/*
 * Copyright (C) 2008 Emweb bvba, Kessel-Lo, Belgium.
 *
 * See the LICENSE file for terms of use.
 */

#include <fstream>

#ifdef WT_HAVE_GNU_REGEX
#include <regex.h>
#else
#include <boost/regex.hpp>
#endif // WT_HAVE_GNU_REGEX

#include <boost/lexical_cast.hpp>
#include <boost/algorithm/string.hpp>

#ifdef WT_THREADED
#include <boost/bind.hpp>
#endif // WT_THREADED

#include "Wt/Utils"
#include "Wt/WApplication"
#include "Wt/WEvent"
#include "Wt/WRandom"
#include "Wt/WResource"
#include "Wt/WServer"
#include "Wt/WSocketNotifier"

#include "Configuration.h"
#include "CgiParser.h"
#include "WebController.h"
#include "WebRequest.h"
#include "WebSession.h"
#include "TimeUtil.h"
#include "WebUtils.h"

#ifdef HAVE_GRAPHICSMAGICK
#include <magick/api.h>
#endif

#ifndef WT_HAVE_POSIX_FILEIO
// boost bug workaround: see WebController constructor
#include <boost/filesystem.hpp>
#endif

#include <csignal>

namespace {

bool matchesPath(const std::string& path, const std::string& prefix)
{
  if (boost::starts_with(path, prefix)) {
    unsigned prefixLength = prefix.length();

    if (path.length() > prefixLength) {
      char next = path[prefixLength];

      if (next == '/')
	return true; 
    } else
      return true;
  }

  return false;
}

}

namespace Wt {

LOGGER("WebController");

WebController::WebController(WServer& server,
			     const std::string& singleSessionId,
			     bool autoExpire)
  : conf_(server.configuration()),
    singleSessionId_(singleSessionId),
    autoExpire_(autoExpire),
    plainHtmlSessions_(0),
    ajaxSessions_(0),
#ifdef WT_THREADED
    socketNotifier_(this),
#endif // WT_THREADED
    server_(server)
{
  CgiParser::init();

#ifndef WT_DEBUG_JS
  WObject::seedId(WRandom::get());
#else
  WObject::seedId(0);
#endif

  redirectSecret_ = WRandom::generateId(32);

#ifdef HAVE_GRAPHICSMAGICK
  InitializeMagick(0);
#endif

#ifndef WT_HAVE_POSIX_FILEIO
  // attempted workaround for:
  // https://svn.boost.org/trac/boost/ticket/6320
  // https://svn.boost.org/trac/boost/ticket/4889
  // https://svn.boost.org/trac/boost/ticket/6690
  // https://svn.boost.org/trac/boost/ticket/6737
  // Invoking the path constructor here should create the global variables
  // in boost.filesystem before the threads are started.
  boost::filesystem::path bugFixFilePath("please-initialize-globals");
#endif

  start();
}

WebController::~WebController()
{
#ifdef HAVE_GRAPHICSMAGICK
  DestroyMagick();
#endif
}

void WebController::start()
{
  running_ = true;
}

void WebController::shutdown()
{
  std::vector<boost::shared_ptr<WebSession> > sessionList;

  {
#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

    running_ = false;

    LOG_INFO_S(&server_, "shutdown: stopping sessions.");

    for (SessionMap::iterator i = sessions_.begin(); i != sessions_.end(); ++i)
      sessionList.push_back(i->second);

    sessions_.clear();

    ajaxSessions_ = 0;
    plainHtmlSessions_ = 0;
  }

  for (unsigned i = 0; i < sessionList.size(); ++i) {
    boost::shared_ptr<WebSession> session = sessionList[i];
    WebSession::Handler handler(session, WebSession::Handler::TakeLock);
    session->expire();
  }
}

Configuration& WebController::configuration()
{
  return conf_;
}

int WebController::sessionCount() const
{
  return sessions_.size();
}

std::vector<std::string> WebController::sessions()
{
#ifdef WT_THREADED
  boost::recursive_mutex::scoped_lock lock(mutex_);
#endif
  std::vector<std::string> sessionIds;
  for (SessionMap::const_iterator i = sessions_.begin(); i != sessions_.end(); ++i) {
    sessionIds.push_back(i->first);
  }
  return sessionIds;
}

bool WebController::expireSessions()
{
  std::vector<boost::shared_ptr<WebSession> > toExpire;

  bool result;
  {
    Time now;

