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system/Events/Events.php

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+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Events;
+
+use Config\Modules;
+use Config\Services;
+
+define('EVENT_PRIORITY_LOW', 200);
+define('EVENT_PRIORITY_NORMAL', 100);
+define('EVENT_PRIORITY_HIGH', 10);
+
+/**
+ * Events
+ */
+class Events
+{
+    /**
+     * The list of listeners.
+     *
+     * @var array
+     */
+    protected static $listeners = [];
+
+    /**
+     * Flag to let us know if we've read from the Config file(s)
+     * and have all of the defined events.
+     *
+     * @var bool
+     */
+    protected static $initialized = false;
+
+    /**
+     * If true, events will not actually be fired.
+     * Useful during testing.
+     *
+     * @var bool
+     */
+    protected static $simulate = false;
+
+    /**
+     * Stores information about the events
+     * for display in the debug toolbar.
+     *
+     * @var array<array<string, float|string>>
+     */
+    protected static $performanceLog = [];
+
+    /**
+     * A list of found files.
+     *
+     * @var string[]
+     */
+    protected static $files = [];
+
+    /**
+     * Ensures that we have a events file ready.
+     */
+    public static function initialize()
+    {
+        // Don't overwrite anything....
+        if (static::$initialized) {
+            return;
+        }
+
+        /** @var Modules $config */
+        $config = config('Modules');
+        $events = APPPATH . 'Config' . DIRECTORY_SEPARATOR . 'Events.php';
+        $files  = [];
+
+        if ($config->shouldDiscover('events')) {
+            $files = Services::locator()->search('Config/Events.php');
+        }
+
+        $files = array_filter(array_map(static function (string $file) {
+            if (is_file($file)) {
+                return realpath($file) ?: $file;
+            }
+
+            return false; // @codeCoverageIgnore
+        }, $files));
+
+        static::$files = array_unique(array_merge($files, [$events]));
+
+        foreach (static::$files as $file) {
+            include $file;
+        }
+
+        static::$initialized = true;
+    }
+
+    /**
+     * Registers an action to happen on an event. The action can be any sort
+     * of callable:
+     *
+     *  Events::on('create', 'myFunction');               // procedural function
+     *  Events::on('create', ['myClass', 'myMethod']);    // Class::method
+     *  Events::on('create', [$myInstance, 'myMethod']);  // Method on an existing instance
+     *  Events::on('create', function() {});              // Closure
+     *
+     * @param string   $eventName
+     * @param callable $callback
+     * @param int      $priority
+     */
+    public static function on($eventName, $callback, $priority = EVENT_PRIORITY_NORMAL)
+    {
+        if (! isset(static::$listeners[$eventName])) {
+            static::$listeners[$eventName] = [
+                true, // If there's only 1 item, it's sorted.
+                [$priority],
+                [$callback],
+            ];
+        } else {
+            static::$listeners[$eventName][0]   = false; // Not sorted
+            static::$listeners[$eventName][1][] = $priority;
+            static::$listeners[$eventName][2][] = $callback;
+        }
+    }
+
+    /**
+     * Runs through all subscribed methods running them one at a time,
+     * until either:
+     *  a) All subscribers have finished or
+     *  b) a method returns false, at which point execution of subscribers stops.
+     *
+     * @param string $eventName
+     * @param mixed  $arguments
+     */
+    public static function trigger($eventName, ...$arguments): bool
+    {
+        // Read in our Config/Events file so that we have them all!
+        if (! static::$initialized) {
+            static::initialize();
+        }
+
+        $listeners = static::listeners($eventName);
+
+        foreach ($listeners as $listener) {
+            $start = microtime(true);
+
+            $result = static::$simulate === false ? $listener(...$arguments) : true;
+
+            if (CI_DEBUG) {
+                static::$performanceLog[] = [
+                    'start' => $start,
+                    'end'   => microtime(true),
+                    'event' => strtolower($eventName),
+                ];
+            }
+
+            if ($result === false) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Returns an array of listeners for a single event. They are
+     * sorted by priority.
+     *
+     * @param string $eventName
+     */
+    public static function listeners($eventName): array
+    {
+        if (! isset(static::$listeners[$eventName])) {
+            return [];
+        }
+
+        // The list is not sorted
+        if (! static::$listeners[$eventName][0]) {
+            // Sort it!
+            array_multisort(static::$listeners[$eventName][1], SORT_NUMERIC, static::$listeners[$eventName][2]);
+
+            // Mark it as sorted already!
+            static::$listeners[$eventName][0] = true;
+        }
+
+        return static::$listeners[$eventName][2];
+    }
+
+    /**
+     * Removes a single listener from an event.
+     *
+     * If the listener couldn't be found, returns FALSE, else TRUE if
+     * it was removed.
+     *
+     * @param string $eventName
+     */
+    public static function removeListener($eventName, callable $listener): bool
+    {
+        if (! isset(static::$listeners[$eventName])) {
+            return false;
+        }
+
+        foreach (static::$listeners[$eventName][2] as $index => $check) {
+            if ($check === $listener) {
+                unset(
+                    static::$listeners[$eventName][1][$index],
+                    static::$listeners[$eventName][2][$index]
+                );
+
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Removes all listeners.
+     *
+     * If the event_name is specified, only listeners for that event will be
+     * removed, otherwise all listeners for all events are removed.
+     *
+     * @param string|null $eventName
+     */
+    public static function removeAllListeners($eventName = null)
+    {
+        if ($eventName !== null) {
+            unset(static::$listeners[$eventName]);
+        } else {
+            static::$listeners = [];
+        }
+    }
+
+    /**
+     * Sets the path to the file that routes are read from.
+     */
+    public static function setFiles(array $files)
+    {
+        static::$files = $files;
+    }
+
+    /**
+     * Returns the files that were found/loaded during this request.
+     *
+     * @return string[]
+     */
+    public function getFiles()
+    {
+        return static::$files;
+    }
+
+    /**
+     * Turns simulation on or off. When on, events will not be triggered,
+     * simply logged. Useful during testing when you don't actually want
+     * the tests to run.
+     */
+    public static function simulate(bool $choice = true)
+    {
+        static::$simulate = $choice;
+    }
+
+    /**
+     * Getter for the performance log records.
+     *
+     * @return array<array<string, float|string>>
+     */
+    public static function getPerformanceLogs()
+    {
+        return static::$performanceLog;
+    }
+}