/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2013 Medical Physics Department, CHU of Liege,
 * Belgium
 *
 * This program 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 3 of the
 * License, or (at your option) any later version.
 *
 * In addition, as a special exception, the copyright holders of this
 * program give permission to link the code of its release with the
 * OpenSSL project's "OpenSSL" library (or with modified versions of it
 * that use the same license as the "OpenSSL" library), and distribute
 * the linked executables. You must obey the GNU General Public License
 * in all respects for all of the code used other than "OpenSSL". If you
 * modify file(s) with this exception, you may extend this exception to
 * your version of the file(s), but you are not obligated to do so. If
 * you do not wish to do so, delete this exception statement from your
 * version. If you delete this exception statement from all source files
 * in the program, then also delete it here.
 * 
 * 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "CommandDispatcher.h"

#include "FindScp.h"
#include "StoreScp.h"
#include "MoveScp.h"
#include "../../Core/Toolbox.h"

#include <dcmtk/dcmnet/dcasccfg.h>      /* for class DcmAssociationConfiguration */
#include <boost/lexical_cast.hpp>
#include <glog/logging.h>

#define ORTHANC_PROMISCUOUS 1

static OFBool    opt_rejectWithoutImplementationUID = OFFalse;



#if ORTHANC_PROMISCUOUS == 1
static
DUL_PRESENTATIONCONTEXT *
findPresentationContextID(LST_HEAD * head,
                          T_ASC_PresentationContextID presentationContextID)
{
  DUL_PRESENTATIONCONTEXT *pc;
  LST_HEAD **l;
  OFBool found = OFFalse;

  if (head == NULL)
    return NULL;

  l = &head;
  if (*l == NULL)
    return NULL;

  pc = OFstatic_cast(DUL_PRESENTATIONCONTEXT *, LST_Head(l));
  (void)LST_Position(l, OFstatic_cast(LST_NODE *, pc));

  while (pc && !found) {
    if (pc->presentationContextID == presentationContextID) {
      found = OFTrue;
    } else {
      pc = OFstatic_cast(DUL_PRESENTATIONCONTEXT *, LST_Next(l));
    }
  }
  return pc;
}


/** accept all presenstation contexts for unknown SOP classes,
 *  i.e. UIDs appearing in the list of abstract syntaxes
 *  where no corresponding name is defined in the UID dictionary.
 *  @param params pointer to association parameters structure
 *  @param transferSyntax transfer syntax to accept
 *  @param acceptedRole SCU/SCP role to accept
 */
static OFCondition acceptUnknownContextsWithTransferSyntax(
  T_ASC_Parameters * params,
  const char* transferSyntax,
  T_ASC_SC_ROLE acceptedRole)
{
  OFCondition cond = EC_Normal;
  int n, i, k;
  DUL_PRESENTATIONCONTEXT *dpc;
  T_ASC_PresentationContext pc;
  OFBool accepted = OFFalse;
  OFBool abstractOK = OFFalse;

  n = ASC_countPresentationContexts(params);
  for (i = 0; i < n; i++)
  {
    cond = ASC_getPresentationContext(params, i, &pc);
    if (cond.bad()) return cond;
    abstractOK = OFFalse;
    accepted = OFFalse;

    if (dcmFindNameOfUID(pc.abstractSyntax) == NULL)
    {
      abstractOK = OFTrue;

      /* check the transfer syntax */
      for (k = 0; (k < OFstatic_cast(int, pc.transferSyntaxCount)) && !accepted; k++)
      {
        if (strcmp(pc.proposedTransferSyntaxes[k], transferSyntax) == 0)
        {
          accepted = OFTrue;
        }
      }
    }

    if (accepted)
    {
      cond = ASC_acceptPresentationContext(
        params, pc.presentationContextID,
        transferSyntax, acceptedRole);
      if (cond.bad()) return cond;
    } else {
      T_ASC_P_ResultReason reason;

