export default class TaskRunner {
  constructor(concurrencyLimit = 1) {
    this.queue = [];
    this.running = 0;
    this.concurrencyLimit = concurrencyLimit;
  }

  execute() {
    if (this.running >= this.concurrencyLimit || this.queue.length === 0) {
      return;
    }
  
    const task = this.queue.shift();
    this.running += 1;
    task();
  }

  async push(fn) {
    return new Promise((resolve, reject) => {
      const task = async () => {
        try {
          const result = await fn();
          resolve(result);
        } catch (error) {
          reject(error);
        } finally {
          this.running -= 1;
          this.execute();
        }
      }
  
      this.queue.push(task);
      this.execute();
    });
  }
}