feat: mail service

mail/internal/config/validation.go

@@ -0,0 +1,88 @@
+package config
+
+import (
+	"fmt"
+	"log/slog"
+	"net"
+	"net/mail"
+	"strings"
+)
+
+// Validate reports whether cfg stores a usable Mail Service process
+// configuration.
+func (cfg Config) Validate() error {
+	switch {
+	case cfg.ShutdownTimeout <= 0:
+		return fmt.Errorf("%s must be positive", shutdownTimeoutEnvVar)
+	case cfg.AttemptWorkerConcurrency <= 0:
+		return fmt.Errorf("%s must be positive", attemptWorkerConcurrencyEnvVar)
+	case cfg.StreamBlockTimeout <= 0:
+		return fmt.Errorf("%s must be positive", streamBlockTimeoutEnvVar)
+	case cfg.OperatorRequestTimeout <= 0:
+		return fmt.Errorf("%s must be positive", operatorRequestTimeoutEnvVar)
+	case cfg.IdempotencyTTL <= 0:
+		return fmt.Errorf("%s must be positive", idempotencyTTLEnvVar)
+	case cfg.DeliveryTTL <= 0:
+		return fmt.Errorf("%s must be positive", deliveryTTLEnvVar)
+	case cfg.AttemptTTL <= 0:
+		return fmt.Errorf("%s must be positive", attemptTTLEnvVar)
+	}
+
+	if err := cfg.InternalHTTP.Validate(); err != nil {
+		return err
+	}
+	if err := cfg.Redis.Validate(); err != nil {
+		return err
+	}
+	if err := cfg.SMTP.Validate(); err != nil {
+		return err
+	}
+	if err := cfg.Templates.Validate(); err != nil {
+		return err
+	}
+	if err := cfg.Telemetry.Validate(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func validateSlogLevel(level string) error {
+	var slogLevel slog.Level
+	if err := slogLevel.UnmarshalText([]byte(strings.TrimSpace(level))); err != nil {
+		return fmt.Errorf("invalid slog level %q: %w", level, err)
+	}
+
+	return nil
+}
+
+func isTCPAddr(value string) bool {
+	host, port, err := net.SplitHostPort(strings.TrimSpace(value))
+	if err != nil {
+		return false
+	}
+
+	if port == "" {
+		return false
+	}
+
+	if host == "" {
+		return true
+	}
+
+	return !strings.Contains(host, " ")
+}
+
+func validateMailbox(name string, value string) error {
+	trimmed := strings.TrimSpace(value)
+	if trimmed == "" {
+		return fmt.Errorf("%s must not be empty", name)
+	}
+
+	parsed, err := mail.ParseAddress(trimmed)
+	if err != nil || parsed == nil || parsed.Name != "" || parsed.Address != trimmed {
+		return fmt.Errorf("%s %q must be a single valid email address", name, value)
+	}
+
+	return nil
+}