      /* do not refuse if already accepted */
      dpc = findPresentationContextID(params->DULparams.acceptedPresentationContext,
                                      pc.presentationContextID);
      if ((dpc == NULL) || ((dpc != NULL) && (dpc->result != ASC_P_ACCEPTANCE)))
      {

        if (abstractOK) {
          reason = ASC_P_TRANSFERSYNTAXESNOTSUPPORTED;
        } else {
          reason = ASC_P_ABSTRACTSYNTAXNOTSUPPORTED;
        }
        /*
         * If previously this presentation context was refused
         * because of bad transfer syntax let it stay that way.
         */
        if ((dpc != NULL) && (dpc->result == ASC_P_TRANSFERSYNTAXESNOTSUPPORTED))
          reason = ASC_P_TRANSFERSYNTAXESNOTSUPPORTED;

        cond = ASC_refusePresentationContext(params, pc.presentationContextID, reason);
        if (cond.bad()) return cond;
      }
    }
  }
  return EC_Normal;
}


/** accept all presenstation contexts for unknown SOP classes,
 *  i.e. UIDs appearing in the list of abstract syntaxes
 *  where no corresponding name is defined in the UID dictionary.
 *  This method is passed a list of "preferred" transfer syntaxes.
 *  @param params pointer to association parameters structure
 *  @param transferSyntax transfer syntax to accept
 *  @param acceptedRole SCU/SCP role to accept
 */
static OFCondition acceptUnknownContextsWithPreferredTransferSyntaxes(
  T_ASC_Parameters * params,
  const char* transferSyntaxes[], int transferSyntaxCount,
  T_ASC_SC_ROLE acceptedRole = ASC_SC_ROLE_DEFAULT)
{
  OFCondition cond = EC_Normal;
  /*
  ** Accept in the order "least wanted" to "most wanted" transfer
  ** syntax.  Accepting a transfer syntax will override previously
  ** accepted transfer syntaxes.
  */
  for (int i = transferSyntaxCount - 1; i >= 0; i--)
  {
    cond = acceptUnknownContextsWithTransferSyntax(params, transferSyntaxes[i], acceptedRole);
    if (cond.bad()) return cond;
  }
  return cond;
}
#endif


namespace Orthanc
{
  namespace Internals
  {
    OFCondition AssociationCleanup(T_ASC_Association *assoc)
    {
      OFString temp_str;
      OFCondition cond = ASC_dropSCPAssociation(assoc);
      if (cond.bad())
      {
        LOG(FATAL) << cond.text();
        return cond;
      }

      cond = ASC_destroyAssociation(&assoc);
      if (cond.bad())
      {
        LOG(FATAL) << cond.text();
        return cond;
      }

      return cond;
    }



    CommandDispatcher* AcceptAssociation(const DicomServer& server, T_ASC_Network *net)
    {
      DcmAssociationConfiguration asccfg;
      char buf[BUFSIZ];
      T_ASC_Association *assoc;
      OFCondition cond;
      OFString sprofile;
      OFString temp_str;

      std::vector<const char*> knownAbstractSyntaxes;

      // For C-STORE
      if (server.HasStoreRequestHandlerFactory())
      {
        knownAbstractSyntaxes.push_back(UID_VerificationSOPClass);
      }

      // For C-FIND
      if (server.HasFindRequestHandlerFactory())
      {
        knownAbstractSyntaxes.push_back(UID_FINDPatientRootQueryRetrieveInformationModel);
        knownAbstractSyntaxes.push_back(UID_FINDStudyRootQueryRetrieveInformationModel);
      }

      // For C-MOVE
      if (server.HasMoveRequestHandlerFactory())
      {
        knownAbstractSyntaxes.push_back(UID_MOVEStudyRootQueryRetrieveInformationModel);
      }

      const char* transferSyntaxes[] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
      int numTransferSyntaxes = 0;

      cond = ASC_receiveAssociation(net, &assoc, 
                                    /*opt_maxPDU*/ ASC_DEFAULTMAXPDU, 
                                    NULL, NULL,
                                    /*opt_secureConnection*/ OFFalse,
                                    DUL_NOBLOCK, 1);

      if (cond == DUL_NOASSOCIATIONREQUEST)
      {
        // Timeout
        AssociationCleanup(assoc);
        return NULL;
      }

