package outpost

import "time"

// Hooks observes relay activity. Every field is optional.
//
// Hook functions are called concurrently, from up to WithWorkers delivery
// goroutines at a time, so implementations must be safe for concurrent use.
type Hooks struct {
	// OnRetry reports a failure the relay will retry at retryAt: the time the
	// relay will next allow delivery, and the same value it records in the
	// store. It is the only backend-neutral way to observe the schedule.
	OnRetry func(info Info, cause error, retryAt time.Time)

	// OnDeadLetter reports a failure the relay abandons, either because the
	// error was Permanent or because the attempts were exhausted.
	OnDeadLetter func(info Info, cause error)

	// OnError reports a store error. Stale claims are expected and are not
	// reported here.
	OnError func(err error)
}

func (h Hooks) retry(info Info, cause error, retryAt time.Time) {
	if h.OnRetry != nil {
		h.OnRetry(info, cause, retryAt)
	}
}

func (h Hooks) deadLetter(info Info, cause error) {
	if h.OnDeadLetter != nil {
		h.OnDeadLetter(info, cause)
	}
}

func (h Hooks) err(err error) {
	if h.OnError != nil {
		h.OnError(err)
	}
}