// Copyright (c) 2013, Sandia Corporation.
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
// 
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//     * Redistributions in binary form must reproduce the above
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include <gtest/gtest.h>                // for AssertHelper, EXPECT_EQ, etc
#include <stddef.h>                     // for size_t
#include <unistd.h>                     // for unlink
#include <ostream>                      // for basic_ostream::operator<<
#include <stk_io/StkMeshIoBroker.hpp>   // for StkMeshIoBroker
#include <stk_mesh/base/Field.hpp>      // for Field
#include <stk_mesh/base/GetEntities.hpp>  // for get_entities
#include <stk_mesh/base/MetaData.hpp>   // for MetaData, put_field
#include <string>                       // for string
#include <vector>                       // for vector
#include "Ioss_DBUsage.h"               // for DatabaseUsage::READ_MODEL
#include "Ioss_Field.h"                 // for Field, etc
#include "Ioss_IOFactory.h"             // for IOFactory
#include "Ioss_NodeBlock.h"             // for NodeBlock
#include "Ioss_Property.h"              // for Property
#include "Ioss_Region.h"                // for Region, NodeBlockContainer
#include "stk_io/DatabasePurpose.hpp"   // for DatabasePurpose::READ_MESH, etc
#include "stk_mesh/base/Entity.hpp"     // for Entity
#include "stk_mesh/base/FieldBase.hpp"  // for field_data
#include "stk_topology/topology.hpp"    // for topology, etc
namespace Ioss { class DatabaseIO; }

namespace {

  TEST(StkMeshIoBrokerHowTo, replaceBulkData)
  {
    std::string mesh_name = "input_mesh_example.e";
    std::string results_name = "output.results";
    MPI_Comm communicator = MPI_COMM_WORLD;

    {
      // ============================================================
      //+ INITIALIZATION:
      //+ Create a basic mesh with a hex block, 3 shell blocks, 3 nodesets, and 3 sidesets.
      stk::io::StkMeshIoBroker stkIo(communicator);

      const std::string generatedFileName = "generated:8x8x8|shell:xyz|nodeset:xyz|sideset:XYZ";
      size_t index = stkIo.add_mesh_database(generatedFileName, stk::io::READ_MESH);
      stkIo.set_active_mesh(index);
      stkIo.create_input_mesh();
      stkIo.populate_bulk_data();

      size_t fh = stkIo.create_output_mesh(mesh_name, stk::io::WRITE_RESULTS);
      stkIo.write_output_mesh(fh);
    }

    {
      //-BEGIN
      // ============================================================
      //+ EXAMPLE: 
      //+ Read mesh data from the specified file.
      stk::io::StkMeshIoBroker stkIo(communicator);
      stkIo.add_mesh_database(mesh_name, stk::io::READ_MESH);

      //+ Creates meta data; creates parts 
      stkIo.create_input_mesh();

      //+ Declare a field
      //+ NOTE: Fields must be declared before "populate_bulk_data()" is called
      //+       since it commits the meta data.
      const std::string fieldName = "disp";
      stk::mesh::Field<double> &field = stkIo.meta_data().declare_field<stk::mesh::Field<double> >(stk::topology::NODE_RANK, fieldName, 1);
      stk::mesh::put_field(field, stkIo.meta_data().universal_part());

      //+ commit the meta data and create the bulk data.  
      //+ populate the bulk data with data from the mesh file.
      stkIo.populate_bulk_data();

      // ============================================================
      //+ Create a new bulk_data from the existing meta_data...
      //+ and replace the current bulk data with the new bulk data.
      //+ This is not a common operation and should be used only if you
      //+ know what you are doing.
      //+
      //+ Note that since we are not adding nodes and elements to the new
      //+ bulk data, there will be no nodes or elements on the output
      //+ mesh. It should have the same meta_data (element blocks, nodesets, ...)
      //+
      //+ A real use of this would require the client to populate the
      //+ bulk data with mesh entities.
      stk::ParallelMachine parallel = stkIo.bulk_data().parallel();

      stk::mesh::MetaData &md = stkIo.meta_data();
      md.set_mesh_bulk_data(nullptr);

      auto bd = new stk::mesh::BulkData(md, parallel);
      stkIo.replace_bulk_data(*bd);
      
      // ============================================================
      //+ Create results file. By default, all parts created from the input
      //+ mesh will be written to the results output file.
      size_t fh = stkIo.create_output_mesh(results_name, stk::io::WRITE_RESULTS);

      //+ The field will be output to the results file with the default field name.
      stkIo.add_field(fh, field); /*@\label{io:results:add_field}*/

      std::vector<stk::mesh::Entity> nodes;
      stk::mesh::get_entities(stkIo.bulk_data(), stk::topology::NODE_RANK, nodes);

      // Iterate the application's execute loop five times and output
      // field data each iteration.
      for (int step=0; step < 5; step++) {
	double time = step;

	//+ Output the field data calculated by the application.
	stkIo.begin_output_step(fh, time);
	stkIo.write_defined_output_fields(fh);
        stkIo.end_output_step(fh);
      }
      //-END      
    }
    // ============================================================
    //+ VERIFICATION
    {
      Ioss::DatabaseIO *resultsDb = Ioss::IOFactory::create("exodus", results_name,
							    Ioss::READ_MODEL, communicator);
      Ioss::Region results(resultsDb);
      // Should be 5 steps on database...
      EXPECT_EQ(results.get_property("state_count").get_int(), 5);
      // Should be 1 nodal field on database named "disp";
      Ioss::NodeBlock *nb = results.get_node_blocks()[0];
      EXPECT_EQ(1u, nb->field_count(Ioss::Field::TRANSIENT));
      EXPECT_TRUE(nb->field_exists("disp"));
      // Empty element blocks are not written, so even though
      // input mesh had 4 blocks, the output mesh will have 0.
      // Allowing the output of empty element blocks causes more
      // problems than it solves
      EXPECT_EQ(0u, results.get_element_blocks().size());
      EXPECT_EQ(3u, results.get_nodesets().size());
    }

    // ============================================================
    // Cleanup
    unlink(mesh_name.c_str());
    unlink(results_name.c_str());
  }
}
