/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkPickingManager.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/

/*==============================================================================

  Library: MSVTK

  Copyright (c) Kitware Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0.txt

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

==============================================================================*/

// VTK includes
#include "vtkPickingManager.h"
#include "vtkAbstractPicker.h"
#include "vtkAbstractPropPicker.h"
#include "vtkCallbackCommand.h"
#include "vtkCamera.h"
#include "vtkCommand.h"
#include "vtkMath.h"
#include "vtkNew.h"
#include "vtkObjectFactory.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkRenderer.h"
#include "vtkSmartPointer.h"
#include "vtkTimeStamp.h"

// STL includes
#include <algorithm>
#include <limits>
#include <map>
#include <vector>

//------------------------------------------------------------------------------
vtkStandardNewMacro(vtkPickingManager);

//------------------------------------------------------------------------------
class vtkPickingManager::vtkInternal
{
public:
  vtkInternal(vtkPickingManager* external);
  ~vtkInternal();

  // Callback used to update the current time
  // of the manager when an event occurs in the RenderWindowInteractor.
  // Time is used to know if the cached information is still valid or obsolete.
  static void UpdateTime(vtkObject* caller, unsigned long event, void* clientData, void* callData);

  // Select the best picker based on various criteria such as z-depth,
  // 2D overlay and/or distance to picked point.
  vtkAbstractPicker* SelectPicker();

  // Compute the selection. The current implementation use the distance
  // between the world coordinates of a pick to the camera's ones.
  vtkAbstractPicker* ComputePickerSelection(double X, double Y, double Z, vtkRenderer* renderer);

  // Check if a given Observator is associated with a given Picker
  bool IsObjectLinked(vtkAbstractPicker* picker, vtkObject* object);

  // Create a new list of associated observers
  void CreateDefaultCollection(vtkAbstractPicker* picker, vtkObject* object);

  // vtkCollection doesn't allow nullptr values. Instead we use a vector
  // containing vtkObject to allow using 0 as a valid value because it is
  // allowed the return a picker event if he is not associated to a specific
  // object.
  // This is related with the capacity when a picker associated with a given
  // object does not manage others object,
  // it will automatically be removed from the list as well.
  typedef std::vector<vtkObject*> CollectionType;

  // For code clearance and performances during the computation std::map is
  // used instead of a vector of pair. Nevertheless, it makes internally use of
  // vtkSmartPointer and this class does not overload the order operators;
  // therefore to following functor has to be implemented to keep the data
  // structure consistent.
  struct less_smartPtrPicker
  {
    bool operator()(const vtkSmartPointer<vtkAbstractPicker>& first,
      const vtkSmartPointer<vtkAbstractPicker>& second) const
    {
      return first < second;
    }
  };

  typedef std::map<vtkSmartPointer<vtkAbstractPicker>, CollectionType, less_smartPtrPicker>
    PickerObjectsType;

  typedef std::pair<vtkSmartPointer<vtkAbstractPicker>, CollectionType> PickerObjectsPairType;

  // Associate a given vtkObject to a particular picker.
  void LinkPickerObject(const PickerObjectsType::iterator& it, vtkObject* object);

  // Predicate comparing a vtkAbstractPicker*
  // and a vtkSmartPointer<vtkAbstractPicker> using the PickerObjectsType.
  // As we use a vtkSmartPointer, this predicate allows to compare the equality
  // of a pointer on a vtkAbstractPicker with the address contained in
  // a corresponding vtkSmartPointer.
  struct equal_smartPtrPicker
  {
    equal_smartPtrPicker(vtkAbstractPicker* picker)
      : Picker(picker)
    {
    }

    bool operator()(const PickerObjectsPairType& pickerObjs) const
    {
      return this->Picker == pickerObjs.first;
    }

    vtkAbstractPicker* Picker;
  };

