// src/backend/pyloader/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 "global_preferences.hh"
#include "policies_gatekeeper.hh"

#include <Python.h>
#include <glibmm/ustring.h>
#include <glibmm/timer.h>
#include <glibmm/fileutils.h>
#include <glibmm/pattern.h>

#include <algorithm>
#include <cassert>
#include <functional>
#include <iostream>
#include <string>
#include <iostream>
#include <unistd.h>
using namespace sgpem;
using std::vector;
using std::cout;
using std::endl;


// Concatenate a string with all the policies directories
struct pol_dirs_concat : public std::unary_function<void, const Glib::ustring&>
{
public:
    pol_dirs_concat(Glib::ustring& cat) : _cat(cat) {}
    void operator()(const Glib::ustring& add) 
	{
	    // Please note that this string will end finishing with
	    // and additional ","!
	    _cat += "'" + add + "', ";
	}
private:
    Glib::ustring& _cat;
};



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


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


PythonPolicyManager::~PythonPolicyManager()
{
  for_each(_policies.begin(), _policies.end(), ptr_fun(operator delete));
}

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)
      // No-op
      return;
  
  Py_Initialize();
  _initialized = true;
  
  // The following lines are 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.
  
  Glib::ustring importdirs = "import sys\n" 
      "sys.path[:0] = [ ";
  for_each(GlobalPreferences::instance().policies_dir_begin(),
	   GlobalPreferences::instance().policies_dir_end(),
	   pol_dirs_concat(importdirs));
  importdirs += " '" SHAREDIR "' ]\n";

  PyRun_SimpleString(importdirs.c_str());

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

  collect_policies();
}

vector<Policy*>
PythonPolicyManager::get_avail_policies()
{
  return _policies;
}

void
PythonPolicyManager::collect_policies()
{
  GlobalPreferences::dir_iterator dir_it = GlobalPreferences::instance().policies_dir_begin();
  GlobalPreferences::dir_iterator dir_end = GlobalPreferences::instance().policies_dir_end();

  for(; dir_it != dir_end; ++dir_it)
  {
    Glib::Dir dir(dir_it->c_str());

    cout << "Opening directory " << *dir_it << "..." << endl;
    
    for(Glib::DirIterator file_it = dir.begin(); file_it != dir.end(); ++file_it)
    {
      cout << "\tChecking if " << *file_it << " is a Python script... " << endl;
      
      Glib::PatternSpec dot_py("*.py");

      if(dot_py.match(*file_it))
      {
        cout << "\t\tIt is.\n";
	
	//strip extension
	std::string policy_name = (*file_it).substr(0, (*file_it).size() - 3);
	
	PythonPolicy *pypolicy = new PythonPolicy(policy_name.c_str());

	_policies.push_back(pypolicy);

	//FIXME remove me when get_policy is dropped
	if(policy_name == "fcfs")
	{
	  _python_policy = pypolicy;
	  PoliciesGatekeeper::get_instance().activate_policy(&History::get_instance(), pypolicy);
	}
      }
    }
  }
}