<?php

/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2012 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Application;

use Joomla\CMS\Event\Application\AfterExecuteEvent;
use Joomla\CMS\Event\Application\BeforeExecuteEvent;
use Joomla\CMS\Event\Application\DaemonForkEvent;
use Joomla\CMS\Event\Application\DaemonReceiveSignalEvent;
use Joomla\CMS\Filesystem\Folder;
use Joomla\CMS\Input\Cli;
use Joomla\CMS\Log\Log;
use Joomla\Event\DispatcherInterface;
use Joomla\Registry\Registry;

// phpcs:disable PSR1.Files.SideEffects
\defined('_JEXEC') or die;
// phpcs:enable PSR1.Files.SideEffects

/**
 * Class to turn CliApplication applications into daemons.  It requires CLI and PCNTL support built into PHP.
 *
 * @link   https://www.php.net/manual/en/book.pcntl.php
 * @link   https://www.php.net/manual/en/features.commandline.php
 * @since  1.7.0
 */
abstract class DaemonApplication extends CliApplication
{
    /**
     * @var    array  The available POSIX signals to be caught by default.
     * @link   https://www.php.net/manual/pcntl.constants.php
     * @since  1.7.0
     */
    protected static $signals = [
        'SIGHUP',
        'SIGINT',
        'SIGQUIT',
        'SIGILL',
        'SIGTRAP',
        'SIGABRT',
        'SIGIOT',
        'SIGBUS',
        'SIGFPE',
        'SIGUSR1',
        'SIGSEGV',
        'SIGUSR2',
        'SIGPIPE',
        'SIGALRM',
        'SIGTERM',
        'SIGSTKFLT',
        'SIGCLD',
        'SIGCHLD',
        'SIGCONT',
        'SIGTSTP',
        'SIGTTIN',
        'SIGTTOU',
        'SIGURG',
        'SIGXCPU',
        'SIGXFSZ',
        'SIGVTALRM',
        'SIGPROF',
        'SIGWINCH',
        'SIGPOLL',
        'SIGIO',
        'SIGPWR',
        'SIGSYS',
        'SIGBABY',
        'SIG_BLOCK',
        'SIG_UNBLOCK',
        'SIG_SETMASK',
    ];

    /**
     * @var    boolean  True if the daemon is in the process of exiting.
     * @since  1.7.0
     */
    protected $exiting = false;

    /**
     * @var    integer  The parent process id.
     * @since  3.0.0
     */
    protected $parentId = 0;

    /**
     * @var    integer  The process id of the daemon.
     * @since  1.7.0
     */
    protected $processId = 0;

    /**
     * @var    boolean  True if the daemon is currently running.
     * @since  1.7.0
     */
    protected $running = false;

    /**
     * Class constructor.
     *
     * @param   ?Cli                  $input       An optional argument to provide dependency injection for the application's
     *                                             input object.  If the argument is a JInputCli object that object will become
     *                                             the application's input object, otherwise a default input object is created.
     * @param   ?Registry             $config      An optional argument to provide dependency injection for the application's
     *                                             config object.  If the argument is a Registry object that object will become
     *                                             the application's config object, otherwise a default config object is created.
     * @param   ?DispatcherInterface  $dispatcher  An optional argument to provide dependency injection for the application's
     *                                             event dispatcher.  If the argument is a DispatcherInterface object that object will become
     *                                             the application's event dispatcher, if it is null then the default event dispatcher
     *                                             will be created based on the application's loadDispatcher() method.
     *
     * @since   1.7.0
     */
    public function __construct(?Cli $input = null, ?Registry $config = null, ?DispatcherInterface $dispatcher = null)
    {
        // Verify that the process control extension for PHP is available.
        if (!\defined('SIGHUP')) {
            Log::add('The PCNTL extension for PHP is not available.', Log::ERROR);
            throw new \RuntimeException('The PCNTL extension for PHP is not available.');
        }

        // Verify that POSIX support for PHP is available.
        if (!\function_exists('posix_getpid')) {
            Log::add('The POSIX extension for PHP is not available.', Log::ERROR);
            throw new \RuntimeException('The POSIX extension for PHP is not available.');
        }

