Enhance Notification Request Structure and Service Interface

- Updated the NotificationRequest struct to include new fields: Title, Type, Priority, and ScheduledAt, improving the flexibility and usability of notification requests.
- Implemented validation for the new ScheduledAt field to ensure it is a future timestamp or zero for immediate delivery.
- Refactored the NotificationService interface and SDK methods to accept a new Model struct, streamlining the parameters for sending notifications.
- Enhanced the builder pattern for constructing notification requests, adding methods for setting Title, Type, Priority, and ScheduledAt, promoting a fluent API design.
- Updated service methods for sending notifications (Email, SMS, Push, OTP) to utilize the new Model struct, ensuring consistency across notification types.

pkg/notification/interfaces.go

@@ -10,19 +10,22 @@ type NotificationService interface {
 	SendNotification(ctx context.Context, req *NotificationRequest) (*NotificationResponse, error)
 
 	// SendEmail sends an email notification
-	SendEmail(ctx context.Context, email, message, userID string) (*NotificationResponse, error)
+	SendEmail(ctx context.Context, model Model) (*NotificationResponse, error)
 
 	// SendSMS sends an SMS notification
-	SendSMS(ctx context.Context, phoneNumber, message, userID string) (*NotificationResponse, error)
+	SendSMS(ctx context.Context, model Model) (*NotificationResponse, error)
 
 	// SendPush sends a push notification
-	SendPush(ctx context.Context, deviceToken, message, userID string) (*NotificationResponse, error)
+	SendPush(ctx context.Context, model Model) (*NotificationResponse, error)
 
 	// SendOTP sends an OTP notification
-	SendOTP(ctx context.Context, phoneNumber, message, userID string) (*NotificationResponse, error)
+	SendOTP(ctx context.Context, model Model) (*NotificationResponse, error)
 
 	// Health checks if the notification service is available
 	Health(ctx context.Context) error
+
+	// NewBuilder creates a new notification builder
+	NewBuilder() Builder
 }
 
 // Builder provides a fluent interface for building notification requests
@@ -48,6 +51,18 @@ type Builder interface {
 	// SetOTP sets the OTP phone number
 	SetOTP(phoneNumber string) Builder
 
+	// SetTitle sets the notification title
+	SetTitle(title string) Builder
+
+	// SetType sets the notification type
+	SetType(notificationType string) Builder
+
+	// SetPriority sets the notification priority
+	SetPriority(priority string) Builder
+
+	// SetScheduledAt sets the scheduled delivery time (0 for immediate)
+	SetScheduledAt(scheduledAt int64) Builder
+
 	// Build creates the notification request
 	Build() (*NotificationRequest, error)