Add inactive subscribers notice

[MAILPOET-2088]

lib/Util/Notices/InactiveSubscribersNotice.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace MailPoet\Util\Notices;
+
+use MailPoet\Models\Subscriber;
+use MailPoet\Settings\SettingsController;
+use MailPoet\Util\Helpers;
+use MailPoet\WP\Functions as WPFunctions;
+use MailPoet\WP\Notice;
+
+class InactiveSubscribersNotice {
+  const OPTION_NAME = 'inactive-subscribers-notice';
+  const MIN_INACTIVE_SUBSCRIBERS_COUNT = 50;
+
+  /** @var SettingsController */
+  private $settings;
+
+  /** @var WPFunctions */
+  private $wp;
+
+  function __construct(SettingsController $settings, WPFunctions $wp) {
+    $this->settings = $settings;
+    $this->wp = $wp;
+  }
+
+  function init($should_display) {
+    if (!$should_display || !$this->settings->get(self::OPTION_NAME, true)) {
+      return;
+    }
+
+    $inactive_subscribers_count = Subscriber::getInactiveSubscribersCount();
+    if ($inactive_subscribers_count < self::MIN_INACTIVE_SUBSCRIBERS_COUNT) {
+      return;
+    }
+    return $this->display($inactive_subscribers_count);
+  }
+
+  function disable() {
+    $this->settings->set(self::OPTION_NAME, false);
+  }
+
+  private function display($inactive_subscribers_count) {
+    $error_string = __('Good news! MailPoet won’t send emails to your [number] inactive subscribers. This is a standard practice to maintain good deliverability and open rates. But if you want to disable it, you can do so in settings. [link]Read more.[/link]', 'mailpoet');
+    $go_to_settings_string = __('Go to the Advanced Settings', 'mailpoet');
+
+    $notice = str_replace('[number]', $this->wp->numberFormatI18n($inactive_subscribers_count), $error_string);
+    $notice = Helpers::replaceLinkTags($notice, 'https://kb.mailpoet.com/article/264-inactive-subscribers', ['target' => '_blank']);
+    $notice = "<p>$notice</p>";
+    $notice .= '<p><a href="admin.php?page=mailpoet-settings#advanced" class="button button-primary">' . $go_to_settings_string . '</a></p>';
+
+    $extra_classes = 'mailpoet-dismissible-notice is-dismissible';
+
+    return Notice::displaySuccess($notice, $extra_classes, self::OPTION_NAME, false);
+  }
+}