        // Call the parent constructor.
        parent::__construct($input, $config, null, null, $dispatcher);

        // Set some system limits.
        if (\function_exists('set_time_limit')) {
            set_time_limit($this->config->get('max_execution_time', 0));
        }

        if ($this->config->get('max_memory_limit') !== null) {
            ini_set('memory_limit', $this->config->get('max_memory_limit', '256M'));
        }

        // Flush content immediately.
        ob_implicit_flush();
    }

    /**
     * Method to handle POSIX signals.
     *
     * @param   integer  $signal  The received POSIX signal.
     *
     * @return  void
     *
     * @since   1.7.0
     * @see     pcntl_signal()
     * @throws  \RuntimeException
     */
    public static function signal($signal)
    {
        // Log all signals sent to the daemon.
        Log::add('Received signal: ' . $signal, Log::DEBUG);

        // Let's make sure we have an application instance.
        if (!is_subclass_of(static::$instance, CliApplication::class)) {
            Log::add('Cannot find the application instance.', Log::EMERGENCY);
            throw new \RuntimeException('Cannot find the application instance.');
        }

        // Fire the onReceiveSignal event.
        static::$instance->getDispatcher()->dispatch(
            'onReceiveSignal',
            new DaemonReceiveSignalEvent('onReceiveSignal', [
                'signal'  => $signal,
                'subject' => static::$instance,
            ])
        );

        switch ($signal) {
            case SIGINT:
            case SIGTERM:
                // Handle shutdown tasks
                if (static::$instance->running && static::$instance->isActive()) {
                    static::$instance->shutdown();
                } else {
                    static::$instance->close();
                }
                break;
            case SIGHUP:
                // Handle restart tasks
                if (static::$instance->running && static::$instance->isActive()) {
                    static::$instance->shutdown(true);
                } else {
                    static::$instance->close();
                }
                break;
            case SIGCHLD:
                // A child process has died
                while (static::$instance->pcntlWait($signal, WNOHANG || WUNTRACED) > 0) {
                    usleep(1000);
                }
                break;
            case SIGCLD:
                while (static::$instance->pcntlWait($signal, WNOHANG) > 0) {
                    $signal = static::$instance->pcntlChildExitStatus($signal);
                }
                break;
            default:
                break;
        }
    }

    /**
     * Check to see if the daemon is active.  This does not assume that $this daemon is active, but
     * only if an instance of the application is active as a daemon.
     *
     * @return  boolean  True if daemon is active.
     *
     * @since   1.7.0
     */
    public function isActive()
    {
        // Get the process id file location for the application.
        $pidFile = $this->config->get('application_pid_file');

        // If the process id file doesn't exist then the daemon is obviously not running.
        if (!is_file($pidFile)) {
            return false;
        }

        // Read the contents of the process id file as an integer.
        $fp  = fopen($pidFile, 'r');
        $pid = fread($fp, filesize($pidFile));
        $pid = (int) $pid;
        fclose($fp);

        // Check to make sure that the process id exists as a positive integer.
        if (!$pid) {
            return false;
        }

        // Check to make sure the process is active by pinging it and ensure it responds.
        if (!posix_kill($pid, 0)) {
            // No response so remove the process id file and log the situation.
            @ unlink($pidFile);
            Log::add('The process found based on PID file was unresponsive.', Log::WARNING);

            return false;
        }

        return true;
    }

    /**
     * Load an object or array into the application configuration object.
     *
     * @param   mixed  $data  Either an array or object to be loaded into the configuration object.
     *
     * @return  DaemonApplication  Instance of $this to allow chaining.
     *
     * @since   1.7.0
     */
    public function loadConfiguration($data)
    {
        /*
         * Setup some application metadata options.  This is useful if we ever want to write out startup scripts
         * or just have some sort of information available to share about things.
         */

        // The application author name.  This string is used in generating startup scripts and has
        // a maximum of 50 characters.
        $tmp = (string) $this->config->get('author_name', 'Joomla Platform');
        $this->config->set('author_name', (\strlen($tmp) > 50) ? substr($tmp, 0, 50) : $tmp);

        // The application author email.  This string is used in generating startup scripts.
        $tmp = (string) $this->config->get('author_email', 'admin@joomla.org');
        $this->config->set('author_email', filter_var($tmp, FILTER_VALIDATE_EMAIL));

