using System;
using gaemstone.ECS.Utility;
using static flecs_hub.flecs;

namespace gaemstone.ECS;

public unsafe partial class World
{
	public ecs_world_t* Handle { get; }

	// Flecs built-ins that are important to internals.
	internal EntityRef ChildOf { get; }
	internal EntityRef Disabled { get; }
	internal EntityRef DependsOn { get; }

	public bool IsDeferred => ecs_is_deferred(this);
	public bool IsQuitRequested => ecs_should_quit(this);

	public World(params string[] args)
	{
		ecs_os_set_api_defaults();
		var api = ecs_os_get_api();
		api.abort_ = new FnPtr_Void { Pointer = &FlecsAbortException.Callback };
		ecs_os_set_api(&api);

		Handle = ecs_init_w_args(args.Length, null);

		ChildOf   = LookupByPathOrThrow("/flecs/core/ChildOf");
		Disabled  = LookupByPathOrThrow("/flecs/core/Disabled");
		DependsOn = LookupByPathOrThrow("/flecs/core/DependsOn");
	}

	public void Dispose()
		=> ecs_fini(this);


	public EntityBuilder New(EntityPath? path = null)
		=> new(this, path);

	public EntityBuilder New(EntityRef? parent, EntityPath? path = null)
	{
		var entity = New(path);
		// If given path is absolute, the new entity won't be created as a
		// child of the specified parent. Alternatively, EntityRef.NewChild
		// can be used, which will throw when an absolute path is given.
		if ((path?.IsRelative != false) && (parent != null))
			entity.ChildOf(parent);
		return entity;
	}


	public bool Progress(TimeSpan delta)
		=> ecs_progress(this, (float)delta.TotalSeconds);

	public void Quit()
		=> ecs_quit(this);


	public static implicit operator ecs_world_t*(World w) => w.Handle;
}