/**
 * Batcher class to batch data and send it to the server
 * @author [Vivek Sudarsan]
 * @version 0.1.0
 */

export class Batcher {
  private queue: any[] = [];
  private batchSize: number;
  private delay: number;
  private callback: any;
  private timer: ReturnType<typeof setTimeout> | null = null;

  /**
   * Create a new Batcher instance with the given batch size and delay
   * @param batchSize
   * @param delay
   */
  constructor(batchSize: number, delay: number, callback: any) {
    this.batchSize = batchSize;
    this.delay = delay;
    this.callback = callback;
  }

  /**
   * Add data to the queue
   * @param data
   */
  addToQueue(data: any) {
    this.queue = [...this.queue, ...data];

    if (this.queue.length >= this.batchSize) {
      this.sendBatch();
    } else if (!this.timer) {
      this.timer = setTimeout(() => this.sendBatch(), this.delay);
    }
  }

  /**
   * Send the current batch to the server
   * and clear the queue. Retry failed requests.
   */
  private async sendBatch() {
    if (this.timer) {
      clearTimeout(this.timer);
      this.timer = null;
    }

    const batch = this.queue.splice(0, this.batchSize);

    try {
      await this.callback(batch);
    } catch (error) {
      console.error('Failed to send batch', error);
      // For now not retrying failed requests
      // uncomment below code to retry failed requests
      // this.queue = [...batch, ...this.queue];
    }

    if (this.queue.length > 0) {
      this.timer = setTimeout(() => this.sendBatch(), this.delay);
    }
  }
}