      // if some kind of error occured, take care of it
      if (cond.bad())
      {
        LOG(ERROR) << "Receiving Association failed: " << cond.text();
        // no matter what kind of error occurred, we need to do a cleanup
        AssociationCleanup(assoc);
        return NULL;
      }

      LOG(INFO) << "Association Received";

      transferSyntaxes[0] = UID_LittleEndianExplicitTransferSyntax;
      transferSyntaxes[1] = UID_BigEndianExplicitTransferSyntax;
      transferSyntaxes[2] = UID_LittleEndianImplicitTransferSyntax;
      numTransferSyntaxes = 3;

      /* accept the Verification SOP Class if presented */
      cond = ASC_acceptContextsWithPreferredTransferSyntaxes( assoc->params, &knownAbstractSyntaxes[0], knownAbstractSyntaxes.size(), transferSyntaxes, numTransferSyntaxes);
      if (cond.bad())
      {
        LOG(INFO) << cond.text();
        AssociationCleanup(assoc);
        return NULL;
      }

      /* the array of Storage SOP Class UIDs comes from dcuid.h */
      cond = ASC_acceptContextsWithPreferredTransferSyntaxes( assoc->params, dcmAllStorageSOPClassUIDs, numberOfAllDcmStorageSOPClassUIDs, transferSyntaxes, numTransferSyntaxes);
      if (cond.bad())
      {
        LOG(INFO) << cond.text();
        AssociationCleanup(assoc);
        return NULL;
      }

#if ORTHANC_PROMISCUOUS == 1
      /* accept everything not known not to be a storage SOP class */
      cond = acceptUnknownContextsWithPreferredTransferSyntaxes(
        assoc->params, transferSyntaxes, numTransferSyntaxes);
      if (cond.bad())
      {
        LOG(INFO) << cond.text();
        AssociationCleanup(assoc);
        return NULL;
      }
#endif

      /* set our app title */
      ASC_setAPTitles(assoc->params, NULL, NULL, server.GetApplicationEntityTitle().c_str());

      /* acknowledge or reject this association */
      cond = ASC_getApplicationContextName(assoc->params, buf);
      if ((cond.bad()) || strcmp(buf, UID_StandardApplicationContext) != 0)
      {
        /* reject: the application context name is not supported */
        T_ASC_RejectParameters rej =
          {
            ASC_RESULT_REJECTEDPERMANENT,
            ASC_SOURCE_SERVICEUSER,
            ASC_REASON_SU_APPCONTEXTNAMENOTSUPPORTED
          };

        LOG(INFO) << "Association Rejected: Bad Application Context Name: " << buf;
        cond = ASC_rejectAssociation(assoc, &rej);
        if (cond.bad())
        {
          LOG(INFO) << cond.text();
        }
        AssociationCleanup(assoc);
        return NULL;
      }

      std::string callingIP;
      std::string callingTitle;
  
      /* check the AETs */
      {
        DIC_AE callingTitle_C;
        DIC_AE calledTitle_C;
        DIC_AE callingIP_C;
        DIC_AE calledIP_C;
        if (ASC_getAPTitles(assoc->params, callingTitle_C, calledTitle_C, NULL).bad() ||
            ASC_getPresentationAddresses(assoc->params, callingIP_C, calledIP_C).bad())
        {
          T_ASC_RejectParameters rej =
            {
              ASC_RESULT_REJECTEDPERMANENT,
              ASC_SOURCE_SERVICEUSER,
              ASC_REASON_SU_NOREASON
            };
          ASC_rejectAssociation(assoc, &rej);
          AssociationCleanup(assoc);
          return NULL;
        }

        callingIP = std::string(/*OFSTRING_GUARD*/(callingIP_C));
        callingTitle = std::string(/*OFSTRING_GUARD*/(callingTitle_C));
        std::string calledTitle(/*OFSTRING_GUARD*/(calledTitle_C));
        Toolbox::ToUpperCase(callingIP);
        Toolbox::ToUpperCase(callingTitle);
        Toolbox::ToUpperCase(calledTitle);