        // The application name.  This string is used in generating startup scripts.
        $tmp = (string) $this->config->get('application_name', 'DaemonApplication');
        $this->config->set('application_name', (string) preg_replace('/[^A-Z0-9_-]/i', '', $tmp));

        // The application description.  This string is used in generating startup scripts.
        $tmp = (string) $this->config->get('application_description', 'A generic Joomla Platform application.');
        $this->config->set('application_description', filter_var($tmp, FILTER_SANITIZE_STRING));

        /*
         * Setup the application path options.  This defines the default executable name, executable directory,
         * and also the path to the daemon process id file.
         */

        // The application executable daemon.  This string is used in generating startup scripts.
        $tmp = (string) $this->config->get('application_executable', basename($this->input->executable));
        $this->config->set('application_executable', $tmp);

        // The home directory of the daemon.
        $tmp = (string) $this->config->get('application_directory', \dirname($this->input->executable));
        $this->config->set('application_directory', $tmp);

        // The pid file location.  This defaults to a path inside the /tmp directory.
        $name = $this->config->get('application_name');
        $tmp  = (string) $this->config->get('application_pid_file', strtolower('/tmp/' . $name . '/' . $name . '.pid'));
        $this->config->set('application_pid_file', $tmp);

        /*
         * Setup the application identity options.  It is important to remember if the default of 0 is set for
         * either UID or GID then changing that setting will not be attempted as there is no real way to "change"
         * the identity of a process from some user to root.
         */

        // The user id under which to run the daemon.
        $tmp     = (int) $this->config->get('application_uid', 0);
        $options = ['options' => ['min_range' => 0, 'max_range' => 65000]];
        $this->config->set('application_uid', filter_var($tmp, FILTER_VALIDATE_INT, $options));

        // The group id under which to run the daemon.
        $tmp     = (int) $this->config->get('application_gid', 0);
        $options = ['options' => ['min_range' => 0, 'max_range' => 65000]];
        $this->config->set('application_gid', filter_var($tmp, FILTER_VALIDATE_INT, $options));

        // Option to kill the daemon if it cannot switch to the chosen identity.
        $tmp = (bool) $this->config->get('application_require_identity', 1);
        $this->config->set('application_require_identity', $tmp);

        /*
         * Setup the application runtime options.  By default our execution time limit is infinite obviously
         * because a daemon should be constantly running unless told otherwise.  The default limit for memory
         * usage is 256M, which admittedly is a little high, but remember it is a "limit" and PHP's memory
         * management leaves a bit to be desired :-)
         */

        // The maximum execution time of the application in seconds.  Zero is infinite.
        $tmp = $this->config->get('max_execution_time');

        if ($tmp !== null) {
            $this->config->set('max_execution_time', (int) $tmp);
        }

        // The maximum amount of memory the application can use.
        $tmp = $this->config->get('max_memory_limit', '256M');

        if ($tmp !== null) {
            $this->config->set('max_memory_limit', (string) $tmp);
        }

        return $this;
    }

    /**
     * Execute the daemon.
     *
     * @return  void
     *
     * @since   1.7.0
     */
    public function execute()
    {
        // Trigger the onBeforeExecute event
        $this->dispatchEvent(
            'onBeforeExecute',
            new BeforeExecuteEvent('onBeforeExecute', ['subject' => $this, 'container' => $this->getContainer()])
        );

        // Enable basic garbage collection.
        gc_enable();

        Log::add('Starting ' . $this->name, Log::INFO);

        // Set off the process for becoming a daemon.
        if ($this->daemonize()) {
            // Declare ticks to start signal monitoring. When you declare ticks, PCNTL will monitor
            // incoming signals after each tick and call the relevant signal handler automatically.
            declare(ticks=1);

            // Start the main execution loop.
            while (true) {
                // Perform basic garbage collection.
                $this->gc();

                // Don't completely overload the CPU.
                usleep(1000);

                // Execute the main application logic.
                $this->doExecute();
            }
        } else {
            // We were not able to daemonize the application so log the failure and die gracefully.
            Log::add('Starting ' . $this->name . ' failed', Log::INFO);
        }

