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-rw-r--r--library/Icinga/Application/Hook.php330
1 files changed, 330 insertions, 0 deletions
diff --git a/library/Icinga/Application/Hook.php b/library/Icinga/Application/Hook.php
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+<?php
+/* Icinga Web 2 | (c) 2013 Icinga Development Team | GPLv2+ */
+
+namespace Icinga\Application;
+
+use Exception;
+use Icinga\Authentication\Auth;
+use Icinga\Application\Modules\Manager;
+use Icinga\Exception\ProgrammingError;
+
+/**
+ * Icinga Hook registry
+ *
+ * Modules making use of predefined hooks have to use this registry
+ *
+ * Usage:
+ * <code>
+ * Hook::register('grapher', 'My\\Grapher\\Class');
+ * </code>
+ */
+class Hook
+{
+ /**
+ * Our hook name registry
+ *
+ * @var array
+ */
+ protected static $hooks = array();
+
+ /**
+ * Hooks that have already been instantiated
+ *
+ * @var array
+ */
+ protected static $instances = array();
+
+ /**
+ * Namespace prefix
+ *
+ * @var string
+ */
+ public static $BASE_NS = 'Icinga\\Application\\Hook\\';
+
+ /**
+ * Append this string to base class
+ *
+ * All base classes renamed to *Hook
+ *
+ * @var string
+ */
+ public static $classSuffix = 'Hook';
+
+ /**
+ * Reset object state
+ */
+ public static function clean()
+ {
+ self::$hooks = array();
+ self::$instances = array();
+ self::$BASE_NS = 'Icinga\\Application\\Hook\\';
+ }
+
+ /**
+ * Whether someone registered itself for the given hook name
+ *
+ * @param string $name One of the predefined hook names
+ *
+ * @return bool
+ */
+ public static function has($name)
+ {
+ $name = self::normalizeHookName($name);
+
+ if (! array_key_exists($name, self::$hooks)) {
+ return false;
+ }
+
+ foreach (self::$hooks[$name] as $hook) {
+ list($class, $alwaysRun) = $hook;
+ if ($alwaysRun || self::hasPermission($class)) {
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ protected static function normalizeHookName($name)
+ {
+ if (strpos($name, '\\') === false) {
+ $parts = explode('/', $name);
+ foreach ($parts as & $part) {
+ $part = ucfirst($part);
+ }
+
+ return implode('\\', $parts);
+ }
+
+ return $name;
+ }
+
+ /**
+ * Create or return an instance of a given hook
+ *
+ * TODO: Should return some kind of a hook interface
+ *
+ * @param string $name One of the predefined hook names
+ * @param string $key The identifier of a specific subtype
+ *
+ * @return mixed
+ */
+ public static function createInstance($name, $key)
+ {
+ $name = self::normalizeHookName($name);
+
+ if (!self::has($name, $key)) {
+ return null;
+ }
+
+ if (isset(self::$instances[$name][$key])) {
+ return self::$instances[$name][$key];
+ }
+
+ $class = self::$hooks[$name][$key][0];
+
+ if (! class_exists($class)) {
+ throw new ProgrammingError(
+ 'Erraneous hook implementation, class "%s" does not exist',
+ $class
+ );
+ }
+ try {
+ $instance = new $class();
+ } catch (Exception $e) {
+ Logger::debug(
+ 'Hook "%s" (%s) (%s) failed, will be unloaded: %s',
+ $name,
+ $key,
+ $class,
+ $e->getMessage()
+ );
+ // TODO: Persist unloading for "some time" or "current session"
+ unset(self::$hooks[$name][$key]);
+ return null;
+ }
+
+ self::assertValidHook($instance, $name);
+ self::$instances[$name][$key] = $instance;
+ return $instance;
+ }
+
+ protected static function splitHookName($name)
+ {
+ $sep = '\\';
+ if (false === $module = strpos($name, $sep)) {
+ return array(null, $name);
+ }
+ return array(
+ substr($name, 0, $module),
+ substr($name, $module + 1)
+ );
+ }
+
+ /**
+ * Extract the Icinga module name from a given namespaced class name
+ *
+ * Does no validation, prefix must have been checked before
+ *
+ * Shameless copy of ClassLoader::extractModuleName()
