--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Framework/Loaders/LoaderStateMachine.cpp	Tue May 28 21:59:20 2019 +0200
@@ -0,0 +1,174 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2019 Osimis S.A., 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 "LoaderStateMachine.h"
+
+#include <Core/OrthancException.h>
+
+namespace OrthancStone
+{
+  void LoaderStateMachine::State::Handle(const OrthancRestApiCommand::SuccessMessage& message)
+  {
+    throw Orthanc::OrthancException(Orthanc::ErrorCode_NotImplemented);
+  }
+      
+
+  void LoaderStateMachine::State::Handle(const GetOrthancImageCommand::SuccessMessage& message)
+  {
+    throw Orthanc::OrthancException(Orthanc::ErrorCode_NotImplemented);
+  }
+
+      
+  void LoaderStateMachine::State::Handle(const GetOrthancWebViewerJpegCommand::SuccessMessage& message)
+  {
+    throw Orthanc::OrthancException(Orthanc::ErrorCode_NotImplemented);
+  }
+
+
+  void LoaderStateMachine::Schedule(OracleCommandWithPayload* command)
+  {
+    std::auto_ptr<OracleCommandWithPayload> protection(command);
+
+    if (command == NULL)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_NullPointer);
+    }
+      
+    if (!command->HasPayload())
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange,
+                                      "The payload must contain the next state");
+    }
+
+    pendingCommands_.push_back(protection.release());
+    Step();
+  }
+
+
+  void LoaderStateMachine::Start()
+  {
+    if (active_)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+
+    active_ = true;
+
+    for (size_t i = 0; i < simultaneousDownloads_; i++)
+    {
+      Step();
+    }
+  }
+
+
+  void LoaderStateMachine::Step()
+  {
+    if (!pendingCommands_.empty() &&
+        activeCommands_ < simultaneousDownloads_)
+    {
+      oracle_.Schedule(*this, pendingCommands_.front());
+      pendingCommands_.pop_front();
+
+      activeCommands_++;
+    }
+  }
+
+
+  void LoaderStateMachine::Clear()
+  {
+    for (PendingCommands::iterator it = pendingCommands_.begin();
+         it != pendingCommands_.end(); ++it)
+    {
+      delete *it;
+    }
+
+    pendingCommands_.clear();
+  }
+
+
+  void LoaderStateMachine::HandleExceptionMessage(const OracleCommandExceptionMessage& message)
+  {
+    LOG(ERROR) << "Error in the state machine, stopping all processing";
+    Clear();
+  }
+
+
+  template <typename T>
+  void LoaderStateMachine::HandleSuccessMessage(const T& message)
+  {
+    assert(activeCommands_ > 0);
+    activeCommands_--;
+
+    try
+    {
+      dynamic_cast<State&>(message.GetOrigin().GetPayload()).Handle(message);
+      Step();
+    }
+    catch (Orthanc::OrthancException& e)
+    {
+      LOG(ERROR) << "Error in the state machine, stopping all processing: " << e.What();
+      Clear();
+    }
+  }
+
+
+  LoaderStateMachine::LoaderStateMachine(IOracle& oracle,
+                                         IObservable& oracleObservable) :
+    IObserver(oracleObservable.GetBroker()),
+    oracle_(oracle),
+    active_(false),
+    simultaneousDownloads_(4),
+    activeCommands_(0)
+  {
+    oracleObservable.RegisterObserverCallback(
+      new Callable<LoaderStateMachine, OrthancRestApiCommand::SuccessMessage>
+      (*this, &LoaderStateMachine::HandleSuccessMessage));
+
+    oracleObservable.RegisterObserverCallback(
+      new Callable<LoaderStateMachine, GetOrthancImageCommand::SuccessMessage>
+      (*this, &LoaderStateMachine::HandleSuccessMessage));
+
+    oracleObservable.RegisterObserverCallback(
+      new Callable<LoaderStateMachine, GetOrthancWebViewerJpegCommand::SuccessMessage>
+      (*this, &LoaderStateMachine::HandleSuccessMessage));
+
+    oracleObservable.RegisterObserverCallback(
+      new Callable<LoaderStateMachine, OracleCommandExceptionMessage>
+      (*this, &LoaderStateMachine::HandleExceptionMessage));
+  }
+
+
+  void LoaderStateMachine::SetSimultaneousDownloads(unsigned int count)
+  {
+    if (active_)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadSequenceOfCalls);
+    }
+    else if (count == 0)
+    {
+      throw Orthanc::OrthancException(Orthanc::ErrorCode_ParameterOutOfRange);        
+    }
+    else
+    {
+      simultaneousDownloads_ = count;
+    }
+  }
+}