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msd2/tracking/piwik/core/EventDispatcher.php

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+<?php
+/**
+ * Piwik - free/libre analytics platform
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ *
+ */
+
+namespace Piwik;
+
+use Piwik\Container\StaticContainer;
+
+/**
+ * This class allows code to post events from anywhere in Piwik and for
+ * plugins to associate callbacks to be executed when events are posted.
+ */
+class EventDispatcher
+{
+    /**
+     * @return EventDispatcher
+     */
+    public static function getInstance()
+    {
+        return StaticContainer::get('Piwik\EventDispatcher');
+    }
+
+    // implementation details for postEvent
+    const EVENT_CALLBACK_GROUP_FIRST = 0;
+    const EVENT_CALLBACK_GROUP_SECOND = 1;
+    const EVENT_CALLBACK_GROUP_THIRD = 2;
+
+    /**
+     * Array of observers (callbacks attached to events) that are not methods
+     * of plugin classes.
+     *
+     * @var array
+     */
+    private $extraObservers = array();
+
+    /**
+     * Array storing information for all pending events. Each item in the array
+     * will be an array w/ two elements:
+     *
+     * array(
+     *     'Event.Name',                  // the event name
+     *     array('event', 'parameters')   // the parameters to pass to event observers
+     * )
+     *
+     * @var array
+     */
+    private $pendingEvents = array();
+
+    /**
+     * Plugin\Manager instance used to get list of loaded plugins.
+     *
+     * @var \Piwik\Plugin\Manager
+     */
+    private $pluginManager;
+
+    private $pluginHooks = array();
+
+    /**
+     * Constructor.
+     */
+    public function __construct(Plugin\Manager $pluginManager, array $observers = array())
+    {
+        $this->pluginManager = $pluginManager;
+
+        foreach ($observers as $observerInfo) {
+            list($eventName, $callback) = $observerInfo;
+            $this->extraObservers[$eventName][] = $callback;
+        }
+    }
+
+    /**
+     * Triggers an event, executing all callbacks associated with it.
+     *
+     * @param string $eventName The name of the event, ie, API.getReportMetadata.
+     * @param array $params The parameters to pass to each callback when executing.
+     * @param bool $pending Whether this event should be posted again for plugins
+     *                      loaded after the event is fired.
+     * @param array|null $plugins The plugins to post events to. If null, the event
+     *                            is posted to all plugins. The elements of this array
+     *                            can be either the Plugin objects themselves
+     *                            or their string names.
+     */
+    public function postEvent($eventName, $params, $pending = false, $plugins = null)
+    {
+        if ($pending) {
+            $this->pendingEvents[] = array($eventName, $params);
+        }
+
+        $manager = $this->pluginManager;
+
+        if (empty($plugins)) {
+            $plugins = $manager->getPluginsLoadedAndActivated();
+        }
+
+        $callbacks = array();
+
+        // collect all callbacks to execute
+        foreach ($plugins as $pluginName) {
+            if (!is_string($pluginName)) {
+                $pluginName = $pluginName->getPluginName();
+            }
+
+            if (!isset($this->pluginHooks[$pluginName])) {
+                $plugin = $manager->getLoadedPlugin($pluginName);
+                $this->pluginHooks[$pluginName] = $plugin->getListHooksRegistered();
+            }
+
+            $hooks = $this->pluginHooks[$pluginName];
+
+            if (isset($hooks[$eventName])) {
+                list($pluginFunction, $callbackGroup) = $this->getCallbackFunctionAndGroupNumber($hooks[$eventName]);
+
+                if (is_string($pluginFunction)) {
+                    $plugin = $manager->getLoadedPlugin($pluginName);
+                    $callbacks[$callbackGroup][] = array($plugin, $pluginFunction) ;
+                } else {
+                    $callbacks[$callbackGroup][] = $pluginFunction;
+                }
+            }
+        }
+
+        if (isset($this->extraObservers[$eventName])) {
+            foreach ($this->extraObservers[$eventName] as $callbackInfo) {
+                list($callback, $callbackGroup) = $this->getCallbackFunctionAndGroupNumber($callbackInfo);
+
+                $callbacks[$callbackGroup][] = $callback;
+            }
+        }
+
+        // sort callbacks by their importance
+        ksort($callbacks);
+
+        // execute callbacks in order
+        foreach ($callbacks as $callbackGroup) {
+            foreach ($callbackGroup as $callback) {
+                call_user_func_array($callback, $params);
+            }
+        }
+    }
+
+    /**
+     * Associates a callback that is not a plugin class method with an event
+     * name.
+     *
+     * @param string $eventName
+     * @param array|callable $callback This can be a normal PHP callback or an array
+     *                        that looks like this:
+     *                        array(
+     *                            'function' => $callback,
+     *                            'before' => true
+     *                        )
+     *                        or this:
+     *                        array(
+     *                            'function' => $callback,
+     *                            'after' => true
+     *                        )
+     *                        If 'before' is set, the callback will be executed
+     *                        before normal & 'after' ones. If 'after' then it
+     *                        will be executed after normal ones.
+     */
+    public function addObserver($eventName, $callback)
+    {
+        $this->extraObservers[$eventName][] = $callback;
+    }
+
+    /**
+     * Re-posts all pending events to the given plugin.
+     *
+     * @param Plugin $plugin
+     */
+    public function postPendingEventsTo($plugin)
+    {
+        foreach ($this->pendingEvents as $eventInfo) {
+            list($eventName, $eventParams) = $eventInfo;
+            $this->postEvent($eventName, $eventParams, $pending = false, array($plugin));
+        }
+    }
+
+    private function getCallbackFunctionAndGroupNumber($hookInfo)
+    {
+        if (is_array($hookInfo)
+            && !empty($hookInfo['function'])
+        ) {
+            $pluginFunction = $hookInfo['function'];
+            if (!empty($hookInfo['before'])) {
+                $callbackGroup = self::EVENT_CALLBACK_GROUP_FIRST;
+            } elseif (!empty($hookInfo['after'])) {
+                $callbackGroup = self::EVENT_CALLBACK_GROUP_THIRD;
+            } else {
+                $callbackGroup = self::EVENT_CALLBACK_GROUP_SECOND;
+            }
+        } else {
+            $pluginFunction = $hookInfo;
+            $callbackGroup = self::EVENT_CALLBACK_GROUP_SECOND;
+        }
+
+        return array($pluginFunction, $callbackGroup);
+    }
+}