using System;
using System.Linq;
using static flecs_hub.flecs;

namespace gaemstone.ECS;

public unsafe partial class Universe
{
	public ecs_world_t* Handle { get; }
	public ModuleManager Modules { get; }

	public EntityRef Wildcard { get; }
	public EntityRef Any { get; }
	public EntityRef ChildOf { get; }

	public bool IsDeferred => ecs_is_deferred(this);

	public Universe(params string[] args)
	{
		Handle  = ecs_init_w_args(args.Length, null);
		Modules = new(this);

		// Bootstrap flecs built-ins that are important to internals.
		Wildcard = LookupOrThrow("/flecs/core/*");
		Any      = LookupOrThrow("/flecs/core/_");
		ChildOf  = LookupOrThrow("/flecs/core/ChildOf");

		// Bootstrap custom "Relation" tag.
		// This will be retrofitted to certain flecs built-ins.
		New("/gaemstone/Relation")
			.Add(LookupOrThrow("/flecs/core/Tag"))
			.Build().CreateLookup<Relation>();

		// Register built-in (static) modules, which
		// are defined in the "gaemstone.Flecs" namespace.
		Modules.RegisterAll(GetType().Assembly.GetTypes()
			.Where(t => t.IsAbstract && t.IsSealed));

		// Create "Game" entity to store global state.
		New("/Game").Symbol("Game").Build()
			.CreateLookup<Game>().Add<Game>();
	}

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

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

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