package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"
	"time"

	"example.com/mqtt5-learning/internal/config"
	"example.com/mqtt5-learning/internal/mqtt"
)

func main() {
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	cfg, err := config.Load(os.Args[1:])
	if err != nil {
		return fmt.Errorf("failed to load config: %w", err)
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	base := "lab/v1/devices/" + cfg.MQTT.DeviceID
	inbox := make(chan mqtt.Message, 16)

	manager, err := mqtt.Start(ctx, cfg, []string{base + "/telemetry", base + "/responses"}, inbox)
	if err != nil {
		return fmt.Errorf("failed to start MQTT client: %w", err)
	}
	defer mqtt.Stop(manager)

	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	runID := time.Now().UnixNano()
	sequence := 0

	for {
		select {
		case <-ctx.Done():
			log.Print("shutting down")
			return nil
		case msg := <-inbox:
			log.Printf("received message on topic %s retained=%t payload=%s", msg.Topic, msg.Retain, string(msg.Payload))

		case <-ticker.C:
			sequence++
			payload, err := json.Marshal(struct {
				ID      string `json:"id"`
				Command string `json:"command"`
			}{
				ID: fmt.Sprintf("ping-%d-%d", runID, sequence), Command: "ping",
			})
			if err != nil {
				return fmt.Errorf("failed to marshal payload: %w", err)
			}
			if err := mqtt.Publish(ctx, manager, base+"/commands", payload); err != nil {
				log.Printf("command publication failed or outcome uncertain: %v", err)
			}
		}
	}

}