Hub: add POST /api/v1/notify endpoint for customer notifications

- New notification relay endpoint: receives events from customer controllers,
  looks up customer email preferences, sends via Resend HTTP API
- New tables: customer_notifications (per-customer email + event prefs),
  notification_log (audit trail for all notification attempts)
- Hungarian email template with severity, event type, timestamp
- Config: notifications.resend_api_key + notifications.from_email
- Test events always pass event-type filter

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hub/cmd/hub/main.go

@@ -31,6 +31,10 @@ type Config struct {
 	API struct {
 		ReportAPIKey string `yaml:"report_api_key"`
 	} `yaml:"api"`
+	Notifications struct {
+		ResendAPIKey string `yaml:"resend_api_key"`
+		FromEmail    string `yaml:"from_email"`
+	} `yaml:"notifications"`
 	Retention struct {
 		MaxDays       int    `yaml:"max_days"`
 		PruneSchedule string `yaml:"prune_schedule"`
@@ -79,7 +83,7 @@ func main() {
 	}
 
 	// Initialize handlers
-	apiHandler := api.New(dataStore, cfg.API.ReportAPIKey, logger)
+	apiHandler := api.New(dataStore, cfg.API.ReportAPIKey, cfg.Notifications.ResendAPIKey, cfg.Notifications.FromEmail, logger)
 	webServer := web.New(dataStore, cfg.Auth.PasswordHash, staleThreshold, logger)
 
 	// Build HTTP mux
@@ -177,6 +181,9 @@ func loadConfig(path string, logger *log.Logger) *Config {
 	if cfg.Alerting.StaleThreshold == "" {
 		cfg.Alerting.StaleThreshold = "30m"
 	}
+	if cfg.Notifications.FromEmail == "" {
+		cfg.Notifications.FromEmail = "monitoring@felhom.eu"
+	}
 
 	return cfg
 }

hub/configs/hub.yaml.example

@@ -17,6 +17,11 @@ api:
   # Bearer token required for report ingest (POST /api/v1/report)
   report_api_key: ""
 
+# --- Notifications ---
+notifications:
+  resend_api_key: ""           # Resend.com API key for sending notification emails
+  from_email: "monitoring@felhom.eu"  # Sender address for notification emails
+
 # --- Data retention ---
 retention:
   max_days: 90               # Keep 90 days of report history

hub/internal/api/handler.go

@@ -1,7 +1,9 @@
 package api
 
 import (
+	"bytes"
 	"encoding/json"
+	"fmt"
 	"io"
 	"log"
 	"net/http"
@@ -13,17 +15,23 @@ import (
 
 // Handler handles API endpoints for report ingest and customer queries.
 type Handler struct {
-	store     *store.Store
-	apiKey    string
-	logger    *log.Logger
+	store        *store.Store
+	apiKey       string
+	resendAPIKey string
+	fromEmail    string
+	logger       *log.Logger
+	httpClient   *http.Client
 }
 
 // New creates a new API handler.
-func New(store *store.Store, apiKey string, logger *log.Logger) *Handler {
+func New(store *store.Store, apiKey, resendAPIKey, fromEmail string, logger *log.Logger) *Handler {
 	return &Handler{
-		store:  store,
-		apiKey: apiKey,
-		logger: logger,
+		store:        store,
+		apiKey:       apiKey,
+		resendAPIKey: resendAPIKey,
+		fromEmail:    fromEmail,
+		logger:       logger,
+		httpClient:   &http.Client{Timeout: 10 * time.Second},
 	}
 }
 