+ *
+ * @param string $class The hook's class path
+ *
+ * @return string
+ */
+ protected static function extractModuleName($class)
+ {
+ return lcfirst(
+ substr(
+ $class,
+ ClassLoader::MODULE_PREFIX_LENGTH,
+ strpos(
+ $class,
+ ClassLoader::NAMESPACE_SEPARATOR,
+ ClassLoader::MODULE_PREFIX_LENGTH + 1
+ ) - ClassLoader::MODULE_PREFIX_LENGTH
+ )
+ );
+ }
+
+ /**
+ * Return whether the user has the permission to access the module which provides the given hook
+ *
+ * @param string $class The hook's class path
+ *
+ * @return bool
+ */
+ protected static function hasPermission($class)
+ {
+ if (Icinga::app()->isCli()) {
+ return true;
+ }
+
+ return Auth::getInstance()->hasPermission(
+ Manager::MODULE_PERMISSION_NS . self::extractModuleName($class)
+ );
+ }
+
+ /**
+ * Test for a valid class name
+ *
+ * @param mixed $instance
+ * @param string $name
+ *
+ * @throws ProgrammingError
+ */
+ private static function assertValidHook($instance, $name)
+ {
+ $name = self::normalizeHookName($name);
+
+ $suffix = self::$classSuffix; // 'Hook'
+ $base = self::$BASE_NS; // 'Icinga\\Web\\Hook\\'
+
+ list($module, $name) = self::splitHookName($name);
+
+ if ($module === null) {
+ $base_class = $base . ucfirst($name) . 'Hook';
+
+ // I'm unsure whether this makes sense. Unused and Wrong.
+ if (strpos($base_class, $suffix) === false) {
+ $base_class .= $suffix;
+ }
+ } else {
+ $base_class = 'Icinga\\Module\\'
+ . ucfirst($module)
+ . '\\Hook\\'
+ . ucfirst($name)
+ . $suffix;
+ }
+
+ if (!$instance instanceof $base_class) {
+ // This is a compatibility check. Should be removed one far day:
+ if ($module !== null) {
+ $compat_class = 'Icinga\\Module\\'
+ . ucfirst($module)
+ . '\\Web\\Hook\\'
+ . ucfirst($name)
+ . $suffix;
+
+ if ($instance instanceof $compat_class) {
+ return;
+ }
+ }
+
+ throw new ProgrammingError(
+ '%s is not an instance of %s',
+ get_class($instance),
+ $base_class
+ );
+ }
+ }
+
+ /**
+ * Return all instances of a specific name
+ *
+ * @param string $name One of the predefined hook names
+ *
+ * @return array
+ */
+ public static function all($name)
+ {
+ $name = self::normalizeHookName($name);
+ if (! self::has($name)) {
+ return array();
+ }
+
+ foreach (self::$hooks[$name] as $key => $hook) {
+ list($class, $alwaysRun) = $hook;
+ if ($alwaysRun || self::hasPermission($class)) {
+ if (self::createInstance($name, $key) === null) {
+ return array();
+ }
+ }
+ }
+
+ return isset(self::$instances[$name]) ? self::$instances[$name] : array();
+ }
+
+ /**
+ * Get the first hook
+ *
+ * @param string $name One of the predefined hook names
+ *
+ * @return null|mixed
+ */
+ public static function first($name)
+ {
+ $name = self::normalizeHookName($name);
+
+ if (self::has($name)) {
+ foreach (self::$hooks[$name] as $key => $hook) {
+ list($class, $alwaysRun) = $hook;
+ if ($alwaysRun || self::hasPermission($class)) {
+ return self::createInstance($name, $key);
+ }
+ }
+ }
+ }
+
+ /**
+ * Register a class
+ *
+ * @param string $name One of the predefined hook names
+ * @param string $key The identifier of a specific subtype
+ * @param string $class Your class name, must inherit one of the
+ * classes in the Icinga/Application/Hook folder
+ * @param bool $alwaysRun To run the hook always (e.g. without permission check)
+ */
+ public static function register($name, $key, $class, $alwaysRun = false)
+ {
+ $name = self::normalizeHookName($name);
+
+ if (!isset(self::$hooks[$name])) {
+ self::$hooks[$name] = array();
+ }
+
+ $class = ltrim($class, ClassLoader::NAMESPACE_SEPARATOR);
+
+ self::$hooks[$name][$key] = [$class, $alwaysRun];
+ }
+}
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