using System;
using System.Collections;
using System.Collections.Generic;
using static flecs_hub.flecs;

namespace gaemstone.ECS;

public unsafe class Query
	: IEnumerable<Iterator>
	, IDisposable
{
	public Universe Universe { get; }
	public ecs_query_t* Handle { get; }

	private Query(Universe universe, ecs_query_t* handle)
		{ Universe = universe; Handle = handle; }

	public Query(Universe universe, ecs_query_desc_t desc)
		: this(universe, ecs_query_init(universe, &desc)) {  }
	public Query(Universe universe, ecs_filter_desc_t desc)
		: this(universe, new ecs_query_desc_t { filter = desc }) {  }
	public Query(Universe universe, string expression)
		: this(universe, new ecs_filter_desc_t { expr = expression }) {  }

	~Query() => Dispose();
	public void Dispose() { ecs_query_fini(this); GC.SuppressFinalize(this); }

	public Iterator Iter() => new(Universe, IteratorType.Query, ecs_query_iter(Universe, this));
	public IEnumerator<Iterator> GetEnumerator() => Iter().GetEnumerator();
	IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();

	public static implicit operator ecs_query_t*(Query q) => q.Handle;
}