Refactor ProjectActivity model to use Filter and Formatter interface

app/Formatter/ProjectActivityEventFormatter.php

@@ -0,0 +1,61 @@
+<?php
+
+namespace Kanboard\Formatter;
+
+use Kanboard\Core\Filter\FormatterInterface;
+
+class ProjectActivityEventFormatter extends BaseFormatter implements FormatterInterface
+{
+    /**
+     * Apply formatter
+     *
+     * @access public
+     * @return array
+     */
+    public function format()
+    {
+        $events = $this->query->findAll();
+
+        foreach ($events as &$event) {
+            $event += $this->unserializeEvent($event['data']);
+            unset($event['data']);
+
+            $event['author'] = $event['author_name'] ?: $event['author_username'];
+            $event['event_title'] = $this->notification->getTitleWithAuthor($event['author'], $event['event_name'], $event);
+            $event['event_content'] = $this->renderEvent($event);
+        }
+
+        return $events;
+    }
+
+    /**
+     * Decode event data, supports unserialize() and json_decode()
+     *
+     * @access protected
+     * @param  string   $data   Serialized data
+     * @return array
+     */
+    protected function unserializeEvent($data)
+    {
+        if ($data{0} === 'a') {
+            return unserialize($data);
+        }
+
+        return json_decode($data, true) ?: array();
+    }
+
+    /**
+     * Get the event html content
+     *
+     * @access protected
+     * @param  array     $params    Event properties
+     * @return string
+     */
+    protected function renderEvent(array $params)
+    {
+        return $this->template->render(
+            'event/'.str_replace('.', '_', $params['event_name']),
+            $params
+        );
+    }
+}