package playback

import "sync"

type StatusStore struct {
	mu         sync.RWMutex
	generation uint64
	statuses   map[Unit]Status
}

func NewStatusStore() *StatusStore {
	return &StatusStore{
		statuses: make(map[Unit]Status),
	}
}

func (s *StatusStore) Observe(status Status) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if status.Generation < s.generation {
		return
	}
	if status.Generation > s.generation {
		clear(s.statuses)
		s.generation = status.Generation
	}
	s.statuses[status.Unit] = status
}

func (s *StatusStore) Snapshot(unit Unit) (Status, bool) {
	s.mu.RLock()
	status, ok := s.statuses[unit]
	s.mu.RUnlock()
	return status, ok
}

func (s *StatusStore) Clear(unit Unit) {
	s.mu.Lock()
	delete(s.statuses, unit)
	s.mu.Unlock()
}