<?php declare(strict_types=1);

/*
 * This file is part of Composer.
 *
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Composer\EventDispatcher;

use Composer\DependencyResolver\Transaction;
use Composer\Installer\InstallerEvent;
use Composer\IO\BufferIO;
use Composer\IO\ConsoleIO;
use Composer\IO\IOInterface;
use Composer\Composer;
use Composer\PartialComposer;
use Composer\Pcre\Preg;
use Composer\Plugin\CommandEvent;
use Composer\Plugin\PreCommandRunEvent;
use Composer\Util\Platform;
use Composer\DependencyResolver\Operation\OperationInterface;
use Composer\Repository\RepositoryInterface;
use Composer\Script;
use Composer\Installer\PackageEvent;
use Composer\Installer\BinaryInstaller;
use Composer\Util\ProcessExecutor;
use Composer\Script\Event as ScriptEvent;
use Composer\Autoload\ClassLoader;
use Symfony\Component\Console\Application;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\StringInput;
use Symfony\Component\Console\Output\ConsoleOutput;
use Symfony\Component\Process\PhpExecutableFinder;
use Symfony\Component\Process\ExecutableFinder;

/**
 * The Event Dispatcher.
 *
 * Example in command:
 *     $dispatcher = new EventDispatcher($this->requireComposer(), $this->getApplication()->getIO());
 *     // ...
 *     $dispatcher->dispatch(ScriptEvents::POST_INSTALL_CMD);
 *     // ...
 *
 * @author François Pluchino <francois.pluchino@opendisplay.com>
 * @author Jordi Boggiano <j.boggiano@seld.be>
 * @author Nils Adermann <naderman@naderman.de>
 */
class EventDispatcher
{
    /** @var PartialComposer */
    protected $composer;
    /** @var IOInterface */
    protected $io;
    /** @var ?ClassLoader */
    protected $loader;
    /** @var ProcessExecutor */
    protected $process;
    /** @var array<string, array<int, array<callable|string>>> */
    protected $listeners = [];
    /** @var bool */
    protected $runScripts = true;
    /** @var list<string> */
    private $eventStack;

    /**
     * Constructor.
     *
     * @param PartialComposer $composer The composer instance
     * @param IOInterface     $io       The IOInterface instance
     * @param ProcessExecutor $process
     */
    public function __construct(PartialComposer $composer, IOInterface $io, ?ProcessExecutor $process = null)
    {
        $this->composer = $composer;
        $this->io = $io;
        $this->process = $process ?? new ProcessExecutor($io);
        $this->eventStack = [];
    }

    /**
     * Set whether script handlers are active or not
     *
     * @return $this
     */
    public function setRunScripts(bool $runScripts = true): self
    {
        $this->runScripts = $runScripts;

        return $this;
    }

    /**
     * Dispatch an event
     *
     * @param  string|null $eventName The event name, required if no $event is provided
     * @param  Event       $event An event instance, required if no $eventName is provided
     * @return int         return code of the executed script if any, for php scripts a false return
     *                          value is changed to 1, anything else to 0
     */
    public function dispatch(?string $eventName, ?Event $event = null): int
    {
        if (null === $event) {
            if (null === $eventName) {
                throw new \InvalidArgumentException('If no $event is passed in to '.__METHOD__.' you have to pass in an $eventName, got null.');
            }
            $event = new Event($eventName);
        }

        return $this->doDispatch($event);
    }

    /**
     * Dispatch a script event.
     *
     * @param  string               $eventName      The constant in ScriptEvents
     * @param  array<int, mixed>    $additionalArgs Arguments passed by the user
     * @param  array<string, mixed> $flags          Optional flags to pass data not as argument
     * @return int                                  return code of the executed script if any, for php scripts a false return
     *                                              value is changed to 1, anything else to 0
     */
    public function dispatchScript(string $eventName, bool $devMode = false, array $additionalArgs = [], array $flags = []): int
    {
        assert($this->composer instanceof Composer, new \LogicException('This should only be reached with a fully loaded Composer'));

        return $this->doDispatch(new Script\Event($eventName, $this->composer, $this->io, $devMode, $additionalArgs, $flags));
    }

