import { Plugin } from "Plugin/Plugin";
import type { Metric } from "Metrics/Metric";

import type { ProcessingQueue } from "./ProcessingQueue";

/**
 * Reporter Plugin
 *
 * This plugin is designed to efficiently send your metrics to an
 * external service. When registering this plugin on a `Metric`, it
 * will be posted to the service you specify each time its `stop()`
 * event is called.
 *
 * This plugin will attempt to batch multiple metrics together using a
 * processing queue to minimize the amount of requests going out in the
 * background of your application. It'll also use the `Beacon API`
 * wherever possible.
 *
 * Setting up the Reporting Plugin and Processing Queue:
 *
 * ```typescript
 * import { Metric, ReporterPlugin, ProcessingQueue } from "@ui-perf/metrics";
 *
 * const Queue = new ProcessingQueue("/analytics", metrics => {
 *   return JSON.stringify({
 *     metrics,
 *     // any other data you wish to add to your requests
 *   });
 * })
 *
 * ```
 */
export class ReporterPlugin<
  T extends Metric<any, any> = Metric<any, any>,
> extends Plugin<T> {
  constructor(private readonly processor: ProcessingQueue<T>) {
    super();
  }

  /**
   * Stop
   *
   * Enqueues the target metric to be sent to the `ProcessingQueue's`
   * endpoint
   */
  protected override stop(metric: T) {
    void this.processor.enqueue(metric);
  }

  /**
   * To JSON
   *
   * Modifies the return value of the `PageLoadPlugin` interface when passed
   * to `JSON.stringify`
   */
  public override toJSON() {
    return {};
  }
}