// Copyright (C) 2005, 2006 Douglas Gregor.

// Use, modification and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

// A test of the gather() and gatherv() collectives.
#include <boost/mpi/collectives/gather.hpp>
#include <boost/mpi/collectives/gatherv.hpp>
#include <boost/mpi/communicator.hpp>
#include <boost/mpi/environment.hpp>
#include "gps_position.hpp"
#include <boost/serialization/string.hpp>
#include <boost/serialization/list.hpp>
#include <boost/iterator/counting_iterator.hpp>
#include <boost/lexical_cast.hpp>

#define BOOST_TEST_MODULE mpi_gather
#include <boost/test/included/unit_test.hpp>

using boost::mpi::communicator;

template<typename Generator>
void
gather_test(const communicator& comm, Generator generator,
            const char* kind, int root = -1)
{
  typedef typename Generator::result_type value_type;
  value_type value = generator(comm.rank());

  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      gather_test(comm, generator, kind, root);
  } else {
    using boost::mpi::gather;

    std::vector<value_type> values;
    if (comm.rank() == root) {
      std::cout << "Gathering " << kind << " from root "
                << root << "..." << std::endl;
    }

    gather(comm, value, values, root);

    if (comm.rank() == root) {
      std::vector<value_type> expected_values;
      for (int p = 0; p < comm.size(); ++p)
        expected_values.push_back(generator(p));
      BOOST_CHECK(values == expected_values);
    } else {
      BOOST_CHECK(values.empty());
    }
  }

  (comm.barrier)();
}


template<typename Generator>
void
gatherv_test(const communicator& comm, Generator generator,
             const char* kind, int root = -1)
{
  typedef typename Generator::result_type value_type;

  if (root == -1) {
    for (root = 0; root < comm.size(); ++root)
      gatherv_test(comm, generator, kind, root);
  } else {
    using boost::mpi::gatherv;

    int mysize = comm.rank() + 1;
    int nprocs = comm.size();

    // process p will send p+1 identical generator(p) elements
    std::vector<value_type> myvalues(mysize, generator(comm.rank()));

    if (comm.rank() == root) {
      std::vector<value_type> values((nprocs*(nprocs+1))/2);
      std::vector<int> sizes(comm.size());
      for (int p = 0; p < comm.size(); ++p)
        sizes[p] = p + 1;

      std::cout << "Gatheringv " << kind << " from root "
                << root << "..." << std::endl;

      gatherv(comm, myvalues, &values[0], sizes, root);

      std::vector<value_type> expected_values;
      for (int p = 0; p < comm.size(); ++p)
        for (int i = 0; i < p+1; ++i)
          expected_values.push_back(generator(p));

      BOOST_CHECK(values == expected_values);
    } else {
      gatherv(comm, myvalues, root);
    }
  }

  (comm.barrier)();
}

//
// Generators to test with gather/gatherv
//
struct int_generator
{
  typedef int result_type;

  int operator()(int p) const { return 17 + p; }
};

struct gps_generator
{
  typedef gps_position result_type;

  gps_position operator()(int p) const
  {
    return gps_position(39 + p, 16, 20.2799);
  }
};

struct string_generator
{
  typedef std::string result_type;

  std::string operator()(int p) const
  {
    std::string result = boost::lexical_cast<std::string>(p);
    result += " rosebud";
    if (p != 1) result += 's';
    return result;
  }
};

struct string_list_generator
{
  typedef std::list<std::string> result_type;

  std::list<std::string> operator()(int p) const
  {
    std::list<std::string> result;
    for (int i = 0; i <= p; ++i) {
      std::string value = boost::lexical_cast<std::string>(i);
      result.push_back(value);
    }
    return result;
  }
};

BOOST_AUTO_TEST_CASE(gather_check)
{
  boost::mpi::environment env;
  communicator comm;

  gather_test(comm, int_generator(), "integers");
  gather_test(comm, gps_generator(), "GPS positions");
  gather_test(comm, string_generator(), "string");
  gather_test(comm, string_list_generator(), "list of strings");

  gatherv_test(comm, int_generator(), "integers");
  gatherv_test(comm, gps_generator(), "GPS positions");
  gatherv_test(comm, string_generator(), "string");
  gatherv_test(comm, string_list_generator(), "list of strings");
}