// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-FileCopyrightText: Copyright (c) Sandia Corporation
// SPDX-License-Identifier: BSD-3-Clause

#include "vtkDIMACSGraphReader.h"

#include "vtkCellData.h"
#include "vtkExecutive.h"
#include "vtkGraph.h"
#include "vtkIntArray.h"
#include "vtkMutableDirectedGraph.h"
#include "vtkMutableUndirectedGraph.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkSmartPointer.h"
#include "vtkStringArray.h"
#include "vtksys/SystemTools.hxx"

#include <fstream>
#include <iostream>
#include <sstream>
#include <vtksys/FStream.hxx>
using std::istringstream;

#define VTK_CREATE(type, name) vtkSmartPointer<type> name = vtkSmartPointer<type>::New()

VTK_ABI_NAMESPACE_BEGIN
typedef enum problemTypes
{
  GENERIC,
  COLORING,
  MAXFLOW
} problemTypes;

vtkStandardNewMacro(vtkDIMACSGraphReader);

vtkDIMACSGraphReader::vtkDIMACSGraphReader()
{
  // Default values for the origin vertex
  this->FileName = nullptr;
  this->SetNumberOfInputPorts(0);
  this->VertexAttributeArrayName = nullptr;
  this->EdgeAttributeArrayName = nullptr;
  this->Directed = false;
  this->fileOk = false;
  this->numVerts = 0;
  this->numEdges = 0;
}

vtkDIMACSGraphReader::~vtkDIMACSGraphReader()
{
  this->SetFileName(nullptr);
  this->SetVertexAttributeArrayName(nullptr);
  this->SetEdgeAttributeArrayName(nullptr);
}

void vtkDIMACSGraphReader::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);

  os << indent << "FileName: " << (this->FileName ? this->FileName : "(none)") << endl;
  os << indent << "Vertex Attribute Array Name: "
     << (this->VertexAttributeArrayName ? this->VertexAttributeArrayName : "color") << endl;
  os << indent << "Edge Attribute Array Name  : "
     << (this->EdgeAttributeArrayName ? this->EdgeAttributeArrayName : "color") << endl;
}

// ============================================================================
// Generic DIMACS file format, which covers many 'DIMACS' style input files.
// This is the default reader if we don't have a special case file.
// * Graphs are undirected.
// * node lines (optional) have a weight value and are formatted as:
//         n id wt
//   Though, technically, some DIMACS formats (i.e., shortest paths) don't
//   specify node-attributes, we'll include them for the generic reader
//   for maximum compatibility.
// * edges, u->v, are formatted as:
//         a u v wt
//   alternatively, edges can also be:
//         e u v wt
int vtkDIMACSGraphReader::buildGenericGraph(vtkGraph* output,
  vtkStdString& defaultVertexAttrArrayName, vtkStdString& defaultEdgeAttrArrayName)
{
  std::string S;
  int iEdgeU, iEdgeV, iVertexID;
  int currentEdgeId = 0;

  VTK_CREATE(vtkMutableUndirectedGraph, builder);
  VTK_CREATE(vtkIntArray, ArrayVertexAttributes);
  VTK_CREATE(vtkIntArray, ArrayEdgeAttributes);

  VTK_CREATE(vtkIntArray, vertexPedigreeIds);
  VTK_CREATE(vtkIntArray, edgePedigreeIds);

  // Set up vertex attribute array for vertex-weights.
  if (this->VertexAttributeArrayName)
  {
    ArrayVertexAttributes->SetName(this->VertexAttributeArrayName);
  }
  else
  {
    ArrayVertexAttributes->SetName(defaultVertexAttrArrayName.c_str());
  }
  ArrayVertexAttributes->SetNumberOfTuples(this->numVerts);

  // Set up Edge attribute array for edge-weights.
  if (this->EdgeAttributeArrayName)
  {
    ArrayEdgeAttributes->SetName(this->EdgeAttributeArrayName);
  }
  else
  {
    ArrayEdgeAttributes->SetName(defaultEdgeAttrArrayName.c_str());
  }
  ArrayEdgeAttributes->SetNumberOfTuples(this->numEdges);

  // Set up Pedigree-IDs arrays.
  vertexPedigreeIds->SetName("vertex id");
  vertexPedigreeIds->SetNumberOfTuples(this->numVerts);
  edgePedigreeIds->SetName("edge id");
  edgePedigreeIds->SetNumberOfTuples(this->numEdges);

