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

namespace gaemstone.ECS;

public unsafe partial class World
{
	public EntityRef? LookupAlive(Entity value)
		=> EntityRef.CreateOrNull(this, new(ecs_get_alive(this, value)));
	public EntityRef LookupAliveOrThrow(Entity entity)
		=> LookupAlive(entity) ?? throw new EntityNotFoundException(
			$"Entity {entity} is not alive");

	// TODO: Simplify method names?
	public EntityRef? LookupByPath(EntityPath path)
		=> LookupByPath(default, path);
	public EntityRef? LookupByPath(Entity parent, EntityPath path)
		=> EntityRef.CreateOrNull(this, EntityPath.Lookup(this, parent, path, false));
	public EntityRef LookupByPathOrThrow(EntityPath path)
		=> LookupByPathOrThrow(default, path);
	public EntityRef LookupByPathOrThrow(Entity parent, EntityPath path)
		=> new(this, EntityPath.Lookup(this, parent, path, true));

	// TODO: Provide overload that uses a UTF-8 byte span?
	public EntityRef? LookupBySymbol(string symbol)
	{
		using var alloc = TempAllocator.Use();
		var entity = ecs_lookup_symbol(this, alloc.AllocateCString(symbol), false);
		return EntityRef.CreateOrNull(this, new(entity));
	}
	public EntityRef LookupBySymbolOrThrow(string symbol)
		=> LookupBySymbol(symbol) ?? throw new EntityNotFoundException(
			$"Entity with symbol '{symbol}' not found");
}

public class EntityNotFoundException : Exception
	{ public EntityNotFoundException(string message) : base(message) {  } }