Calendar/src/core/EventBus.ts

// Core EventBus using pure DOM CustomEvents
import { EventLogEntry, ListenerEntry, IEventBus } from '../types/CalendarTypes';

/**
 * Central event dispatcher for calendar using DOM CustomEvents
 * Provides logging and debugging capabilities
 */
export class EventBus implements IEventBus {
  private eventLog: EventLogEntry[] = [];
  private debug: boolean = false;
  private listeners: Set<ListenerEntry> = new Set();

  /**
   * Subscribe to an event via DOM addEventListener
   */
  on(eventType: string, handler: EventListener, options?: AddEventListenerOptions): () => void {
    document.addEventListener(eventType, handler, options);
    
    // Track for cleanup
    this.listeners.add({ eventType, handler, options });
    
    // Return unsubscribe function
    return () => this.off(eventType, handler);
  }

  /**
   * Subscribe to an event once
   */
  once(eventType: string, handler: EventListener): () => void {
    return this.on(eventType, handler, { once: true });
  }

  /**
   * Unsubscribe from an event
   */
  off(eventType: string, handler: EventListener): void {
    document.removeEventListener(eventType, handler);
    
    // Remove from tracking
    for (const listener of this.listeners) {
      if (listener.eventType === eventType && listener.handler === handler) {
        this.listeners.delete(listener);
        break;
      }
    }
  }

  /**
   * Emit an event via DOM CustomEvent
   */
  emit(eventType: string, detail: any = {}): boolean {
    const event = new CustomEvent(eventType, {
      detail,
      bubbles: true,
      cancelable: true
    });

    // Log event
    if (this.debug) {
      console.log(`📢 Event: ${eventType}`, detail);
    }

    this.eventLog.push({
      type: eventType,
      detail,
      timestamp: Date.now()
    });

    // Emit on document (only DOM events now)
    return !document.dispatchEvent(event);
  }

  /**
   * Get event history
   */
  getEventLog(eventType?: string): EventLogEntry[] {
    if (eventType) {
      return this.eventLog.filter(e => e.type === eventType);
    }
    return this.eventLog;
  }

  /**
   * Enable/disable debug mode
   */
  setDebug(enabled: boolean): void {
    this.debug = enabled;
  }

  /**
   * Clean up all tracked listeners
   */
  destroy(): void {
    for (const listener of this.listeners) {
      document.removeEventListener(listener.eventType, listener.handler);
    }
    this.listeners.clear();
    this.eventLog = [];
  }
}

// Create singleton instance
export const eventBus = new EventBus();