feat: support async module intialization

[tobycodes]

Overview

Added full asynchronous configuration support to NotificationModule following NestJS best practices. The module now supports three async configuration patterns: useFactory, useClass, and useExisting.

What Was Added

NotificationOptionsFactory

• Interface for creating factory classes that provide module options
• Supports both sync and async option resolution via createNotificationOptions()

NotificationModuleAsyncOptions

• Configuration interface for async module registration
• Extends ModuleMetadata to support imports
• Includes useFactory, useClass, useExisting, and inject options

NotificationModule.forRootAsync()

• Configures the module with async options
• Supports dependency injection for configuration

NOTIFICATION_MODULE_OPTIONS

• Symbol token for injecting module configuration
• Used internally by the module lifecycle

Usage Examples

useFactory Pattern

NotificationModule.forRootAsync({
    imports: [ConfigModule],
    useFactory: (config: ConfigService) => ({
        autoDiscoverNotifications: config.get('AUTO_DISCOVER'),
        worker: {
            enabled: config.get('WORKER_ENABLED'),
            blockTimeoutSeconds: config.get('WORKER_TIMEOUT'),
        },
        databaseAdapter: {
            provide: DATABASE_ADAPTER,
            useClass: PrismaNotificationsAdapter,
        },
    }),
    inject: [ConfigService],
})

useClass Pattern

@Injectable()
class NotificationConfigService implements NotificationOptionsFactory {
    constructor(private config: ConfigService) {}

    async createNotificationOptions(): Promise<NotificationModuleOptions> {
        return {
            worker: { enabled: this.config.get('WORKER_ENABLED') },
            autoDiscoverNotifications: false,
        };
    }
}

NotificationModule.forRootAsync({
    imports: [ConfigModule],
    useClass: NotificationConfigService,
})

useExisting Pattern

NotificationModule.forRootAsync({
    imports: [ConfigModule],
    useExisting: NotificationConfigService,
})