#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

    for (SessionMap::iterator i = sessions_.begin(); i != sessions_.end();) {
      boost::shared_ptr<WebSession> session = i->second;

      int diff = session->expireTime() - now;

      if (diff < 1000 && configuration().sessionTimeout() != -1) {
	if (session->shouldDisconnect()) {
	  if (session->app()->connected_) {
	    session->app()->connected_ = false;
	    LOG_INFO_S(session, "timeout: disconnected");
	  }
	  ++i;
	} else {
	  toExpire.push_back(session);

	  if (session->env().ajax())
	    --ajaxSessions_;
	  else
	    --plainHtmlSessions_;

	  sessions_.erase(i++);
	}
      } else
	++i;
    }

    result = !sessions_.empty();
  }

  for (unsigned i = 0; i < toExpire.size(); ++i) {
    boost::shared_ptr<WebSession> session = toExpire[i];

    LOG_INFO_S(session, "timeout: expiring");
    WebSession::Handler handler(session, WebSession::Handler::TakeLock);
    session->expire();
  }

  toExpire.clear();

  if (configuration().singleSession()) {
#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED
    if (sessions_.size() == 0) {
      server_.scheduleStop();
    }
  }

  return result;
}

void WebController::addSession(boost::shared_ptr<WebSession> session)
{
#ifdef WT_THREADED
  boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

  sessions_[session->sessionId()] = session;
}

void WebController::removeSession(const std::string& sessionId)
{
#ifdef WT_THREADED
  boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

  LOG_INFO("Removing session " << sessionId);

  SessionMap::iterator i = sessions_.find(sessionId);
  if (i != sessions_.end()) {
    if (i->second->env().ajax())
      --ajaxSessions_;
    else
      --plainHtmlSessions_;
    sessions_.erase(i);
  }

  if (configuration().singleSession() && sessions_.size() == 0) {
    server_.scheduleStop();
  }
}

std::string WebController::appSessionCookie(const std::string& url)
{
  return Utils::urlEncode(url);
}

std::string WebController::sessionFromCookie(const char *cookies,
					     const std::string& scriptName,
					     int sessionIdLength)
{
  if (!cookies)
    return std::string();

  std::string cookieName = appSessionCookie(scriptName);

#ifndef WT_HAVE_GNU_REGEX
  boost::regex
    cookieSession_e(".*\\Q" + cookieName
		    + "\\E=\"?([a-zA-Z0-9]{"
		    + boost::lexical_cast<std::string>(sessionIdLength)
		    + "})\"?.*");

  boost::smatch what;
  std::string cookiesAsStdString(cookies);
  if (boost::regex_match(cookiesAsStdString, what, cookieSession_e))
    return what[1];
  else
    return std::string();
#else
  std::string cookieSession_ep
    = cookieName + "=\"\\?\\([a-zA-Z0-9]\\{"
    + boost::lexical_cast<std::string>(sessionIdLength) + "\\}\\)\"\\?";
  regex_t cookieSession_e;
  regcomp(&cookieSession_e, cookieSession_ep.c_str(), 0);
  regmatch_t pmatch[2];
  int res = regexec(&cookieSession_e, cookies.c_str(), 2, pmatch, 0);
  regfree(&cookieSession_e);

  if (res == 0) {
    return cookies.substr(pmatch[1].rm_so,
			  pmatch[1].rm_eo - pmatch[1].rm_so);
  } else
    return std::string();
#endif
}

#ifdef WT_THREADED
WebController::SocketNotifierMap&
WebController::socketNotifiers(WSocketNotifier::Type type)
{
  switch (type) {
  case WSocketNotifier::Read:
    return socketNotifiersRead_;
  case WSocketNotifier::Write:
    return socketNotifiersWrite_;
  case WSocketNotifier::Exception:
  default: // to avoid return warning
    return socketNotifiersExcept_;
  }
}
#endif // WT_THREADED

void WebController::socketSelected(int descriptor, WSocketNotifier::Type type)
{
#ifdef WT_THREADED
  /*
   * Find notifier, extract session Id
   */
  std::string sessionId;
  {
    boost::recursive_mutex::scoped_lock lock(notifierMutex_);