    /**
     * Dispatch a package event.
     *
     * @param string               $eventName  The constant in PackageEvents
     * @param bool                 $devMode    Whether or not we are in dev mode
     * @param RepositoryInterface  $localRepo  The installed repository
     * @param OperationInterface[] $operations The list of operations
     * @param OperationInterface   $operation  The package being installed/updated/removed
     *
     * @return int return code of the executed script if any, for php scripts a false return
     *             value is changed to 1, anything else to 0
     */
    public function dispatchPackageEvent(string $eventName, bool $devMode, RepositoryInterface $localRepo, array $operations, OperationInterface $operation): int
    {
        assert($this->composer instanceof Composer, new \LogicException('This should only be reached with a fully loaded Composer'));

        return $this->doDispatch(new PackageEvent($eventName, $this->composer, $this->io, $devMode, $localRepo, $operations, $operation));
    }

    /**
     * Dispatch a installer event.
     *
     * @param string      $eventName         The constant in InstallerEvents
     * @param bool        $devMode           Whether or not we are in dev mode
     * @param bool        $executeOperations True if operations will be executed, false in --dry-run
     * @param Transaction $transaction       The transaction contains the list of operations
     *
     * @return int return code of the executed script if any, for php scripts a false return
     *             value is changed to 1, anything else to 0
     */
    public function dispatchInstallerEvent(string $eventName, bool $devMode, bool $executeOperations, Transaction $transaction): int
    {
        assert($this->composer instanceof Composer, new \LogicException('This should only be reached with a fully loaded Composer'));

        return $this->doDispatch(new InstallerEvent($eventName, $this->composer, $this->io, $devMode, $executeOperations, $transaction));
    }

    /**
     * Triggers the listeners of an event.
     *
     * @param  Event                        $event The event object to pass to the event handlers/listeners.
     * @throws \RuntimeException|\Exception
     * @return int                          return code of the executed script if any, for php scripts a false return
     *                                            value is changed to 1, anything else to 0
     */
    protected function doDispatch(Event $event)
    {
        if (Platform::getEnv('COMPOSER_DEBUG_EVENTS')) {
            $details = null;
            if ($event instanceof PackageEvent) {
                $details = (string) $event->getOperation();
            } elseif ($event instanceof CommandEvent) {
                $details = $event->getCommandName();
            } elseif ($event instanceof PreCommandRunEvent) {
                $details = $event->getCommand();
            }
            $this->io->writeError('Dispatching <info>'.$event->getName().'</info>'.($details ? ' ('.$details.')' : '').' event');
        }

        $listeners = $this->getListeners($event);

        $this->pushEvent($event);

        $autoloadersBefore = spl_autoload_functions();

        try {
            $returnMax = 0;
            foreach ($listeners as $callable) {
                $return = 0;
                $this->ensureBinDirIsInPath();

                $additionalArgs = $event->getArguments();
                if (is_string($callable) && str_contains($callable, '@no_additional_args')) {
                    $callable = Preg::replace('{ ?@no_additional_args}', '', $callable);
                    $additionalArgs = [];
                }
                $formattedEventNameWithArgs = $event->getName() . ($additionalArgs !== [] ? ' (' . implode(', ', $additionalArgs) . ')' : '');
                if (!is_string($callable)) {
                    if (!is_callable($callable)) {
                        $className = is_object($callable[0]) ? get_class($callable[0]) : $callable[0];

                        throw new \RuntimeException('Subscriber '.$className.'::'.$callable[1].' for event '.$event->getName().' is not callable, make sure the function is defined and public');
                    }
                    if (is_array($callable) && (is_string($callable[0]) || is_object($callable[0])) && is_string($callable[1])) {
                        $this->io->writeError(sprintf('> %s: %s', $formattedEventNameWithArgs, (is_object($callable[0]) ? get_class($callable[0]) : $callable[0]).'->'.$callable[1]), true, IOInterface::VERBOSE);
                    }
                    $return = false === $callable($event) ? 1 : 0;
                } elseif ($this->isComposerScript($callable)) {
                    $this->io->writeError(sprintf('> %s: %s', $formattedEventNameWithArgs, $callable), true, IOInterface::VERBOSE);

                    $script = explode(' ', substr($callable, 1));
                    $scriptName = $script[0];
                    unset($script[0]);