@@ -34,6 +42,8 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch {
 	case r.Method == http.MethodPost && path == "/report":
 		h.handleReport(w, r)
+	case r.Method == http.MethodPost && path == "/notify":
+		h.handleNotify(w, r)
 	case r.Method == http.MethodGet && path == "/customers":
 		h.handleCustomers(w, r)
 	case r.Method == http.MethodGet && strings.HasPrefix(path, "/customers/"):
@@ -182,3 +192,168 @@ func (h *Handler) handleCustomerHistory(w http.ResponseWriter, r *http.Request,
 	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(result)
 }
+
+// handleNotify processes notification events from customer controllers.
+func (h *Handler) handleNotify(w http.ResponseWriter, r *http.Request) {
+	// Verify bearer token (same auth as /report)
+	if h.apiKey != "" {
+		auth := r.Header.Get("Authorization")
+		if !strings.HasPrefix(auth, "Bearer ") || strings.TrimPrefix(auth, "Bearer ") != h.apiKey {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+			return
+		}
+	}
+
+	body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20))
+	if err != nil {
+		http.Error(w, "Bad request", http.StatusBadRequest)
+		return
+	}
+
+	var payload struct {
+		CustomerID string `json:"customer_id"`
+		EventType  string `json:"event_type"`
+		Severity   string `json:"severity"`
+		Message    string `json:"message"`
+		Details    string `json:"details"`
+	}
+	if err := json.Unmarshal(body, &payload); err != nil || payload.CustomerID == "" || payload.EventType == "" {
+		http.Error(w, "Invalid payload: customer_id and event_type required", http.StatusBadRequest)
+		return
+	}
+
+	h.logger.Printf("[INFO] Notification from %s: %s (%s) — %s", payload.CustomerID, payload.EventType, payload.Severity, payload.Message)
+
+	// Look up customer notification preferences
+	prefs, err := h.store.GetNotificationPrefs(payload.CustomerID)
+	if err != nil {
+		h.logger.Printf("[ERROR] Failed to get notification prefs for %s: %v", payload.CustomerID, err)
+		http.Error(w, "Internal error", http.StatusInternalServerError)
+		return
+	}
+
+	// Check if customer has email configured and event type is enabled
+	if prefs == nil || prefs.Email == "" {
+		h.logger.Printf("[INFO] No email configured for %s, skipping notification", payload.CustomerID)
+		h.store.LogNotification(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, "skipped", "no email configured")
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"status":"ok","sent":false,"reason":"no_email"}`))
+		return
+	}
+
+	// Check if event type is in the enabled list (test events always pass)
+	eventEnabled := payload.EventType == "test"
+	for _, e := range prefs.EnabledEvents {
+		if e == payload.EventType {
+			eventEnabled = true
+			break
+		}
+	}
+	if !eventEnabled {
+		h.logger.Printf("[INFO] Event %s not enabled for %s, skipping", payload.EventType, payload.CustomerID)
+		h.store.LogNotification(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, "skipped", "event not enabled")
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"status":"ok","sent":false,"reason":"event_disabled"}`))
+		return
+	}
+
+	// Send email via Resend API
+	if h.resendAPIKey == "" {
+		h.logger.Printf("[WARN] Resend API key not configured, cannot send notification email")
+		h.store.LogNotification(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, "skipped", "resend api key not configured")
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"status":"ok","sent":false,"reason":"no_api_key"}`))
+		return
+	}
+
+	subject, emailBody := formatNotificationEmail(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, payload.Details)
+	sendErr := h.sendResendEmail(prefs.Email, subject, emailBody)
+	if sendErr != nil {
+		h.logger.Printf("[ERROR] Failed to send notification email to %s: %v", prefs.Email, sendErr)
+		h.store.LogNotification(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, "failed", sendErr.Error())
+		http.Error(w, "Failed to send email", http.StatusInternalServerError)
+		return
+	}
+
+	h.logger.Printf("[INFO] Notification email sent to %s for %s/%s", prefs.Email, payload.CustomerID, payload.EventType)
+	h.store.LogNotification(payload.CustomerID, payload.EventType, payload.Severity, payload.Message, "sent", "")
+
+	w.WriteHeader(http.StatusOK)
+	w.Write([]byte(`{"status":"ok","sent":true}`))
+}
+
+// sendResendEmail sends an email via the Resend HTTP API.
+func (h *Handler) sendResendEmail(to, subject, textBody string) error {
+	payload := map[string]interface{}{
+		"from":    h.fromEmail,
+		"to":      []string{to},
+		"subject": subject,
+		"text":    textBody,
+	}
+
+	jsonData, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("marshaling email payload: %w", err)
+	}
+
+	req, err := http.NewRequest("POST", "https://api.resend.com/emails", bytes.NewReader(jsonData))
+	if err != nil {
+		return fmt.Errorf("creating request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+h.resendAPIKey)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := h.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("sending request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 400 {
+		respBody, _ := io.ReadAll(io.LimitReader(resp.Body, 1024))
+		return fmt.Errorf("resend API returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	return nil
+}
+
+// formatNotificationEmail creates a Hungarian email subject and body.
+func formatNotificationEmail(customerID, eventType, severity, message, details string) (string, string) {
+	severityLabel := map[string]string{
+		"info":     "Információ",
+		"warning":  "Figyelmeztetés",
+		"critical": "Kritikus",
+	}
+	label := severityLabel[severity]
+	if label == "" {
+		label = severity
+	}
+
+	subject := fmt.Sprintf("[Felhom] %s: %s", label, message)
+
+	now := time.Now().Format("2006-01-02 15:04")
+	emailText := fmt.Sprintf(`Kedves Ügyfél!
+
+A Felhom rendszered a következő figyelmeztetést jelezte:
+
+%s
+
+Részletek:
+- Szerver: %s
+- Időpont: %s
+- Szint: %s
+- Típus: %s`, message, customerID, now, label, eventType)
+
+	if details != "" {
+		emailText += fmt.Sprintf("\n- Megjegyzés: %s", details)
+	}
+
+	emailText += `
+
+Ha kérdésed van, vedd fel a kapcsolatot az üzemeltetővel.
+
+Üdvözlettel,
+Felhom.eu monitoring`
+
+	return subject, emailText
+}

