// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-FileCopyrightText: Copyright (c) Kitware Inc.
// SPDX-License-Identifier: BSD-3-Clause AND Apache-2.0

// 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>

//------------------------------------------------------------------------------
VTK_ABI_NAMESPACE_BEGIN
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;
  }

  // Link 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 exist 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";
  }
}
VTK_ABI_NAMESPACE_END