/**
 * Lightweight streaming event store for agents.
 * Agents publish partial responses so external subscribers can poll for streaming updates.
 */

export type StreamingEventType = 'start' | 'progress' | 'done' | 'error';

export interface StreamingEvent {
  sessionId: string;
  type: StreamingEventType;
  content: string;
  timestamp: string;
  metadata?: Record<string, any>;
}

class StreamingService {
  private events = new Map<string, StreamingEvent[]>();
  private readonly maxEventsPerSession = 50;

  publish(sessionId: string, event: Omit<StreamingEvent, 'sessionId' | 'timestamp'> & { timestamp?: string }): void {
    const timestamp = event.timestamp || new Date().toISOString();
    const payload: StreamingEvent = {
      sessionId,
      content: event.content,
      type: event.type,
      metadata: event.metadata,
      timestamp
    };

    const existing = this.events.get(sessionId) || [];
    existing.push(payload);
    if (existing.length > this.maxEventsPerSession) {
      existing.shift();
    }

    this.events.set(sessionId, existing);
  }

  consume(sessionId: string): StreamingEvent[] {
    const stored = this.events.get(sessionId) || [];
    this.events.delete(sessionId);
    return stored;
  }

  clear(sessionId: string): void {
    this.events.delete(sessionId);
  }
}

export const streamingService = new StreamingService();