/*=========================================================================
 *
 *  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.
 *
 *=========================================================================*/

#include "itkSquaredDifferenceImageFilter.h"
#include "itkImageRegionIteratorWithIndex.h"


int itkSquaredDifferenceImageFilterTest(int, char* [] )
{

  // Define the dimension of the images
  const unsigned int myDimension = 3;

  // Define the values of the input images
  const float input1Value = 3.0;
  const float input2Value = 4.0;

  // Define the values of the output images
  const float outputValue = 1.0;

  // Define the precison for output comparison
  const float epsilon = 1e-6;

  // Declare the types of the images
  typedef itk::Image<float, myDimension>  myImageType1;
  typedef itk::Image<float, myDimension>  myImageType2;
  typedef itk::Image<float, myDimension>  myImageType4;

  // Declare the type of the index to access images
  typedef itk::Index<myDimension>         myIndexType;

  // Declare the type of the size
  typedef itk::Size<myDimension>          mySizeType;

  // Declare the type of the Region
  typedef itk::ImageRegion<myDimension>        myRegionType;

  // Create two images
  myImageType1::Pointer inputImageA  = myImageType1::New();
  myImageType2::Pointer inputImageB  = myImageType2::New();

  // Define their size, and start index
  mySizeType size;
  size[0] = 2;
  size[1] = 2;
  size[2] = 2;

  myIndexType start;
  start[0] = 0;
  start[1] = 0;
  start[2] = 0;

  myRegionType region;
  region.SetIndex( start );
  region.SetSize( size );

  // Initialize Image A
  inputImageA->SetLargestPossibleRegion( region );
  inputImageA->SetBufferedRegion( region );
  inputImageA->SetRequestedRegion( region );
  inputImageA->Allocate();

  // Initialize Image B
  inputImageB->SetLargestPossibleRegion( region );
  inputImageB->SetBufferedRegion( region );
  inputImageB->SetRequestedRegion( region );
  inputImageB->Allocate();

  // Declare Iterator types apropriated for each image
  typedef itk::ImageRegionIteratorWithIndex<myImageType1>  myIteratorType1;
  typedef itk::ImageRegionIteratorWithIndex<myImageType2>  myIteratorType2;
  typedef itk::ImageRegionIteratorWithIndex<myImageType4>  myIteratorType4;

  // Create one iterator for Image A (this is a light object)
  myIteratorType1 it1( inputImageA, inputImageA->GetBufferedRegion() );

  // Initialize the content of Image A
  std::cout << "First operand " << std::endl;
  while( !it1.IsAtEnd() )
  {
    it1.Set( input1Value );
    std::cout << it1.Get() << std::endl;
    ++it1;
  }

  // Create one iterator for Image B (this is a light object)
  myIteratorType2 it2( inputImageB, inputImageB->GetBufferedRegion() );

  // Initialize the content of Image B
  std::cout << "Second operand " << std::endl;
  while( !it2.IsAtEnd() )
  {
    it2.Set( input2Value );
    std::cout << it2.Get() << std::endl;
    ++it2;
  }


  // Declare the type for the Magnitude Filter
  typedef itk::SquaredDifferenceImageFilter<
                                myImageType1,
                                myImageType2,
                                myImageType4  >       myFilterType;


  // Create a MagnitudeImageFilter
  myFilterType::Pointer filter = myFilterType::New();


  // Connect the input images
  filter->SetInput1( inputImageA );
  filter->SetInput2( inputImageB );

  // Get the Smart Pointer to the Filter Output
  myImageType4::Pointer outputImage = filter->GetOutput();


  // Execute the filter
  filter->Update();
  filter->SetFunctor(filter->GetFunctor());

  // Create an iterator for going through the image output
  myIteratorType4 it4(outputImage, outputImage->GetBufferedRegion());

  //  Print the content of the result image
  std::cout << " Result " << std::endl;
  while( !it4.IsAtEnd() )
  {
    std::cout << it4.Get() << std::endl;
    if( std::fabs( it4.Get() - outputValue ) > epsilon )
    {
      std::cerr << "Error in the output" << std::endl;
      std::cerr << "Value should be  " << outputValue << std::endl;
      std::cerr << "but is           " << it4.Get()  << std::endl;
      return EXIT_FAILURE;
    }

    ++it4;
  }


  // All objects should be automatically destroyed at this point
  return EXIT_SUCCESS;
}