  PickerObjectsType Pickers;           // Map the picker with the objects
  vtkTimeStamp CurrentInteractionTime; // Time of the last interaction event
  vtkTimeStamp LastPickingTime;        // Time of the last picking process
  vtkSmartPointer<vtkAbstractPicker> LastSelectedPicker;

  // Define callback to keep track of the CurrentTime and the LastPickingTime.
  // The timeStamp is use to avoid repeating the picking process if the
  // vtkWindowInteractor has not been modified, it is a huge optimization
  // avoiding each picker to relaunch the whole mechanisme to determine which
  // picker has been selected at a state of the rendering.
  vtkSmartPointer<vtkCallbackCommand> TimerCallback;

  vtkPickingManager* External;
};

//------------------------------------------------------------------------------
// vtkInternal methods

//------------------------------------------------------------------------------
vtkPickingManager::vtkInternal::vtkInternal(vtkPickingManager* external)
{
  this->External = external;

  this->TimerCallback = vtkSmartPointer<vtkCallbackCommand>::New();
  this->TimerCallback->SetClientData(this);
  this->TimerCallback->SetCallback(UpdateTime);
}

//------------------------------------------------------------------------------
vtkPickingManager::vtkInternal::~vtkInternal() = default;

//------------------------------------------------------------------------------
void vtkPickingManager::vtkInternal::CreateDefaultCollection(
  vtkAbstractPicker* picker, vtkObject* object)
{
  CollectionType objects;
  objects.push_back(object);

  this->Pickers.insert(PickerObjectsPairType(picker, objects));
}

//------------------------------------------------------------------------------
void vtkPickingManager::vtkInternal::LinkPickerObject(
  const PickerObjectsType::iterator& it, vtkObject* object)
{
  CollectionType::iterator itObj = std::find(it->second.begin(), it->second.end(), object);

  if (itObj != it->second.end() && object)
  {
    vtkDebugWithObjectMacro(this->External,
      "vtkPickingtManager::Internal::LinkPickerObject: "
        << "Current object already linked with the given picker.");

    return;
  }

  it->second.push_back(object);
}

//------------------------------------------------------------------------------
bool vtkPickingManager::vtkInternal::IsObjectLinked(vtkAbstractPicker* picker, vtkObject* obj)
{
  if (!picker || !obj)
  {
    return false;
  }

  PickerObjectsType::iterator itPick =
    std::find_if(this->Pickers.begin(), this->Pickers.end(), equal_smartPtrPicker(picker));
  if (itPick == this->Pickers.end())
  {
    return false;
  }

  CollectionType::iterator itObj = std::find(itPick->second.begin(), itPick->second.end(), obj);
  return (itObj != itPick->second.end());
}

//------------------------------------------------------------------------------
vtkAbstractPicker* vtkPickingManager::vtkInternal::SelectPicker()
{
  if (!this->External->Interactor)
  {
    return nullptr;
  }
  else if (this->External->GetOptimizeOnInteractorEvents() &&
    this->CurrentInteractionTime.GetMTime() == this->LastPickingTime)
  {
    return this->LastSelectedPicker;
  }

  // Get the event position
  double X = this->External->Interactor->GetEventPosition()[0];
  double Y = this->External->Interactor->GetEventPosition()[1];

  // Get the poked renderer
  vtkRenderer* renderer =
    this->External->Interactor->FindPokedRenderer(static_cast<int>(X), static_cast<int>(Y));
  vtkAbstractPicker* selectedPicker = this->ComputePickerSelection(X, Y, 0., renderer);

