/*!
  \file
  \author Wenqing Wang
  \date   2014.06
  \brief  Definition of mesh class for partitioned mesh (by node) for parallel
  computing within the framework of domain decomposition (DDC).

  \copyright
  Copyright (c) 2012-2021, OpenGeoSys Community (http://www.opengeosys.org)
             Distributed under a Modified BSD License.
               See accompanying file LICENSE.txt or
               http://www.opengeosys.org/project/license

*/

#pragma once

#include <algorithm>
#include <string>
#include <vector>

#include "Mesh.h"
#include "Node.h"

namespace MeshLib
{
/// A subdomain mesh.
class NodePartitionedMesh : public Mesh
{
public:
    // Copy a global mesh for the case of the thread number is one,
    // i.e the global mesh is not partitioned.
    // \param mesh The global mesh
    explicit NodePartitionedMesh(const Mesh& mesh)
        : Mesh(mesh),
          _global_node_ids(mesh.getNumberOfNodes()),
          _n_global_nodes(mesh.getNumberOfNodes()),
          _n_active_base_nodes(mesh.getNumberOfBaseNodes()),
          _n_active_nodes(mesh.getNumberOfNodes()),
          _is_single_thread(true)
    {
        for (std::size_t i = 0; i < _nodes.size(); i++)
        {
            _global_node_ids[i] = _nodes[i]->getID();
        }
    }

    /*!
        \brief Constructor
        \param name          Name assigned to the mesh.
        \param nodes         Vector for nodes, which storage looks like:
                             ||--active base nodes--|--ghost base nodes--|
                              --active extra nodes--|--ghost extra nodes--||
                             (extra nodes: nodes for high order interpolations)
        \param glb_node_ids  Global IDs of nodes of a partition.
        \param elements      Vector for elements. Ghost elements are stored
                             after regular (non-ghost) elements.
        \param properties    Mesh property.
        \param n_global_nodes      Number of all nodes of the global mesh.
        \param n_active_base_nodes Number of the active base nodes.
        \param n_active_nodes      Number of all active nodes.
    */
    NodePartitionedMesh(const std::string& name,
                        const std::vector<Node*>& nodes,
                        const std::vector<std::size_t>& glb_node_ids,
                        const std::vector<Element*>& elements,
                        Properties properties,
                        const std::size_t n_global_nodes,
                        const std::size_t n_active_base_nodes,
                        const std::size_t n_active_nodes)
        : Mesh(name, nodes, elements, properties),
          _global_node_ids(glb_node_ids),
          _n_global_nodes(n_global_nodes),
          _n_active_base_nodes(n_active_base_nodes),
          _n_active_nodes(n_active_nodes),
          _is_single_thread(false)
    {
    }

    /// Get the number of all nodes of the global mesh.
    std::size_t getNumberOfGlobalNodes() const { return _n_global_nodes; }
    /// Get the global node ID of a node with its local ID.
    std::size_t getGlobalNodeID(const std::size_t node_id) const
    {
        return _global_node_ids[node_id];
    }

    /// Get the number of the active nodes of the partition for linear elements.
    std::size_t getNumberOfActiveBaseNodes() const
    {
        return _n_active_base_nodes;
    }

    /// Get the number of all active nodes of the partition.
    std::size_t getNumberOfActiveNodes() const { return _n_active_nodes; }
    /// Check whether a node with ID of node_id is a ghost node
    bool isGhostNode(const std::size_t node_id) const
    {
        if (node_id < _n_active_base_nodes)
        {
            return false;
        }
        if (!isBaseNode(*_nodes[node_id],
                        getElementsConnectedToNode(node_id)) &&
            node_id < getLargestActiveNodeID())
        {
            return false;
        }
        return true;
    }

    /// Get the largest ID of active nodes for higher order elements in a
    /// partition.
    std::size_t getLargestActiveNodeID() const
    {
        return getNumberOfBaseNodes() + _n_active_nodes - _n_active_base_nodes;
    }

    // TODO I guess that is a simplified version of computeSparsityPattern()
    /// Get the maximum number of connected nodes to node.
    std::size_t getMaximumNConnectedNodesToNode() const
    {
        auto const& nodes_connections =
            MeshLib::calculateNodesConnectedByElements(*this);
        auto const max_connections = std::max_element(
            nodes_connections.cbegin(), nodes_connections.cend(),
            [](auto const& connections_node_a, auto const& connections_node_b) {
                return (connections_node_a.size() < connections_node_b.size());
            });
        // Return the number of connected nodes +1 for the node itself.
        return max_connections->size() + 1;
    }

    bool isForSingleThread() const { return _is_single_thread; }

private:
    /// Global IDs of nodes of a partition
    std::vector<std::size_t> _global_node_ids;

    /// Number of all nodes of the global mesh.
    std::size_t _n_global_nodes;

    /// Number of the active nodes for linear interpolations
    std::size_t _n_active_base_nodes;

    /// Number of the all active nodes.
    std::size_t _n_active_nodes;

    const bool _is_single_thread;
};

}  // namespace MeshLib