        // Trigger the onAfterExecute event.
        $this->dispatchEvent(
            'onAfterExecute',
            new AfterExecuteEvent('onAfterExecute', ['subject' => $this])
        );
    }

    /**
     * Restart daemon process.
     *
     * @return  void
     *
     * @since   1.7.0
     */
    public function restart()
    {
        Log::add('Stopping ' . $this->name, Log::INFO);
        $this->shutdown(true);
    }

    /**
     * Stop daemon process.
     *
     * @return  void
     *
     * @since   1.7.0
     */
    public function stop()
    {
        Log::add('Stopping ' . $this->name, Log::INFO);
        $this->shutdown();
    }

    /**
     * Method to change the identity of the daemon process and resources.
     *
     * @return  boolean  True if identity successfully changed
     *
     * @since   1.7.0
     * @see     posix_setuid()
     */
    protected function changeIdentity()
    {
        // Get the group and user ids to set for the daemon.
        $uid = (int) $this->config->get('application_uid', 0);
        $gid = (int) $this->config->get('application_gid', 0);

        // Get the application process id file path.
        $file = $this->config->get('application_pid_file');

        // Change the user id for the process id file if necessary.
        if ($uid && (fileowner($file) != $uid) && (!@ chown($file, $uid))) {
            Log::add('Unable to change user ownership of the process id file.', Log::ERROR);

            return false;
        }

        // Change the group id for the process id file if necessary.
        if ($gid && (filegroup($file) != $gid) && (!@ chgrp($file, $gid))) {
            Log::add('Unable to change group ownership of the process id file.', Log::ERROR);

            return false;
        }

        // Set the correct home directory for the process.
        if ($uid && ($info = posix_getpwuid($uid)) && is_dir($info['dir'])) {
            system('export HOME="' . $info['dir'] . '"');
        }

        // Change the user id for the process necessary.
        if ($uid && (posix_getuid() != $uid) && (!@ posix_setuid($uid))) {
            Log::add('Unable to change user ownership of the process.', Log::ERROR);

            return false;
        }

        // Change the group id for the process necessary.
        if ($gid && (posix_getgid() != $gid) && (!@ posix_setgid($gid))) {
            Log::add('Unable to change group ownership of the process.', Log::ERROR);

            return false;
        }

        // Get the user and group information based on uid and gid.
        $user  = posix_getpwuid($uid);
        $group = posix_getgrgid($gid);

        Log::add('Changed daemon identity to ' . $user['name'] . ':' . $group['name'], Log::INFO);

        return true;
    }

    /**
     * Method to put the application into the background.
     *
     * @return  boolean
     *
     * @since   1.7.0
     * @throws  \RuntimeException
     */
    protected function daemonize()
    {
        // Is there already an active daemon running?
        if ($this->isActive()) {
            Log::add($this->name . ' daemon is still running. Exiting the application.', Log::EMERGENCY);

            return false;
        }

        // Reset Process Information
        $this->processId = 0;
        $this->running   = false;

        // Detach process!
        try {
            // Check if we should run in the foreground.
            if (!$this->input->get('f')) {
                // Detach from the terminal.
                $this->detach();
            } else {
                // Setup running values.
                $this->exiting = false;
                $this->running = true;

                // Set the process id.
                $this->processId = (int) posix_getpid();
                $this->parentId  = $this->processId;
            }
        } catch (\RuntimeException $e) {
            Log::add('Unable to fork.', Log::EMERGENCY);

            return false;
        }

        // Verify the process id is valid.
        if ($this->processId < 1) {
            Log::add('The process id is invalid; the fork failed.', Log::EMERGENCY);

            return false;
        }

        // Clear the umask.
        @ umask(0);

        // Write out the process id file for concurrency management.
        if (!$this->writeProcessIdFile()) {
            Log::add('Unable to write the pid file at: ' . $this->config->get('application_pid_file'), Log::EMERGENCY);

            return false;
        }

        // Attempt to change the identity of user running the process.
        if (!$this->changeIdentity()) {
            // If the identity change was required then we need to return false.
            if ($this->config->get('application_require_identity')) {
                Log::add('Unable to change process owner.', Log::CRITICAL);

                return false;
            }

            Log::add('Unable to change process owner.', Log::WARNING);
        }

        // Setup the signal handlers for the daemon.
        if (!$this->setupSignalHandlers()) {
            return false;
        }

