// Filename: p3dInstanceManager.cxx
// Created by:  drose (29May09)
//
////////////////////////////////////////////////////////////////////
//
// PANDA 3D SOFTWARE
// Copyright (c) Carnegie Mellon University.  All rights reserved.
//
// All use of this software is subject to the terms of the revised BSD
// license.  You should have received a copy of this license along
// with this source code in a file named "LICENSE."
//
////////////////////////////////////////////////////////////////////

#include "p3dInstanceManager.h"
#include "p3dInstance.h"
#include "p3dSession.h"
#include "p3dPackage.h"

P3DInstanceManager *P3DInstanceManager::_global_ptr;

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::Constructor
//       Access: Private
//  Description: 
////////////////////////////////////////////////////////////////////
P3DInstanceManager::
P3DInstanceManager() {
  cerr << "creating instance manager\n";
  _unique_session_index = 0;

  _request_seq = 0;
#ifdef _WIN32
  _request_ready = CreateEvent(NULL, false, false, NULL);
#else
  INIT_LOCK(_request_ready_lock);
  pthread_cond_init(&_request_ready_cvar, NULL);
#endif

  _command_instance = NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::Destructor
//       Access: Private
//  Description: 
////////////////////////////////////////////////////////////////////
P3DInstanceManager::
~P3DInstanceManager() {
  // Actually, this destructor is never called, since this is a global
  // object that never gets deleted.

  assert(_instances.empty());
  assert(_sessions.empty());

  delete _command_instance;

#ifdef _WIN32
  CloseHandle(_request_ready);
#else
  DESTROY_LOCK(_request_ready_lock);
  pthread_cond_destroy(&_request_ready_cvar);
#endif
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::initialize
//       Access: Public
//  Description: Called by the host at application startup.  It
//               returns true if the DLL is successfully initialized,
//               false if it should be immediately shut down and
//               redownloaded.
////////////////////////////////////////////////////////////////////
bool P3DInstanceManager::
initialize() {
  _root_dir = "c:/cygwin/home/drose/p3ddir";
  _download_url = "http://10.196.143.118/~drose/";
  return true;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::create_instance
//       Access: Public
//  Description: Returns a newly-allocated P3DInstance with the
//               indicated startup information.
////////////////////////////////////////////////////////////////////
P3DInstance *P3DInstanceManager::
create_instance(P3D_request_ready_func *func,
                const string &p3d_filename, 
                P3D_window_type window_type,
                int win_x, int win_y,
                int win_width, int win_height,
                P3D_window_handle parent_window,
                const P3D_token tokens[], size_t num_tokens) {
  P3DInstance *inst = new P3DInstance(func, p3d_filename, 
                                      window_type, win_x, win_y,
                                      win_width, win_height, parent_window,
                                      tokens, num_tokens);
  _instances.insert(inst);

  P3DSession *session;
  Sessions::iterator si = _sessions.find(inst->get_session_key());
  if (si == _sessions.end()) {
    session = new P3DSession(inst);
    bool inserted = _sessions.insert(Sessions::value_type(session->get_session_key(), session)).second;
    assert(inserted);
  } else {
    session = (*si).second;
  }

  session->start_instance(inst);

  return inst;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::finish_instance
//       Access: Public
//  Description: Terminates and removes a previously-returned
//               instance.
////////////////////////////////////////////////////////////////////
void P3DInstanceManager::
finish_instance(P3DInstance *inst) {
  assert(inst != _command_instance);

  Instances::iterator ii;
  ii = _instances.find(inst);
  assert(ii != _instances.end());
  _instances.erase(ii);

  Sessions::iterator si = _sessions.find(inst->get_session_key());
  assert(si != _sessions.end());
  P3DSession *session = (*si).second;
  session->terminate_instance(inst);

