class Limiter {
  private running = 0;
  private queue: (() => void)[] = [];

  constructor(private max: number) {}

  async run<T>(fn: () => Promise<T>): Promise<T> {
    await this.acquire();
    try {
      return await fn();
    } finally {
      this.release();
    }
  }

  private acquire(): Promise<void> {
    if (this.running < this.max) {
      this.running++;
      return Promise.resolve();
    }
    return new Promise(resolve => {
      this.queue.push(() => { this.running++; resolve(); });
    });
  }

  private release() {
    this.running--;
    const next = this.queue.shift();
    if (next) next();
  }

  get active() { return this.running; }

  get queued() { return this.queue.length; }
}

// ElevenLabs recommends max 2-3 concurrent requests
export const ttsLimiter = new Limiter(2);

// OpenRouter concurrent request cap
export const aiLimiter = new Limiter(4);