        if (server.HasCalledApplicationEntityTitleCheck() &&
            calledTitle != server.GetApplicationEntityTitle())
        {
          T_ASC_RejectParameters rej =
            {
              ASC_RESULT_REJECTEDPERMANENT,
              ASC_SOURCE_SERVICEUSER,
              ASC_REASON_SU_CALLEDAETITLENOTRECOGNIZED
            };
          ASC_rejectAssociation(assoc, &rej);
          AssociationCleanup(assoc);
          return NULL;
        }

        if (server.HasApplicationEntityFilter() &&
            !server.GetApplicationEntityFilter().IsAllowedConnection(callingIP, callingTitle))
        {
          T_ASC_RejectParameters rej =
            {
              ASC_RESULT_REJECTEDPERMANENT,
              ASC_SOURCE_SERVICEUSER,
              ASC_REASON_SU_CALLINGAETITLENOTRECOGNIZED
            };
          ASC_rejectAssociation(assoc, &rej);
          AssociationCleanup(assoc);
          return NULL;
        }
      }

      if (opt_rejectWithoutImplementationUID && strlen(assoc->params->theirImplementationClassUID) == 0)
      {
        /* reject: the no implementation Class UID provided */
        T_ASC_RejectParameters rej =
          {
            ASC_RESULT_REJECTEDPERMANENT,
            ASC_SOURCE_SERVICEUSER,
            ASC_REASON_SU_NOREASON
          };

        LOG(INFO) << "Association Rejected: No Implementation Class UID provided";
        cond = ASC_rejectAssociation(assoc, &rej);
        if (cond.bad())
        {
          LOG(INFO) << cond.text();
        }
        AssociationCleanup(assoc);
        return NULL;
      }

      {
        cond = ASC_acknowledgeAssociation(assoc);
        if (cond.bad())
        {
          LOG(ERROR) << cond.text();
          AssociationCleanup(assoc);
          return NULL;
        }
        LOG(INFO) << "Association Acknowledged (Max Send PDV: " << assoc->sendPDVLength << ")";
        if (ASC_countAcceptedPresentationContexts(assoc->params) == 0)
          LOG(INFO) << "    (but no valid presentation contexts)";
      }

      IApplicationEntityFilter* filter = server.HasApplicationEntityFilter() ? &server.GetApplicationEntityFilter() : NULL;
      return new CommandDispatcher(server, assoc, callingIP, callingTitle, filter);
    }

    bool CommandDispatcher::Step()
    /*
     * This function receives DIMSE commmands over the network connection
     * and handles these commands correspondingly. Note that in case of
     * storscp only C-ECHO-RQ and C-STORE-RQ commands can be processed.
     */
    {
      bool finished = false;

      // receive a DIMSE command over the network, with a timeout of 1 second
      DcmDataset *statusDetail = NULL;
      T_ASC_PresentationContextID presID = 0;
      T_DIMSE_Message msg;

      OFCondition cond = DIMSE_receiveCommand(assoc_, DIMSE_NONBLOCKING, 1, &presID, &msg, &statusDetail);
      elapsedTimeSinceLastCommand_++;
    
      // if the command which was received has extra status
      // detail information, dump this information
      if (statusDetail != NULL)
      {
        //LOG4CPP_WARN(Internals::GetLogger(), "Status Detail:" << OFendl << DcmObject::PrintHelper(*statusDetail));
        delete statusDetail;
      }

      if (cond == DIMSE_OUTOFRESOURCES)
      {
        finished = true;
      }
      else if (cond == DIMSE_NODATAAVAILABLE)
      {
        // Timeout due to DIMSE_NONBLOCKING
        if (clientTimeout_ != 0 && 
            elapsedTimeSinceLastCommand_ >= clientTimeout_)
        {
          // This timeout is actually a client timeout
          finished = true;
        }
      }
      else if (cond == EC_Normal)
      {
        // Reset the client timeout counter
        elapsedTimeSinceLastCommand_ = 0;

