/**
 *  @file operator-idle.cc
 *  @brief  Operator for the IDLE command. Described in RFC2177 / June 1997.
 *  @author Andreas Aardal Hanssen
 *  @date 2002-2005
 */

#include "convert.h"
#include "depot.h"
#include "globals.h"
#include "iodevice.h"
#include "iofactory.h"
#include "mailbox.h"
#include "operators.h"
#include "pendingupdates.h"
#include "recursivedescent.h"
#include "session.h"

#include <iostream>
#include <string>

#include <unistd.h>

static bool directoryChangeNotification = false;

#ifdef HAVE_FNOTIFY  // GNU dependencies removed
#include <signal.h>
#include <stdio.h>

#include <fcntl.h>
#include <sys/select.h>
#include <sys/types.h>

void fnotifyEventHandler(int sig)
{
  directoryChangeNotification = true;
}
#endif

using namespace Binc;
using std::endl;

// Seconds between each poll. With FNOTIFY support, we can idle for 30
// minutes before timing out.
#ifdef HAVE_FNOTIFY
static const int POLLTIMEOUT = 30 * 60;
#else
static const int POLLTIMEOUT = 30;
#endif

IdleOperator::IdleOperator(void) {}

IdleOperator::~IdleOperator(void) {}

const std::string IdleOperator::getName(void) const
{
  return "IDLE";
}

int IdleOperator::getState(void) const
{
  return Session::SELECTED;
}

Operator::ProcessResult IdleOperator::process(Depot &depot, Request &command)
{
  Mailbox *mailbox = depot.getSelected();
  std::string mailboxDir = depot.mailboxToFilename(mailbox->getName());

#ifdef HAVE_FNOTIFY
  // Check for FNOTIFY support.
  bool waitForNotification = false;
  int newfd = open((mailboxDir + "/new").c_str(), O_RDONLY);
  int curfd = open((mailboxDir + "/cur").c_str(), O_RDONLY);

  // Watch for notifications for renames, deletes or creates.
  if (newfd && curfd && !fcntl(newfd, F_NOTIFY, DN_RENAME | DN_DELETE | DN_CREATE)
      && !fcntl(curfd, F_NOTIFY, DN_RENAME | DN_DELETE | DN_CREATE))
  {
    struct sigaction fnotifyAction;
    fnotifyAction.sa_handler = fnotifyEventHandler;
    sigemptyset(&fnotifyAction.sa_mask);
    fnotifyAction.sa_flags = SA_RESTART;
    sigaction(SIGUSR1, &fnotifyAction, 0);
    fcntl(newfd, F_SETSIG, SIGUSR1);
    fcntl(curfd, F_SETSIG, SIGUSR1);
    waitForNotification = true;
  }
#endif

  // when not using FNOTIFY, we need to check the session timeout.
  time_t startTime = time(nullptr);
#ifdef HAVE_FNOTIFY
  (void)startTime;  // removes a compile warning
#endif

  bincClient << "+ idling" << endl;
  bincClient.flush();

  // loop until the session times out or the client submits DONE.
  for (;;) {
    int maxfd = 0;
    fd_set readfds;
    FD_ZERO(&readfds);
    FD_SET(0, &readfds);

    // check for data from stdin. with FNOTIFY enabled, this select
    // will be interrupted by the notification signal.
    std::string input;
    struct timeval tv = {POLLTIMEOUT, 0};
    int ret = select(maxfd + 1, &readfds, nullptr, nullptr, &tv);

    // check if the select timed out.
    if (ret == 0) {
      Session &session = Session::getInstance();
#ifdef HAVE_FNOTIFY
      if (waitForNotification) {
        bincClient << "* BYE Timeout after " << session.timeout() << " seconds of inactivity." << endl;
        session.setState(Session::LOGOUT);
        close(newfd);
        close(curfd);
        return NOTHING;
      } else
#endif
          if (time(nullptr) > startTime + IDLE_TIMEOUT)
      {
        bincClient << "* BYE Timeout after " << IDLE_TIMEOUT << " seconds of inactivity." << endl;
        session.setState(Session::LOGOUT);
        return NOTHING;
      }
    }

    // unless the select failed, attempt to read client input.
    if (ret > 0 && FD_ISSET(0, &readfds)) {
      if (bincClient.readStr(&input) == false) {
        break;
      } else {
        uppercase(input);
        trim(input);
        if (input == "DONE") {
          break;
        } else {
          bincClient << "* BAD Syntax error: \"" << input << "\"" << endl;
          bincClient.flush();
          continue;
        }
      }
    }

    // at this point, we either got a directory change notification,
    // or the select simply timed out, in which case we poll.
    bool scanForChanges = false;
#ifdef HAVE_FNOTIFY
    if (directoryChangeNotification)
      scanForChanges = true;
    else if (!waitForNotification)
#endif
      scanForChanges = true;

    if (scanForChanges) {
      if (directoryChangeNotification) {
        // sleep the magic 1 second to ensure that anything that
        // arrived in new/ the last second isn't skipped by
        // pendingUpdates' scan.
        sleep(1);
      }

      // scan for changes in the mailbox and report to the client.
      if (!pendingUpdates(mailbox,
                          PendingUpdates::EXPUNGE | PendingUpdates::EXISTS | PendingUpdates::RECENT
                              | PendingUpdates::FLAGS,
                          true))
      {
        Session &session = Session::getInstance();
        bincClient << "* NO " << session.getLastError() << endl;
        bincWarning << "when scanning mailbox: " << session.getLastError() << endl;

#ifdef HAVE_FNOTIFY
        close(newfd);
        close(curfd);
#endif
        return NO;
      }

#ifdef HAVE_FNOTIFY
      // if FNOTIFY is enabled, set it up again.
      if (waitForNotification) {
        directoryChangeNotification = false;

        // set up F_NOTIFY again.
        if (!fcntl(newfd, F_NOTIFY, DN_MODIFY | DN_RENAME | DN_DELETE | DN_CREATE)
            && !fcntl(curfd, F_NOTIFY, DN_MODIFY | DN_RENAME | DN_DELETE | DN_CREATE))
        {
          struct sigaction fnotifyAction;
          fnotifyAction.sa_handler = fnotifyEventHandler;
          sigemptyset(&fnotifyAction.sa_mask);
          fnotifyAction.sa_flags = SA_RESTART;
          sigaction(SIGUSR1, &fnotifyAction, 0);
        } else {
          waitForNotification = false;
        }
      }
#endif
      bincClient.flush();
    }
  }

#ifdef HAVE_FNOTIFY
  close(newfd);
  close(curfd);
#endif
  return OK;
}

Operator::ParseResult IdleOperator::parse(Request &c_in) const
{
  Session &session = Session::getInstance();

  if (c_in.getUidMode()) return REJECT;

  Operator::ParseResult res;
  if ((res = expectCRLF()) != ACCEPT) {
    session.setLastError("Expected CRLF after IDLE");
    return res;
  }

  c_in.setName("IDLE");
  return ACCEPT;
}