package observers

import (
	"github.com/mlange-42/arche/ecs"
	"github.com/mlange-42/arche/ecs/event"
	"github.com/mlange-42/arche/generic"
	"github.com/mlange-42/arche/listener"
)

// will be added as  an ecs.Resource to the world so we  can use it in
// CollisionSystem to dynamically make it appear or disappear
type ObstacleObserver struct {
	// we only have one obstacle so far, if we use multiple ones, turn
	// this in to a map, see player_observer.go for an example
	Entities map[ecs.Entity]int
}

// Create a  new resource of  type PlayerObserver which will  hold all
// obstacle  entities.   We  also  add  a  Listener  which  looks  for
// EntityRemoved events and  if a player gets removed,  we also remove
// it from the Entity map in our observer.
func NewObstacleObserver(world *ecs.World) {
	observer := &ObstacleObserver{}
	observer.Entities = make(map[ecs.Entity]int)

	resmanger := generic.NewResource[ObstacleObserver](world)
	resmanger.Add(observer)

	listen := listener.NewCallback(
		func(world *ecs.World, event ecs.EntityEvent) {
			observerID := ecs.ResourceID[ObstacleObserver](world)
			observer := world.Resources().Get(observerID).(*ObstacleObserver)
			observer.RemoveEntity(event.Entity)
		},

		event.EntityRemoved,
	)

	world.SetListener(&listen)
}

func GetObstacleObserver(world *ecs.World) *ObstacleObserver {
	observerID := ecs.ResourceID[ObstacleObserver](world)
	observer := world.Resources().Get(observerID).(*ObstacleObserver)
	return observer
}

func (observer *ObstacleObserver) AddEntity(entity ecs.Entity) {
	observer.Entities[entity] = 1
}

func (observer *ObstacleObserver) RemoveEntity(entity ecs.Entity) {
	observer.Entities = make(map[ecs.Entity]int)
}