        // Convert the type of request to Orthanc's internal type
        bool supported = false;
        DicomRequestType request;
        switch (msg.CommandField)
        {
          case DIMSE_C_ECHO_RQ:
            request = DicomRequestType_Echo;
            supported = true;
            break;

          case DIMSE_C_STORE_RQ:
            request = DicomRequestType_Store;
            supported = true;
            break;

          case DIMSE_C_MOVE_RQ:
            request = DicomRequestType_Move;
            supported = true;
            break;

          case DIMSE_C_FIND_RQ:
            request = DicomRequestType_Find;
            supported = true;
            break;

          default:
            // we cannot handle this kind of message
            cond = DIMSE_BADCOMMANDTYPE;
            LOG(ERROR) << "cannot handle command: 0x" << std::hex << msg.CommandField;
            break;
        }


        // Check whether this request is allowed by the security filter
        if (supported && 
            filter_ != NULL &&
            !filter_->IsAllowedRequest(callingIP_, callingAETitle_, request))
        {
          LOG(ERROR) << EnumerationToString(request) 
                     << " requests are disallowed for the AET \"" 
                     << callingAETitle_ << "\"";
          cond = DIMSE_BADCOMMANDTYPE;
          supported = false;
        }

        // in case we received a supported message, process this command
        if (supported)
        {
          // If anything goes wrong, there will be a "BADCOMMANDTYPE" answer
          cond = DIMSE_BADCOMMANDTYPE;

          switch (request)
          {
            case DicomRequestType_Echo:
              cond = EchoScp(assoc_, &msg, presID);
              break;

            case DicomRequestType_Store:
              if (server_.HasStoreRequestHandlerFactory()) // Should always be true
              {
                std::auto_ptr<IStoreRequestHandler> handler
                  (server_.GetStoreRequestHandlerFactory().ConstructStoreRequestHandler());
                cond = Internals::storeScp(assoc_, &msg, presID, *handler);
              }
              break;

            case DicomRequestType_Move:
              if (server_.HasMoveRequestHandlerFactory()) // Should always be true
              {
                std::auto_ptr<IMoveRequestHandler> handler
                  (server_.GetMoveRequestHandlerFactory().ConstructMoveRequestHandler());
                cond = Internals::moveScp(assoc_, &msg, presID, *handler);
              }
              break;

            case DicomRequestType_Find:
              if (server_.HasFindRequestHandlerFactory()) // Should always be true
              {
                std::auto_ptr<IFindRequestHandler> handler
                  (server_.GetFindRequestHandlerFactory().ConstructFindRequestHandler());
                cond = Internals::findScp(assoc_, &msg, presID, *handler);
              }
              break;

            default:
              // Should never happen
              break;
          }
        }
      }
      else
      {
        // Bad status, which indicates the closing of the connection by
        // the peer or a network error
        finished = true;
      }
    
      if (finished)
      {
        if (cond == DUL_PEERREQUESTEDRELEASE)
        {
          LOG(INFO) << "Association Release";
          ASC_acknowledgeRelease(assoc_);
        }
        else if (cond == DUL_PEERABORTEDASSOCIATION)
        {
          LOG(INFO) << "Association Aborted";
        }
        else
        {
          OFString temp_str;
          LOG(ERROR) << "DIMSE failure (aborting association): " << cond.text();
          /* some kind of error so abort the association */
          ASC_abortAssociation(assoc_);
        }
      }

      return !finished;
    }


    OFCondition EchoScp( T_ASC_Association * assoc, T_DIMSE_Message * msg, T_ASC_PresentationContextID presID)
    {
      OFString temp_str;
      LOG(INFO) << "Received Echo Request";
      //LOG(DEBUG) << DIMSE_dumpMessage(temp_str, msg->msg.CEchoRQ, DIMSE_INCOMING, NULL, presID));

      /* the echo succeeded !! */
      OFCondition cond = DIMSE_sendEchoResponse(assoc, presID, &msg->msg.CEchoRQ, STATUS_Success, NULL);
      if (cond.bad())
      {
        LOG(ERROR) << "Echo SCP Failed: " << cond.text();
      }
      return cond;
    }
  }
}