  // Keep track of the last picker chosen & last picking time.
  this->LastSelectedPicker = selectedPicker;
  this->LastPickingTime = this->CurrentInteractionTime;

  return selectedPicker;
}

//------------------------------------------------------------------------------
vtkAbstractPicker* vtkPickingManager::vtkInternal::ComputePickerSelection(
  double X, double Y, double Z, vtkRenderer* renderer)
{
  vtkAbstractPicker* closestPicker = nullptr;
  if (!renderer)
  {
    return closestPicker;
  }

  double* camPos = renderer->GetActiveCamera()->GetPosition();
  double smallestDistance2 = std::numeric_limits<double>::max();

  for (PickerObjectsType::iterator it = this->Pickers.begin(); it != this->Pickers.end(); ++it)
  {
    int pickResult = it->first->Pick(X, Y, Z, renderer);
    double* pPos = it->first->GetPickPosition();

    if (pickResult > 0) // Keep closest object picked.
    {
      double distance2 = vtkMath::Distance2BetweenPoints(camPos, pPos);

      if (smallestDistance2 > distance2)
      {
        smallestDistance2 = distance2;
        closestPicker = it->first;
      }
    }
  }

  return closestPicker;
}

//------------------------------------------------------------------------------
void vtkPickingManager::vtkInternal::UpdateTime(vtkObject* vtkNotUsed(caller),
  unsigned long vtkNotUsed(event), void* clientData, void* vtkNotUsed(calldata))
{
  vtkPickingManager::vtkInternal* self =
    reinterpret_cast<vtkPickingManager::vtkInternal*>(clientData);
  if (!self)
  {
    return;
  }

  self->CurrentInteractionTime.Modified();
}

//------------------------------------------------------------------------------
// vtkPickingManager methods

//------------------------------------------------------------------------------
vtkPickingManager::vtkPickingManager()
  : Interactor(nullptr)
  , Enabled(false)
  , OptimizeOnInteractorEvents(true)
  , Internal(nullptr)
{
  this->Internal = new vtkInternal(this);
}

//------------------------------------------------------------------------------
vtkPickingManager::~vtkPickingManager()
{
  this->SetInteractor(nullptr);
  delete this->Internal;
}

//------------------------------------------------------------------------------
void vtkPickingManager::SetInteractor(vtkRenderWindowInteractor* rwi)
{
  if (rwi == this->Interactor)
  {
    return;
  }
  if (this->Interactor)
  {
    this->Interactor->RemoveObserver(this->Internal->TimerCallback);
  }

  this->Interactor = rwi;
  if (this->Interactor)
  {
    this->Interactor->AddObserver(vtkCommand::ModifiedEvent, this->Internal->TimerCallback);
  }

  this->Modified();
}

//------------------------------------------------------------------------------
void vtkPickingManager::SetOptimizeOnInteractorEvents(bool optimize)
{
  if (this->OptimizeOnInteractorEvents == optimize)
  {
    return;
  }

  this->OptimizeOnInteractorEvents = optimize;
  this->Modified();
}

//------------------------------------------------------------------------------
void vtkPickingManager::AddPicker(vtkAbstractPicker* picker, vtkObject* object)
{
  if (!picker)
  {
    return;
  }

  // Linke the object if the picker is already registered
  vtkPickingManager::vtkInternal::PickerObjectsType::iterator it =
    std::find_if(this->Internal->Pickers.begin(), this->Internal->Pickers.end(),
      vtkPickingManager::vtkInternal::equal_smartPtrPicker(picker));

  if (it != this->Internal->Pickers.end())
  {
    vtkDebugMacro("vtkPickingtManager::AddPicker: "
      << "Picker already in the manager, the object will be linked");

    this->Internal->LinkPickerObject(it, object);
    return;
  }

  // The picker does not exists in the manager yet.
  // Create the list of associated objects
  this->Internal->CreateDefaultCollection(picker, object);
}

//------------------------------------------------------------------------------
void vtkPickingManager::RemovePicker(vtkAbstractPicker* picker, vtkObject* object)
{
  vtkPickingManager::vtkInternal::PickerObjectsType::iterator it =
    std::find_if(this->Internal->Pickers.begin(), this->Internal->Pickers.end(),
      vtkPickingManager::vtkInternal::equal_smartPtrPicker(picker));

