<?php
/** DomFramework
  * @package domframework
  * @author Dominique Fournier <dominique@fournier38.fr>
  */

require_once ("domframework/fork.php");
require_once ("domframework/file.php");

/** Manage a daemon.
  * Allow to start, stop, get status of a callable method
  */
class daemon
{
  /** Set the directory to store the PID of the daemon
    */
  private $runDir = "/var/run";

  /** The constructor check if /proc is mounted
    */
  public function __construct ()
  {
    if (! file_exists ("/proc"))
      throw new \Exception ("Can't manage daemon: /proc doesn't exists", 500);
  }

  /** Get/set the directory to store the PID of the daemon
    * @param string|null $val The directory
    */
  public function runDir ($val = null)
  {
    if ($val === null)
      return $this->runDir;
    if (! is_string ($val))
      throw new \Exception ("Can not set daemon runDir: not a string", 500);
    $this->runDir = "$val";
  }

  /** Start the callable method. The terminal is closed. All the displayed
    * messages from the child are silently dropped.
    * If some parameters are provided, the called child method will receive them
    * This function fork and return the child PID
    * @param string $name The name of daemon to start.
    * @param callable $callable The callback method to use in child
    * @param mixed|null $params The params to provide to child method
    * @return The child PID
    */
  public function start ($name, $callable, $params = array ())
  {
    $file = new \file ();
    if (! $file->is_writeable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not writeable",
        $this->runDir), 500);
    if (! $file->is_readable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not readable",
        $this->runDir), 500);
    if ($file->file_exists ($this->runDir."/$name.pid"))
    {
      $pid = trim ($file->file_get_contents ($this->runDir."/$name.pid"));
      if (file_exists ("/proc/$pid"))
        throw new \Exception (sprintf (
          "Can't start the daemon: already running with PID %d", $pid), 500);
    }
    $fork = new \fork ();
    $pid = $fork->startDetachedChild ($name, $callable, $params);
    file_put_contents ($this->runDir."/$name.pid", $pid);
    return $pid;
  }

  /** Stop a $name daemon
    * @param string $name The name of daemon to stop. The name must be the same
    * as the name used in the start method
    * @param integer $maxWaitStop The waiting maximum time after SIGTERM before
    * sending SIGKILL
    * @param integer $maxWaitKill The waiting maximum time after SIGKILL before
    * raising an error
    */
  public function stop ($name, $maxWaitStop = 3, $maxWaitKill = 3)
  {
    $file = new \file ();
    if (! $file->is_writeable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not writeable",
        $this->runDir), 500);
    if (! $file->is_readable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not readable",
        $this->runDir), 500);
    if (! $file->file_exists ($this->runDir."/$name.pid"))
      throw new \Exception (sprintf (
        "PID file %s not found : can't stop the daemon",
        $this->runDir."/$name.pid"), 500);
    $pid = $file->file_get_contents ($this->runDir."/$name.pid");
    if (! file_exists ("/proc/$pid"))
    {
      $file->unlink ($this->runDir."/$name.pid");
      throw new \Exception (
        "Can't stop daemon $name. There is no process with the PID $pid",
        500);
    }
    posix_kill ($pid, SIGTERM);
    usleep (10000);
    $startWait = time ();
    while (time () < $startWait + $maxWaitStop)
    {
      // If the child is zombie and is connected to me, pcntl_waitpid allow it
      // to be destroyed to close correctely the parent
      pcntl_waitpid ($pid, $status, WNOHANG);
      if (! file_exists ("/proc/$pid"))
      {
        $file->unlink ($this->runDir."/$name.pid");
        return true;
      }
      usleep (100000);
      echo ".";
    }
    posix_kill ($pid, SIGKILL);
    $startWait = time ();
    while (time () < $startWait + $maxWaitKill)
    {
      if (! file_exists ("/proc/$pid"))
      {
        $file->unlink ($this->runDir."/$name.pid");
        return true;
      }
      usleep (100000);
      echo "X";
    }
    throw new \Exception ("Can't stop and can't kill the process $pid", 500);
  }

  /** Status of a daemon
    * @param string $name The name of daemon to have status. The name must be
    * the same as the name used in the start method
    */
  public function status ($name)
  {
    $file = new \file ();
    if (! $file->is_writeable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not writeable",
        $this->runDir), 500);
    if (! $file->is_readable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not readable",
        $this->runDir), 500);
    if (! $file->file_exists ($this->runDir."/$name.pid"))
      return "The daemon is be stopped";
    $pid = $file->file_get_contents ($this->runDir."/$name.pid");
    if (! file_exists ("/proc/$pid"))
    {
      $file->unlink ($this->runDir."/$name.pid");
      return "The daemon is stopped, but the PID file was remaining. Delete";
    }
    return "The daemon is running on PID $pid\n";
  }

  /** Send a HUP Signal to the daemon
    * @param string $name The name of daemon to HUP. The name must be
    * the same as the name used in the start method
    */
  public function reload ($name)
  {
    $file = new \file ();
    if (! $file->is_writeable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not writeable",
        $this->runDir), 500);
    if (! $file->is_readable ($this->runDir))
      throw new \Exception (sprintf ("Run Directory '%s' is not readable",
        $this->runDir), 500);
    if (! $file->file_exists ($this->runDir."/$name.pid"))
      return "The daemon is be stopped";
    $pid = $file->file_get_contents ($this->runDir."/$name.pid");
    if (! file_exists ("/proc/$pid"))
    {
      $file->unlink ($this->runDir."/$name.pid");
      return "The daemon is stopped, but the PID file was remaining. Delete";
    }
    return posix_kill ($pid, SIGHUP);
  }
}