import { HookRegistry, HookContext } from './hook-registry';
import { Logger } from '../../utils/logger';

/**
 * @interface EventTriggerConfig
 * @description Configuration for Event Triggers.
 */
export interface EventTriggerConfig {
  projectID: string;
  pubSubTopic?: string; // Default Pub/Sub topic for events
  // Add configurations for Cloud Storage buckets, database instances, etc.
}

/**
 * @class EventTriggers
 * @description Manages real-time event detection and publishes them to the Hook Registry.
 */
export class EventTriggers {
  private config: EventTriggerConfig;
  private hookRegistry: HookRegistry;
  private logger: Logger;
  // Placeholder for Pub/Sub client
  // private pubSubClient: any;

  constructor(config: EventTriggerConfig, hookRegistry: HookRegistry) {
    this.config = config;
    this.hookRegistry = hookRegistry;
    this.logger = new Logger('EventTriggers');
    this.logger.info('Event Triggers initialized.');
  }

  /**
   * Starts listening for events from various sources and publishes them to the Hook Registry.
   * @returns {Promise<void>}
   */
  public async startListening(): Promise<void> {
    this.logger.info('Starting event listeners...');
    // Initialize Pub/Sub listener
    this.setupPubSubListener();
    // Conceptual: setup other listeners (file system, database, API, scheduler)
    this.setupFileSystemWatcher();
    this.setupDatabaseTriggers();
    this.setupApiEndpointHooks();
    this.setupSchedulerTriggers();
    this.logger.info('All event listeners started.');
  }

  /**
   * Sets up a Google Cloud Pub/Sub listener to receive real-time events.
   * @private
   */
  private setupPubSubListener(): void {
    if (!this.config.pubSubTopic) {
      this.logger.warn('Pub/Sub topic not configured. Skipping Pub/Sub listener setup.');
      return;
    }
    this.logger.info(`Setting up Pub/Sub listener for topic: ${this.config.pubSubTopic}`);
    // Placeholder for actual Pub/Sub subscription setup
    // Simulate receiving messages periodically
    setInterval(() => {
      const simulatedEventPayload = { message: `Simulated Pub/Sub event at ${Date.now()}` };
      this.publishEvent('pubsub:message', simulatedEventPayload);
    }, 5000); // Every 5 seconds
  }

  /**
   * Conceptual: Sets up file system watchers for Cloud Storage change notifications.
   * @private
   */
  private setupFileSystemWatcher(): void {
    this.logger.info('Setting up conceptual File System Watcher for Cloud Storage.');
    // In a real scenario, this would involve Cloud Storage event notifications
    // triggering a Cloud Function that then publishes to Pub/Sub.
  }

  /**
   * Conceptual: Sets up database triggers for Cloud SQL and Firestore event streams.
   * @private
   */
  private setupDatabaseTriggers(): void {
    this.logger.info('Setting up conceptual Database Triggers for Cloud SQL/Firestore.');
    // In a real scenario, this would involve Cloud Functions triggered by database changes
    // or direct database change streams publishing events.
  }

  /**
   * Conceptual: Sets up API endpoint hooks with Cloud Endpoints monitoring.
   * @private
   */
  private setupApiEndpointHooks(): void {
    this.logger.info('Setting up conceptual API Endpoint Hooks.');
    // In a real scenario, this would involve Cloud Endpoints or API Gateway
    // integrating with Eventarc or Pub/Sub.
  }

  /**
   * Conceptual: Sets up schedule-based triggers using Google Cloud Scheduler.
   * @private
   */
  private setupSchedulerTriggers(): void {
    this.logger.info('Setting up conceptual Scheduler Triggers.');
    // In a real scenario, Cloud Scheduler would trigger Cloud Functions or Pub/Sub messages.
  }

  /**
   * Publishes an event to the Hook Registry, triggering relevant hooks.
   * @param {string} eventType The type of event to publish.
   * @param {any} payload The payload associated with the event.
   * @returns {Promise<void>}
   */
  public async publishEvent(eventType: string, payload: any): Promise<void> {
    this.logger.info(`Publishing event: ${eventType}`);
    const context: HookContext = {
      event: { type: eventType, payload: payload, timestamp: Date.now() },
      data: payload, // For simplicity, payload is also data
    };
    await this.hookRegistry.executeHooks(eventType, context);
  }
}