  // The Picker does not exist
  if (it == this->Internal->Pickers.end())
  {
    return;
  }

  vtkPickingManager::vtkInternal::CollectionType::iterator itObj =
    std::find(it->second.begin(), it->second.end(), object);

  // The object is not associated with the given picker.
  if (itObj == it->second.end())
  {
    return;
  }

  it->second.erase(itObj);

  // Delete the picker when it is not associated with any object anymore.
  if (it->second.empty())
  {
    this->Internal->Pickers.erase(it);
  }
}

//------------------------------------------------------------------------------
void vtkPickingManager::RemoveObject(vtkObject* object)
{
  vtkPickingManager::vtkInternal::PickerObjectsType::iterator it = this->Internal->Pickers.begin();

  for (; it != this->Internal->Pickers.end();)
  {
    vtkPickingManager::vtkInternal::CollectionType::iterator itObj =
      std::find(it->second.begin(), it->second.end(), object);

    if (itObj != it->second.end())
    {
      it->second.erase(itObj);

      if (it->second.empty())
      {
        vtkPickingManager::vtkInternal::PickerObjectsType::iterator toRemove = it;
        ++it;
        this->Internal->Pickers.erase(toRemove);
        continue;
      }
    }

    ++it;
  }
}

//------------------------------------------------------------------------------
bool vtkPickingManager::Pick(vtkAbstractPicker* picker, vtkObject* obj)
{
  if (!this->Internal->IsObjectLinked(picker, obj))
  {
    return false;
  }

  return (this->Pick(picker));
}

//------------------------------------------------------------------------------
bool vtkPickingManager::Pick(vtkObject* obj)
{
  vtkAbstractPicker* picker = this->Internal->SelectPicker();
  if (!picker)
  {
    return false;
  }
  // If the object is not contained in the list of the associated active pickers
  // return false
  return (this->Internal->IsObjectLinked(picker, obj));
}

//------------------------------------------------------------------------------
bool vtkPickingManager::Pick(vtkAbstractPicker* picker)
{
  return (picker == this->Internal->SelectPicker());
}

//------------------------------------------------------------------------------
vtkAssemblyPath* vtkPickingManager::GetAssemblyPath(double X, double Y, double Z,
  vtkAbstractPropPicker* picker, vtkRenderer* renderer, vtkObject* obj)
{
  if (this->Enabled)
  {
    // Return 0 when the Picker is not selected
    if (!this->Pick(picker, obj))
    {
      return nullptr;
    }
  }
  else
  {
    picker->Pick(X, Y, Z, renderer);
  }

  return picker->GetPath();
}

//------------------------------------------------------------------------------
int vtkPickingManager::GetNumberOfPickers()
{
  return static_cast<int>(this->Internal->Pickers.size());
}

//------------------------------------------------------------------------------
int vtkPickingManager::GetNumberOfObjectsLinked(vtkAbstractPicker* picker)
{
  if (!picker)
  {
    return 0;
  }

  vtkPickingManager::vtkInternal::PickerObjectsType::iterator it =
    std::find_if(this->Internal->Pickers.begin(), this->Internal->Pickers.end(),
      vtkPickingManager::vtkInternal::equal_smartPtrPicker(picker));

  if (it == this->Internal->Pickers.end())
  {
    return 0;
  }

  return static_cast<int>(it->second.size());
}

//------------------------------------------------------------------------------
void vtkPickingManager::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);

  os << indent << "RenderWindowInteractor: " << this->Interactor << "\n";
  os << indent << "NumberOfPickers: " << this->Internal->Pickers.size() << "\n";

  vtkPickingManager::vtkInternal::PickerObjectsType::iterator it = this->Internal->Pickers.begin();

  for (; it != this->Internal->Pickers.end(); ++it)
  {
    os << indent << indent << "Picker: " << it->first << "\n";
    os << indent << indent << "NumberOfObjectsLinked: " << it->second.size() << "\n";
  }
}