/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkRegionConstrainedSubsampler_h
#define itkRegionConstrainedSubsampler_h

#include "itkSubsamplerBase.h"
#include "itkImageRegion.h"

namespace itk {
namespace Statistics {
/** \class RegionConstrainedSubsampler
 * \brief This an abstract subsampler that constrains subsamples
 * to be contained within a given image region.
 *
 * This is an Abstract class that can not be instantiated.
 * There are multiple subsamplers that derive from this class and
 * provide specific implementations of subsampling strategies.
 *
 * This class is templatized over both the Sample and the Region
 * with an assumed consistency between the Region and the way
 * the Sample is generated.
 *
 * Use SetRegionConstraint(region) to provide the region
 * constraint.  All returned subsamples will be contained
 * within this region.  This assumes that the instance
 * identifiers in the sample correspond to an offset
 * computed with the provided region.
 *
 * \sa SubsamplerBase, SpatialNeighborSubsampler
 * \sa GaussianRandomSpatialNeighborSubsampler
 * \sa UniformRandomSpatialNeighborSubsampler
 * \ingroup ITKStatistics
 */

template < typename TSample, typename TRegion >
class RegionConstrainedSubsampler : public SubsamplerBase<TSample>
{
public:
  /** Standard class typedefs */
  typedef RegionConstrainedSubsampler<TSample, TRegion>  Self;
  typedef SubsamplerBase<TSample>                        Superclass;
  typedef typename Superclass::Baseclass                 Baseclass;
  typedef SmartPointer<Self>                             Pointer;
  typedef SmartPointer<const Self>                       ConstPointer;

  /** Run-time type information (and related methods) */
  itkTypeMacro(RegionConstrainedSubsampler, SubsamplerBase);

  /** typedef alias for the source data container */
  typedef TSample                                          SampleType;
  typedef typename SampleType::ConstPointer                SampleConstPointer;
  typedef typename TSample::MeasurementVectorType          MeasurementVectorType;
  typedef typename TSample::InstanceIdentifier             InstanceIdentifier;

  typedef Subsample<TSample>                               SubsampleType;
  typedef typename SubsampleType::Pointer                  SubsamplePointer;
  typedef typename SubsampleType::ConstIterator            SubsampleConstIterator;
  typedef typename SubsampleType::InstanceIdentifierHolder InstanceIdentifierHolder;

  /** typedefs related to image region */
  typedef TRegion                              RegionType;
  typedef typename RegionType::IndexType       IndexType;
  typedef typename IndexType::IndexValueType   IndexValueType;
  typedef typename RegionType::SizeType        SizeType;

  /** Method to set the sample domain.
   * This should correspond to the entire region of the input sample. */
  void SetSampleRegion(const RegionType& region);

  /** Method to get the sample domain. */
  itkGetConstReferenceMacro( SampleRegion, RegionType );

  /** Method to get the flag indicating that the sample region has been initialized */
  itkGetConstReferenceMacro(SampleRegionInitialized, bool);

  /** Method to set the region constraint.
   * Any subsamples selected must ALSO be inside this region. */
  void SetRegionConstraint(const RegionType& region);

  /** Method to get the region constraint. */
  itkGetConstReferenceMacro( RegionConstraint, RegionType );

  /** Method to get the flag indicating that the region constraint has been initialized */
  itkGetConstReferenceMacro(RegionConstraintInitialized, bool);

  /** Main Search method that MUST be implemented by each subclass
   * The Search method will find all points similar to query and return
   * them as a Subsample.  The definition of similar will be subclass-
   * specific.  And could mean spatial similarity or feature similarity
   * etc.  */
  virtual void Search(const InstanceIdentifier& query,
                      SubsamplePointer& results) ITK_OVERRIDE = 0;

protected:
  /**
   * Clone the current subsampler.
   * This does a complete copy of the subsampler state
   * to the new subsampler
   */
  virtual typename LightObject::Pointer InternalClone() const ITK_OVERRIDE;

  RegionConstrainedSubsampler();
  virtual ~RegionConstrainedSubsampler() {};

  virtual void PrintSelf(std::ostream& os, Indent indent) const ITK_OVERRIDE;

  RegionType m_RegionConstraint;
  bool       m_RegionConstraintInitialized;
  RegionType m_SampleRegion;
  bool       m_SampleRegionInitialized;

private:
  RegionConstrainedSubsampler(const Self&) ITK_DELETE_FUNCTION;
  void operator=(const Self&) ITK_DELETE_FUNCTION;

}; // end of class RegionConstrainedSubsampler

} // end of namespace Statistics
} // end of namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkRegionConstrainedSubsampler.hxx"
#endif

#endif