  // Allocate Vertices in the graph builder
  for (int i = 0; i < this->numVerts; i++)
  {
    builder->AddVertex();
    vertexPedigreeIds->SetValue(i, i + 1);
  }

  // set starting edge id number.
  int baseEdgeId = 1;

  vtksys::ifstream IFP(this->FileName);
  if (IFP.is_open())
  {
    while (vtksys::SystemTools::GetLineFromStream(IFP, S))
    {
      int value;
      istringstream iss(S);
      char lineType;
      iss >> lineType;
      switch (lineType)
      {
        case 'n': /* vertex (node) definition */
          iss >> iVertexID >> value;
          ArrayVertexAttributes->SetValue(iVertexID - 1, value);
          vertexPedigreeIds->SetValue(iVertexID - 1, iVertexID);
          break;
        case 'a': /* edge arc */
        case 'e':
        {
          iss >> iEdgeU >> iEdgeV >> value;

          if (iEdgeU == 0 || iEdgeV == 0)
          {
            vtkErrorMacro(<< "DIMACS graph vertices are numbered 1..n; 0 is not allowed");
            return 0;
          }

          vtkEdgeType edgeObj = builder->AddEdge(iEdgeU - 1, iEdgeV - 1);
          ArrayEdgeAttributes->SetValue(edgeObj.Id, value);
          edgePedigreeIds->SetValue(currentEdgeId, currentEdgeId + baseEdgeId);
          currentEdgeId++;
        }
        break;
        case 'c': /* Comment line, ignore it! */
          break;
        default:
          break;
      }
    }
  }

  // Add the pedigree ids to the graph
  builder->GetVertexData()->SetPedigreeIds(vertexPedigreeIds);
  builder->GetEdgeData()->SetPedigreeIds(edgePedigreeIds);

  // Add the attribute arrays to the graph
  builder->GetVertexData()->AddArray(ArrayVertexAttributes);
  builder->GetEdgeData()->AddArray(ArrayEdgeAttributes);

  if (!output->CheckedShallowCopy(builder))
  {
    vtkErrorMacro(<< "Invalid graph structure");
    return 0;
  }
  return 1;
}

// ============================================================================
// Build a graph from a max-flow problem.
// * These are directed.
// * These should have TWO node descriptor lines of the format:
//         n  ID  <char>
//   where <char> is either an 's' or a 't', for the source and sink,
//   respectively.
// * Format of edge lines is:
//         a u v cap
//   to create an edge u->v, and cap gives the edge capacity.
int vtkDIMACSGraphReader::buildMaxflowGraph(vtkGraph* output)
{
  std::string S;
  int iEdgeU, iEdgeV, iVertexID;
  int currentEdgeId = 0;
  int numSrcs = 0;
  int numSinks = 0;

  std::string sAttribute;
  VTK_CREATE(vtkMutableDirectedGraph, builder);

  VTK_CREATE(vtkIntArray, vertexSourceArray);
  VTK_CREATE(vtkIntArray, vertexSinkArray);
  VTK_CREATE(vtkIntArray, edgeCapacityArray);

  VTK_CREATE(vtkIntArray, vertexPedigreeIds);
  VTK_CREATE(vtkIntArray, edgePedigreeIds);

  vertexSourceArray->SetName("sources");
  vertexSinkArray->SetName("sinks");
  edgeCapacityArray->SetName("capacity");

  vertexSourceArray->SetNumberOfTuples(this->numVerts);
  vertexSinkArray->SetNumberOfTuples(this->numVerts);
  edgeCapacityArray->SetNumberOfTuples(this->numEdges);

  for (int i = 0; i < this->numVerts; i++)
  {
    vertexSourceArray->SetValue(i, 0);
    vertexSinkArray->SetValue(i, 0);
  }

  for (int i = 0; i < this->numEdges; i++)
  {
    edgeCapacityArray->SetValue(i, 0);
  }

  // Set up Pedigree-IDs arrays.
  vertexPedigreeIds->SetName("vertex id");
  vertexPedigreeIds->SetNumberOfTuples(this->numVerts);
  edgePedigreeIds->SetName("edge id");
  edgePedigreeIds->SetNumberOfTuples(this->numEdges);