        // Change the current working directory to the application working directory.
        @ chdir($this->config->get('application_directory'));

        return true;
    }

    /**
     * This is truly where the magic happens.  This is where we fork the process and kill the parent
     * process, which is essentially what turns the application into a daemon.
     *
     * @return  void
     *
     * @since   3.0.0
     * @throws  \RuntimeException
     */
    protected function detach()
    {
        Log::add('Detaching the ' . $this->name . ' daemon.', Log::DEBUG);

        // Attempt to fork the process.
        $pid = $this->fork();

        // If the pid is positive then we successfully forked, and can close this application.
        if ($pid) {
            // Add the log entry for debugging purposes and exit gracefully.
            Log::add('Ending ' . $this->name . ' parent process', Log::DEBUG);
            $this->close();
        } else {
            // We are in the forked child process.
            // Setup some protected values.
            $this->exiting = false;
            $this->running = true;

            // Set the parent to self.
            $this->parentId = $this->processId;
        }
    }

    /**
     * Method to fork the process.
     *
     * @return  integer  The child process id to the parent process, zero to the child process.
     *
     * @since   1.7.0
     * @throws  \RuntimeException
     */
    protected function fork()
    {
        // Attempt to fork the process.
        $pid = $this->pcntlFork();

        // If the fork failed, throw an exception.
        if ($pid === -1) {
            throw new \RuntimeException('The process could not be forked.');
        }

        if ($pid === 0) {
            // Update the process id for the child.
            $this->processId = (int) posix_getpid();
        } else {
            // Log the fork in the parent.
            // Log the fork.
            Log::add('Process forked ' . $pid, Log::DEBUG);
        }

        // Trigger the onFork event.
        $this->postFork();

        return $pid;
    }

    /**
     * Method to perform basic garbage collection and memory management in the sense of clearing the
     * stat cache.  We will probably call this method pretty regularly in our main loop.
     *
     * @return  void
     *
     * @since   1.7.0
     */
    protected function gc()
    {
        // Perform generic garbage collection.
        gc_collect_cycles();

        // Clear the stat cache so it doesn't blow up memory.
        clearstatcache();
    }

    /**
     * Method to attach the DaemonApplication signal handler to the known signals.  Applications
     * can override these handlers by using the pcntl_signal() function and attaching a different
     * callback method.
     *
     * @return  boolean
     *
     * @since   1.7.0
     * @see     pcntl_signal()
     */
    protected function setupSignalHandlers()
    {
        // We add the error suppression for the loop because on some platforms some constants are not defined.
        foreach (self::$signals as $signal) {
            // Ignore signals that are not defined.
            if (!\defined($signal) || !\is_int(\constant($signal)) || (\constant($signal) === 0)) {
                // Define the signal to avoid notices.
                Log::add('Signal "' . $signal . '" not defined. Defining it as null.', Log::DEBUG);
                \define($signal, null);

                // Don't listen for signal.
                continue;
            }

            // Attach the signal handler for the signal.
            if (!$this->pcntlSignal(\constant($signal), ['DaemonApplication', 'signal'])) {
                Log::add(\sprintf('Unable to reroute signal handler: %s', $signal), Log::EMERGENCY);

                return false;
            }
        }

        return true;
    }

    /**
     * Method to shut down the daemon and optionally restart it.
     *
     * @param   boolean  $restart  True to restart the daemon on exit.
     *
     * @return  void
     *
     * @since   1.7.0
     */
    protected function shutdown($restart = false)
    {
        // If we are already exiting, chill.
        if ($this->exiting) {
            return;
        }

        // If not, now we are.
        $this->exiting = true;

        // If we aren't already daemonized then just kill the application.
        if (!$this->running && !$this->isActive()) {
            Log::add('Process was not daemonized yet, just halting current process', Log::INFO);
            $this->close();
        }

        // Only read the pid for the parent file.
        if ($this->parentId == $this->processId) {
            // Read the contents of the process id file as an integer.
            $fp  = fopen($this->config->get('application_pid_file'), 'r');
            $pid = fread($fp, filesize($this->config->get('application_pid_file')));
            $pid = (int) $pid;
            fclose($fp);