    SocketNotifierMap &notifiers = socketNotifiers(type);
    SocketNotifierMap::iterator k = notifiers.find(descriptor);

    if (k == notifiers.end()) {
      LOG_ERROR_S(&server_, "socketSelected(): socket notifier should have been "
		  "cancelled?");

      return;
    } else {
      sessionId = k->second->sessionId();
    }
  }

  server_.post(sessionId, boost::bind(&WebController::socketNotify,
				      this, descriptor, type));
#endif // WT_THREADED
}

#ifdef WT_THREADED
void WebController::socketNotify(int descriptor, WSocketNotifier::Type type)
{
  WSocketNotifier *notifier = 0;
  {
    boost::recursive_mutex::scoped_lock lock(notifierMutex_);
    SocketNotifierMap &notifiers = socketNotifiers(type);
    SocketNotifierMap::iterator k = notifiers.find(descriptor);	
    if (k != notifiers.end()) {
      notifier = k->second;
      notifiers.erase(k);
    }
  }

  if (notifier)
    notifier->notify();
}
#endif // WT_THREADED

void WebController::addSocketNotifier(WSocketNotifier *notifier)
{
#ifdef WT_THREADED
  {
    boost::recursive_mutex::scoped_lock lock(notifierMutex_);
    socketNotifiers(notifier->type())[notifier->socket()] = notifier;
  }

  switch (notifier->type()) {
  case WSocketNotifier::Read:
    socketNotifier_.addReadSocket(notifier->socket());
    break;
  case WSocketNotifier::Write:
    socketNotifier_.addWriteSocket(notifier->socket());
    break;
  case WSocketNotifier::Exception:
    socketNotifier_.addExceptSocket(notifier->socket());
    break;
  }
#endif // WT_THREADED
}

void WebController::removeSocketNotifier(WSocketNotifier *notifier)
{
#ifdef WT_THREADED
  switch (notifier->type()) {
  case WSocketNotifier::Read:
    socketNotifier_.removeReadSocket(notifier->socket());
    break;
  case WSocketNotifier::Write:
    socketNotifier_.removeWriteSocket(notifier->socket());
    break;
  case WSocketNotifier::Exception:
    socketNotifier_.removeExceptSocket(notifier->socket());
    break;
  }

  boost::recursive_mutex::scoped_lock lock(notifierMutex_);

  SocketNotifierMap &notifiers = socketNotifiers(notifier->type());
  SocketNotifierMap::iterator i = notifiers.find(notifier->socket());
  if (i != notifiers.end())
    notifiers.erase(i);
#endif // WT_THREADED
}

bool WebController::requestDataReceived(WebRequest *request,
					boost::uintmax_t current,
					boost::uintmax_t total)
{
#ifdef WT_THREADED
  boost::mutex::scoped_lock lock(uploadProgressUrlsMutex_);
#endif // WT_THREADED

  if (!running_)
    return false;

  if (uploadProgressUrls_.find(request->queryString())
      != uploadProgressUrls_.end()) {
#ifdef WT_THREADED
    lock.unlock();
#endif // WT_THREADED

    CgiParser cgi(conf_.maxRequestSize());

    try {
      cgi.parse(*request, CgiParser::ReadHeadersOnly);
    } catch (std::exception& e) {
      LOG_ERROR_S(&server_, "could not parse request: " << e.what());
      return false;
    }

    const std::string *wtdE = request->getParameter("wtd");
    if (!wtdE)
      return false;

    std::string sessionId = *wtdE;

    ApplicationEvent event(sessionId,
			   boost::bind(&WebController::updateResourceProgress,
				       this, request, current, total));

    if (handleApplicationEvent(event))
      return !request->postDataExceeded();
    else
      return false;
  }

  return true;
}

void WebController::updateResourceProgress(WebRequest *request,
					   boost::uintmax_t current,
					   boost::uintmax_t total)
{
  WebSession::Handler::instance()->setRequest(request, (WebResponse *)request);
  WApplication *app = WApplication::instance();

  const std::string *requestE = request->getParameter("request");

  WResource *resource = 0;
  if (!requestE && !request->pathInfo().empty())
    resource = app->decodeExposedResource("/path/" + request->pathInfo());

  if (!resource) {
    const std::string *resourceE = request->getParameter("resource");
    resource = app->decodeExposedResource(*resourceE);
  }

  if (resource)
    resource->dataReceived().emit(current, total);
}

bool WebController::handleApplicationEvent(const ApplicationEvent& event)
{
  /*
   * This should always be run from within a virgin thread of the
   * thread-pool
   */
  assert(!WebSession::Handler::instance());