  // Allocate Vertices in the graph builder
  for (int i = 0; i < this->numVerts; i++)
  {
    builder->AddVertex();
    vertexPedigreeIds->SetValue(i, i + 1);
  }

  // set starting edge id number.
  int baseEdgeId = 1;

  vtksys::ifstream IFP(this->FileName);
  if (IFP.is_open())
  {
    while (vtksys::SystemTools::GetLineFromStream(IFP, S))
    {
      istringstream iss(S);
      char lineType;
      iss >> lineType;
      switch (lineType)
      {
        case 'n': /* vertex (node) definition */
          iss >> iVertexID >> sAttribute;
          vertexPedigreeIds->SetValue(iVertexID - 1, iVertexID);

          if (sAttribute == "s" && numSrcs == 0)
          {
            numSrcs++;
            vertexSourceArray->SetValue(iVertexID - 1, 1);
          }
          else if (sAttribute == "t" && numSinks == 0)
          {
            numSinks++;
            vertexSinkArray->SetValue(iVertexID - 1, 1);
          }
          else
          {
            vtkWarningMacro(<< "In DIMACS Max-Flow file: " << this->FileName
                            << "  multiple sources or sinks specified!" << endl
                            << "  Ignoring all but first source/sink found.");
          }
          break;
        case 'a': /* edge arc */
        {
          int edgeCapacity;
          iss >> iEdgeU >> iEdgeV >> edgeCapacity;

          if (iEdgeU == 0 || iEdgeV == 0)
          {
            vtkErrorMacro(<< "DIMACS graph vertices are numbered 1..n; 0 is not allowed");
            return 0;
          }

          vtkEdgeType edgeObj = builder->AddEdge(iEdgeU - 1, iEdgeV - 1);
          edgeCapacityArray->SetValue(edgeObj.Id, edgeCapacity);
          edgePedigreeIds->SetValue(currentEdgeId, currentEdgeId + baseEdgeId);
          currentEdgeId++;
        }
        break;
        case 'c': /* Comment line, ignore it! */
          break;
        default:
          break;
      }
    }
  }

  // Add the pedigree ids to the graph
  builder->GetVertexData()->SetPedigreeIds(vertexPedigreeIds);
  builder->GetEdgeData()->SetPedigreeIds(edgePedigreeIds);

  // Add the attribute arrays to the graph
  builder->GetVertexData()->AddArray(vertexSourceArray);
  builder->GetVertexData()->AddArray(vertexSinkArray);
  builder->GetEdgeData()->AddArray(edgeCapacityArray);

  if (!output->CheckedShallowCopy(builder))
  {
    vtkErrorMacro(<< "Invalid graph structure");
    return 0;
  }
  return 1;
}

// ============================================================================
// Builder method for creating coloring problem graphs.
// * These are undirected.
// * nodes and edges have no weights associated with them.
// * edges (u->v) are formatted as:
//         e u v
int vtkDIMACSGraphReader::buildColoringGraph(vtkGraph* output)
{
  std::string S;
  int iEdgeU, iEdgeV;
  int currentEdgeId = 0;

  VTK_CREATE(vtkMutableUndirectedGraph, builder);
  VTK_CREATE(vtkIntArray, vertexPedigreeIds);
  VTK_CREATE(vtkIntArray, edgePedigreeIds);

  // Set up Pedigree-IDs arrays.
  vertexPedigreeIds->SetName("vertex id");
  vertexPedigreeIds->SetNumberOfTuples(this->numVerts);
  edgePedigreeIds->SetName("edge id");
  edgePedigreeIds->SetNumberOfTuples(this->numEdges);

  // Allocate Vertices in the graph builder
  for (int i = 0; i < this->numVerts; i++)
  {
    builder->AddVertex();
    vertexPedigreeIds->SetValue(i, i + 1);
  }

  // set starting edge id number.
  int baseEdgeId = 1;

  vtksys::ifstream IFP(this->FileName);
  if (IFP.is_open())
  {
    while (vtksys::SystemTools::GetLineFromStream(IFP, S))
    {
      istringstream iss(S);
      char lineType;
      iss >> lineType;
      switch (lineType)
      {
        case 'e': /* edge arc */
        {
          iss >> iEdgeU >> iEdgeV;

          if (iEdgeU == 0 || iEdgeV == 0)
          {
            vtkErrorMacro(<< "DIMACS graph vertices are numbered 1..n; 0 is not allowed");
            return 0;
          }

          builder->AddEdge(iEdgeU - 1, iEdgeV - 1);
          edgePedigreeIds->SetValue(currentEdgeId, currentEdgeId + baseEdgeId);
          currentEdgeId++;
        }
        break;
        default:
          break;
      }
    }
  }

