package backthink

// eventRedundant reports whether tr is a duplicate of the immediately preceding
// event-driven push (same source + summary), so a repeating device/reminder event
// does not spam the owner (防刷). It is the one guard that still applies to an
// event-driven push while the PushGate itself is bypassed for events (owner
// mandate: "该发就发" — a genuine event goes out, only a true duplicate is held).
//
// It atomically records tr as the latest event key when the push proceeds, and
// clears the key on any non-event push (heartbeat) so a later repeat of a prior
// event is not spuriously suppressed by an intervening reflection.
//
// The caller runs it before handing the push to the Pusher; a true duplicate is
// recorded as suppressed (RouteNone) rather than delivered.
func (b *Backthink) eventRedundant(tr Trigger) bool {
	if tr.Kind != TriggerEvent {
		// A non-event push (heartbeat) breaks the same-event chain.
		b.eventMu.Lock()
		b.lastEventKey = ""
		b.eventMu.Unlock()
		return false
	}
	key := tr.Source + "\x00" + tr.Summary
	b.eventMu.Lock()
	defer b.eventMu.Unlock()
	if b.lastEventKey == key {
		return true
	}
	b.lastEventKey = key
	return false
}