// Compile with:
//    mkoctfile --link-stand-alone embedded.cc -o embedded

#include <iostream>
#include <octave/oct.h>
#include <octave/octave.h>
#include <octave/parse.h>
#include <octave/interpreter.h>

int
run_some_octave_code_with_output ()
{
  octave::interpreter interpreter;
  int status = -1;

  try
    {
      status = interpreter.execute ();

      if (status != 0)
        {
          std::cerr << "creating embedded Octave interpreter failed!"
                    << std::endl;
          return status;
        }

      octave_idx_type n = 2;
      octave_value_list in;

      for (octave_idx_type i = 0; i < n; i++)
        in(i) = octave_value (5 * (i + 2));

      octave_value_list out = octave::feval ("gcd", in, 1);

      if (out.length () > 0)
        std::cout << "GCD of ["
                  << in(0).int_value ()
                  << ", "
                  << in(1).int_value ()
                  << "] is " << out(0).int_value ()
                  << std::endl;
      else
        std::cout << "invalid\n";

      // Bad function call
      octave_value_list bad_in;
      octave::feval ("gcd", bad_in, 1);
    }
  catch (const octave::exit_exception& ex)
    {
      std::cerr << "Octave interpreter exited with status = "
                << ex.exit_status () << std::endl;
    }
  catch (const octave::execution_exception&)
    {
      std::cerr << "error encountered in Octave evaluator!" << std::endl;
    }
  return status;
}

int
main (void)
{
  // see https://stackoverflow.com/questions/5419356/redirect-stdout-stderr-to-a-string
  // and https://en.cppreference.com/w/cpp/io/basic_ios/rdbuf
  std::stringstream buffer_cout;
  std::stringstream buffer_cerr;

  // remember old buffers
  auto old_cout = std::cout.rdbuf();
  auto old_cerr = std::cerr.rdbuf();

  // set our buffers
  std::cout.rdbuf(buffer_cout.rdbuf());
  std::cerr.rdbuf(buffer_cerr.rdbuf());

  int status = run_some_octave_code_with_output ();

  // restore usual cout and cerr
  std::cout.rdbuf(old_cout);
  std::cerr.rdbuf(old_cerr);

  // grab buffer contents
  std::string text_cout = buffer_cout.str();
  std::string text_cerr = buffer_cerr.str();

  std::cout << std::endl << std::endl << "My message first"
            << std::endl              << "----------------"
            << std::endl << std::endl;

  std::cout << "COUT $$$$ " << text_cout << std::endl << std::endl;
  std::cout << "CERR $$$$ " << text_cerr << std::endl << std::endl;

  return status;
}