach (FieldInfo fieldInfo in typeData.Fields)
        {
            if (fieldInfo.FieldType?.IsPrimitive ?? true || fieldInfo.FieldType == typeof(string))
                continue;

            if (fieldInfo.HasAttribute<System.Runtime.CompilerServices.CompilerGeneratedAttribute>())
                continue;

            // if (!fieldInfo.HasAttribute<SerializeAttribute>())
            //     continue;

            if (fieldInfo.GetValue(@object) is object fieldObject)
                FindEntitiesUnder(fieldObject);
        }

        FindEntitiesUnder(entity);
    }
}