                    $index = array_search('@additional_args', $script, true);
                    if ($index !== false) {
                        $args = array_splice($script, $index, 0, $additionalArgs);
                    } else {
                        $args = array_merge($script, $additionalArgs);
                    }
                    $flags = $event->getFlags();
                    if (isset($flags['script-alias-input'])) {
                        $argsString = implode(' ', array_map(static function ($arg) { return ProcessExecutor::escape($arg); }, $script));
                        $flags['script-alias-input'] = $argsString . ' ' . $flags['script-alias-input'];
                        unset($argsString);
                    }
                    if (strpos($callable, '@composer ') === 0) {
                        $exec = $this->getPhpExecCommand() . ' ' . ProcessExecutor::escape(Platform::getEnv('COMPOSER_BINARY')) . ' ' . implode(' ', $args);
                        if (0 !== ($exitCode = $this->executeTty($exec))) {
                            $this->io->writeError(sprintf('<error>Script %s handling the %s event returned with error code '.$exitCode.'</error>', $callable, $event->getName()), true, IOInterface::QUIET);

                            throw new ScriptExecutionException('Error Output: '.$this->process->getErrorOutput(), $exitCode);
                        }
                    } else {
                        if (!$this->getListeners(new Event($scriptName))) {
                            $this->io->writeError(sprintf('<warning>You made a reference to a non-existent script %s</warning>', $callable), true, IOInterface::QUIET);
                        }

                        try {
                            /** @var InstallerEvent $event */
                            $scriptEvent = new Script\Event($scriptName, $event->getComposer(), $event->getIO(), $event->isDevMode(), $args, $flags);
                            $scriptEvent->setOriginatingEvent($event);
                            $return = $this->dispatch($scriptName, $scriptEvent);
                        } catch (ScriptExecutionException $e) {
                            $this->io->writeError(sprintf('<error>Script %s was called via %s</error>', $callable, $event->getName()), true, IOInterface::QUIET);
                            throw $e;
                        }
                    }
                } elseif ($this->isPhpScript($callable)) {
                    $className = substr($callable, 0, strpos($callable, '::'));
                    $methodName = substr($callable, strpos($callable, '::') + 2);

                    if (!class_exists($className)) {
                        $this->io->writeError('<warning>Class '.$className.' is not autoloadable, can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);
                        continue;
                    }
                    if (!is_callable($callable)) {
                        $this->io->writeError('<warning>Method '.$callable.' is not callable, can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);
                        continue;
                    }

                    try {
                        $return = false === $this->executeEventPhpScript($className, $methodName, $event) ? 1 : 0;
                    } catch (\Exception $e) {
                        $message = "Script %s handling the %s event terminated with an exception";
                        $this->io->writeError('<error>'.sprintf($message, $callable, $event->getName()).'</error>', true, IOInterface::QUIET);
                        throw $e;
                    }
                } elseif ($this->isCommandClass($callable)) {
                    $className = $callable;
                    if (!class_exists($className)) {
                        $this->io->writeError('<warning>Class '.$className.' is not autoloadable, can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);
                        continue;
                    }
                    if (!is_a($className, Command::class, true)) {
                        $this->io->writeError('<warning>Class '.$className.' does not extend '.Command::class.', can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);
                        continue;
                    }
                    if (defined('Composer\Script\ScriptEvents::'.str_replace('-', '_', strtoupper($event->getName())))) {
                        $this->io->writeError('<warning>You cannot bind '.$event->getName().' to a Command class, use a non-reserved name</warning>', true, IOInterface::QUIET);
                        continue;
                    }

                    $app = new Application();
                    $app->setCatchExceptions(false);
                    if (method_exists($app, 'setCatchErrors')) {
                        $app->setCatchErrors(false);
                    }
                    $app->setAutoExit(false);
                    $cmd = new $className($event->getName());
                    $app->add($cmd);
                    $app->setDefaultCommand((string) $cmd->getName(), true);
                    try {
                        $args = implode(' ', array_map(static function ($arg) { return ProcessExecutor::escape($arg); }, $additionalArgs));
                        // reusing the output from $this->io is mostly needed for tests, but generally speaking
                        // it does not hurt to keep the same stream as the current Application
                        if ($this->io instanceof ConsoleIO) {
                            $reflProp = new \ReflectionProperty($this->io, 'output');
                            if (\PHP_VERSION_ID < 80100) {
                                $reflProp->setAccessible(true);
                            }
                            $output = $reflProp->getValue($this->io);
                        } else {
                            $output = new ConsoleOutput();
                        }
                        $return = $app->run(new StringInput($event->getFlags()['script-alias-input'] ?? $args), $output);
                    } catch (\Exception $e) {
                        $message = "Script %s handling the %s event terminated with an exception";
                        $this->io->writeError('<error>'.sprintf($message, $callable, $event->getName()).'</error>', true, IOInterface::QUIET);
                        throw $e;
                    }
                } else {
                    $args = implode(' ', array_map(['Composer\Util\ProcessExecutor', 'escape'], $additionalArgs));

