icingaweb2/modules/monitoring/application/views/scripts/show/history.phtml

<?php
use Icinga\Module\Monitoring\Object\Host;
use Icinga\Module\Monitoring\Object\Service;

$self = $this;
$hostContext = $object->getType() === 'host';

if (! $this->compact): ?>
<div class="controls">
  <?= $this->tabs; ?>
 <?php if ($hostContext): ?>
  <?= $this->render('partials/host/object-header.phtml'); ?>
 <?php else: ?>
  <?= $this->render('partials/service/object-header.phtml'); ?>
 <?php endif ?>
  <h1><?= $this->translate('This Object\'s Event History'); ?></h1>
  <?= $this->sortBox; ?>
  <?= $this->limiter; ?>
  <?= $this->paginator; ?>
  <?= $this->filterEditor; ?>
</div>
<?php endif ?>
<div class="content">
<?php

if (count($history) === 0) {
    echo $this->translate('No history available for this object') . '</div>';
    return;
}
?>

<?php
function contactsLink($match, $view) {
    $links = array();
    foreach (preg_split('/,\s/', $match[1]) as $contact) {
        $links[] = $view->qlink(
            $contact,
            'monitoring/show/contact',
            array('contact_name' => $contact),
            array('title' => sprintf($view->translate('Show detailed information about %s'), $contact))
        );
    }
    return '[' . implode(', ', $links) . ']';
}
?>

  <table data-base-target="_next" class="action objecthistory">
    <tbody>
    <?php foreach ($history as $event): ?>
    <?php
      $stateClass = 'invalid';
      $isService = isset($event->service_description);
      switch ($event->type) {
        case 'notify':
          $icon = 'notification';
          $title = $this->translate('Notification');
          $stateClass = $isService ? Service::getStateText($event->state) : Host::getStateText($event->state);

          $msg = preg_replace_callback(
              '/^\[([^\]]+)\]/',
              function($match) use ($self) { return contactsLink($match, $self); },
              $this->escape($event->output)
          );
          break;
        case 'comment':
          $icon = 'comment';
          $title = $this->translate('Comment');
          $msg = $this->escape($event->output);
          break;
        case 'comment_deleted':
          $icon = 'remove';
          $title = $this->translate('Comment deleted');
          $msg = $this->escape($event->output);
          break;
        case 'ack':
          $icon = 'acknowledgement';
          $title = $this->translate('Acknowledge');
          $msg = $this->escape($event->output);
          break;
        case 'ack_deleted':
          $icon = 'remove';
          $title = $this->translate('Ack removed');
          $msg = $this->escape($event->output);
          break;
        case 'dt_comment':
          $icon = 'in_downtime';
          $title = $this->translate('In Downtime');
          $msg = $this->escape($event->output);
          break;
        case 'dt_comment_deleted':
          $icon = 'remove';
          $title = $this->translate('Downtime removed');
          $msg = $this->escape($event->output);
          break;
        case 'flapping':
          $icon = 'flapping';
          $title = $this->translate('Flapping');
          $msg = $this->escape($event->output);
          break;
        case 'flapping_deleted':
          $icon = 'remove';
          $title = $this->translate('Flapping stopped');
          $msg = $this->escape($event->output);
          break;
        case 'hard_state':
          $msg = '[ ' . $event->attempt . '/' . $event->max_attempts . ' ] ' . $this->escape($event->output);
          $stateClass = $isService ? Service::getStateText($event->state) : Host::getStateText($event->state);
          $icon = 'attention-alt';
          $title = $isService ? Service::getStateText($event->state) : Host::getStateText($event->state);
          break;
        case 'soft_state':
          $icon = 'spinner';
          $msg = '[ ' . $event->attempt . '/' . $event->max_attempts . ' ] ' . $this->escape($event->output);
          $stateClass = $isService ? Service::getStateText($event->state) : Host::getStateText($event->state);
          $title = $isService ? Service::getStateText($event->state) : Host::getStateText($event->state);
          break;
        case 'dt_start':
          $icon = 'downtime_start';
          $title = $this->translate('Downtime Start');
          $msg = $this->escape($event->output);
          break;
        case 'dt_end':
          $icon = 'downtime_end';
          $title = $this->translate('Downtime End');
          $msg = $this->escape($event->output);
          break;
      }
    ?>
      <tr class="state <?= $stateClass; ?>">
        <td class="state">
          <strong><?= $this->escape($title); ?></strong>
          <br>
          <?= date('d.m. H:i', $event->timestamp); ?>
        </td>
        <td><?php

$output = $this->tickets ? preg_replace_callback(
    $this->tickets->getPattern(),
    array($this->tickets, 'createLink'),
    $msg
) : $msg;

?>
        <?php if ($isService): ?>
          <?= sprintf(
              $this->translate('%s on %s', 'Service running on host'),
              $hostContext ? $this->qlink(
                  $event->service_display_name,
                  'monitoring/show/service',
                  array(
                      'host' => $event->host_name,
                      'service' => $event->service_description
                  ),
                  array('title' => sprintf(
                      $this->translate('Show detailed information for service %s on host %s'),
                      $event->service_display_name,
                      $event->host_display_name
                  ))
              ) : $this->escape($event->service_display_name),
              $event->host_display_name
          ) ?>
        <?php else: ?>
          <?= $this->escape($event->host_name); ?>
        <?php endif ?>
          <br>
          <div>
            <?= $this->icon($icon, $title); ?> <?= empty($msg) ? '' : $msg; ?>
          </div>
        </td>
      </tr>
<?php endforeach; ?>
    </tbody>
  </table>
</div>