package entities

import (
	"strings"
	"sync/atomic"

	"gitea.nik4nao.com/nik/home-services/alexa-bridge/internal/core/domain"
)

// Resolver implements driven.EntityResolver via an atomically-swapped
// snapshot map, so an in-flight Alexa request never observes a half-built
// map while a refresh is in progress.
type Resolver struct {
	snapshot atomic.Pointer[map[string]domain.Entity]
}

// NewResolver constructs a Resolver with an empty snapshot; call Replace
// (directly, or via Refresher.Start) to populate it before serving requests.
func NewResolver() *Resolver {
	r := &Resolver{}
	empty := map[string]domain.Entity{}
	r.snapshot.Store(&empty)
	return r
}

// Replace rebuilds the lookup map, keyed by normalized friendly name, and
// swaps it in atomically.
func (r *Resolver) Replace(list []domain.Entity) {
	m := make(map[string]domain.Entity, len(list))
	for _, e := range list {
		m[normalize(e.FriendlyName)] = e
	}
	r.snapshot.Store(&m)
}

// Resolve implements driven.EntityResolver. Matching is exact-match only on
// the normalized (lowercased, trimmed) friendly name — see
// alexa-bridge/plan.md's Decisions on open questions #5 for why fuzzy
// matching isn't implemented here.
func (r *Resolver) Resolve(friendlyName string) (domain.Entity, bool) {
	m := *r.snapshot.Load()
	e, ok := m[normalize(friendlyName)]
	return e, ok
}

func normalize(s string) string {
	return strings.ToLower(strings.TrimSpace(s))
}