  // Add the pedigree ids to the graph
  builder->GetVertexData()->SetPedigreeIds(vertexPedigreeIds);
  builder->GetEdgeData()->SetPedigreeIds(edgePedigreeIds);

  if (!output->CheckedShallowCopy(builder))
  {
    vtkErrorMacro(<< "Invalid graph structure");
    return 0;
  }

  return 1;
}

// ============================================================================
// Searches for the problem line in a dimacs graph (starts with 'p')
// and gets the problem type and the number of vertices and edges.
// Sets the directedness of the graph as well based on what the problem
// definition is (i.e, max-flow problems are directed, but coloring is not).
int vtkDIMACSGraphReader::ReadGraphMetaData()
{
  if (this->FileName == nullptr)
  {
    vtkErrorMacro("File name undefined");
    return 0;
  }

  vtksys::ifstream IFP(this->FileName);
  if (!IFP.is_open())
  {
    vtkErrorMacro("Could not open file " << this->FileName << ".");
    return (0);
  }
  std::string S;
  bool foundProblemLine = false;
  bool foundMultipleProblemLines = false;

  // Look at lines until we find the problem line (this should always
  // be one of the first lines in a DIMACS graph)
  while (!foundProblemLine && vtksys::SystemTools::GetLineFromStream(IFP, S))
  {
    istringstream iss(S);
    char lineType;
    iss >> lineType;
    switch (lineType)
    {
      case 'p':
        if (!foundProblemLine)
        {
          foundProblemLine = true;
          iss >> this->dimacsProblemStr >> this->numVerts >> this->numEdges;
        }
        else
        {
          foundMultipleProblemLines = true;
        }
    }
  }
  IFP.close();

  if (!foundProblemLine)
  {
    vtkErrorMacro(<< "Error in DIMACS file: " << this->FileName
                  << ", could not find a problem description line.");
    return 0;
  }

  if (foundMultipleProblemLines)
  {
    vtkWarningMacro(<< "Found multiple problem lines in DIMACS file: " << this->FileName
                    << "; using the first one found.");
  }

  // Set directed if necessary
  if (this->dimacsProblemStr == "max")
  {
    this->Directed = true;
  }

  this->fileOk = true;

  return 1;
}

// ============================================================================
int vtkDIMACSGraphReader::RequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** vtkNotUsed(inputVector), vtkInformationVector* outputVector)
{
  int rval = 0;
  if (!this->fileOk)
  {
    return 0;
  }

  vtkGraph* output = vtkGraph::GetData(outputVector);

  if (this->dimacsProblemStr == "edge")
  {
    vtkDebugMacro("Loading DIMACS coloring problem graph.");
    rval = buildColoringGraph(output);
  }
  else if (this->dimacsProblemStr == "max")
  {
    vtkDebugMacro("Loading DIMACS max-flow problem graph.");
    rval = buildMaxflowGraph(output);
  }
  else
  {
    vtkDebugMacro("Loading DIMACS default graph.");
    vtkStdString vWeightName = "weight";
    vtkStdString eWeightName = "weight";
    rval = buildGenericGraph(output, vWeightName, eWeightName);
  }
  return rval;
}

//------------------------------------------------------------------------------
int vtkDIMACSGraphReader::RequestDataObject(
  vtkInformation*, vtkInformationVector**, vtkInformationVector*)
{
  ReadGraphMetaData();

  vtkDataObject* current = this->GetExecutive()->GetOutputData(0);
  if (!current || (this->Directed && !vtkDirectedGraph::SafeDownCast(current)) ||
    (!this->Directed && vtkDirectedGraph::SafeDownCast(current)))
  {
    vtkGraph* output = nullptr;
    if (this->Directed)
    {
      output = vtkDirectedGraph::New();
    }
    else
    {
      output = vtkUndirectedGraph::New();
    }
    this->GetExecutive()->SetOutputData(0, output);
    output->Delete();
  }
  return 1;
}
VTK_ABI_NAMESPACE_END