  // If that was the last instance in this session, terminate the
  // session.
  if (session->get_num_instances() == 0) {
    _sessions.erase(session->get_session_key());
    delete session;
  }

  delete inst;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::check_request
//       Access: Public
//  Description: If a request is currently pending on any instance,
//               returns its pointer.  Otherwise, returns NULL.
////////////////////////////////////////////////////////////////////
P3DInstance *P3DInstanceManager::
check_request() {
  Instances::iterator ii;
  for (ii = _instances.begin(); ii != _instances.end(); ++ii) {
    P3DInstance *inst = (*ii);
    if (inst->has_request()) {
      return inst;
    }
  }

  if (_command_instance->has_request()) {
    return _command_instance;
  }

  return NULL;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::wait_request
//       Access: Public
//  Description: Does not return until a request is pending on some
//               instance, or until no instances remain.  Use
//               check_request to retrieve the pending request.  Due
//               to the possibility of race conditions, it is possible
//               for this function to return when there is in fact no
//               request pending (another thread may have extracted
//               the request first).
////////////////////////////////////////////////////////////////////
void P3DInstanceManager::
wait_request() {
  int seq = _request_seq;

  while (true) {
    if (check_request() != (P3DInstance *)NULL) {
      return;
    }
    if (_instances.empty()) {
      return;
    }
    
    // No pending requests; go to sleep.
#ifdef _WIN32
    if (seq == _request_seq) {
      WaitForSingleObject(_request_ready, INFINITE);
    }
#else
    ACQUIRE_LOCK(_request_ready_lock);
    if (seq == _request_seq) {
      pthread_cond_wait(&_request_ready_cvar, &_request_ready_lock);
    }
    RELEASE_LOCK(_request_ready_lock);
#endif
    seq = _request_seq;
  }
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::get_package
//       Access: Public
//  Description: Returns a (possibly shared) pointer to the indicated
//               package.
////////////////////////////////////////////////////////////////////
P3DPackage *P3DInstanceManager::
get_package(const string &package_name, const string &package_version) {
  string key = package_name + "_" + package_version;
  Packages::iterator pi = _packages.find(key);
  if (pi != _packages.end()) {
    return (*pi).second;
  }

  P3DPackage *package = new P3DPackage(package_name, package_version);
  bool inserted = _packages.insert(Packages::value_type(key, package)).second;
  assert(inserted);

  return package;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::get_unique_session_index
//       Access: Public
//  Description: Returns a number used to uniquify the session_key for
//               different instances.  This number is guaranteed to be
//               different at each call.
////////////////////////////////////////////////////////////////////
int P3DInstanceManager::
get_unique_session_index() {
  ++_unique_session_index;
  return _unique_session_index;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::signal_request_ready
//       Access: Public
//  Description: May be called in any thread to indicate that a new
//               P3D_request is available in some instance.  This will
//               wake up a sleeping wait_request() call, if any.
////////////////////////////////////////////////////////////////////
void P3DInstanceManager::
signal_request_ready() {
#ifdef _WIN32
  ++_request_seq;
  SetEvent(_request_ready);
#else
  ACQUIRE_LOCK(_request_ready_lock);
  ++_request_seq;
  pthread_cond_signal(&_request_ready_cvar);
  RELEASE_LOCK(_request_ready_lock);
#endif
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::get_global_ptr
//       Access: Public, Static
//  Description: 
////////////////////////////////////////////////////////////////////
P3DInstanceManager *P3DInstanceManager::
get_global_ptr() {
  if (_global_ptr == NULL) {
    _global_ptr = new P3DInstanceManager;
    _global_ptr->create_command_instance();
  }
  return _global_ptr;
}

////////////////////////////////////////////////////////////////////
//     Function: P3DInstanceManager::create_command_instance;
//       Access: Private
//  Description: Create a command instance.  This is used to handle
//               requests that have nothing to do with any particular
//               host-created instance.
////////////////////////////////////////////////////////////////////
void P3DInstanceManager::
create_command_instance() {
  P3D_window_handle dummy_handle;
  _command_instance = 
    new P3DInstance(NULL, "", P3D_WT_hidden, 0, 0, 0, 0, 
                    dummy_handle, NULL, 0);
}