            // Remove the process id file.
            @ unlink($this->config->get('application_pid_file'));

            // If we are supposed to restart the daemon we need to execute the same command.
            if ($restart) {
                $this->close(exec(implode(' ', $GLOBALS['argv']) . ' > /dev/null &'));
            } else {
                // If we are not supposed to restart the daemon let's just kill -9.
                passthru('kill -9 ' . $pid);
                $this->close();
            }
        }
    }

    /**
     * Method to write the process id file out to disk.
     *
     * @return  boolean
     *
     * @since   1.7.0
     */
    protected function writeProcessIdFile()
    {
        // Verify the process id is valid.
        if ($this->processId < 1) {
            Log::add('The process id is invalid.', Log::EMERGENCY);

            return false;
        }

        // Get the application process id file path.
        $file = $this->config->get('application_pid_file');

        if (empty($file)) {
            Log::add('The process id file path is empty.', Log::ERROR);

            return false;
        }

        // Make sure that the folder where we are writing the process id file exists.
        $folder = \dirname($file);

        if (!is_dir($folder) && !Folder::create($folder)) {
            Log::add('Unable to create directory: ' . $folder, Log::ERROR);

            return false;
        }

        // Write the process id file out to disk.
        if (!file_put_contents($file, $this->processId)) {
            Log::add('Unable to write process id file: ' . $file, Log::ERROR);

            return false;
        }

        // Make sure the permissions for the process id file are accurate.
        if (!chmod($file, 0644)) {
            Log::add('Unable to adjust permissions for the process id file: ' . $file, Log::ERROR);

            return false;
        }

        return true;
    }

    /**
     * Method to handle post-fork triggering of the onFork event.
     *
     * @return  void
     *
     * @since   3.0.0
     */
    protected function postFork()
    {
        // Trigger the onFork event.
        $this->dispatchEvent(
            'onFork',
            new DaemonForkEvent('onFork', ['subject' => $this])
        );
    }

    /**
     * Method to return the exit code of a terminated child process.
     *
     * @param   integer  $status  The status parameter is the status parameter supplied to a successful call to pcntl_waitpid().
     *
     * @return  integer  The child process exit code.
     *
     * @see     pcntl_wexitstatus()
     * @since   1.7.3
     */
    protected function pcntlChildExitStatus($status)
    {
        return pcntl_wexitstatus($status);
    }

    /**
     * Method to return the exit code of a terminated child process.
     *
     * @return  integer  On success, the PID of the child process is returned in the parent's thread
     *                   of execution, and a 0 is returned in the child's thread of execution. On
     *                   failure, a -1 will be returned in the parent's context, no child process
     *                   will be created, and a PHP error is raised.
     *
     * @see     pcntl_fork()
     * @since   1.7.3
     */
    protected function pcntlFork()
    {
        return pcntl_fork();
    }

    /**
     * Method to install a signal handler.
     *
     * @param   integer   $signal   The signal number.
     * @param   callable  $handler  The signal handler which may be the name of a user created function,
     *                              or method, or either of the two global constants SIG_IGN or SIG_DFL.
     * @param   boolean   $restart  Specifies whether system call restarting should be used when this
     *                              signal arrives.
     *
     * @return  boolean  True on success.
     *
     * @see     pcntl_signal()
     * @since   1.7.3
     */
    protected function pcntlSignal($signal, $handler, $restart = true)
    {
        return pcntl_signal($signal, $handler, $restart);
    }

    /**
     * Method to wait on or return the status of a forked child.
     *
     * @param   integer  &$status  Status information.
     * @param   integer  $options  If wait3 is available on your system (mostly BSD-style systems),
     *                             you can provide the optional options parameter.
     *
     * @return  integer  The process ID of the child which exited, -1 on error or zero if WNOHANG
     *                   was provided as an option (on wait3-available systems) and no child was available.
     *
     * @see     pcntl_wait()
     * @since   1.7.3
     */
    protected function pcntlWait(&$status, $options = 0)
    {
        return pcntl_wait($status, $options);
    }
}