                    // @putenv does not receive arguments
                    if (strpos($callable, '@putenv ') === 0) {
                        $exec = $callable;
                    } else {
                        if (str_contains($callable, '@additional_args')) {
                            $exec = str_replace('@additional_args', $args, $callable);
                        } else {
                            $exec = $callable . ($args === '' ? '' : ' '.$args);
                        }
                    }

                    if ($this->io->isVerbose()) {
                        $this->io->writeError(sprintf('> %s: %s', $event->getName(), $exec));
                    } elseif ($event->getName() !== '__exec_command') {
                        // do not output the command being run when using `composer exec` as it is fairly obvious the user is running it
                        $this->io->writeError(sprintf('> %s', $exec));
                    }

                    $possibleLocalBinaries = $this->composer->getPackage()->getBinaries();
                    if (count($possibleLocalBinaries) > 0) {
                        foreach ($possibleLocalBinaries as $localExec) {
                            if (Preg::isMatch('{\b'.preg_quote($callable).'$}', $localExec)) {
                                $caller = BinaryInstaller::determineBinaryCaller($localExec);
                                $exec = Preg::replace('{^'.preg_quote($callable).'}', $caller . ' ' . $localExec, $exec);
                                break;
                            }
                        }
                    }

                    if (strpos($exec, '@putenv ') === 0) {
                        if (false === strpos($exec, '=')) {
                            Platform::clearEnv(substr($exec, 8));
                        } else {
                            [$var, $value] = explode('=', substr($exec, 8), 2);
                            Platform::putEnv($var, $value);
                        }

                        continue;
                    }
                    if (strpos($exec, '@php ') === 0) {
                        $pathAndArgs = substr($exec, 5);
                        if (Platform::isWindows()) {
                            $pathAndArgs = Preg::replaceCallback('{^\S+}', static function ($path) {
                                return str_replace('/', '\\', $path[0]);
                            }, $pathAndArgs);
                        }
                        // match somename (not in quote, and not a qualified path) and if it is not a valid path from CWD then try to find it
                        // in $PATH. This allows support for `@php foo` where foo is a binary name found in PATH but not an actual relative path
                        $matched = Preg::isMatchStrictGroups('{^[^\'"\s/\\\\]+}', $pathAndArgs, $match);
                        if ($matched && !file_exists($match[0])) {
                            $finder = new ExecutableFinder;
                            if ($pathToExec = $finder->find($match[0])) {
                                if (Platform::isWindows()) {
                                    $execWithoutExt = Preg::replace('{\.(exe|bat|cmd|com)$}i', '', $pathToExec);
                                    // prefer non-extension file if it exists when executing with PHP
                                    if (file_exists($execWithoutExt)) {
                                        $pathToExec = $execWithoutExt;
                                    }
                                    unset($execWithoutExt);
                                }
                                $pathAndArgs = $pathToExec . substr($pathAndArgs, strlen($match[0]));
                            }
                        }
                        $exec = $this->getPhpExecCommand() . ' ' . $pathAndArgs;
                    } else {
                        $finder = new PhpExecutableFinder();
                        $phpPath = $finder->find(false);
                        if ($phpPath) {
                            Platform::putEnv('PHP_BINARY', $phpPath);
                        }

                        if (Platform::isWindows()) {
                            $exec = Preg::replaceCallback('{^\S+}', static function ($path) {
                                return str_replace('/', '\\', $path[0]);
                            }, $exec);
                        }
                    }

                    // if composer is being executed, make sure it runs the expected composer from current path
                    // resolution, even if bin-dir contains composer too because the project requires composer/composer
                    // see https://github.com/composer/composer/issues/8748
                    if (strpos($exec, 'composer ') === 0) {
                        $exec = $this->getPhpExecCommand() . ' ' . ProcessExecutor::escape(Platform::getEnv('COMPOSER_BINARY')) . substr($exec, 8);
                    }

                    if (0 !== ($exitCode = $this->executeTty($exec))) {
                        $this->io->writeError(sprintf('<error>Script %s handling the %s event returned with error code '.$exitCode.'</error>', $callable, $event->getName()), true, IOInterface::QUIET);

                        throw new ScriptExecutionException('Error Output: '.$this->process->getErrorOutput(), $exitCode);
                    }
                }

                $returnMax = max($returnMax, $return);

                if ($event->isPropagationStopped()) {
                    break;
                }
            }
        } finally {
            $this->popEvent();

