// of watches in the system for the purpose of estimating the
// cost of incoming mutating requests.
type WatchTracker interface {
	// RegisterWatch reqisters a watch based on the provided http.Request
	// in the tracker. It returns the function that should be called
	// to forget the watcher once it is finished.
	RegisterWatch(r *http.Request) ForgetWatchFunc

	// GetInterestedWatchCount returns the number of watches that are

)

// registerHandlerAsBatched is a helper to register the provided handler as a batched handler. This allows collections to
// only implement RegisterBatch.
func registerHandlerAsBatched[T any](c internalCollection[T], f func(o Event[T])) Syncer {
	return c.RegisterBatch(func(events []Event[T], initialSync bool) {
		for _, o := range events {
			f(o)
		}
	}, true)
}

// castEvent converts an Event[I] to Event[O].

}

func (j *join[T]) Register(f func(o Event[T])) Syncer {
	return registerHandlerAsBatched[T](j, f)
}

func (j *join[T]) RegisterBatch(f func(o []Event[T], initialSync bool), runExistingState bool) Syncer {
	sync := multiSyncer{}
	for _, c := range j.collections {
		sync.syncers = append(sync.syncers, c.RegisterBatch(f, runExistingState))
	}
	return sync
}

// nolint: unused // (not true, its to implement an interface)

}

func (s *staticList[T]) Register(f func(o Event[T])) Syncer {
	return registerHandlerAsBatched(s, f)
}

func (s *staticList[T]) Synced() Syncer {
	return alwaysSynced{}
}

func (s *staticList[T]) RegisterBatch(f func(o []Event[T], initialSync bool), runExistingState bool) Syncer {
	if runExistingState {
		f(slices.Map(s.List(), func(e T) Event[T] {
			return Event[T]{
				New:   &e,
				Event: controllers.EventAdd,
			}

	Synced() Syncer

	// RegisterBatch registers a handler that accepts multiple events at once. This can be useful as an optimization.
	// Otherwise, behaves the same as Register.
	// Additionally, skipping the default behavior of "send all current state through the handler" can be turned off.
	// This is important when we register in a handler itself, which would cause duplicative events.

		// rerunning the same collection's recomputation at the same time (once for the initial event, then for the initial registration).
		c.RegisterBatch(ff, false)
	})

	// Now we can do the real fetching
	// Compute our list of all possible objects that can match. Then we will filter them later.
	// This pre-filtering upfront avoids extra work
	var list []T

	v := d.val.Load()
	if v == nil {
		return nil
	}
	return []T{*v}
}

func (d *static[T]) Register(f func(o Event[T])) Syncer {
	return registerHandlerAsBatched[T](d, f)
}

func (d *static[T]) RegisterBatch(f func(o []Event[T], initialSync bool), runExistingState bool) Syncer {
	d.eventHandlers.Insert(f)
	if runExistingState {
		v := d.val.Load()
		if v != nil {
			f([]Event[T]{{
				New:   v,

		return &got
	}
	return nil
}

func (i *informer[I]) Register(f func(o Event[I])) Syncer {
	return registerHandlerAsBatched[I](i, f)
}

func (i *informer[I]) RegisterBatch(f func(o []Event[I], initialSync bool), runExistingState bool) Syncer {
	// Note: runExistingState is NOT respected here.