hub/internal/store/store.go

@@ -69,10 +69,88 @@ func (s *Store) migrate() error {
 
 		CREATE INDEX IF NOT EXISTS idx_reports_customer
 			ON reports(customer_id, received_at DESC);
+
+		CREATE TABLE IF NOT EXISTS customer_notifications (
+			customer_id TEXT PRIMARY KEY,
+			email TEXT NOT NULL DEFAULT '',
+			enabled_events TEXT NOT NULL DEFAULT '[]',
+			created_at DATETIME DEFAULT (datetime('now')),
+			updated_at DATETIME DEFAULT (datetime('now'))
+		);
+
+		CREATE TABLE IF NOT EXISTS notification_log (
+			id INTEGER PRIMARY KEY AUTOINCREMENT,
+			customer_id TEXT NOT NULL,
+			event_type TEXT NOT NULL,
+			severity TEXT NOT NULL,
+			message TEXT NOT NULL,
+			status TEXT NOT NULL DEFAULT 'pending',
+			error_message TEXT,
+			created_at DATETIME DEFAULT (datetime('now'))
+		);
+
+		CREATE INDEX IF NOT EXISTS idx_notification_log_customer
+			ON notification_log(customer_id, created_at DESC);
 	`)
 	return err
 }
 
+// NotificationPrefs holds per-customer notification preferences.
+type NotificationPrefs struct {
+	CustomerID    string
+	Email         string
+	EnabledEvents []string
+}
+
+// GetNotificationPrefs returns notification preferences for a customer.
+func (s *Store) GetNotificationPrefs(customerID string) (*NotificationPrefs, error) {
+	var email, eventsJSON string
+	err := s.db.QueryRow(
+		"SELECT email, enabled_events FROM customer_notifications WHERE customer_id = ?",
+		customerID,
+	).Scan(&email, &eventsJSON)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	var events []string
+	json.Unmarshal([]byte(eventsJSON), &events)
+
+	return &NotificationPrefs{
+		CustomerID:    customerID,
+		Email:         email,
+		EnabledEvents: events,
+	}, nil
+}
+
+// SaveNotificationPrefs creates or updates notification preferences for a customer.
+func (s *Store) SaveNotificationPrefs(customerID, email string, enabledEvents []string) error {
+	eventsJSON, _ := json.Marshal(enabledEvents)
+	_, err := s.db.Exec(`
+		INSERT INTO customer_notifications (customer_id, email, enabled_events, updated_at)
+		VALUES (?, ?, ?, datetime('now'))
+		ON CONFLICT(customer_id) DO UPDATE SET
+			email = excluded.email,
+			enabled_events = excluded.enabled_events,
+			updated_at = datetime('now')`,
+		customerID, email, string(eventsJSON),
+	)
+	return err
+}
+
+// LogNotification records a notification attempt.
+func (s *Store) LogNotification(customerID, eventType, severity, message, status, errorMsg string) error {
+	_, err := s.db.Exec(`
+		INSERT INTO notification_log (customer_id, event_type, severity, message, status, error_message)
+		VALUES (?, ?, ?, ?, ?, ?)`,
+		customerID, eventType, severity, message, status, errorMsg,
+	)
+	return err
+}
+
 // SaveReport stores a new report. The reportJSON should be the raw JSON payload.
 func (s *Store) SaveReport(customerID string, reportJSON []byte) error {
 	// Parse denormalized fields from the JSON