[locationinfo] Add skeleton for pluggable course backend infrastructure

1 files changed, 108 insertions, 0 deletions

diff --git a/modules-available/locationinfo/inc/coursebackend.inc.php b/modules-available/locationinfo/inc/coursebackend.inc.php
new file mode 100644
index 00000000..39ba3b90
--- /dev/null
+++ b/modules-available/locationinfo/inc/coursebackend.inc.php
@@ -0,0 +1,108 @@
+<?php
+
+/**
+ * Base class for course query backends
+ */
+abstract class CourseBackend
+{
+
+	/*
+	 * Static part for handling interfaces
+	 */
+
+	/**
+	 * @var array list of known backends
+	 */
+	private static $backendTypes = false;
+
+	/**
+	 * Load all known backend types. This is done
+	 * by including *.inc.php from inc/coursebackend/.
+	 */
+	public static function loadDb()
+	{
+		if (self::$backendTypes !== false)
+			return;
+		self::$backendTypes = array();
+		foreach (glob(dirname(__FILE__) . '/coursebackend/coursebackend_*.inc.php', GLOB_NOSORT) as $file) {
+			require_once $file;
+			preg_match('#coursebackend_([^/\.]+)\.inc\.php$#i', $file, $out);
+			if (!class_exists('coursebackend_' . $out[1])) {
+				trigger_error("Backend type source unit $file doesn't seem to define class CourseBackend_{$out[1]}", E_USER_ERROR);
+			}
+			self::$backendTypes[$out[1]] = true;
+		}
+	}
+
+	/**
+	 * Get all known config module types.
+	 *
+	 * @return array list of modules
+	 */
+	public static function getList()
+	{
+		self::loadDb();
+		return array_keys(self::$backendTypes);
+	}
+
+	/**
+	 * Get fresh instance of ConfigModule subclass for given module type.
+	 *
+	 * @param string $moduleType name of module type
+	 * @return \ConfigModule module instance
+	 */
+	public static function getInstance($moduleType)
+	{
+		self::loadDb();
+		if (!isset(self::$backendTypes[$moduleType])) {
+			error_log('Unknown module type: ' . $moduleType);
+			return false;
+		}
+		if (!is_object(self::$backendTypes[$moduleType])) {
+			$class = "coursebackend_$moduleType";
+			self::$backendTypes[$moduleType] = new $class;
+		}
+		return self::$backendTypes[$moduleType];
+	}
+
+
+	/*
+	 * TODO: Insert required methods here
+	 */
+
+	/**
+	 * @return string return display name of backend
+	 */
+	public abstract function getDisplayName();
+
+	/**
+	 * @return int desired caching time of results, in seconds. 0 = no caching
+	 */
+	public abstract function getCacheTime();
+
+	/**
+	 * Internal version of fetch, to be overridden by subclasses.
+	 * @param $roomIds
+	 * @return mixed
+	 */
+	protected abstract function fetchSchedulesInternal($roomIds);
+
+	/**
+	 * Method for fetching the schedules of the given rooms.
+	 * @param array $roomIds Array of room IDs to fetch
+	 * @return array|bool some multidimensional array of rooms as result, or false on error
+	 */
+	public final function fetchSchedules($roomIds)
+	{
+		// TODO: Check if in cache
+		// TODO: Check if we should refresh other rooms recently requested by front ends but not included in $roomIds
+		$aggregatedRoomIds = $roomIds; // + extra rooms
+		// ...
+		// If not in cache:
+		$result = $this->fetchSchedulesInternal($aggregatedRoomIds);
+		// TODO: Place in cache if necessary
+		// TODO: Remove entries from result that were not in $roomsIds
+		return $result;
+	}
+
+}