res_levis_backend/internal/app/location/app.go

package location

import (
	"context"
	"encoding/json"
	"log/slog"
	"sync"
	"time"

	"github.com/AFASystems/presence/internal/pkg/common/appcontext"
	"github.com/AFASystems/presence/internal/pkg/config"
	"github.com/AFASystems/presence/internal/pkg/kafkaclient"
	pkglocation "github.com/AFASystems/presence/internal/pkg/location"
	"github.com/AFASystems/presence/internal/pkg/logger"
	"github.com/AFASystems/presence/internal/pkg/model"
	"github.com/segmentio/kafka-go"
)

// LocationApp holds dependencies for the location service.
type LocationApp struct {
	Cfg          *config.Config
	KafkaManager *kafkaclient.KafkaManager
	AppState     *appcontext.AppState
	Inferencer   pkglocation.Inferencer
	ChRaw        chan appcontext.BeaconAdvertisement
	ChSettings   chan map[string]any
	Cleanup      func()
	wg           sync.WaitGroup
}

// New creates a LocationApp with Kafka readers (rawbeacons, settings) and writer (locevents).
func New(cfg *config.Config) (*LocationApp, error) {
	appState := appcontext.NewAppState()
	kafkaManager := kafkaclient.InitKafkaManager()

	srvLogger, cleanup := logger.CreateLogger("location.log")
	slog.SetDefault(srvLogger)

	readerTopics := []string{"rawbeacons", "settings"}
	writerTopics := []string{"locevents"}
	kafkaManager.PopulateKafkaManager(cfg.KafkaURL, "location", readerTopics)
	kafkaManager.PopulateKafkaManager(cfg.KafkaURL, "", writerTopics)
	slog.Info("location service initialized", "readers", readerTopics, "writers", writerTopics)

	return &LocationApp{
		Cfg:          cfg,
		KafkaManager: kafkaManager,
		AppState:     appState,
		Inferencer:   pkglocation.NewDefaultInferencer(cfg.TLSInsecureSkipVerify),
		ChRaw:        make(chan appcontext.BeaconAdvertisement, config.LARGE_CHANNEL_SIZE),
		ChSettings:   make(chan map[string]any, config.SMALL_CHANNEL_SIZE),
		Cleanup:      cleanup,
	}, nil
}

// Run starts consumers and the event loop until ctx is cancelled.
func (a *LocationApp) Run(ctx context.Context) {
	a.wg.Add(2)
	go kafkaclient.Consume(a.KafkaManager.GetReader("rawbeacons"), a.ChRaw, ctx, &a.wg)
	go kafkaclient.Consume(a.KafkaManager.GetReader("settings"), a.ChSettings, ctx, &a.wg)

	locTicker := time.NewTicker(config.LARGE_TICKER_INTERVAL)
	defer locTicker.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case <-locTicker.C:
			settings := a.AppState.GetSettings()
			slog.Info("current algorithm", "algorithm", settings.CurrentAlgorithm)
			switch settings.CurrentAlgorithm {
			case "filter":
				pkglocation.GetLikelyLocations(a.AppState, a.KafkaManager.GetWriter("locevents"))
			case "ai":
				inferred, err := a.Inferencer.Infer(ctx, a.Cfg)
				if err != nil {
					slog.Error("AI inference", "err", err)
					continue
				}

				for _, item := range inferred.Items {
					r := model.HTTPLocation{
						Method:   "AI",
						Y:        item.Y,
						X:        item.X,
						Z:        item.Z,
						MAC:      item.Mac,
						LastSeen: time.Now().Unix(),
					}

					js, err := json.Marshal(r)
					if err != nil {
						slog.Error("marshaling location", "err", err, "beacon_id", item.Mac)
						continue
					}

					if err := a.KafkaManager.GetWriter("locevents").WriteMessages(ctx, kafka.Message{Value: js}); err != nil {
						slog.Error("sending kafka location message", "err", err, "beacon_id", item.Mac)
					}
				}

				slog.Info("AI algorithm", "count", inferred.Count, "items", len(inferred.Items))
			}
		case msg := <-a.ChRaw:
			pkglocation.AssignBeaconToList(msg, a.AppState)
		case msg := <-a.ChSettings:
			slog.Info("settings update", "msg", msg)
			a.AppState.UpdateSettings(msg)
		}
	}
}

// Shutdown waits for consumers and cleans up Kafka and logger.
func (a *LocationApp) Shutdown() {
	a.wg.Wait()
	a.KafkaManager.CleanKafkaReaders()
	a.KafkaManager.CleanKafkaWriters()
	if a.Cleanup != nil {
		a.Cleanup()
	}
	slog.Info("location service shutdown complete")
}