import { run } from "@ember/runloop";
import { ajax } from "discourse/lib/ajax";
const { debounce } = run;

let _queue = [];
let _processing = 0;

// max number of reports which will be requested in one bulk request
const MAX_JOB_SIZE = 4;

// max number of concurrent bulk requests
const MAX_CONCURRENCY = 3;

// max number of jobs stored, first entered jobs will be evicted first
const MAX_QUEUE_SIZE = 20;

const BULK_REPORTS_ENDPOINT = "/admin/reports/bulk";

const DEBOUNCING_DELAY = 50;

export default {
  enqueue(type, params, callback) {
    // makes sures the queue is not filling indefinitely
    if (_queue.length >= MAX_QUEUE_SIZE) {
      const removedJobs = _queue.splice(0, 1)[0];
      removedJobs.forEach(job => {
        // this is technically not a 429, but it's the result
        // of client doing too many requests so we want the same
        // behavior
        job.runnable()(429);
      });
    }

    _queue.push({ runnable: () => callback, type, params });

    debounce(this, this._processQueue, DEBOUNCING_DELAY);
  },

  _processQueue() {
    if (_queue.length === 0) return;
    if (_processing >= MAX_CONCURRENCY) return;

    _processing++;

    const jobs = _queue.splice(0, MAX_JOB_SIZE);

    // if queue has still jobs after splice, we request a future processing
    if (_queue.length > 0) {
      debounce(this, this._processQueue, DEBOUNCING_DELAY);
    }

    let reports = {};
    jobs.forEach(job => {
      reports[job.type] = job.params;
    });

    ajax(BULK_REPORTS_ENDPOINT, { data: { reports } })
      .then(response => {
        jobs.forEach(job => {
          const report = response.reports.findBy("type", job.type);
          job.runnable()(report);
        });
      })
      .catch(data => {
        jobs.forEach(job => {
          if (data.jqXHR && data.jqXHR.status === 429) {
            job.runnable()(429);
          } else if (data.jqXHR && data.jqXHR.status === 500) {
            job.runnable()(500);
          } else {
            job.runnable()();
          }
        });
      })
      .finally(() => {
        _processing--;

        debounce(this, this._processQueue, DEBOUNCING_DELAY);
      });
  },

  _reset() {
    _queue = [];
    _processing = 0;
  }
};