  /*
   * Find session (and guard it against deletion)
   */
  boost::shared_ptr<WebSession> session;
  {
#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

    SessionMap::iterator i = sessions_.find(event.sessionId);

    if (i != sessions_.end() && !i->second->dead())
      session = i->second;
  }

  if (!session) {
    if (event.fallbackFunction)
      event.fallbackFunction();
    return false;
  } else
    session->queueEvent(event);

  /*
   * Try to take the session lock now to propagate the event to the
   * application.
   */
  {
    WebSession::Handler handler(session, WebSession::Handler::TryLock);
  }

  return true;
}

void WebController::addUploadProgressUrl(const std::string& url)
{
#ifdef WT_THREADED
  boost::mutex::scoped_lock lock(uploadProgressUrlsMutex_);
#endif // WT_THREADED

  uploadProgressUrls_.insert(url.substr(url.find("?") + 1));
}

void WebController::removeUploadProgressUrl(const std::string& url)
{
#ifdef WT_THREADED
  boost::mutex::scoped_lock lock(uploadProgressUrlsMutex_);
#endif // WT_THREADED

  uploadProgressUrls_.erase(url.substr(url.find("?") + 1));
}

std::string WebController::computeRedirectHash(const std::string& url)
{
  return Utils::base64Encode(Utils::md5(redirectSecret_ + url));
}

void WebController::handleRequest(WebRequest *request)
{
  if (!running_) {
    request->setStatus(500);
    request->flush();
    return;
  }

  if (!request->entryPoint_) {
    request->entryPoint_ = getEntryPoint(request);
    if (!request->entryPoint_) {
      request->setStatus(404);
      request->flush();
      return;
    }
  }

  CgiParser cgi(conf_.maxRequestSize());

  try {
    cgi.parse(*request, conf_.needReadBodyBeforeResponse()
	      ? CgiParser::ReadBodyAnyway
	      : CgiParser::ReadDefault);
  } catch (std::exception& e) {
    LOG_ERROR_S(&server_, "could not parse request: " << e.what());

    request->setContentType("text/html");
    request->out()
      << "<title>Error occurred.</title>"
      << "<h2>Error occurred.</h2>"
         "Error parsing CGI request: " << e.what() << std::endl;

    request->flush(WebResponse::ResponseDone);
    return;
  }

  if (request->entryPoint_->type() == StaticResource) {
    request
      ->entryPoint_->resource()->handle(request, (WebResponse *)request);
    return;
  }

  const std::string *requestE = request->getParameter("request");
  if (requestE && *requestE == "redirect") {
    const std::string *urlE = request->getParameter("url");
    const std::string *hashE = request->getParameter("hash");

    if (urlE && hashE) {
      if (*hashE != computeRedirectHash(*urlE))
	hashE = 0;
    }

    if (urlE && hashE) {
      request->setRedirect(*urlE);
    } else {
      request->setContentType("text/html");
      request->out()
	<< "<title>Error occurred.</title>"
	<< "<h2>Error occurred.</h2><p>Invalid redirect.</p>" << std::endl;
    }

    request->flush(WebResponse::ResponseDone);
    return;
  }

  std::string sessionId;

  /*
   * Get session from request.
   */
  const std::string *wtdE = request->getParameter("wtd");

  if (conf_.sessionTracking() == Configuration::CookiesURL
      && !conf_.reloadIsNewSession())
    sessionId = sessionFromCookie(request->headerValue("Cookie"),
				  request->scriptName(),
				  conf_.sessionIdLength());

  if (sessionId.empty() && wtdE)
    sessionId = *wtdE;

  boost::shared_ptr<WebSession> session;
  {
#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

    if (!singleSessionId_.empty() && sessionId != singleSessionId_) {
      if (conf_.persistentSessions()) {
	// This may be because of a race condition in the filesystem:
	// the session file is renamed in generateNewSessionId() but
	// still a request for an old session may have arrived here
	// while this was happening.
	//
	// If it is from the old app, We should be sent a reload signal,
	// this is what will be done by a new session (which does not create
	// an application).
	//
	// If it is another request to take over the persistent session,
	// it should be handled by the persistent session. We can distinguish
	// using the type of the request
	LOG_INFO_S(&server_, 
		   "persistent session requested Id: " << sessionId << ", "
		   << "persistent Id: " << singleSessionId_);

	if (sessions_.empty() || strcmp(request->requestMethod(), "GET") == 0)
	  sessionId = singleSessionId_;
      } else
	sessionId = singleSessionId_;
    }

