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/*! \file  example_02.cpp
    \brief Shows how to solve a finite minimax problem.
*/

#include "ROL_Algorithm.hpp"
#include "ROL_BundleStep.hpp"
#include "ROL_BundleStatusTest.hpp"
#include "ROL_Types.hpp"
#include "ROL_StdVector.hpp"
#include "ROL_Minimax2.hpp"

#include "Teuchos_oblackholestream.hpp"
#include "Teuchos_GlobalMPISession.hpp"
#include "Teuchos_XMLParameterListHelpers.hpp"
#include "Teuchos_LAPACK.hpp"

#include <iostream>
#include <algorithm>

typedef double RealT;

int main(int argc, char *argv[]) {

  Teuchos::GlobalMPISession mpiSession(&argc, &argv);

  // This little trick lets us print to std::cout only if a (dummy) command-line argument is provided.
  int iprint = argc - 1;
  Teuchos::RCP<std::ostream> outStream;
  Teuchos::oblackholestream bhs; // outputs nothing
  if (iprint > 0)
    outStream = Teuchos::rcp(&std::cout, false);
  else
    outStream = Teuchos::rcp(&bhs, false);

  int errorFlag  = 0;

  // *** Example body.

  try {
    // Initialize objective function.
    int dim = 2;
    ROL::Minimax2<RealT> obj;

    // Initialize iteration vectors.
    Teuchos::RCP<std::vector<RealT> > x_rcp = Teuchos::rcp( new std::vector<RealT> (dim, 0.0) );
    (*x_rcp)[0] = 1.0; (*x_rcp)[1] = -0.1;
    ROL::StdVector<RealT> x(x_rcp);
    Teuchos::RCP<std::vector<RealT> > z_rcp = Teuchos::rcp( new std::vector<RealT> (dim, 0.0) );
    (*z_rcp)[0] = 1.0; (*z_rcp)[1] = 1.0;
    ROL::StdVector<RealT> z(x_rcp);

    // Algorithmic input parameters.
    std::string filename = "input.xml";
    Teuchos::RCP<Teuchos::ParameterList> parlist = Teuchos::rcp( new Teuchos::ParameterList() );
    Teuchos::updateParametersFromXmlFile( filename, parlist.ptr() );
    std::string stepname = "Bundle";
    ROL::Algorithm<RealT> algo(stepname,*parlist);

    // Run algorithm.
    algo.run(x, obj, true, *outStream);

    // Compute error 
    Teuchos::RCP<ROL::Vector<RealT> > diff = x.clone();
    diff->set(x);
    diff->axpy(-1.0,z);
    RealT error = diff->norm();
    *outStream << "\nAbsolute Error: " << error << "\n";
    *outStream <<   "Relative Error: " << error/z.norm() << "\n";
    errorFlag = ((error > 1e2*std::sqrt(ROL::ROL_EPSILON<RealT>())) ? 1 : 0);
  }
  catch (std::logic_error err) {
    *outStream << err.what() << "\n";
    errorFlag = -1000;
  }; // end try

  if (errorFlag != 0)
    std::cout << "End Result: TEST FAILED\n";
  else
    std::cout << "End Result: TEST PASSED\n";

  return 0;

}

