updated and tested till end of lesson 4

2026-10-11 15:00:58 +03:30
parent d73090946b
commit 2d639d78eb
18 changed files with 1120 additions and 187 deletions
@@ -0,0 +1,87 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"example.com/mqtt5-learning/internal/config"
+	mqtt "example.com/mqtt5-learning/internal/mqtt"
+)
+
+func main() {
+	// Convert a returned application error into a visible nonzero process exit.
+	if err := run(); err != nil {
+		log.Print(err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	// Load settings and bind cancellation to Ctrl+C or the container stop signal.
+	cfg, err := config.Load(os.Args[1:])
+	if err != nil {
+		return err
+	}
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+	// Build this device's topic namespace and bounded receive queue.
+	base := "lab/v1/devices/" + cfg.MQTT.DeviceID
+	inbox := make(chan mqtt.Message, 16)
+	manager, err := mqtt.Start(ctx, cfg, []string{base + "/commands"}, inbox)
+	if err != nil {
+		return err
+	}
+	defer mqtt.Stop(manager)
+	// Heartbeats are periodic; command handling remains active between ticks.
+	ticker := time.NewTicker(3 * time.Second)
+	defer ticker.Stop()
+	for {
+		// Handle cancellation, telemetry publication, and inbound commands together.
+		select {
+		case <-ctx.Done():
+			return nil
+		case <-ticker.C:
+			payload, err := json.Marshal(struct {
+				DeviceID string `json:"device_id"`
+				Time     string `json:"time"`
+			}{cfg.MQTT.DeviceID, time.Now().UTC().Format(time.RFC3339)})
+			if err != nil {
+				return err
+			}
+			if err := mqtt.Publish(ctx, manager, base+"/telemetry", payload); err != nil {
+				log.Printf("heartbeat: %v", err)
+			}
+		case message := <-inbox:
+			// Decode into a local command value only after rejecting retained messages.
+			var command struct {
+				ID      string `json:"id"`
+				Command string `json:"command"`
+			}
+			if message.Retain {
+				log.Print("ignoring retained command")
+				continue
+			}
+			if err := json.Unmarshal(message.Payload, &command); err != nil || command.ID == "" || command.Command != "ping" {
+				log.Print("ignoring malformed or unsupported command")
+				continue
+			}
+			// Echo the command ID so the backend can associate this pong with its ping.
+			response, err := json.Marshal(struct {
+				ID       string `json:"id"`
+				DeviceID string `json:"device_id"`
+				Status   string `json:"status"`
+			}{command.ID, cfg.MQTT.DeviceID, "pong"})
+			if err != nil {
+				return err
+			}
+			if err := mqtt.Publish(ctx, manager, base+"/responses", response); err != nil {
+				log.Printf("response: %v", err)
+			}
+		}
+	}
+}