            $knownIdentifiers = [];
            foreach ($autoloadersBefore as $key => $cb) {
                $knownIdentifiers[$this->getCallbackIdentifier($cb)] = ['key' => $key, 'callback' => $cb];
            }
            foreach (spl_autoload_functions() as $cb) {
                // once we get to the first known autoloader, we can leave any appended autoloader without problems
                if (isset($knownIdentifiers[$this->getCallbackIdentifier($cb)]) && $knownIdentifiers[$this->getCallbackIdentifier($cb)]['key'] === 0) {
                    break;
                }

                // other newly appeared prepended autoloaders should be appended instead to ensure Composer loads its classes first
                if ($cb instanceof ClassLoader) {
                    $cb->unregister();
                    $cb->register(false);
                } else {
                    spl_autoload_unregister($cb);
                    spl_autoload_register($cb);
                }
            }
        }

        return $returnMax;
    }

    protected function executeTty(string $exec): int
    {
        if ($this->io->isInteractive()) {
            return $this->process->executeTty($exec);
        }

        return $this->process->execute($exec);
    }

    protected function getPhpExecCommand(): string
    {
        $finder = new PhpExecutableFinder();
        $phpPath = $finder->find(false);
        if (!$phpPath) {
            throw new \RuntimeException('Failed to locate PHP binary to execute '.$phpPath);
        }
        $phpArgs = $finder->findArguments();
        $phpArgs = $phpArgs ? ' ' . implode(' ', $phpArgs) : '';
        $allowUrlFOpenFlag = ' -d allow_url_fopen=' . ProcessExecutor::escape(ini_get('allow_url_fopen'));
        $disableFunctionsFlag = ' -d disable_functions=' . ProcessExecutor::escape(ini_get('disable_functions'));
        $memoryLimitFlag = ' -d memory_limit=' . ProcessExecutor::escape(ini_get('memory_limit'));

        return ProcessExecutor::escape($phpPath) . $phpArgs . $allowUrlFOpenFlag . $disableFunctionsFlag . $memoryLimitFlag;
    }

    /**
     * @param Event  $event      Event invoking the PHP callable
     *
     * @return mixed
     */
    protected function executeEventPhpScript(string $className, string $methodName, Event $event)
    {
        if ($this->io->isVerbose()) {
            $this->io->writeError(sprintf('> %s: %s::%s', $event->getName(), $className, $methodName));
        } else {
            $this->io->writeError(sprintf('> %s::%s', $className, $methodName));
        }

        return $className::$methodName($event);
    }

    /**
     * Add a listener for a particular event
     *
     * @param string          $eventName The event name - typically a constant
     * @param callable|string $listener  A callable expecting an event argument, or a command string to be executed (same as a composer.json "scripts" entry)
     * @param int             $priority  A higher value represents a higher priority
     */
    public function addListener(string $eventName, $listener, int $priority = 0): void
    {
        $this->listeners[$eventName][$priority][] = $listener;
    }

    /**
     * @param callable|object $listener A callable or an object instance for which all listeners should be removed
     */
    public function removeListener($listener): void
    {
        foreach ($this->listeners as $eventName => $priorities) {
            foreach ($priorities as $priority => $listeners) {
                foreach ($listeners as $index => $candidate) {
                    if ($listener === $candidate || (is_array($candidate) && is_object($listener) && $candidate[0] === $listener)) {
                        unset($this->listeners[$eventName][$priority][$index]);
                    }
                }
            }
        }
    }

    /**
     * Adds object methods as listeners for the events in getSubscribedEvents
     *
     * @see EventSubscriberInterface
     */
    public function addSubscriber(EventSubscriberInterface $subscriber): void
    {
        foreach ($subscriber->getSubscribedEvents() as $eventName => $params) {
            if (is_string($params)) {
                $this->addListener($eventName, [$subscriber, $params]);
            } elseif (is_string($params[0])) {
                $this->addListener($eventName, [$subscriber, $params[0]], $params[1] ?? 0);
            } else {
                foreach ($params as $listener) {
                    $this->addListener($eventName, [$subscriber, $listener[0]], $listener[1] ?? 0);
                }
            }
        }
    }

    /**
     * Retrieves all listeners for a given event
     *
     * @return array<callable|string> All listeners: callables and scripts
     */
    protected function getListeners(Event $event): array
    {
        $scriptListeners = $this->runScripts ? $this->getScriptListeners($event) : [];

        if (!isset($this->listeners[$event->getName()][0])) {
            $this->listeners[$event->getName()][0] = [];
        }
        krsort($this->listeners[$event->getName()]);

