--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/calendar/drivers/resources_driver.php	Sat Jan 13 08:56:12 2018 -0500
@@ -0,0 +1,114 @@
+<?php
+
+/**
+ * Resources directory interface definition
+ *
+ * @author Thomas Bruederli <bruederli@kolabsys.com>
+ *
+ * Copyright (C) 2014, Kolab Systems AG <contact@kolabsys.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+/**
+ * Interface definition for a resources directory driver classe
+ */
+abstract class resources_driver
+{
+  protected$cal;
+
+  /**
+   * Default constructor
+   */
+  function __construct($cal)
+  {
+      $this->cal = $cal;
+  }
+
+  /**
+   * Fetch resource objects to be displayed for booking
+   *
+   * @param  string  Search query (optional)
+   * @return array  List of resource records available for booking
+   */
+  abstract public function load_resources($query = null);
+
+  /**
+   * Return properties of a single resource
+   *
+   * @param string  Unique resource identifier
+   * @return array  Resource object as hash array
+   */
+  abstract public function get_resource($id);
+
+  /**
+   * Return properties of a resource owner
+   *
+   * @param string  Owner identifier
+   * @return array  Resource object as hash array
+   */
+  public function get_resource_owner($id)
+  {
+      return null;
+  }
+
+  /**
+   * Get event data to display a resource's calendar
+   *
+   * The default implementation extracts the resource's email address
+   * and fetches free-busy data using the calendar backend driver.
+   *
+   * @param  integer Event's new start (unix timestamp)
+   * @param  integer Event's new end (unix timestamp)
+   * @return array A list of event objects (see calendar_driver specification)
+   */
+  public function get_resource_calendar($id, $start, $end)
+  {
+      $events = array();
+      $rec = $this->get_resource($id);
+      if ($rec && !empty($rec['email']) && $this->cal->driver) {
+          $fbtypemap = array(
+              calendar::FREEBUSY_BUSY => 'busy',
+              calendar::FREEBUSY_TENTATIVE => 'tentative',
+              calendar::FREEBUSY_OOF => 'outofoffice',
+          );
+
+          // if the backend has free-busy information
+          $fblist = $this->cal->driver->get_freebusy_list($rec['email'], $start, $end);
+          if (is_array($fblist)) {
+              foreach ($fblist as $slot) {
+                  list($from, $to, $type) = $slot;
+                  if ($type == calendar::FREEBUSY_FREE || $type == calendar::FREEBUSY_UNKNOWN) {
+                      continue;
+                  }
+                  if ($from < $end && $to > $start) {
+                      $event = array(
+                          'id'     => sha1($id . $from . $to),
+                          'title'  => $rec['name'],
+                          'start'  => new DateTime('@' . $from),
+                          'end'    => new DateTime('@' . $to),
+                          'status' => $fbtypemap[$type],
+                          'calendar' => '_resource',
+                      );
+                      $events[] = $event;
+                  }
+              }
+          }
+      }
+
+      return $events;
+  }
+
+}