package econetui

import (
	"sync"
	"time"
)

// pendingStore holds best-effort "desired mode" hints for the brief, async
// window between a SetMode publish and the Rheem cloud reporting the new mode.
// Entries expire after a TTL so a mode change that never takes hold quietly
// falls back to the reported state (a "fresh get") rather than showing a stuck
// pending badge forever.
type pendingStore struct {
	mu  sync.Mutex
	ttl time.Duration
	m   map[string]pendingEntry
}

type pendingEntry struct {
	desired   string // desired mode slug
	expiresAt time.Time
}

func newPendingStore(ttl time.Duration) *pendingStore {
	return &pendingStore{ttl: ttl, m: make(map[string]pendingEntry)}
}

func (p *pendingStore) set(serial, desired string) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.m[serial] = pendingEntry{desired: desired, expiresAt: time.Now().Add(p.ttl)}
}

// get returns the desired mode slug for a serial, or ("", false) if there is no
// pending change or it has expired (expired entries are dropped).
func (p *pendingStore) get(serial string) (string, bool) {
	p.mu.Lock()
	defer p.mu.Unlock()
	e, ok := p.m[serial]
	if !ok {
		return "", false
	}
	if time.Now().After(e.expiresAt) {
		delete(p.m, serial)
		return "", false
	}
	return e.desired, true
}

func (p *pendingStore) clear(serial string) {
	p.mu.Lock()
	defer p.mu.Unlock()
	delete(p.m, serial)
}