        $listeners = $this->listeners;
        $listeners[$event->getName()][0] = array_merge($listeners[$event->getName()][0], $scriptListeners);

        return array_merge(...$listeners[$event->getName()]);
    }

    /**
     * Checks if an event has listeners registered
     */
    public function hasEventListeners(Event $event): bool
    {
        $listeners = $this->getListeners($event);

        return count($listeners) > 0;
    }

    /**
     * Finds all listeners defined as scripts in the package
     *
     * @param  Event $event Event object
     * @return string[] Listeners
     */
    protected function getScriptListeners(Event $event): array
    {
        $package = $this->composer->getPackage();
        $scripts = $package->getScripts();

        if (empty($scripts[$event->getName()])) {
            return [];
        }

        assert($this->composer instanceof Composer, new \LogicException('This should only be reached with a fully loaded Composer'));

        if ($this->loader) {
            $this->loader->unregister();
        }

        $generator = $this->composer->getAutoloadGenerator();
        if ($event instanceof ScriptEvent) {
            $generator->setDevMode($event->isDevMode());
        }

        $packages = $this->composer->getRepositoryManager()->getLocalRepository()->getCanonicalPackages();
        $packageMap = $generator->buildPackageMap($this->composer->getInstallationManager(), $package, $packages);
        $map = $generator->parseAutoloads($packageMap, $package);
        $this->loader = $generator->createLoader($map, $this->composer->getConfig()->get('vendor-dir'));
        $this->loader->register(false);

        return $scripts[$event->getName()];
    }

    /**
     * Checks if string given references a class path and method
     */
    protected function isPhpScript(string $callable): bool
    {
        return false === strpos($callable, ' ') && false !== strpos($callable, '::');
    }

    /**
     * Checks if string given references a command class
     */
    protected function isCommandClass(string $callable): bool
    {
        return str_contains($callable, '\\') && !str_contains($callable, ' ') && str_ends_with($callable, 'Command');
    }

    /**
     * Checks if string given references a composer run-script
     */
    protected function isComposerScript(string $callable): bool
    {
        return strpos($callable, '@') === 0 && strpos($callable, '@php ') !== 0 && strpos($callable, '@putenv ') !== 0;
    }

    /**
     * Push an event to the stack of active event
     *
     * @throws \RuntimeException
     */
    protected function pushEvent(Event $event): int
    {
        $eventName = $event->getName();
        if (in_array($eventName, $this->eventStack)) {
            throw new \RuntimeException(sprintf("Circular call to script handler '%s' detected", $eventName));
        }

        return array_push($this->eventStack, $eventName);
    }

    /**
     * Pops the active event from the stack
     */
    protected function popEvent(): ?string
    {
        return array_pop($this->eventStack);
    }

    private function ensureBinDirIsInPath(): void
    {
        $pathEnv = 'PATH';

        // checking if only Path and not PATH is set then we probably need to update the Path env
        // on Windows getenv is case-insensitive so we cannot check it via Platform::getEnv and
        // we need to check in $_SERVER directly
        if (!isset($_SERVER[$pathEnv]) && isset($_SERVER['Path'])) {
            $pathEnv = 'Path';
        }

        // add the bin dir to the PATH to make local binaries of deps usable in scripts
        $binDir = $this->composer->getConfig()->get('bin-dir');
        if (is_dir($binDir)) {
            $binDir = realpath($binDir);
            $pathValue = (string) Platform::getEnv($pathEnv);
            if (!Preg::isMatch('{(^|'.PATH_SEPARATOR.')'.preg_quote($binDir).'($|'.PATH_SEPARATOR.')}', $pathValue)) {
                Platform::putEnv($pathEnv, $binDir.PATH_SEPARATOR.$pathValue);
            }
        }
    }

    /**
     * @param callable $cb DO NOT MOVE TO TYPE HINT as private autoload callbacks are not technically callable
     */
    private function getCallbackIdentifier($cb): string
    {
        if (is_string($cb)) {
            return 'fn:'.$cb;
        }
        if (is_object($cb)) {
            return 'obj:'.spl_object_hash($cb);
        }
        if (is_array($cb)) {
            return 'array:'.(is_string($cb[0]) ? $cb[0] : get_class($cb[0]) .'#'.spl_object_hash($cb[0])).'::'.$cb[1];
        }

        // not great but also do not want to break everything here
        return 'unsupported';
    }
}
