Add cron worker for reporting subscriber stats

[MAILPOET-3868]

lib/Cron/Workers/SubscribersStatsReport.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace MailPoet\Cron\Workers;
+
+use MailPoet\Config\ServicesChecker;
+use MailPoet\Cron\CronWorkerScheduler;
+use MailPoet\Entities\ScheduledTaskEntity;
+use MailPoet\Services\Bridge;
+use MailPoet\WP\Functions as WPFunctions;
+use MailPoetVendor\Carbon\Carbon;
+
+class SubscribersStatsReport extends SimpleWorker {
+  const TASK_TYPE = 'subscribers_stats_report';
+
+  /** @var Bridge */
+  private $bridge;
+
+  /** @var ServicesChecker */
+  private $serviceChecker;
+
+  /** @var CronWorkerScheduler */
+  private $workerScheduler;
+
+  public function __construct(
+    Bridge $bridge,
+    ServicesChecker $servicesChecker,
+    CronWorkerScheduler $workerScheduler,
+    WPFunctions $wp
+  ) {
+    parent::__construct($wp);
+    $this->bridge = $bridge;
+    $this->serviceChecker = $servicesChecker;
+    $this->workerScheduler = $workerScheduler;
+  }
+
+  public function checkProcessingRequirements() {
+    return (bool)$this->serviceChecker->getAnyValidKey();
+  }
+
+  public function processTaskStrategy(ScheduledTaskEntity $task, $timer): bool {
+    $key = $this->serviceChecker->getAnyValidKey();
+    if ($key === null) {
+      return false;
+    }
+    $result = $this->bridge->updateSubscriberCount($key);
+    // We have a valid key, but request failed
+    if ($result === false) {
+      $this->workerScheduler->rescheduleProgressively($task);
+    }
+    return $result;
+  }
+
+  public function getNextRunDate() {
+    $date = Carbon::createFromTimestamp($this->wp->currentTime('timestamp'));
+    // Spread the check within 6 hours after midnight so that all plugins don't ping the service at the same time
+    return $date->startOfDay()
+      ->addDay()
+      ->addHours(rand(0, 5))
+      ->addMinutes(rand(0, 59))
+      ->addSeconds(rand(0, 59));
+  }
+}