/**
 * Advanced authorization plugin for Orthanc
 * Copyright (C) 2017 Osimis, Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * This program 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
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/

#include "CachedAuthorizationService.h"

#include "../Resources/Orthanc/Core/OrthancException.h"

#include <boost/lexical_cast.hpp>

namespace OrthancPlugins
{
  std::string CachedAuthorizationService::ComputeKey(OrthancPluginHttpMethod method,
                                                     const AccessedResource& access,
                                                     const Token& token,
                                                     const std::string& tokenValue) const
  {
    return (boost::lexical_cast<std::string>(method) + "|" +
            boost::lexical_cast<std::string>(access.GetLevel()) + "|" +
            access.GetOrthancId() + "|" + token.GetKey() + "|" + tokenValue);
  }
    

  CachedAuthorizationService::CachedAuthorizationService(IAuthorizationService* decorated /* takes ownership */,
                                                         ICacheFactory& factory) :
    decorated_(decorated),
    cache_(factory.Create())
  {
    if (decorated_.get() == NULL)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_InternalError);
    }
  }


  bool CachedAuthorizationService::IsGranted(unsigned int& validity,
                                             OrthancPluginHttpMethod method,
                                             const AccessedResource& access,
                                             const Token& token,
                                             const std::string& tokenValue)
  {
    assert(decorated_.get() != NULL);

    std::string key = ComputeKey(method, access, token, tokenValue);
    std::string value;

    if (cache_->Retrieve(value, key))
    {
      // Return the previously cached value
      return (value == "1");
    }        
        
    bool granted = decorated_->IsGranted(validity, method, access, token, tokenValue);

    if (granted)
    {
      if (validity > 0)
      {
        cache_->Store(key, "1", validity);
      }
        
      return true;
    }
    else
    {
      if (validity > 0)
      {
        cache_->Store(key, "0", validity);
      }
        
      return false;
    }
  }

  
  bool CachedAuthorizationService::IsGranted(unsigned int& validity,
                                             OrthancPluginHttpMethod method,
                                             const AccessedResource& access)
  {
    assert(decorated_.get() != NULL);

    // The cache is not used if no token is available
    return decorated_->IsGranted(validity, method, access);
  }
}