// src/backend/python_policy_manager.cc - Copyright 2005, 2006, University
//               of Padova, dept. of Pure and Applied
//               Mathematics
//
// This file is part of SGPEMv2.
//
// This is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// SGPEMv2 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with SGPEMv2; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

#include "python_policy_manager.hh"

#include <Python.h>
#include <glibmm/timer.h>

#include <string>
#include <cassert>
#include <iostream>
#include <unistd.h>
using namespace sgpem;

//static object
PythonPolicyManager* PythonPolicyManager::_instance = NULL;

PythonPolicyManager::PythonPolicyManager()
  : _initialized(false)
{
  PyEval_InitThreads();
}

PythonPolicyManager* const
PythonPolicyManager::get_instance()
{
  if(!_instance)
    _instance = new PythonPolicyManager();
  return _instance;
}

Policy&
PythonPolicyManager::get_policy()
{
  // FIXME : assumes that _python_policy is always != NULL!
  return *_python_policy;
}

void
PythonPolicyManager::init()
{
  if(_initialized)
    Py_Finalize();
  
  Py_Initialize();
  _initialized = true;
  
  // The following line is ugly, but necessary if we use 
  // non-standard installation directories. Theoretically,
  // it should be up to the user to set correct 
  // environment variables. 
  // FIXME: find better way to achieve this.
  
  PyRun_SimpleString("import sys\n"
		     "sys.path[:0] = [ '" MODDIR "', '" PYCDIR "' ]\n");

  // Okay, here we go.
  // Black magic at work. 

  // FIXME : Hardcoded policy name
  char* policy_name = "fcfs";
  PyObject* pLoadmeStr = PyString_FromString(policy_name);
  PyObject* pUserPolicyModule = PyImport_Import(pLoadmeStr);
  Py_DECREF(pLoadmeStr);
  
  if( !pUserPolicyModule ) 
  {
      PyErr_Print(); // Error in import
      // FIXME : don't exit abruptly, but fall back gracefully
      exit(-1);
  }

  // Dictionary with defined ``symbols'' for .pyc file
  PyObject* pUserPolicyDict = PyModule_GetDict(pUserPolicyModule);
  assert(pUserPolicyDict);

  // Loads ScriptAdapter module and get its dictionary
  pLoadmeStr = PyString_FromString("ScriptAdapter");
  PyObject* pScriptAdapterModule = PyImport_Import(pLoadmeStr);
  Py_DECREF(pLoadmeStr);
  assert(pScriptAdapterModule);
  PyObject* pScriptAdapterDict = PyModule_GetDict(pScriptAdapterModule);
  assert(pScriptAdapterDict);
  
  // Now takes the user-defined policy class from pUserPolicyDict
  PyObject* pPolicyClass = PyDict_GetItemString(pUserPolicyDict, policy_name);
  assert(pPolicyClass); // FIXME needs stricter checking and exception throwing
    
  // Creates a new object of type ScriptAdapter :
  // takes init function from ScriptAdapter class
  PyObject* pAdapterClass = PyDict_GetItemString(pScriptAdapterDict, "ScriptAdapter");
  PyObject* pAdapterCtorParam = PyTuple_New(1);
  Py_INCREF(pPolicyClass); // PyTuple_SetItem steals a reference
  PyTuple_SetItem(pAdapterCtorParam, 0, pPolicyClass);
  PyObject* pAdapterObject = PyInstance_New(pAdapterClass, pAdapterCtorParam, NULL);
    
  // try code
  PyObject_CallMethod(pAdapterObject, "async_configure", NULL);
    
  PyThreadState *_save;
  Py_UNBLOCK_THREADS
    sleep(5); // hack'a'ton! magggggiccc nummmbeeerrrrrs!!
  
  Py_BLOCK_THREADS
      
  // And now, who's your daddy, huh?

}