    SessionMap::iterator i = sessions_.find(sessionId);

    if (i == sessions_.end() || i->second->dead()) {
      try {
	if (singleSessionId_.empty()) {
	  do {
	    sessionId = conf_.generateSessionId();
	    if (!conf_.registerSessionId(std::string(), sessionId))
	      sessionId.clear();
	  } while (sessionId.empty());
	}

	std::string favicon = request->entryPoint_->favicon();
	if (favicon.empty())
	  conf_.readConfigurationProperty("favicon", favicon);

	session.reset(new WebSession(this, sessionId,
				     request->entryPoint_->type(),
				     favicon, request));

	if (configuration().sessionTracking() == Configuration::CookiesURL)
	  request->addHeader("Set-Cookie",
			     appSessionCookie(request->scriptName())
			     + "=" + sessionId + "; Version=1;"
			     + " Path=" + session->env().deploymentPath()
			     + "; httponly;");

	sessions_[sessionId] = session;
	++plainHtmlSessions_;
      } catch (std::exception& e) {
	LOG_ERROR_S(&server_, "could not create new session: " << e.what());
	request->flush(WebResponse::ResponseDone);
	return;
      }
    } else {
      session = i->second;
    }
  }

  bool handled = false;
  {
    WebSession::Handler handler(session, *request, *(WebResponse *)request);

    if (!session->dead()) {
      handled = true;
      session->handleRequest(handler);
    }
  }

  if (session->dead())
    removeSession(sessionId);

  session.reset();

  if (autoExpire_)
    expireSessions();

  if (!handled)
    handleRequest(request);
}

WApplication *WebController::doCreateApplication(WebSession *session)
{
  const EntryPoint *ep 
    = WebSession::Handler::instance()->request()->entryPoint_;

  return ep->appCallback()(session->env());
}

const EntryPoint *WebController::getEntryPoint(WebRequest *request)
{
  const std::string& scriptName = request->scriptName();
  const std::string& pathInfo = request->pathInfo();

  // Only one default entry point.
  if (conf_.entryPoints().size() == 1
      && conf_.entryPoints()[0].path().empty())
    return &conf_.entryPoints()[0];

  // Multiple entry points.
  int bestMatch = -1;
  std::size_t bestLength = 0;

  for (unsigned i = 0; i < conf_.entryPoints().size(); ++i) {
    const Wt::EntryPoint& ep = conf_.entryPoints()[i];

    if (ep.path().empty()) {
      if (bestLength == 0)
	bestMatch = i;
    } else {
      if (ep.path().length() > bestLength) {
	if (matchesPath(scriptName + pathInfo, ep.path()) ||
	    matchesPath(pathInfo, ep.path())) {
	  bestLength = ep.path().length();
	  bestMatch = i;
	}
      }
    }
  }

  if (bestMatch >= 0)
    return &conf_.entryPoints()[bestMatch];
  else
    return 0;
}

std::string
WebController::generateNewSessionId(boost::shared_ptr<WebSession> session)
{
#ifdef WT_THREADED
  boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED  

  std::string newSessionId;
  do {
    newSessionId = conf_.generateSessionId();
    if (!conf_.registerSessionId(session->sessionId(), newSessionId))
      newSessionId.clear();
  } while (newSessionId.empty());

  sessions_[newSessionId] = session;

  SessionMap::iterator i = sessions_.find(session->sessionId());
  sessions_.erase(i);

  if (!singleSessionId_.empty())
    singleSessionId_ = newSessionId;

  return newSessionId;
}

void WebController::newAjaxSession()
{
#ifdef WT_THREADED
  boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED  

  --plainHtmlSessions_;
  ++ajaxSessions_;
}

bool WebController::limitPlainHtmlSessions()
{
  if (conf_.maxPlainSessionsRatio() > 0) {
#ifdef WT_THREADED
    boost::recursive_mutex::scoped_lock lock(mutex_);
#endif // WT_THREADED

    if (plainHtmlSessions_ + ajaxSessions_ > 20)
      return plainHtmlSessions_ > conf_.maxPlainSessionsRatio()
	* (ajaxSessions_ + plainHtmlSessions_);
    else
      return false;
  } else
    return false;
}

}
