package westworldwithmessaging

import (
	"fmt"
	"sync"
)

// visitBathroom is a "blip" state: it interrupts whatever Elsa was
// doing, does its one bit of business, and immediately hands control
// straight back to whatever she was doing before - it never leads
// anywhere new on its own.
type visitBathroom struct{}

var (
	visitBathroomInstance *visitBathroom
	visitBathroomOnce     sync.Once
)

// VisitBathroom is the Go stand-in for "VisitBathroom::Instance()".
func VisitBathroom() *visitBathroom {
	visitBathroomOnce.Do(func() {
		visitBathroomInstance = &visitBathroom{}
	})
	return visitBathroomInstance
}

var _ State[Elsa] = (*visitBathroom)(nil)

// Enter announces the trip to the bathroom.
func (s *visitBathroom) Enter(e *Elsa) {
	fmt.Printf("\n%s: Walkin' to the can. Need to powda mah pretty li'l nose", GetNameOfEntity(e.ID()))
}

// Execute is the entire "blip": do the business, then immediately
// revert to whatever state was active before VisitBathroom
// interrupted it. RevertToPreviousState runs the normal ChangeState
// dance (Exit here, Enter there), so nothing extra is needed.
func (s *visitBathroom) Execute(e *Elsa) {
	fmt.Printf("\n%s: Ahhhhhh! Sweet relief!", GetNameOfEntity(e.ID()))
	e.FSM().RevertToPreviousState()
}

// Exit announces leaving the bathroom - this runs automatically as
// part of the RevertToPreviousState call above.
func (s *visitBathroom) Exit(e *Elsa) {
	fmt.Printf("\n%s: Leavin' the john", GetNameOfEntity(e.ID()))
}

// OnMessage is required now that State[T] includes it. This state
// doesn't handle any messages yet - false ("not handled") is the
// correct default until the book shows otherwise.
func (s *visitBathroom) OnMessage(e *Elsa, msg Telegram) bool {
	return false
}